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  • Understanding the Charge Carrier Dynamics of Metal@TiO 2 Core–Shell Nanorods in Photocatalytic Hydrogen Generation
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-20
    Na Zhou, Ruiyao Yan, Yanlin Pan, Xue-Qian Fang

    Abstract The fast recombination of photogenerated electrons and holes in the pure TiO2 leads to a low photocatalytic efficiency in hydrogen generation or solar energy conversion. Noble metal nanoparticles have been used to combine with TiO2 for effective photocatalysis. Herein, Au@Ag@TiO2 nanorods (NRs) with core–shell structure have been prepared by hydrolysis the precursor of titanium in acid environment. UV light–driven H2 generation rate of Au@Ag@TiO2 samples demonstrated 14 times enhancement compared to P25 TiO2 at the same experimental conditions. The improved photocatalytic performance was due to the charge transfer from the conduction band of excited TiO2 to Au@Ag NRs leading to effective separation of electron–hole pairs. This mechanism has been proved by transient absorption spectroscopy and photo-electrochemical (PEC) measurements. The time resolved photocurrents of P25 TiO2 NPs is ~ 13 times higher that of Au@Ag@TiO2, indicating that a fraction of the photogenerated electrons of TiO2 driven by UV light transfer to Au@Ag nanocores instead of transporting entirely to the ITO substrates. The ultrafast transient absorption and pump-probe measurements demonstrated a faster decay in Au@Ag@TiO2 NRs compared to pure TiO2 system, indicating that the photogenerated electron–hole recombination in TiO2 is substantially suppressed by Au@Ag@TiO2 NRs attributed to the effective trapping of the photogenerated electrons by the Au@Ag cores. Graphic Abstract Au@Ag@TiO2 nanocomposites with core-shell structure have been prepared and its UV light–driven H2 generation rate has been demonstrated 14 times enhancement compared to P25 TiO2 at the same experimental conditions. The improved photocatalytic performance was due to the charge transfer, which has been proved by photocurrent measurement and the ultrafast transient absorption and pump-probe measurements.

    更新日期:2020-01-21
  • Cu-Catalyzed Oxidative-Reaction of Tosylmethylisocyanide and Benzyl Alcohols: Efficient Synthesis of 4-( tert- butylperoxy)-5-aryloxazol-2(3 H )-ones and 5-Aryloxazol-2(5 H )-ones
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-20
    Heshmatollah Sepahvand, Ayoob Bazgir, Ahmad Shaabani

    Abstract Herein, a novel copper-catalyzed reaction of tosylmethylisocyanide (TosMIC) with benzyl alcohols has been developed using tert-butyl hydroperoxide (TBHP) for the first time. The reaction involves the in-situ oxidation of benzyl alcohol to corresponding benzaldehyde, followed by sequential formal [3+2] cycloaddition/radical addition/ring oxidation reactions, and provides an efficient method for the construction of 4-(tert-butylperoxy)-5-aryloxazol-2(3H)-ones from readily available starting materials. Replacement of TBHP with H2O2 led to the production of 5-aryloxazol-2(5H)-ones in good yields. Graphic Abstract Tandem oxidative Van Leusen reaction: efficient three-component approach for the synthesis of 4-(tert-butylperoxy)-5-aryloxazol-2(3H)-ones and 5-phenyloxazol-2(5H)-one for the first time.

    更新日期:2020-01-21
  • Insight into Deactivation Reasons for Nanogold Catalysts Used in Gas-Phase Epoxidation of Propylene
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-17
    Zhishan Li, Weihua Ma, Qin Zhong

    Gas-phase epoxidation of propylene over nanogold catalysts has attracted extensive attention in recent years. Among the Au/Ti-based catalysts, Au/titanium silicalite-1 (denoted as Au/TS-1) shows excellent activity of PO generation. However, Au/TS-1 is reported to suffer from rapid deactivation. To prolong its lifetime, the main deactivation reason was investigated. In this work, Au/TS-1 and Au/TS-1 coated with silicalite-1 (denoted as Au/TS-1@S-1) were prepared. Compared to the traditional Au/TS-1, Au/TS-1@S-1 exhibits better catalytic stability during the same reaction time. This is most likely due to the confinement effect of TS-1@S-1 channels on Au clusters. Multiple types of characterization further confirm that the deactivation of Au/TS-1 is mainly caused by the agglomeration of Au clusters. Moreover, higher reaction temperature as well as longer reaction time results in greater Au particles and the gradual catalyst deactivation.

    更新日期:2020-01-17
  • Cobalt Phosphate Cocatalyst Loaded-CdS Nanorod Photoanode with Well-Defined Junctions for Highly Efficient Photoelectrochemical Water Splitting
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-17
    Zhimin Song, Xiaodi Zhu, Yusheng Zeng, Azhu Wang, Shikuo Li, Yi Fan, Mengdie Cai, Qin Cheng, Yuxue Wei, Song Sun

    Abstract Cocatalysts play important roles in photocatalytic and photoelectrochemical water splitting reactions. However, the formation of well-defined junctions between low dimensional semiconductors and cocatalysts is still challenging. In this study, CdS nanorod photoanodes loaded with cobalt phosphate (CoPi) cocatalyst were synthesized by a facile two-step route, in which CdS nanorods were prepared using a hydrothermal method followed by photo-assisted electrodeposition of CoPi. It was found that the formation of intimate junctions between CoPi and CdS nanorods in the form of Co–S bonding effectively facilitated the charge separation and lowered the activation energy of the water oxidation reaction. This resulted in highly efficient and stable photoelectrochemical water splitting on the CdS photoanode. The optimal CdS/CoPi photoanode showed a maximum photocurrent of 4.7 mA/cm2 at 0 V versus reversible hydrogen electrode under an AM 1.5 G solar simulator, which was 5.5-fold higher than that of bare CdS photoanode. This work expands the potential application of the cocatalyst CoPi in CdS photoanode systems and improves our understanding of the nature of cocatalysts with well-defined interface junctions in semiconductors. Graphic Abstract Well-defined interfacial junction with Co–S bonding over cobalt phosphate cocatalyzed CdS nanorod photoanode facilitates the charge separation and lowers the activation energy, thus achieving a considerable photocurrent of 4.7 mA/cm2 at 0 V vs. RHE.

    更新日期:2020-01-17
  • Tuning the Basic Properties of ZnAl Hydrotalcites Modified with Ce Applied to Transesterification of Soybean Oil
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-17
    Denis A. Cabrera-Munguia, Horacio González, Mónica Barreto-Gutiérrez, Aída Gutiérrez-Alejandre, José L. Rico, Dora A. Solís-Casados

    Abstract The basicity of ZnAl hydrotalcite type materials was modified through the incorporation of Ce into their structure and used as heterogeneous catalysts in the transesterification of soybean oil. A series of novel ZnAl–Ce(X) catalysts was synthesized by the co-precipitation method varying the loading of Ce (X = Ce/Al molar ratio). The larger ionic radius of Ce3+ (1.01 Å) compared with Al3+ (0.53 Å) and Zn2+ (0.72 Å), hinders the appropriate incorporation of Ce3+ in the brucite-like structure, causing a small segregation of Ce3+ as CeO2. However, the concentration of basic sites (acid–basic Lewis pairs) and specific surface area of the ZnAl–Ce(0.0) sample were enhanced with the incorporation of Ce, improving its catalytic activity. The most appropriate Ce loading was obtained with a Ce/Al molar ratio of 0.03, which was attributed to its large surface area, along with a higher amount of acid–basic Lewis pairs related to the presence of aluminum in pentahedral coordination. Thus, the total amount of basic sites (−OH and M–O−) of ZnAl–Ce(0.03) was triplicated, leading to a FAME yield of 80% with this catalyst, which represents an increase of 11.3% when compared with the ZnAl hydrotalcite without Ce. Graphic Abstract

    更新日期:2020-01-17
  • Adsorption of CH 4 and SO 2 on Unsupported Pd 1−x M x O(101) Surface
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-14
    Ryan Lacdao Arevalo, Susan Meñez Aspera, Roland Emerito Otadoy, Hiroshi Nakanishi, Hideaki Kasai

    PdO is known to efficiently catalyze the oxidation of methane but suffers tremendously from sulfur poisoning that lowers its catalytic activity. In this paper, dispersion-corrected density functional theory based first principles calculations were performed to systematically screen the metal impurities M (where M is a transition metal) on a Pd1−xMxO catalyst that promote the desired adsorption energies for CH4 and SO2 to gain insights into the design of sulfation-resistant PdO-based methane oxidation catalysts. Specific Pd1−xMxO(101) catalyst was identified to thermodynamically avoid surface sulfation while maintaining the active sites for methane activation at typical experimental conditions. Results indicate a potential route of tuning the catalytic property of PdO by the introduction of a surface metal impurity.

    更新日期:2020-01-14
  • Deactivation of Co-Al 2 O 3 /SiO 2 Fischer–Trospch Synthesis Catalyst in Industrially Relevant Conditions
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-11
    Alexander P. Savost’yanov, Oleg L. Eliseev, Roman E. Yakovenko, Grigoriy B. Narochniy, Konstantin I. Maslakov, Ivan Zubkov, Vitaliy N. Soromotin, Alexey T. Kozakov, Anatolii V. Nicolskii, Serge A. Mitchenko

    The deactivation rate of Co-Al2O3/SiO2 Fischer–Tropsch synthesis catalyst have been experimentally assessed at industrially relevant conditions (T 198–237 °C, P = 60 bar, H2/CO = 1.85, GHSV 2000–7000 h–1). The fresh and spent catalyst was characterized by XRD, XPS, BET, TEM, and SEM–EDX techniques. Decreasing active surface area due to cobalt oxidation by product water and sintering of cobalt crystallites were found to be minor factors for the deactivation. The principal reason of activity loss seems is diffusion limitations arising due to catalyst pores plugging by product wax. The linear dependence between gas flow rate and estimated catalyst lifetime was revealed. High GHSV of fresh synthesis gas and/or high circulation ratio of product gas should be employed to prevent rapid loss of catalyst activity.

    更新日期:2020-01-13
  • Recent Advances on the Use of Nickel Nano Layered Double Hydroxides as Green, and Efficient, Catalysts for Water Splitting
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-11
    Daniel Likius, Ateeq Rahman, Chiguvare Zivayi, Veikko Uahengo

    Abstract This review focusses on the recent developments in designing Layered Double Hydroxides (LDHs) with conductive, interlayer anion replacement, for efficient hydrogen fuel production by water splitting through Oxygen Evolution Reactions (OER) and Hydrogen Evolution Reactions (HER). Nickel nano structured catalysts improves OER performance are highlighted in detail in terms of compositional differences between transitional metal components, and challenges in future designing of rationalized Ni and Ni nano LDHs. The layered structure has exceptional flexibility of incorporating mixed valence transition metal ions into the LDHs structure in different compositions and this opens the massive potential to design high-performance LDHs catalysts on the molecular and nanometer scales. LDHs such as NiCoFe LDHs, Ni foam, Co Ni nano spheres, RuO2, Ir(dppe)2Cl, NiS2, Ni–N–Co-doped carbon nano fibers, NiCoSe2/cHRD are attracting increasing interest in the field of water splitting into hydrogen and oxygen due to their unique physicochemical properties. The highlighted summary will provide useful information in the development of novel Ni LDHs catalysts, which enables better understanding of OER properties valuable to address key issues. Increased fundamental understanding of water splitting catalysts would allow for rationally-directed improvements. Graphic Abstract

    更新日期:2020-01-13
  • Cerium–Copper–Manganese Oxides Synthesized via Solution Combustion Synthesis (SCS) for Total Oxidation of VOCs
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-09
    Miguel Jose Marin Figueredo, Tahrizi Andana, Samir Bensaid, Melodj Dosa, Debora Fino, Nunzio Russo, Marco Piumetti

    Abstract A set of cerium–manganese–copper oxide catalysts with various foreign metal contents was prepared via the solution combustion synthesis (SCS). The catalysts were characterized by complementary techniques such as N2 physisorption at − 196 °C, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), H2-temperature-programmed reduction (H2-TPR), O2-temperature-programmed desorption (O2-TPD) and X-ray photoelectron spectroscopy (XPS). Their catalytic activity was tested towards the VOC oxidation using ethylene and propylene as probe molecules. As a whole, it has been observed that the Ce55Mn45 sample (Mn 45 at.%), containing MnOx clusters interacting with the ceria phase, was the most active catalyst for propylene oxidation, exhibiting a complete conversion at 250 °C. On the other hand, the ternary oxide catalyst (Ce55Mn22.5Cu22.5 with Mn = 22.5 at.% and Cu = 22.5 at.%) has exhibited the best results for the oxidation of ethylene. These findings suggest that the co-presence of different active phases on the catalytic surface may have a beneficial (multiplicative) role on the whole reactivity. Finally, the most active powder catalysts were wash-coated in a SiC monolith and tested in a bench-scale reactor. As a whole, the catalyzed monoliths performed the complete oxidation of either ethylene or propylene at lower temperatures (550 and 450 °C, respectively) than those required to thermally decompose these molecules. Graphic Abstract

    更新日期:2020-01-11
  • Core–Shell HZSM-5@silicalite-1 Composite: Controllable Synthesis and Catalytic Performance in Alkylation of Toluene with Methanol
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-09
    Guixian Li, Chao Wu, Peng Dong, Dong Ji, Yongfu Zhang

    Abstract HZSM-5@silicalite-1 catalysts were prepared by the hydrothermal method, and the structure, morphology, acidity and pore texture of core–shell catalysts were studied by XRD, SEM, TEM, NH3-TPD, Py-IR and N2 adsorption/desorption isotherms in detail. Their catalytic performances were tested in the alkylation reaction of toluene with methanol. The results showed that a coating layer was formed in the form of silicalite-1 on HZSM-5. NH3-TPD measurements indicated that HZSM-5@silicalite-1 contained less strong acid sites but more weak acid sites than the parent HZSM-5. The selectivity of p-xylene for toluene alkylation was approximately linear with the percentage of weak acid in total acid. Under the optimal reaction conditions, the conversion of toluene was 34.15%, and the selectivity of p-xylene was 96.77%. Graphic Abstract

    更新日期:2020-01-09
  • Mn Supported on Ce Substituted Hydroxyapatite for VOC Oxidation: Catalytic Activity and Calcination Effect
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-08
    R. K. More, N. R. Lavande, P. M. More

    Abstract The Mn supported on Ce substituted hydroxyapatite (HAp) catalyst was prepared by co-precipitation method and investigated for the low-temperature oxidation of toluene as a model component of VOC. The present work demonstrated the substitution of Ce in HAp in place of Ca. Furthermore, the effect of calcination temperature on oxidation activity of the catalyst was examined by calcining the catalyst at 400, 500 and 600 °C. The low-temperature calcination could favour the insertion of Ce in HAp, whereas higher calcination temperature could lead to the formation of separate CeO2 phase. The catalyst was characterized by using XRD, surface area, XPS, H2-TPR, ATR-FTIR techniques. The probable bonding between Ce and hexagonal HAp, which favors the oxidation of toluene at lower temperature has been explained with the calcination effect. The Ce substitution in HAp leads to the decrease in toluene activation energy which consequently increases the toluene conversion rate. The improvement in Mn2O3/Mn3O4 ↔ MnO2 redox cycle was observed due to the Ce substitution compared to unsubstituted Mn supported on HAp. The ATR-FTIR toluene adsorption study demonstrated the plausible mechanism of toluene oxidation. The activation of toluene on Ce substituted catalyst surface could proceed through the adsorption of the –CH3 group, whereas toluene adsorbed on unsubstituted catalyst surface through ortho, meta or para C–H bond. Graphic Abstract

    更新日期:2020-01-08
  • Ligninolytic Enzymes Mediated Ligninolysis: An Untapped Biocatalytic Potential to Deconstruct Lignocellulosic Molecules in a Sustainable Manner
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-08
    Muhammad Bilal, Hafiz M. N. Iqbal

    From the last two decades, white biotechnology, with particular reference to deploying enzyme bio-catalysis, has gained special research interest to valorize the bio-sources lignocellulosic biomass. In this context, ligninolytic enzymes from a white biotechnology background have tremendous potentialities to transform biomass following the green agenda. The enzyme-based white biotechnology is now considered a key endeavor of twenty-first century, as it offers socio-economic and environmental merits over traditional biotechnology, such as eco-friendlier processing conditions, no/limited use of harsh chemicals/reagents, high catalytic turnover, high yield, cost-effective ratio, low energy costs, green alternative of complex synthesis, renewability, reusability, and recyclability. Research efforts are underway, around the globe, to exploit naturally occurring biomass, as a green feedstock and low-cost substrates, to generate value-added bio-products, bio-fuels, and bio-energy. One core problem in developing an eco-friendlier and economical bioprocess is the pre-treatment of lignocellulosic biomass to entirely or partially remove the lignin barrier from cellulose fibers, thereby allowing the enzymes to access the cellulose fibers and generate the products of industrial interests. The entire process requires lignocelluloses deconstruction where ligninolytic enzymes in synergies with redox mediators systems have not explored much. The limited exploitation of ligninolytic enzymes with tremendous catalytic efficiencies has created a massive research gap that we have tried to cover herein. This review further insights the white biotechnology, also termed industrial biotechnology, which uses microorganisms and their unique enzyme system to facilitate the clean and sustainable deconstruction process.

    更新日期:2020-01-08
  • The Effect of Ceria Content on the Acid–Base and Catalytic Characteristics of ZrO 2 –CeO 2 Oxide Compositions in the Process of Ethanol to n -Butanol Condensation
    Catal. Lett. (IF 2.372) Pub Date : 2019-09-07
    Nina V. Vlasenko, Pavlo I. Kyriienko, Olena I. Yanushevska, Karina V. Valihura, Sergii O. Soloviev, Peter E. Strizhak

    Ethanol conversion into n-butanol was performed over ZrO2–CeO2 mixed oxide catalysts. The effect of ceria content on the acid–base and catalytic properties of ZrO2–CeO2 compositions has been studied. The introduction of CeO2 additives into zirconia stabilizes the tetragonal phase of ZrO2 leading to an increase in basicity of the samples and, as a result, increases the activity of catalysts towards n-butanol. The highest ethanol conversion, selectivity and the rate of n-butanol formation were obtained over the ZrO2–CeO2 sample with 10% of ceria, which exhibited the highest concentration and strength of base sites. This sample consists of a solid solution of ZrO2–CeO2, whereas at higher concentrations of additive, CeO2 forms an individual phase.

    更新日期:2020-01-08
  • Oxygen Deficient TiO 2−x with Dual Reaction Sites for Activation of H 2 O 2 to Degrade Organic Pollutants
    Catal. Lett. (IF 2.372) Pub Date : 2019-09-03
    Jiang-yuan Qiu, Jian-hua Chen, Bi-yuan Xiao, Xing-xing Li, Ting Wan, Fang-hong Qin, Yan Mi, Zai-yin Huang

    The present study reports the development of a novel defective TiO2−x catalyst with oxygen vacancy (OV) which carries dual types of reaction sites for H2O2 activation. The performance of this catalyst on the degradation of organic pollutants was evaluated using organic dyes [such as methyl orange, methylene blue, and rhodamine B (RhB)] as model pollutants. The defects in TiO2−x exhibited a wide pH working window (pH 2–9) for RhB degradation which is wider than that of traditional Fenton systems. Furthermore, this catalyst retained its high catalytic activity even after five cycles. It was confirmed that the surface OV and Ti3+ of TiO2−x served as the active sites for H2O2 activation while the oxygen vacancy promoted adsorption of the organic pollutants, thus enhancing the Fenton-like catalytic performance. The results are applicable to Fenton catalysts via surface engineering and can stimulate new opportunities for the optimization of defect-type Fenton catalysts.

    更新日期:2020-01-08
  • Highly Selective Lanthanum-Modified Zirconia Catalyst for the Conversion of Ethanol to Propylene: A Combined Experimental and Simulation Study
    Catal. Lett. (IF 2.372) Pub Date : 2019-08-02
    Wei Xia, Fangfang Wang, Longxiang Wang, Junguo Wang, Kun Chen

    Abstract La/ZrO2 catalysts were prepared by co-precipitation method. The physical and chemical properties of the catalysts were characterized by N2 adsorption–desorption method, X-ray diffraction and temperature programmed desorption. The selective conversions of ethanol to propylene over these synthesized La/ZrO2 catalysts were also investigated. The optimum propylene yield reached 42.3% over La(1)/ZrO2 catalyst. A coordination of redox and acid–base properties accounts for the remarkable improvement of reaction performance over La/ZrO2 catalysts. On the basis of calculation results, the introduction of oxygen vacancy or La results in significant charge transfer. The Lewis acid–base (Zr–O) pair sites become more active as a result of charge transfer over La/ZrO2 catalysts. Furthermore, the formation of O vacancies over La/ZrO2 (101) is easier than that over t-ZrO2(101). Therefore, La modification improves the performance of ZrO2 on conversion of ethanol to propylene. Graphic Abstract

    更新日期:2020-01-08
  • N-Doped Porous Carbon Supported Au Nanoparticles for Benzyl Alcohol Oxidation
    Catal. Lett. (IF 2.372) Pub Date : 2019-09-07
    Donglei Mao, Mingmin Jia, Jianhao Qiu, Xiong-Fei Zhang, Jianfeng Yao

    Abstract N-doped porous carbon (NPC) was produced through a simple and efficient method using biomass-derived pine sawdust as the carbon source, NH4Cl as nitrogen source and NaHCO3 as the activator. Both NPC and porous carbon (PC, prepared without nitrogen-doping) were used as support for Au nanoparticles to catalytic oxidation of benzyl alcohol. As expected, Au/NPC performs a substantially enhanced catalytic activity for benzyl alcohol oxidation in comparison with that of Au/PC (conversion of benzyl alcohol is 98.9% for Au/NPC and 51.4% for Au/PC under the same condition). The better catalytic performance of Au/NPC should be due to the introduction of N atoms into PC support, which not only adsorbs the benzyl alcohol molecules more easily, but also makes the Au nanoparticles smaller and more dispersed. Our experimental results also show that mild temperature (60 °C) is more beneficial for the reaction, O2 atmosphere is a necessity for benzyl alcohol oxidation and Au/NPC can also be used to catalyze oxidation of other aromatic alcohols. Graphic Abstract

    更新日期:2020-01-08
  • Metal Cocatalyst Directing Photocatalytic Acetonylation of Toluene via Dehydrogenative Cross-Coupling with Acetone
    Catal. Lett. (IF 2.372) Pub Date : 2019-08-12
    Akanksha Tyagi, Tomoya Matsumoto, Akira Yamamoto, Tatsuhisa Kato, Hisao Yoshida

    Abstract A heterogeneous metal-loaded titanium oxide photocatalyst provided an efficient route to bring out direct dehydrogenative cross-coupling between toluene and acetone without consuming any additional oxidizing agent. The nature of the metal nanoparticle cocatalyst deposited on TiO2 photocatalyst dictated the product selectivity for the cross-coupling. Pd nanoparticles on TiO2 photocatalyst allowed a C–C bond formation between the aromatic ring of toluene and acetone to give 1-(o-tolyl)propan-2-one (1a1) with high regioselectivity, while Pt nanoparticles on TiO2 photocatalyst promoted the cross-coupling between the methyl group of toluene and acetone to give 4-phenylbutan-2-one (1b) as the acetonylated product. These results demonstrated that the selection of the metal cocatalyst on TiO2 photocatalyst could determine which C–H bonds in toluene, aromatic or aliphatic, can react with acetone. Two kinds of reaction mechanisms were proposed for the photocatalytic dehydrogenative cross-coupling reaction, depending on the property of the metal nanoparticles, i.e., only Pd nanoparticles can catalyze the reaction between aromatic ring and the acetonyl radical species. Graphic Abstract

    更新日期:2020-01-08
  • Dehydrogenative Coupling of Toluene Promoted by Multi-Walled Carbon Nanotubes
    Catal. Lett. (IF 2.372) Pub Date : 2019-09-09
    Soliman I. El-Hout, Yang Zhou, Jun Kano, Yoshiaki Uchida, Yuta Nishina

    We report here the formation of carbon–carbon bonds via carbon-hydrogen bond activation catalysed by multi-walled carbon nanotubes (mwcnts), the catalytic activity of which is influenced by nanocarbon morphology and structure. Control of nanocarbon defects and edges allows the realisation of a high-performance carbon-based catalyst that can replace its metal-based counterparts.

    更新日期:2020-01-08
  • Molecular Oxygen Activation on Suspended Doped Cerium(IV) Oxide Particles in Molten Chloride Salts
    Catal. Lett. (IF 2.372) Pub Date : 2019-09-09
    Behzad Tangeysh, Horia Metiu, Michael J. Gordon, Eric W. McFarland

    Abstract Suspensions of cerium(IV) oxide (CeO2) particles in molten chloride salts were found to be active for molecular oxygen activation when doped with the larger Lanthanides, gadolinium (Gd), praseodymium, (Pr), and samarium, (Sm). The activity for O2 oxidation of gas phase CO on suspended doped ceria in molten mixtures of LiCl–LiBr–KBr and NaCl–KCl is significantly higher than undoped ceria or the salt mixtures alone in the temperature ranges of 350–600 °C, and 700–800 °C, respectively. Surface tension measurements show that the solid doped ceria particles suspended in the melt are contacting the gas–liquid interface of the bubbles. The activity for O2 oxidation of liquid phase MgCl2 in molten MgCl2–KCl to produce Cl2 and solid MgO was also observed to be significantly increased on suspended CeO2 doped with 5 wt% or 10 wt% Gd. The rates of oxidation were observed to increase with catalyst loading. Graphic Abstract

    更新日期:2020-01-08
  • β-CD-SO 3 H: Synthesis, Characterization and Its Application for the Synthesis of Benzylpyrazolyl Naphthoquinone and Pyrazolo Pyranopyrimidine Derivatives in Water
    Catal. Lett. (IF 2.372) Pub Date : 2019-08-28
    Audumbar Patil, Shivanand Gajare, Gajanan Rashinkar, Rajashri Salunkhe

    Abstract Green and economical method has been reported for the synthesis of benzylpyrazolyl naphthoquinone and pyrazolo pyranopyrimidines in water at room temperature by using β-CD-SO3H. β-Cyclodextrin supported sulfonic acid was prepared by simple one step procedure and characterized by FT-IR spectrum, 1H NMR, 13C NMR spectra, TGA, EDAX, XRD, BET surface area analysis and acid–base titration. The present protocol is environmental benign due to heterogeneous reusable catalyst and green reaction medium. This methodology provides excellent yield of the desired product with short reaction time at room temperature, easy workup procedure and no need of column chromatographic separation. Pyrazolyl derivatives are of much importance because this fragment is a key moiety in numerous biologically active compounds. Graphic Abstract

    更新日期:2020-01-08
  • Mesoporous Carbon Shell Encapsulated Co/Co 2 P Composite for Electrocatalytic Hydrogen Evolution Reaction: The Effect of Cd Initiator on its Catalytic Performance
    Catal. Lett. (IF 2.372) Pub Date : 2019-08-19
    Huagen Liang, Chen Yang, Linhui Jia, Ningyi Jiang, Fenghua Tan, Liangpeng Wu, Xu Yang, Fu Chen

    Abstract Herein, a novel cadmium nitrite initiated mesoporous carbon shell encapsulated binary cobalt/cobalt phosphide (Co/Co2P@MC-(Cdx)) composites were first prepared by a facile solvothermal reaction following a phosphorization procedure. The Co/Co2P@MC-(Cd0.5), with molar ratio of Cd/Co = 0.5 in the initial feeding stock, exhibited overpotentials of as low as 99 mV at 10 mA cm−2 and small Tafel slopes of 53 mV dec−1 under 0.5 M H2SO4 conditions. Various techniques further demonstrated that the superior activity of Co/Co2P@MC-(Cd0.5) was attributed to the introduction of Cd initiator, which resulted in the mesoporisity on carbon shell and the modified electron state between the Co and Co2P. This novel Cd initiated mesoporous carbon encapsulated Co/Co2P composites hold promising potential for utilization in the hydrogen evolution from electrocatalytic water splitting. Graphic Abstract A novel cadmium nitrite initiated mesoporous carbon shell encapsulated binary cobalt/cobalt phosphide (Co/Co2P@MC-(Cdx)) composites were first prepared. The Co/Co2P@MC-(Cd0.5), with molar ratio of Cd/Co = 0.5 in the initial feeding stock, exhibited overpotentials of as low as 99 mV at 10 mA cm−2 and small Tafel slopes of 53 mV dec−1 under 0.5 M H2SO4 conditions. The superior activity of Co/Co2P@MC-(Cd0.5) was attributed to the introduction of Cd initiator, which resulted in the mesoporisity on carbon shell and the modified electron state between the Co and Co2P.

    更新日期:2020-01-08
  • Synthesis of Sm 2 MoO 6 /Ni(OH) 2 by Simple Impregnation Method: Photocatalyst for Non-precious Metal and Efficient Hydrogen Production
    Catal. Lett. (IF 2.372) Pub Date : 2019-09-09
    Zeying Liu, Jing Xu, Qiuting Liao, Yanru Li, Lingjiao Li, Min Mao

    Abstract Sm2MoO6/Ni(OH)2 was successfully immersed in water first, and the sensitizer is Eosin Y and the sacrificial agent is triethanolamine agent for high-efficiency photocatalytic production of H2. When Sm2MoO6 was loaded onto the surface of Ni(OH)2, the photocatalytic activity (2407.48 μmol g−1 h−1) was 2.6 times that of Ni(OH)2 (925.36 μmol g−1 h−1), which was Sm2MoO6 (169.36 μmol g−1 h−1) is 14.2 times. From a series of characterizations, Sm2MoO6 is an effective cocatalyst to improve the separation of photo-generated charges and the efficiency of electron transfer. Large specific surface areas are a primary requirement for high efficiency catalysts, and the catalyst is sufficiently into contact with the sensitizer and the sacrificial agent to soar the photocatalytic activity. Graphic Abstract The first condition for an excellent catalyst is that it has a large specific surface area and can provide more active sites. In the dye sensitization system, the photocatalytic activity of Sm2MoO6/Ni(OH)2 is 2.6 times that of Ni(OH)2 and 14.2 times that of Sm2MoO6. Sm2MoO6 is an effective co-catalyst.

    更新日期:2020-01-08
  • Oxidative Esterification of Aldehydes and Alcohols Catalyzed by Camphor-Based Imidazolium Salts
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-06
    Tiancen Bian, Li Feng, Danfeng Li, Jiaxin Huang, Yuxun Zhao, Xu Xu, Yiqin Yang, Shifa Wang

    Abstract Sixteen new camphor-based imidazolium salts have been synthesized with renewable camphorsulfonic acid as the starting material. The chemical shifts of the characteristic proton of C2 on the imidazolium ring (N−C=N) were discussed thoroughly and all of these imidazolium salts exhibit good thermal stability. Furthermore, the excellent catalytic performance of the synthesized imidazolium salts were observed in the oxidative esterification between aromatic or aliphatic aldehydes containing electron-withdrawing or electron-donating groups on aromatic ring and primary or secondary alcohol by air as the sole oxidant. Graphic Abstract

    更新日期:2020-01-06
  • Seed-Induced Zeolitic TS-1 Immobilized with Bioinspired-Au Nanoparticles for Propylene Epoxidation with O 2 and H 2
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-03
    Yingling Hong, Lanting Ke, Zhanhai Li, Jiale Huang, Guowu Zhan, Yao Zhou, Daohua Sun, Jinli Zhang, Qingbiao Li

    In this work, bio-inspired Au nanoparticles (NPs) were loaded through an ionic-liquid-enhanced-immobilization method onto TS-1 support, leading to efficient Au/TS-1 catalysts for gas-phase propylene epoxidation in the presence of O2 and H2. Specifically, the mesoporous TS-1 was synthesized by a hydrothermal method using nanosized TS-1 (size of ∼ 220 nm) as seeds, and the support was then etched with acid (HCl or HNO3). Both the pristine TS-1 and Au/TS-1 catalysts were fully characterized to understand the effects of preparation conditions on the catalytic performance in propylene epoxidation. Interestingly, it was found that the amount of Lewis acid sites in the seed-induced TS-1 was greater than that on the control sample formed without seed; more importantly, the size of the loaded Au NPs can be regulated by changing the amount of Lewis acid site. Furthermore, we have demonstrated that the post-treatment of TS-1 with appropriate acid sites could enhance the propylene conversion and propylene oxide (PO) selectivity.

    更新日期:2020-01-04
  • Effect of Crystal Form Control on Improving Performance of Cu 3 (BTC) 2 Immobilized Phosphotungstic Acid in Esterification of Cyclohexene with Formic Acid
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-03
    Haoran Jiang, Biao Lu, Lijuan Ma, Xia Yuan

    The esterification of cyclohexene with formic acid is the first step for indirect hydration to cyclohexanol. In the work reported in this study, phosphotungstic acid (HPW) was incorporated into the metal–organic framework Cu3(BTC)2 through a one-step hydrothermal synthesis method to catalyze the esterification reaction. The crystal structure of composite HPW–Cu3(BTC)2 was modulated during the preparation process to convert the catalyst from the {111} crystal facets of the original regular octahedral structure to the {100} crystal facets of the cubic structure using p-toluic acid (pTA) as the regulator. The conversion of the crystal facets reduces the formation through holes while exposing more active sites of HPW. When the mass ratio of the modulator to the organic ligand terephthalic acid was 20, the crystal facets of the catalyst were completely covered by the {100} crystal facets. After the crystal transformation, the conversion of cyclohexene was increased to 86.8%, and the selectivity of cyclohexyl formate was 84.2%. Agglomeration occurred after the catalyst was used twice in the esterification reaction.

    更新日期:2020-01-04
  • Molybdovanadophosphoric Heteropolyacid-Catalyzed Aerobic Oxidation of Methacrolein: The Crucial Role of Ionic Liquid as a Modifier
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-02
    Yun-Li Cao, Lei Wang, Yin-Ge Bai, Rui-Yi Yan, Bao-Hua Xu

    Abstract [EMIM]PAV[X] (X = Ac, NO3, BF4) was synthesized by a facile method using imidazolium-based ionic liquids ([EMIM][X], X = Ac, NO3, BF4) as the modifying reagent. Characterization by FT-IR, XRD, SEM, TG/DTA, H2-TPR and XPS demonstrated that [EMIM]PAV[Ac] has uniform rod-like morphology, better redox property and higher amount of NH4+ composite, which therefore provides a high selectivity of 98% in the oxidative transformation of methacrolein (MAL) to methacrylic acid (MAA) as a catalyst. Theoretical calculations suggested the relatively strong H-bond basicity of C2−H in [EMIM][Ac] has a great positive influence on the structure and redox property of [EMIM]PAV[X] hybrids. Graphic Abstract

    更新日期:2020-01-02
  • Co II Immobilized on Aminated Magnetic-Based Metal–Organic Framework: An Efficient Heterogeneous Nanostructured Catalyst for the C–O Cross-Coupling Reaction in Solvent-Free Conditions
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-02
    Arezou Mohammadinezhad, Batool Akhlaghinia

    In this paper, we report the synthesis of Fe3O4@AMCA-MIL53(Al)-NH2-CoII NPs based on the metal–organic framework structures as a magnetically separable and environmentally friendly heterogeneous nanocatalyst. The prepared nanostructured catalyst efficiently promotes the C–O cross-coupling reaction in solvent-free conditions without the need for using toxic solvents and/or expensive palladium catalyst.

    更新日期:2020-01-02
  • Immobilized N -Heterocyclic Carbene-Palladium(II) Complex on Graphene Oxide as Efficient and Recyclable Catalyst for Suzuki–Miyaura Cross-Coupling and Reduction of Nitroarenes
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-02
    Vishal Kandathil, Bhakti Kulkarni, Aisha Siddiqa, Manjunatha Kempasiddaiah, B. S. Sasidhar, Shivaputra A. Patil, Siddappa A. Patil

    Abstract A new and efficient N-heterocyclic carbene (NHC)-palladium(II) complex immobilized on graphene oxide (NHC-Pd@GO) has been successfully designed and synthesized. The prepared NHC-Pd@GO heterogeneous catalyst was fully characterized using a combination of fourier transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller surface area analysis (BET). This new air- and moisture-stable NHC-Pd@GO heterogeneous catalytic system was found to be a highly active catalyst in the Suzuki–Miyaura cross-coupling between phenylboronic acid and various aryl halides (bromides/chlorides/iodides) and in the reduction of nitroarenes. These organic transformations were best performed in an aqueous ethanol and aqueous methanol solvent system respectively with low catalyst loading under mild reaction conditions. Furthermore, NHC-Pd@GO heterogeneous catalyst could be recovered easily and reused at least eleven times in Suzuki–Miyaura cross-coupling and nine times in reduction of nitroarenes without any considerable loss of its catalytic activity. The stability and good selectivity of the NHC-Pd@GO heterogeneous catalyst in recycling experiments signify that it could be useful for practical application in various organic transformations. Graphic Abstract

    更新日期:2020-01-02
  • Hydrazinylbenzenesulfonic Acid-Modified Nieuwland Catalyst for Acetylene Dimerization Reaction
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-02
    Qixia Zhang, Congcong Li, Juan Luo, Jianwei Xie, Jinli Zhang, Bin Dai

    Abstract A novel Nieuwland catalytic system, containing 5 mol% of 4-hydrazinylbenzenesulfonic acid (S8), was developed and exhibited an excellent catalytic performance and good stability in the acetylene dimerization reaction. The acetylene conversion reached 57.1%, while the selectivity of monovinylacetylene (MVA) was 75.1%. The yield of MVA was maintained at 42.9% under an acetylene gas hourly space velocity (GHSV) of 80 h−1 at 80 °C, which was increased by 18.8% over the control Nieuwland catalytic system. The addition of S8 increased the dissolution of CuCl in water, inhibited the polymer formation, and hindered the Cu+ loss during the reaction process, thus improving the activity and the long-term stability of the modified Nieuwland catalyst. Graphic Abstract

    更新日期:2020-01-02
  • Synthesis of Imines by Selective Oxidation of Amines on alloy nanoparticles of palladium and gold under visible light irradiation at ambient temperatures
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-01
    Eerdemutu, Lijun Ding, Chun Li, Shuang Zhao, Xianliang Sheng

    Abstract Imines are important intermediates in organic synthesis. To avoid derivatives, the research on direct oxidized amines as an alternative method is imminent. The gold (Au)–palladium (Pd) alloy nanoparticles (NPs) catalyst shows a favourable activity and high selectivity on benzylamine oxidation reaction under light irradiation. The yield of the reaction on the alloy NPs with a Au:Pd ratio of 1:1.86 in the dark was 36% at 45 °C, while the yield increased to 95% under light illumination. The study demonstrates different properties from alloy NP to pure Au NP and Pd NP catalysts which may be caused by increased surface charge heterogeneity in the alloy system. The conversion rate of the reaction can also be enhanced by light irradiation and heat. The light energy which utilized by Localized Surface Plasmon Resonance effect of gold in alloy system can highly enhanced the efficiency of reaction. These findings provide useful guidelines for designing efficient alloy catalysts with a plasmonic metal and a catalytically active transition metal for various organic syntheses driven by sunlight. Graphic Abstract

    更新日期:2020-01-02
  • Binuclear Palladium Complex Immobilized on Mesoporous SBA-16: Efficient Heterogeneous Catalyst for the Carbonylative Suzuki Coupling Reaction of Aryl Iodides and Arylboronic Acids Using Cr(CO) 6 as Carbonyl Source
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-01
    Mahsa Niakan, Zahra Asadi, Mohammad Emami

    Abstract In this study, a binuclear palladium complex immobilized on the organo-functionalized SBA-16 was prepared and structurally characterized by routine techniques. Characterizations indicated that the mesostructure of SBA-16 was maintained after the immobilization of palladium complex. Then, the prepared nanomaterial was applied as a heterogeneous catalyst in the carbonylative Suzuki coupling reaction of aryl iodides with arylboronic acids using Cr(CO)6 as carbonyl source. The catalyst was efficiently promoted the coupling reactions of various aryl iodides and arylboronic acids to give the corresponding diaryl ketones in excellent yields. Moreover, the catalyst was readily recovered by filtration and could be reused for seven cycles without losing its structural integrity and catalytic activity. Graphic Abstract

    更新日期:2020-01-01
  • Electrifying Oxide Model Catalysis: Complex Electrodes Based on Atomically-Defined Oxide Films
    Catal. Lett. (IF 2.372) Pub Date : 2020-01-01
    Olaf Brummel, Jörg Libuda

    By studying complex model catalysts based on well-defined oxide surfaces, fundamental insights have been obtained into the surface chemistry of many heterogeneously catalyzed processes. In this perspective, we summarize a series of studies, in which we have transferred this model catalysis approach to the field of electrocatalysis. Our model electrocatalysts consisted of Pt nanoparticles (NPs) grown on atomically-defined oxide films. Specifically, we used well-ordered Co3O4(111) thin films on an Ir(100) support. The Pt NPs were prepared by physical vapor deposition (PVD) and the particle size was varied from a few nanometers to the sub-nanometer size range. We prepared all model catalysts under ultra-high vacuum (UHV) conditions using a dedicated preparation system. This setup enables us to transfer the model catalysts from UHV into the electrochemical environment to apply various in-situ techniques without exposure to air. We investigated the stability window of pristine Co3O4(111) and Pt/Co3O4(111) using online inductively coupled plasma mass spectrometry (ICPMS), electrochemical infrared reflection absorption spectroscopy (EC-IRRAS), scanning tunneling microscopy (STM), ex-situ emersion X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). Within the stability window (pH 10, 0.3–1.1 VRHE) the surface structure of the model electrocatalysts is preserved. We analyzed identical samples both in UHV and in the electrochemical environment. Specifically, we applied synchrotron radiation photoelectron spectroscopy (SR-PES) and ex-situ emersion XPS to analyze the electronic structure and we used infrared reflection absorption spectroscopy (IRAS), temperature programmed desorption (TPD), EC-IRRAS, and cyclic voltammetry (CV) to study CO adsorption and oxidation. The model electrocatalysts show pronounced particle size effects and metal support interactions are shown to play a key role in their catalytic reactivity. Of particular importance is an interfacial Pt oxide, which is stabilized by the oxide support and exists at electrode potentials as low as 0.5 VRHE. Moreover, spillover effects enable new reaction mechanisms, which involve oxygen from the oxide support. This review demonstrates the potential of the model electrocatalysis approach to provide fundamental insights into complex oxide-based electrocatalysis.

    更新日期:2020-01-01
  • Influence of Structure Sensitivity on Apparent Activation Energy of Parallel Heterogeneous Catalytic Reactions
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-28
    Dmitry Yu. Murzin

    Analysis of apparent activation energy is presented for different heterogeneous catalytic reactions with parallel reaction routes. In the case of kinetic coupling between catalytic cycles the activation energy in a particular route depends not only on the activation energies of the elementary steps comprising this route, but also on the frequency of the steps in a parallel route. Expressions were derived for coupling between routes through irreversible adsorption of the substrate, quasi-equilibrated binding as well as different substrate adsorption modes. Theoretical analysis of the apparent activation energy was extended for the reaction network with two routes possessing mechanistically different rate determining steps (i.e. monomolecular vs bimolecular). For structure sensitive reactions an expression for the apparent activation energy for parallel reactions was developed for cases with a continuous distribution of active centers and a cubo-octahedral representation of the metal clusters. A comparison between the theoretical analysis and experimental data on transformations of furfural to furfuryl alcohol and furan on ruthenium clusters shows applicability of the developed theoretical framework.

    更新日期:2019-12-30
  • Kinetics of Reaction on a Single Catalytic Particle in a Fluidic Nanochannel
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-27
    Vladimir P. Zhdanov

    Abstract One of the frontiers in heterogeneous catalysis is focused on reactions occurring on single catalytic nanoparticles. In this context, a reaction taking place on a single nanoparticle in a fluidic nanochannel is herein described by using the equation similar to that employed for a plug-flow reactor with dispersion. In the literature, one can find various boundary conditions for this equation. In the practically interesting case of a relatively long channel, the Dirichlet boundary conditions are shown to be valid. The corresponding analytical and numerical results illustrate the specifics of the profiles of the reactant concentration along the channel and the dependence of the reaction rate on the parameters. For comparison, the Danckwerts boundary conditions were used as well. Graphic Abstract

    更新日期:2019-12-27
  • The Role of Coke as the Crystal Structure Protective Agent in the Synthesis of CHA Zeolites from Spent MFI
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-24
    Debing Li, Zhikai Liu, Yi Liu, Yi Zhang

    The CHA zeolites were synthesized using coke-free and coke-containing spent MFI zeolites via the steam-assisted dry gel conversion method. The results indicate that the coke within the spent MFI precursor has played a vital role in preventing the crystal structure from collapse in a steam condition with the excess synthesis time of 3 days, but the SSZ-13 obtained from coke-free MFI zeolites suffered from a partial collapse in the same synthetic conditions. These could be attributed to the surrounding of some hydrophobic coke onto the surface of SSZ-13 crystallite during the synthesis. Besides, the sample produced from coke-containing spent MFI had better catalytic stability in methanol to olefins as well.

    更新日期:2019-12-25
  • Green synthesis of Dy 2 Ce 2 O 7 Nanoparticles Immobilized on Fibrous Nano-silica for Synthesis of 3-Aryl-2-oxazolidinones from Alkenes, Amines, and Carbon Dioxide
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-23
    Li Feng, Xuhao Li, Chuang Xu, Seyed Mohsen Sadeghzadeh

    Abstract In the present research, a new dendritic fibrous nanosilica (DFNS) based nanocatalyst (DFNS/Dy2Ce2O7) that has high surface zone as well as easy availability of active zones has been properly expanded using an easy approach. DFNS that possess high surface zone is functionalized by amino groups working as the anchors such that the nanoparticles of Dy2Ce2O7 are fine-dispersed onto the DFNS microspheres fibres, without any aggregation. The nanoparticles of Dy2Ce2O7 are produced by a green approach in the attendance of gum of ferula assa-foetida of Dy(NO3)3 and (NH4)2Ce(NO3)6 as ceric and dysprosium sources. The structural evaluation of the samples proved the synthesis of Dy2Ce2O7 NPs. Moreover, a straight way for the production of 3-aryl-2-oxazolidinones by carbon dioxide, olefins, and anilines was obtained utilizing nano catalyst of DFNS/Dy2Ce2O7 in the lack of solvent. The reaction works properly at moderate states. This method that is cheap and simple may be used to different olefins that has proper to excellent 3-aryl-2-oxazolidinones productions. The catalyst may be simply recycled for ten times without considerable losing the activity of its catalytic. Graphic Abstract

    更新日期:2019-12-25
  • Morphology Control of Molybdenum Titanium Oxide and Its Enhanced NO Removal Performance
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-21
    Liuchang Wang, Lu Zhang, Yong Jiang, Pengna Li

    A series of molybdenum titanium oxides (TiO2–MoO3) were successfully prepared by hydrothermal method using P25 and TiCl4 as titanium resource, respectively. The particle size and morphology of molybdenum titanium oxides was controlled by adding thiourea as surfactant. The catalytic activity of the obtained materials was evaluated by degradation of NO under simulated solar light irradiation. The results showed that the morphology of obtained molybdenum titanium oxide can be significantly controlled by adding thiourea. And the samples with novel curly petal-like layered structure exhibited superior catalytic activity. Trapping experiments revealed that ·O2− was the main active specie in the catalytic system. Also the catalyst had superior stability and reusability.

    更新日期:2019-12-22
  • Ce-Doped V 2 O 5 -WO 3 /TiO 2 with Low Vanadium Loadings as SCR Catalysts and the Resistance of H 2 O and SO 2
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-20
    Xiaolong Liu, Ziwei Zhao, Ruliang Ning, Yu Qin, Tingyu Zhu, Fagao Liu

    The promoting effect of Ce on V-W/Ti catalyst for selective catalytic reduction (SCR) of NOx by NH3 was studied. Compared with the original V-W/Ti samples, addition of Ce contributed better NH3-SCR performance. The H2O and SO2 resistance of Ce modified V-W/Ti catalyst was improved by the different impregnation sequence of Ce. The catalysts were characterized by NH3-temperature programmed desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), and H2-temperature programmed reduction (H2-TPR) techniques. The results showed that the impregnation sequence of W and Ce influenced the NH3 adsorption capacity of the catalysts. In comparison to 0.2V-5Ce-5W/Ti and 0.2V-(5Ce5W)/Ti, 0.2V-5W-5Ce/Ti catalyst contributed better H2O and SO2 resistance, with the highest Ce3+/(Ce4+ + Ce3+) value of 36.6%. Besides, a catalytic mechanism of SCR reactions over Ce-doped V-W/Ti catalysts was proposed.

    更新日期:2019-12-20
  • Peroxotungstate-Based Ionic Hybrid as a Triphase Heterogeneous Catalyst for Efficient Benzyl Alcohol Oxidation Under Mild Conditions
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-20
    Manman Jin, Qingtao Niu, Chongdian Si, Zhiguo Lv, Hongyue Guo, Zhenmei Guo

    Supported ionic-liquid-phases (SILPs) were synthesized via reaction of 1-methyl-3-(3-triethoxysilylpropyl)imidazolium hexafluorophosphate (ImCl-PF6) with SBA-15 and then peroxotungstate molecules were immobilized on SILPs. The resulting material (W-ImCl-PF6-SBA-15) was characterized via 29Si MAS NMR to detect the chemical environment around Si and its textural and thermogravimetric behavior were determined. To obtain insight into the role of ImCl-PF6 during catalysis, an ImCl-PF6-free catalyst (W/SBA-15) was also synthesized. W-ImCl-PF6-SBA-15 and W/SBA-15 were investigated as catalysts for benzyl alcohol oxidation, as a model reaction, under solvent-free conditions with H2O2.The presence of ImCl-PF6 was crucial for obtaining excellent catalytic activity, and W-ImCl-PF6-SBA-15 showed higher activity and stability than these of W/SBA-15. Optimized reaction conditions were employed to several selected alcohols oxidation and, remarkably, excellent aldehydes selectivity was achieved. The importance of ImCl-PF6-functionalized SBA-15 was evidenced via recycling experiments of benzyl alcohol oxidation, and W-ImCl-PF6-SBA-15 was recycled for ten reaction runs without significant change in benzyl alcohol conversion, benzaldehyde selectivity, and tungsten content.

    更新日期:2019-12-20
  • The Carboxylated Multi-walled Carbon Nanotubes/ l -Asparaginase Doped Calcium-Alginate Beads: Structural and Biocatalytic Characterization
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-19
    Ahmet Ulu, Muhammet Karaman, Fatma Yapıcı, Mehmet Naz, Selin Sayın, Eyüp İlker Saygılı, Burhan Ateş

    The calcium-alginate/multi-walled carbon nanotube hybrid beads (Ca-ALG/MWCNT-COOH) as a novel kind of matrix were fabricated and characterized in detailed. l-Asparaginase (l-ASNase), which is important chemotherapeutic enzyme-drug in leukemia, was immobilized on the Ca-ALG/MWCNT-COOH hybrid beads. To the best of our knowledge, this is the first study using Ca-ALG/MWCNT-COOH hybrid beads for l-ASNase immobilization. Our characterization investigations displayed that the hybridization between ALG and MWCNT-COOH caused significant changes on the surface morphology and structure. ALG of 0.5% (w/v), CaCl2 of 0.2 M concentration, enzyme of 187.5 U and bead size of 2 mm was found to be best with respect to enzyme loading efficiency. The enzyme was loaded a high yield (97.0%) on these hybrid beads. Remarkably, the tolerance of immobilized enzyme developed towards temperature and pH changes. The maximum activity for the free enzyme was observed at 35 °C, pH 7.5, whereas the immobilized enzyme showed maximum activity at 45 °C pH 8.5. After immobilization, storage stability of enzyme improved and retained more than 70% of its initial activity after 4 weeks at ~ 30 °C as compared with free enzyme which showed only 20% of residual activity. After immobilization, Km value decreased 1.27-fold compared to free counterpart, indicating increased the affinity between the substrate and enzyme. Moreover, immobilized enzyme maintained more than 36% of its original activity even after consecutive 14 reuse. As result, it is worthy of noting that this kind of hybrid materials may become a promising support material for the immobilization of commercial enzymes in areas such as industrial and medical.

    更新日期:2019-12-19
  • C–N Cross-coupling Reactions of Amines with Aryl Halides Using Amide-Based Pincer Nickel(II) Catalyst
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-14
    Yahya M. Albkuri, Ambar B. RanguMagar, Andrew Brandt, Hunter A. Wayland, Bijay P. Chhetri, Charlette M. Parnell, Peter Szwedo, Anil Parameswaran-Thankam, Anindya Ghosh

    An approach to C–N cross-coupling reactions of aryl halides with amines in the presence of an amide-based pincer nickel(II) catalyst (2) is described. For 3 h reactions at 110 °C with 0.2 mol% catalyst, aryl bromides gave higher turnover numbers (TON) than the corresponding chlorides or iodides. Both primary and secondary amines could be used with the former giving higher TON. However, sterically hindered amines showed lower TON. In elucidating the mechanism of this nickel complex-catalyzed C–N cross coupling reaction it was found that the rate of reaction was unchanged in the presence of radical quenchers and a plausible Ni(I)–Ni(III) pathway is proposed.

    更新日期:2019-12-17
  • Study of CoCu Alloy Nanoparticles Supported on MOF-Derived Carbon for Hydrosilylation of Ketones
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-12
    David B. Christensen, Rasmus L. Mortensen, Søren Kramer, Søren Kegnæs

    Carbonized zeolitic imidazolate frameworks (ZIFs) show potential as mesoporous heterogeneous catalysts with high metal loadings. ZIF-67 and ZIF-8 were used to create mono- and bimetallic CoCu particles supported on nitrogen-doped carbon via self-assembly in methanol at room temperature, followed by carbonization at 675 °C. A Cu precursor, Cu(NO3)2·2H2O, was impregnated into the ZIF-67 before carbonization to obtain bimetallic catalysts. Nanoalloy particles with different CoCu ratio were synthesized and characterized using XRD. The materials were further characterized using TEM, SEM, XRF and nitrogen physisorption. The different alloys were tested in conversion of cyclohexanone to the corresponding silyl ether. Complete conversion of cyclohexanone at 90 °C for 24 h were obtained. The catalyst Co99Cu1@NC gave a 60% increase in yield over a pure Co analogue.

    更新日期:2019-12-13
  • A Convenient and Green Synthetic Approach for Benzo[ a ]pyrano[2,3- c ]phenazines via Supramolecular Catalysis
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-11
    Anu Mishra, Yogesh Kumar Pandey, Fatima Tufail, Jaya Singh, Jagdamba Singh

    A pragmatic and swift method for the synthesis of Benzo[a]pyrano[2,3-c]phenazine derivatives via one pot, multicomponent strategy by employing β-cyclodextrin in EtOH:H2O (1:1) solvent at 70 °C has been documented here. Utilization of supramolecular catalyst β-cyclodextrin which is highly efficient, green, biodegradable and reusable catalyst augments the synthesis amazingly, is the key feature of the current pathway. The catalyst could be recovered for four successive cycles without significant loss in catalytic activity.

    更新日期:2019-12-11
  • Conversion of Dihydroxyacetone to Methyl Pyruvate Catalyzed by Hybrid Molecular Sieves at Low Temperature: A Strategy for the Green Utilization of Glycerol
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-11
    Qianqian Luo, Tianliang Lu, Jun Xu, Xiaomei Yang, Lipeng Zhou

    Methyl pyruvate (MPA) was synthesized from dihydroxyacetone (DHA), the oxidation product of glycerol, over Sn-β and TS-1 hybrid molecular sieves at low temperature. Sn-β and TS-1 provide the active sites for conversion of DHA to methyl lactate (MLA) and oxidation of MLA to MPA, respectively. Synergism of Lewis acid sites on Sn-β and TS-1 realize the production of MPA from DHA. After optimization, 71% yield of MPA can be obtained under 50 °C. This is the first report for the synthesis of MPA from DHA directly.

    更新日期:2019-12-11
  • High-Throughput Screening of Multimetal Sulfides-Modified g-C 3 N 4 for Degradation of Organic Contaminations Based on Ink-Jet Printing (IJP) Technology
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-11
    Sifan Bi, Fenli Liu, Wenjing Wang, Qiannan Duan, Jiayuan Chen, Run Luo, Yunjin Feng, Jianchao Lee

    In this study, a novel method combining microplate fluorescence imaging (FI) and high-throughput screening (HTS) technology was applied to screen and evaluate the multicomponent metal (Zn, Cd, Ni) sulfides-modified g-C3N4 with high-activity photocatalytic performance. Glass screen printing was creatively used in preparing a photocatalytic reaction microplate containing 225 independent micro-reaction chambers (μRCs) as experiment carriers. A photocatalyst chip comprising 225 ZnxCdyNi1−x−yS/g-C3N4 multicomponent photocatalysts was made via chemical ink-jet printing (IJP) technology, at last 23 high-efficiency M3S/g-C3N4were screened out from the photocatalyst chip by the optical density (OD) method.

    更新日期:2019-12-11
  • Exploration of Catalytic Activity of Quercetin Mediated Hydrothermally Synthesized NiO Nanoparticles Towards C–N Coupling of Nitrogen Heterocycles
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-10
    T. Krishnaveni, K. Lakshmi, K. Kadirvelu, M. V. Kaveri

    A new approach towards the preparation of phase pure NiO nanoparticles via quercetin mediated hydrothermal method is proposed in this work. The performance of quercetin as capping agent is found to be good. The XRD and SEM results confirm that the NiO nanoparticles prepared with quercetin are smaller in size and have refined morphology than that prepared without quercetin. Thermal stability, elemental composition and particle size of prepared nanoparticles have been revealed by TG-DSC, EDAX and HR-TEM analysis respectively. N2 adsorption–desorption isotherm (BET) analysis was done to reveal specific surface area. The prepared NiO nanoparticles act as cost effective, environmental friendly and efficient catalyst for the C–N cross coupling of indole and electron deficient pyrrole, under very mild reaction conditions. The catalytic system is able to tolerate many functional groups with different electronic and structural properties. Hence the present catalytic system may be possibly applied in large scale synthesis.

    更新日期:2019-12-11
  • CO Dissociation Mechanism on Mn-Doped Fe(100) Surface: A Computational Investigation
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-09
    Heyuan Huang, Yingzhe Yu, Minhua Zhang

    Periodic density function theory (DFT) and kinetic Monte Carlo (kMC) method are carried out to investigate CO dissociation process on the Mn-doped Fe(100) surface. The energetics information of relevant atomistic processes and adsorption features of relevant species are obtained from DFT calculations. Subsequently, kMC simulations are performed with DFT results employed as database. Simulations show that the energy barriers for CHO and COH formations are 0.09 eV and 0.35 eV larger than that for direct CO dissociation on Mn/Fe(100), respectively. An empty site is created with a CO hydrogenation (CO* + H* → COH* + *, CO* + H* → CHO* + *), while an active site is consumed with a CO direct dissociation (CO* + * → C* + O*). The number of unoccupied active sites can affect the way of CO dissociation. On surfaces with considerable unoccupied active sites, direct CO dissociation mechanism is the preferred route. Under conditions favoring a very low number of unoccupied active sites and a mass of adsorbed H on surfaces, H-assisted CO dissociation via COH will take place.

    更新日期:2019-12-09
  • Ni–Zn–Al-Based Oxide/Spinel Nanostructures for High Performance, Methane-Selective CO 2 Hydrogenation Reactions
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-07
    T. Rajkumar, András Sápi, Marietta Ábel, Ferenc Farkas, Juan Fernando Gómez-Pérez, Ákos Kukovecz, Zoltán Kónya

    In the present study, NiO modified ZnAl2O4 and ZnO modified NiAl2O4 spinel along with pure Al2O3, ZnAl2O4 and NiAl2O4 for comparison in the CO2 hydrogenation reaction have been investigated. It was found that NiAl2O4, NiO/ZnAl2O4 and ZnO/NiAl2O4 catalysts exhibited outstanding activity and selectivity towards methane even at high temperature compared to similar spinel structures reported in the literature. NiO/ZnAl2O4 catalyst showed CO2 consumption rate of ~ 19 μmol/g·s at 600 °C and ~ 85% as well as ~ 50% of methane selectivity at 450 °C and 600 °C, respectively. The high activity and selectivity of methane can be attributed to the presence of metallic Ni and Ni/NiO/ZnAl2O4 interface under the reaction conditions as evidenced by the XRD results.

    更新日期:2019-12-07
  • Ni–Mg–Al Catalysts Effectively Promote Depolymerization of Rice Husk Lignin to Bio-Oil
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-05
    Boyu Du, Changzhou Chen, Yang Sun, Bingyang Liu, Yingying Yang, Si Gao, Zhenshu Zhang, Xing Wang, Jinghui Zhou

    Catalytic depolymerization of lignin to produce bio-oil, liquid fuels, and aromatic chemicals in high yields is important for a biorefinery to remain competitive. In this study, undoped and Ni-doped catalysts for depolymerization of rice husk lignin (RHL) were developed and analyzed. The results showed that the catalysts had hydrotalcite-like structures with lamellar morphology. With suitable Ni-doping amount, the catalysts had high activity, thus better promoted the depolymerization of RHL. Among all catalysts, the Ni1/4MgAl catalyst could best promote the cleavage of the β-O-4 aryl ether bond in RHL molecule and thus could substantially increase the yields of bio-oil. The depolymerization catalyzed by this catalyst was also found to be temperature-, time-, and solvent-dependent. This study provides information that can be beneficial to the biorefinery industries and may help promote the valorization of lignin.

    更新日期:2019-12-05
  • Ba-Ni-Hexaaluminate as a New Catalyst in the Steam Reforming of 1-Methyl Naphthalene and Methane
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-05
    Charlotte Parsland, Phuoc Hoang Ho, Patricia Benito, Ann-Charlotte Larsson, Giuseppe Fornasari, Jan Brandin

    This work investigates the long-term performance of Ba-Ni-hexaaluminate, BaNixAl12−xO19 as a catalyst in reforming of 1-methyl naphthalene and/or methane in a model-gas simulating that from a circulating fluidized bed (CFB) gasifier during 23–29 h in a lab scale set-up, as well as the tendency for coke formation, sintering and sulphur poisoning. 1-Methyl naphthalene is used as a tar model substance. The Ba-Ni-hexaaluminate induces a high conversion of both compounds in the temperatures investigated (850 and 950 °C) under sulphur-free conditions. In sulphur-containing gas, the methane conversion stops at 20 ppm H2S and the reforming of 1-MNP at 850 °C is slightly reduced at 100 ppm.

    更新日期:2019-12-05
  • Design, Synthesis, Characterization and Application of BNPs@SiO 2 (CH 2 ) 3 NH-CC-AMP-Pd (0) as a New Reusable Nano-Catalyst for Suzuki and Heck Cross-Coupling Reactions
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-04
    Minoo Khodamorady, Kiumars Bahrami

    A simple and effective method was used for the successful preparation of the Boehmite@(CH2)3NH-CC-AMP-Pd (0) NPs as an environmentally friendly heterogeneous nano-catalyst. The synthesized nano-catalyst was well identified by different techniques like FT-IR, XRD, XPS, TEM, SEM, EDX, TGA, mapping, and ICP analysis. The BNPs@SiO2(CH2)3NH-CC-AMP-Pd was used as a recoverable nano-catalyst for Suzuki‐Miyaura and Mizoroki‐Heck coupling reactions under mild, green and sustainable conditions with excellent yields (H2O, EtOH as solvent for Suzuki reaction and solvent-free conditions for Heck reaction). Also, the distribution of palladium on the catalyst surface is uniform and the average palladium size is between 20 and 30 nm. Compared to similar works, this protocol has some of the important aspects such as: thermal and mechanical stability of the catalyst, low palladium leaching (9.7%), the simplicity of the preparation, the availability of raw materials, not expensive, no need for neutral atmosphere, appropriate times, green conditions, use low amount of catalyst (1.42 mol%) and reused catalyst for several consecutive times (at least seven times).

    更新日期:2019-12-04
  • A Comparative Study on C 2 Hydrocarbons and Methanol Synthesis from CO Hydrogenation Catalyzed by M 1 /W 6 S 8 (M = Ir and Ca) Single-Atom Catalysts
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-04
    Zijun Hao, Yu Han, Sibei Guo, Qian Zhang, Ling Guo

    Exploring highly selective catalysts for CO hydrogenation reactions remains a significant challenge as a critical stage in the conversion of CO resources into chemicals or fuels. Here, we provide guidelines on this issue, exploring the generation of major production in the CO hydrogenation process of M1/W6S8 (M = Ir and Ca) single-atom catalysts, and performing density functional calculations. Calculate the reaction energy and barrier for each basic step. Calculations represent that the Ca1/W6S8 catalyst is very advantageous for methanol synthesis (CO* + 4H* → CHO* + 3H* → CH2O* + 3H* → CH3O* + H* → CH3OH*). On the other hand, the Ir1/W6S8 catalyst strongly favors the production of C2 hydrocarbons. We use the harmonic transition state theory to calculate the rate constant of the subsequent step of converting CH3O* species on M1/W6S8 (M = Ir and Ca). The results of the rate constants are consistent with our kinetic results. These results add new insights into the basic understanding of complex CO hydrogenation reactions.

    更新日期:2019-12-04
  • Protein Engineering of a Metalloprotease in Order to Improve Organic Solvents Stability and Activity
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-03
    Arastoo Badoei-dalfard, Khosro Khajeh, Zahra Karami

    Recently, improve the protease activity in the presence of organic solvents has been appreciated for the researchers. In the current study, we have tried to increase the organic solvent stability of salinovibrio proteolyticus protease (SVP) by site-directed mutagenesis. Five variants were constructed to substitute the surface charged, and polar amino acid residues in SVP with hydrophobic ones (T21V, Y23V, K30P, D25P and N248G) to examine the outcome of surface hydrophobicity on the enzyme efficiency in the presence of organic solvent. The catalytic efficiency of Y23V and N248G mutants not only increased about 1.8 and 2.6 folds in DMF and methanol but also increased it about 3.8 and 5.0 folds in isopropanol and n-propanol, compared to SVP. ∆∆G‡ values of Y23V and N248G variants, increased about 6.5 and 9.5 kcal mol−1 in DMF and methanol, and it improved about 13.6 and 16.6 kcal mol−1 in isopropanol and n-propanol, respectively. These results show that irreversible thermoinactivation rate of protease has a straight relationship with hydrophobicity of organic solvents.

    更新日期:2019-12-04
  • Ultrasound-Ionic Liquid Pretreatment Enhanced Conversion of the Sugary Food Waste to 5-Hydroxymethylfurfural in Ionic Liquid/Solid Acid Catalyst System
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-03
    Qinghua Ji, Xiaojie Yu, Abu El-Gasim A. Yagoub, Mo Li, Olugbenga Abiola Fakayode, Dong Yan, Cunshan Zhou, Li Chen

    The purpose of this study was to efficiently convert the sugary food waste (SFW) to 5-hydroxymethylfurfural (5-HMF) by ultrasound-[Bmim]Cl pretreatment in ionic liquids (ILs)-ion exchange resin system. The effect of ultrasonic pretreatment on SFW and the effect of ultrasonic frequency, ILs, acid resin and catalyst load on SFW conversion were studied. The kinetic curve and the relationship between products and intermediates were studied. In addition, the structure of SFW was also studied by FT-IR and SEM. The results indicated ultrasound-[Bmim]Cl pretreatment can significantly promote the dissolution of cellulose in SFW, and the optimal ultrasonic frequency, solvent and catalyst were 20 + 40 + 60 kHz, [Bmim]Cl and D001-cc resin, respectively; under the best reaction conditions, the maximum 5-HMF yields from the orange and apple wastes were 42.15 and 44.66 mol%, respectively. The kinetic studies showed that the early stage of 100 and 120 °C was mainly the hydrolysis reaction, and late stage was mainly isomerization and dehydration reaction; the early stage of 140 and 160 °C was a rapid hydrolysis and dehydration reaction, and the late stage was mainly the rehydration reaction of 5-HMF. The relationship between the intermediate precursors and 5-HMF showed that the rates of formation and rehydration of 5-HMF increased with the increase in temperature, and the formation reaction was mainly concentrated in zone II. The FT-IR and SEM results of degradation products showed that cellulose in SFW was more easily hydrolyzed at high temperature and long time.

    更新日期:2019-12-04
  • The Effect of Mn Content on Catalytic Activity of the Co–Mn–Ce Catalysts for Propane Oxidation: Importance of Lattice Defect and Surface Active Species
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-03
    Pan Wang, Chenrui Cui, Kai Li, Jing Yi, Lili Lei

    Composite oxide catalysts with Co/Mn/Ce molar ratio of 3:x:2(x = 1, 3, 5 and 7) have been successfully prepared by co-precipitation method. The crystal phase structure, elemental valence, oxygen vacancy and reductivity of the catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), H2 temperature program reduction(H2-TPR) and in situ DRIFTs. The results demonstrated that when x = 1, the Co–Mn–Ce catalyst had the smallest grain size and oxygen vacancy. A flow reactor experimental system was used to analyze the effect of Mn content on light-off temperature (T10) and complete oxidation temperature (T90) of propane oxidation over Co–Mn–Ce catalysts under anhydrous condition and 5% vol of water vapor. The results showed that when x = 1, the catalyst exhibits the highest activity (T10 = 200 °C, T90 = 307 °C) and water tolerance among the four catalysts. It indicated that when x = 1, the incorporation of Mn content can improve the ability of Co–Mn–Ce catalysts for propane oxidation. Based on the Langmuir–Hinshelwood theory, the surface chemical reaction pathway of propane oxidation was constructed and it revealed that the major active sites of Co–Mn–Ce catalysts mainly depend on surface oxygen vacancy and the surface active species (Mn4+,Oads).

    更新日期:2019-12-03
  • Lipase-Catalyzed Highly Efficient 1,6-Conjugated Addition for Synthesis of Triarylmethanes
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-03
    Zeng-Jie Yang, Na Wang, Wei-Xun He, Yuan Yu, Qing-Tian Gong, Xiao-Qi Yu

    Lipase from porcine pancreas (PPL) is first reported to catalyze direct 1,6-conjugated addition for synthesis of triarylmethanes using p-quinonemethides (p-QMs) and 2-naphthols. The catalytic activity of PPL was evaluated through investigating the solvent, the ratio of substrates, the enzyme loading and the temperature of the enzyme-catalyzed reactions. The present method proves to be environmentally friendly and efficient in terms of high yield, green catalyst and simple synthesis method.

    更新日期:2019-12-03
  • Insights into the Phosphate Species on Niobia Treated with H 3 PO 4
    Catal. Lett. (IF 2.372) Pub Date : 2019-12-02
    Angela S. Rocha, Gustavo C. Costa, Lúcia R. Raddi de Araujo, Wilken A. Misael, Ricardo R. Oliveira, Alexandre B. Rocha

    Solid acid catalysts are largely used in several industrial processes, and the development of materials with high activity, selectivity and reusability is a subject of study of research groups around the world. The improvement of oxide acidity could be performed by phosphation with phosphoric acid but the investigation of phosphated niobia is still incipient. In this work, niobia was treated with phosphoric acid solutions to generate catalysts with higher esterification activity at mild condition. The phosphated catalysts were obtained and characterized by XRD, N2 adsorption, NH3 and pyridine chemisorption and FTIR, and were tested in the esterification of acetic acid with ethanol at 60 °C and RT. DFPT calculations indicated that H2PO4 group was the predominant phosphate species on the hydroxylated surface. Theoretical results also show that ethanol adsorbs preferentially at H2PO4 acidic sites on the phosphated catalyst as compared to acetic acid.

    更新日期:2019-12-02
  • Enhanced Catalytic Performance of CuO–ZnO–Al 2 O 3 /SAPO-5 Bifunctional Catalysts for Direct Conversion of Syngas to Light Hydrocarbons and Insights into the Role of Zeolite Acidity
    Catal. Lett. (IF 2.372) Pub Date : 2019-07-17
    Tao Liu, Tianliang Lu, Mingming Yang, Lipeng Zhou, Xiaomei Yang, Beibei Gao, Yunlai Su

    Synthesis of light hydrocarbons from synthesis gas using bifunctional catalysts consisting of CuO–ZnO–Al2O3 methanol synthesis catalysts and SAPO-5 were investigated in a fixed bed reactor. The operating results showed that both the temperature and the ratio of CZA/SAPO-5 influenced the CO conversion and the selectivity of the catalysts. The effects of different dehydration component such as HZSM-5, HMOR and SAPO-5 and subsequently the impact of the zeolite acidity on the catalytic performance were also investigated. Experimental results indicated that zeolites in bifunctional catalysts played the crucial role for the distribution of hydrocarbons, and SAPO-5 was superior to the other zeolites in terms of better conversion and C3–C5 selectivity due to its suitable topology and proper acidic property. The efficiency of the CZA/SAPO-5 catalysts was found to be directly proportional to the Brönsted acid sites density of the zeolite and Brönsted acid sites are the likely zeolite active sites for DME dehydration. High time–space yield (461.6 mg mL−1 h−1) and high selectivity (88.1%) of light hydrocarbons (C3–C5) could be achieved on the CZA/SAPO-5-0.4 catalyst at 290 °C.

    更新日期:2019-11-01
  • Synthesis, Characterization and Catalytic Application of Starch Supported Cuprous Iodide Nanoparticles
    Catal. Lett. (IF 2.372) Pub Date : 2019-07-29
    Sadhucharan Mallick, Priyabrata Mukhi, Poonam Kumari, Kumari Reshmi Mahato, Suryadev Kumar Verma, Debjit Das

    The starch supported cuprous iodide nanoparticles (CuI-NPs@Starch) were synthesized in aqueous medium and characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, energy-dispersive X-ray spectroscopy and atomic absorption spectra analysis. The newly synthesized CuI NPs on starch have been demonstrated first time as an efficient catalyst for the regioselective 3-allylation reaction of N-substituted indoles as well as ring-substituted indoles using various allyl alcohols under moisture and air insensitive conditions.

    更新日期:2019-11-01
  • Penetration of Poisons Along the Monolith Length of a V 2 O 5 /TiO 2 Diesel SCR Catalyst and Its Effect on Activity
    Catal. Lett. (IF 2.372) Pub Date : 2019-07-18
    C. U. Ingemar Odenbrand

    Catalysts used for selective catalytic reduction of NOx on diesel engines were deactivated for 890 and 2299 h in the exhausts from a diesel engine running on Swedish diesel fuel mark 1. The deactivated catalytic monoliths (100 mm long) were cut in 10 mm pieces along their axis and were characterized by physicochemical methods as well as by determination of the activity in the reduction of NOx by NH3 and in the oxidation of NH3 by O2.

    更新日期:2019-11-01
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