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  • Optimization of biogas supply networks considering multiple objectives and auction trading prices of electricity
    BMC Chem. Eng. Pub Date : 2020-01-08
    Jafaru Musa Egieya; Lidija Čuček; Klavdija Zirngast; Adeniyi Jide Isafiade; Zdravko Kravanja

    This contribution presents an hourly-based optimization of a biogas supply network to generate electricity, heat and organic fertilizer while considering multiple objectives and auction trading prices of electricity. The optimization model is formulated as a mixed-integer linear programming (MILP) utilizing a four-layer biogas supply chain. The model accounts for biogas plants based on two capacity levels of methane to produce on average 1 ± 0.1 MW and 5 ± 0.2 MW electricity. Three objectives are put forward: i) maximization of economic profit, ii) maximization of economic profit while considering cost/benefits from greenhouse gas (GHG) emissions (economic+GHG profit) and iii) maximization of sustainability profit. The results show that the economic profit accrued on hourly-based auction trading prices is negative (loss), hence, four additional scenarios are put forward: i) a scenario whereby carbon prices are steadily increased to the prevalent eco-costs/eco-benefits of global warming; ii) a scenario whereby all the electricity auction trading prices are multiplied by certain factors to find the profitability breakeven factor, iii) a scenario whereby shorter time periods are applied, and investment cost of biogas storage is reduced showing a relationship between cost, volume of biogas stored and the variations in electricity production and (iv) a scenario whereby the capacity of the biogas plant is varied from 1 MW and 5 MW as it affects economics of the process. The models are applied to an illustrative case study of agricultural biogas plants in Slovenia where a maximum of three biogas plants could be selected. The results hence present the effects of the simultaneous relationship of economic profit, economic+GHG profit and sustainability profit on the supply and its benefit to decision-making.

    更新日期:2020-01-09
  • Process intensification technologies for CO2 capture and conversion – a review
    BMC Chem. Eng. Pub Date : 2020-01-07
    Abdullahi Adamu; Fernando Russo-Abegão; Kamelia Boodhoo

    With the concentration of CO2 in the atmosphere increasing beyond sustainable limits, much research is currently focused on developing solutions to mitigate this problem. Possible strategies involve sequestering the emitted CO2 for long-term storage deep underground, and conversion of CO2 into value-added products. Conventional processes for each of these solutions often have high-capital costs associated and kinetic limitations in different process steps. Additionally, CO2 is thermodynamically a very stable molecule and difficult to activate. Despite such challenges, a number of methods for CO2 capture and conversion have been investigated including absorption, photocatalysis, electrochemical and thermochemical methods. Conventional technologies employed in these processes often suffer from low selectivity and conversion, and lack energy efficiency. Therefore, suitable process intensification techniques based on equipment, material and process development strategies can play a key role at enabling the deployment of these processes. In this review paper, the cutting-edge intensification technologies being applied in CO2 capture and conversion are reported and discussed, with the main focus on the chemical conversion methods.

    更新日期:2020-01-07
  • Economic feasibility of gasoline production from lignocellulosic wastes in Hong Kong
    BMC Chem. Eng. Pub Date : 2019-12-06
    Weixiang Guan; Sim-Ying Chua; Chi-Wing Tsang; Xiao Chen; Carol Sze Ki Lin; Raymond Sze Wai Fu; Haoquan Hu; Changhai Liang

    In this study, the conceptual process flowsheet was developed and the economic feasibility of woody biomass conversion to biofuel as feedstock was analysed by considering several promising experimental processes for lignin depolymerization, such as hydrodeoxygenation and hydrogenolysis, along with lignocellulosic biomass fractionation processes. The engineering simulation process toward the commercial production of bio-gasoline from lignocellulosic biomass using SuperPro Designer® was modeled. The compatibility of the end products with the current gasoline specifications was evaluated and various blending options were investigated to meet the octane number and Reid vapor pressure requirement of the product. The economic potential of the simulated engineering process was then evaluated from an economic perspective. The operating costs and capital investment of three scenario using three different catalytic systems were estimated and discussed to assess of the potential of commercializing of woody biomass valorization process. The main potential market segments were identified, including the process by-products such as xylose and cellulose pulp. From the economic evaluation study, it was found that selling the biomass fractionation products alone does have a greater profit than valorization of lignin to produce bio-gasoline, with net present value of RMB 22,653,000 and RMB 177,000, respectively at the same return on investment if the plant is set up in Hong Kong. It was also found that catalysts play a pivotal role in determination of the profitability in the valorization process, not only because of the price of the catalyst, but also the product distributions obtained with various types of it. To obtain the same gross profit, the sale price of bio-gasoline has to be set higher with platinum catalysts than with ruthenium catalysts (nearly 10 folds). Thus, catalyst development and process improvement are crucial in the establishment of bio-based circular economy.

    更新日期:2019-12-06
  • BMC Chemical Engineering: an open access publishing venue for the chemical engineering community
    BMC Chem. Eng. Pub Date : 2019-01-30
    Harriet E. Manning; Robert Field; Rafiqul Gani; Adam Lee; Hyunjoo Lee; Jay H. Lee; Gongping Liu; Sang Yup Lee

    This editorial accompanies the launch of BMC Chemical Engineering, a new addition to the BMC Series. The journal follows the BMC Series ethos of being fully open access and making editorial decisions based on scientific validity and quality rather than perceived interest or impact. The scope of the journal is broad, considering fundamental and applied research in all areas of chemical engineering with the ultimate aim of providing an inclusive, community-focussed venue to ensure that the most relevant chemical engineering research is disseminated widely for all to read and build upon.

    更新日期:2019-11-28
  • Incorporation of Cu3BTC2 nanocrystals to increase the permeability of polymeric membranes in O2/N2 separation
    BMC Chem. Eng. Pub Date : 2019-01-30
    Chong Yang Chuah; Tae-Hyun Bae

    To increase permeability in O2/N2 separation without compromising selectivity, Cu3BTC2 (or HKUST-1) nanocrystals, which possess well-defined channels and high surface area, were used as the filler for mixed-matrix membrane fabrication. The Cu3BTC2 nanocrystals, which were synthesized at room temperature with a facile method, showed desirable physical properties and porosity comparable to those of a commercial Cu3BTC2 adsorbent (Basolite C300). High-quality mixed-matrix membranes without appreciable defects were successfully fabricated with both Matrimid and polysulfone, which are commercial membrane polymers that suffer from poor permeability. Gas permeation testing revealed that 20 wt% Cu3BTC2 nanocrystals loading dramatically improved the O2 permeability of both polymer membranes (106% for Matrimid and 379% for polysulfone), with modest increases in O2/N2 selectivity. A detailed analysis of diffusivity and solubility showed that the overall O2/N2 diffusion selectivity was improved substantially over that of a neat polymeric membrane with the incorporation of Cu3BTC2 nanocrystals. A comparative study with literature data demonstrated that Cu3BTC2 nanocrystals are far more effective than other metal-organic framework fillers tested to increase permeability in O2/N2 separation.

    更新日期:2019-11-28
  • Noble gas separation by a MOF with one-dimensional channels
    BMC Chem. Eng. Pub Date : 2019-01-30
    Yang Liu; Jing Liu; Jianbo Hu

    Noble gas separation by microporous materials is a promising alternative to energy-intensive cryogenic distillation method by reducing the separation cost; however, developing novel microporous materials with excellent noble gas separation performance is still challenging due to closing chemical and physical properties among the gases. In this study, we propose to separate the noble gases (He, Ne, Ar, Kr and Xe) utilizing a metal organic framework (MOF), named SIFSIX-3-Zn, with ultra-micron sized 1-dimenssional (1D) channels (3.84 Å). Density functional theory (DFT) calculations reveal that the 1D channels provide significant adsorption potential differences among the noble gas molecules in various sizes: the larger the molecular size, the stronger the adsorption potential. Grand canonical Monte Carlo (GCMC) simulations verify that the MOF exhibits exceptional equilibrium separation performance of noble gases. Remarkably, Xe/He and Xe/Ne adsorption selectivity can be as high as 645 and 596, respectively, at 298 K and 10 kPa. While Xe/Kr selectivity in mixed gas is around 12 with a Xe adsorption amount of about 2.27 mmol/g at 273 K and 100 kPa, making SIFSIX-3-Zn one of the promising materials for equilibrium separation of Xe/Kr mixtures.

    更新日期:2019-11-28
  • Integration of aqueous (micellar) two-phase systems on the proteins separation
    BMC Chem. Eng. Pub Date : 2019-01-30
    Filipa A. Vicente; João H. P. M. Santos; Inês M. M. Pereira; Cátia V. M. Gonçalves; Ana C. R. V. Dias; João A. P. Coutinho; Sónia P. M. Ventura

    A two-step approach combining an aqueous two-phase system (ATPS) and an aqueous micellar two-phase system (AMTPS), both based on the thermo-responsive copolymer Pluronic L-35, is here proposed for the purification of proteins and tested on the sequential separation of three model proteins, cytochrome c, ovalbumin and azocasein. Phase diagrams were established for the ATPS, as well as co-existence curves for the AMTPS. Then, by scanning and choosing the most promising systems, the separation of the three model proteins was performed. The aqueous systems based on Pluronic L-35 and potassium phosphate buffer (pH = 6.6) proved to be the most selective platform to separate the proteins (SAzo/Cyt = 1667; SOva/Cyt = 5.33 e SAzo/Ova = 1676). The consecutive fractionation of these proteins as well as their isolation from the aqueous phases was proposed, envisaging the industrial application of this downstream strategy. The environmental impact of this downstream process was studied, considering the carbon footprint as the final output. The main contribution to the total carbon footprint comes from the ultrafiltration (~ 49%) and the acid precipitation (~ 33%) due to the energy consumption in the centrifugation. The ATPS step contributes to ~ 17% while the AMTPS only accounts for 0.30% of the total carbon footprint.

    更新日期:2019-11-28
  • Chemical engineering role in the use of renewable energy and alternative carbon sources in chemical production
    BMC Chem. Eng. Pub Date : 2019-02-06
    Gabriele Centi; Gaetano Iaquaniello; Siglinda Perathoner

    There is a demand for new chemical reaction technologies and associated engineering aspects due to on-going transition in energy and chemistry associated to moving out progressively from the use of fossil fuels. Focus is given in this review on two main aspects: i) the development of alternative carbon sources and ii) the integration of renewable energy in the chemical production. It is shown how addressing properly these aspects requires to develop also a) new tools for chemical engineering assessment and b) innovative methodologies for the development of the materials, reactors and processes. This review evidences the need to accelerate studies on these directions, being a crucial element to catalyze the transition to a more sustainable use of energy and chemistry. It is remarked, however, the need to go beyond the traditional approaches, with some examples given. In fact, the presence of radical changes in the way of production is underlined, requiring thus novel fundamentals and applied engineering approaches.

    更新日期:2019-11-28
  • Application of soda-AQ pulping to agricultural waste (okra stalks) from Sudan
    BMC Chem. Eng. Pub Date : 2019-02-20
    Safaa Hassan Omer; Tarig Osman Khider; Osman Taha Elzaki; Salaheldin Dafalla Mohieldin; Suhair Kamal Shomeina

    Abelmoschus esculentus okra as whole stalks was examined for its suitability for pulp and paper production. It’s, fiber dimensions, morphological and chemical characteristics were reported. The pulping trials with soda- Anthraquinone (AQ,) at different chemical charges. Application of 21% as NaOH with 0.1% AQ gave good results in degree of delignification, mechanical properties. Utilization of okra pulps and blender is recommended due to good pulp properties. Evaluation of general characteristics of okra stalks in terms of fiber dimensions morphological indices, chemical components, Soda-AQ cooking and to study their suitability for paper production. Okra Fiber dimension evaluation done after maceration with a mixture of 30% hydrogen peroxide and acetic acid (1:1) for core and bark parts separately and was carried out under microscope staining with aqueous safranin. The Soda-AQ cooks at different active alkali levels were calculated as NaOH on oven dry raw material. The fibers from okra stalks studied (core and bark) were in the range of hardwood fibers, with short fiber length, especially the core with more or less moderate walls, narrow lumen and fiber width. The fiber width of bark was medium –narrow with medium wall thickness. The ash content was rather high whereas the silica content was comparatively high The hot water extractives from okra stalks was (4.1%), cold water (0.4) ethanol/ cyclohexane (1.1), ethanol extractives (1.2%) and 1% NaOH (27.6%) were rather high. The cellulose (Kurschner-Hoffer) was (48.5%) The lignin content was (15.3%) which was relatively moderate. The use of 0.1% AQ enhanced the delignification in the three trials applied. The screened yield increase with increase of chemical dose applied while the rejects decrease. When 21% NaOH was applied, the screened yield was 32.2% with negligible amount of rejects, however with lower alkali charge 18% the screened yield was decreased to 28% with very low rejects 1.5%. on the other hand rejects were increased to 7% when 15% NaOH was applied with very low screened yield 19%.The pulps produced from okra soda-AQ are suitable for production of printing and writing papers and it is advisable to use them in blending due to good papermaking properties.

    更新日期:2019-11-28
  • Energy and CO2 management for chemical and related industries: issues, opportunities and challenges
    BMC Chem. Eng. Pub Date : 2019-03-07
    Ramsagar Vooradi; Sarath Babu Anne; Anjan K. Tula; Mario R. Eden; Rafiqul Gani

    This paper gives a brief review of energy and CO2 emissions related topics resulting from the chemical and related industries. The main issues, challenges and opportunities are highlighted together with perspectives of process alternatives for more efficient energy consumption and CO2 emission management. Analysis of the data indicate that not all available energy resources are being utilized efficiently, while the energy resources causing the largest emissions of CO2 are being used in the largest amounts. Also, the chemical and related industries are among the largest consumers of energy, indicating that solutions for reduction of energy consumption and CO2 emissions in these industries need to be investigated. Information on promising alternatives for reduction of energy consumption and CO2 emissions are collected and a selection of them are evaluated. Also, two specific case studies involving energy intensive separation operations replaced by recently developed technologies that may achieve significant reductions in energy consumption, CO2 emissions and total annualized costs are presented. Through these examples issues of energy need versus CO2 neutral design, sustainable conversion, retrofit design, and process intensification for chemical and related industries are highlighted.

    更新日期:2019-11-28
  • Heterogeneous catalysts for catalytic CO2 conversion into value-added chemicals
    BMC Chem. Eng. Pub Date : 2019-03-27
    Ho Seok Whang; Jinkyu Lim; Min Suk Choi; Jonghyeok Lee; Hyunjoo Lee

    As climate change becomes increasingly evident, reducing greenhouse gases including CO2 has received growing attention. Because CO2 is thermodynamically very stable, its conversion into value-added chemicals such as CO, CH4, or C2H4 is difficult, and developing efficient catalysts for CO2 conversion is important work. CO2 can be converted using the gas-phase reaction, liquid-phase reaction, photocatalytic reaction, or electrochemical reaction. The gas-phase reaction includes the dry reforming of methane using CO2 and CH4, or CO2 hydrogenation using CO2 and H2. The liquid-phase reaction includes formic acid formation from pressurized CO2 and H2 in aqueous solution. The photocatalytic reaction is commonly known as artificial photo-synthesis, and produces chemicals from CO2 and H2O under light irradiation. The electrochemical reaction can produce chemicals from CO2 and H2O using electricity. In this review, the heterogeneous catalysts used for the gas-phase reaction or electrochemical reactions are discussed, because the liquid-phase reaction and photocatalytic reaction typically suffer from low productivity and poor durability. Because the gas-phase reaction requires a high reaction temperature of > 600 °C, obtaining good durability is important. The strategies for designing catalysts with good activity and durability will be introduced. Various materials have been tested for electrochemical conversion, and it has been shown that specific metals can produce specific products, such as Au or Ag for CO, Sn or Bi for formate, Cu for C2H4. Other unconventional catalysts for electrochemical CO2 reduction are also introduced.

    更新日期:2019-11-28
  • Energy systems engineering - a guided tour
    BMC Chem. Eng. Pub Date : 2019-04-10
    C. Doga Demirhan; William W. Tso; Gerald S. Ogumerem; Efstratios N. Pistikopoulos

    As future energy systems aim to be more efficient, cost-effective, environmentally benign, and interconnected with each other, their design and operation become ever challenging tasks for decision-makers, engineers, and scientists. Sustainability of life on earth will be heavily affected by the improvements of these complex energy systems. Therefore, experts from various fields need to come together to find common solution strategies. However, since different technologies are usually developed separately by their own technical community, a generally accepted unified systematic approach to tackle integrated systems is lacking. With this article, we want to introduce and highlight the power of energy systems engineering as a generic framework to arrive at synergistic solutions to complex energy and environmental problems. Tools of energy systems engineering are numerous, and its application areas cover a wide range of energy systems. In this commentary, we present an overview of state-of-the-art methodologies of energy systems engineering, list its applications and describe few examples in detail, and finally introduce some possible new directions.

    更新日期:2019-11-28
  • Liquid-phase hydrogenation of bio-refined succinic acid to 1,4-butanediol using bimetallic catalysts
    BMC Chem. Eng. Pub Date : 2019-04-24
    Pabitra Kumar Baidya; Ujjaini Sarkar; Raffaela Villa; Suvra Sadhukhan

    Development of a Crotalaria juncea based biorefinery produce large quantity of waste glycerol after trans-esterification of the juncea seeds. This glycerol, after purification, is used as a substrate for producing succinic acid on a microbial route. Hydrogenation of this bio-refined succinic acid is carried out under high pressure in order to produce 1,4-butanediol (BDO) using a batch slurry reactor with cobalt supported ruthenium bimetallic catalysts, synthesized in-house. It is demonstrated that, using small amounts of ruthenium to cobalt increases the overall hydrogenation activity for the production of 1,4-butanediol. Hydrogenation reactions are carried out at various operating temperatures and pressures along with changes in the mixing ratios of ruthenium chloride and cobalt chloride hexahydrate, which are used to synthesize the catalyst. The Ru-Co bimetallic catalysts are characterized by XRD, FE-SEM and TGA. Concentrations of the hydrogenation product are analyzed using Gas chromatography-Mass spectrometry (GC-MS). Statistical analysis of the overall hydrogenation process is performed using a Box-Behnken Design (BBD).

    更新日期:2019-11-28
  • Rheological properties of concentrated slurries of harvested, incubated and ruptured Nannochloropsis sp. cells
    BMC Chem. Eng. Pub Date : 2019-05-08
    Srinivas Mettu; Shunyu Yao; Sam Q. K. Law; Zheng Sun; Peter J. Scales; Muthupandian Ashokkumar; Gregory J. O. Martin

    Biorefining of microalgae biomass requires processing of high-solids (> 10%) slurries. To date there is little knowledge of how processes for weakening and rupturing microalgae cells affect the rheological properties of these materials. To fill this gap in the literature, the rheological properties of concentrated slurries of marine microalgae Nannochloropsis sp. were investigated as a function of processing and solids concentration (12, 20 and 24% w/w). Freshly harvested, incubated (autolysed), and high-pressure homogenised (HPH) slurries were found to be shear thinning up to a shear rate of approximately 200 s− 1. Viscosity increases were far more prominent for partially processed versus unprocessed algal pastes at the higher concentrations. Slurry viscosity as a function of cell volume fraction could not be fitted to the Krieger-Dougherty model due to a network structure resulting from extracellular polymeric substances (EPS) and the intracellular cell components released during incubation and cell rupture. The 24% slurry, which was near the close packing limit, was much more viscous than the less concentrated slurries when comprising whole cells (i.e. harvested and incubated slurries). Cell rupture by HPH completely altered the characteristics of the slurry, increasing the viscosity of even the less concentrated slurries, and producing irreversible shear thinning behaviour. The magnitude of the increases in viscosities and the irreversible shear thinning behaviour observed in this study, have significant implications for processing and optimising the solids concentration of algal slurries.

    更新日期:2019-11-28
  • 2D-enabled membranes: materials and beyond
    BMC Chem. Eng. Pub Date : 2019-05-22
    Taehoon Hyun; Jinhong Jeong; Ari Chae; Young Kwan Kim; Dong-Yeun Koh

    Membranes could reform the field of molecular separations by enabling new low energy manufacturing technologies. This review article discusses the current state of the art and the potential in the 2D-enabled membrane separation processes by highlighting emerging and existing areas in which robust 2D materials significantly impact the energy-efficient separation process. Analysis of 2D-enabled membrane classes and prospective materials for 2D-enabled membranes are also discussed with emphasis on the surface chemistry of basal plane engineered 2D materials.

    更新日期:2019-11-28
  • Lipids detection and quantification in oleaginous microorganisms: an overview of the current state of the art
    BMC Chem. Eng. Pub Date : 2019-06-05
    Alok Patel; Io Antonopoulou; Josefine Enman; Ulrika Rova; Paul Christakopoulos; Leonidas Matsakas

    Oleaginous microorganisms are among the most promising feedstocks for the production of lipids for biofuels and oleochemicals. Lipids are synthesized in intracellular compartments in the form of lipid droplets. Therefore, their qualitative and quantitative analysis requires an initial pretreatment step that allows their extraction. Lipid extraction techniques vary with the type of microorganism but, in general, the presence of an outer membrane or cell wall limits their recovery. This review discusses the various types of oleaginous microorganisms, their lipid accumulating capabilities, lipid extraction techniques, and the pretreatment of cellular biomass for enhanced lipid recovery. Conventional methods for lipid quantification include gravimetric and chromatographic approaches; whereas non-conventional methods are based on infrared, Raman, nuclear magnetic resonance, and fluorescence spectroscopic analysis. Recent advances in these methods, their limitations, and fields of application are discussed, with the aim of providing a guide for selecting the best method or combination of methods for lipid quantification.

    更新日期:2019-11-28
  • On the application of the Spiegler-Kedem model to forward osmosis
    BMC Chem. Eng. Pub Date : 2019-06-19
    Jun Jie Wu

    In Forward Osmosis the diffusion of the solute is counter to that of the solvent i.e. there is so-called “reverse salt diffusion”. Furthermore, the ratio of the two fluxes is generally taken to be a constant because of the assumption of ideal semi-permeability. However with the Spiegler-Kedem (S-K) model there is an allowance for a minor deviation from ideal semi-permeability and the ratio of the solute flux and solvent flux is no longer constant. The theoretical variation of the solute flux with increasing draw solution concentration is illustrated for various degrees of deviation from ideal semi-permeability. A novel variant of the S-K model is also introduced and predictions compared with those obtained using the standard form. With the acceptance that the form of “breakthrough” involving co-current flow is impossible, a limitation is imposed upon the S-K model but even with this limitation the theoretically predicted variation of solvent flux with increasing draw concentration is for certain sets of parameters of an unexpected form for minor deviation from ideal semi-permeability. That intriguing counter-intuitive outcomes can result from application of the S-K model indicates a need to rethink its formulation of the equations and the expressions for the coefficients. This will have implications for forward osmosis and possibly reverse osmosis modelling.

    更新日期:2019-11-28
  • NiMoAl catalysts derived from heptamolybdate-intercalated layered double hydroxides for hydrodeoxygenation of anisole
    BMC Chem. Eng. Pub Date : 2019-06-27
    Chuang Li; Xingzhao Zhang; Xiao Chen; Zhijian Peng; Chi-Wing Tsang; Changhai Liang

    The catalytic performance of NiMoAl catalysts derived from layered double hydroxide (LDH) precursors with molybdenum species incorporated into the interlayers was investigated for the hydrodeoxygenation (HDO) of anisole as a model compound of the lignin. The results showed that high dispersion of small Ni nanoparticles with 2–5 nm due to the pinning effect of Mo from Mo7O246− intercalated the LDHs. Due to presence of the oxygen vacancy sites on the molybdenum oxide, the NiMoAl catalysts exhibit higher conversion of anisole than the corresponding NiAl catalyst. The activity for hydrodeoxygenation was enhanced with the increased content of molybdenum species, which can be attributed to the larger amount of acid sites-promoted removal of oxygen from anisole. In addition, the NiMoAl catalysts show higher resistance to deactivation than the NiAl catalyst, and can be broadly applied to other hydrodeoxygenation reactions.

    更新日期:2019-11-28
  • Advances in mechanochemical processes for biomass valorization
    BMC Chem. Eng. Pub Date : 2019-07-11
    Camilla Maria Cova; Rafael Luque

    Compared to standard time and solvent consuming procedures, mechanically-assisted processes offer numerous environmentally-friendly advantages for nano-catalytically active materials design. Mechanochemistry displays high reproducibility, simplicity, cleanliness and versatility, avoiding, in most cases, the use of any solvent. Moreover, mechanically-assisted procedures are normally faster and cheaper as compared to conventional processes. Due to these outstanding characteristics, mechanochemistry has evolved as an exceptional technique for the synthesis of novel and advanced catalysts designed for a large range of applications. The literature reports numerous works showing that mechanosynthetic procedures offer more promising paths than traditional solvent-based techniques. This review aims to disclose the latest advances in the mechanochemical assisted synthesis of catalytically active materials, focusing on nanocatalysts designed for biomass conversion and on bio-based catalysts.

    更新日期:2019-11-28
  • Standing-wave Design of Three-Zone, open-loop non-isocratic SMB for purification
    BMC Chem. Eng. Pub Date : 2019-07-25
    David Harvey; Yi Ding; Nien-Hwa Linda Wang

    Chromatography with step changes in modulator properties such as pH, solvent strength, or ionic strength to facilitate desorption is widely used in the purification of proteins and other chemicals. Step changes can be incorporated into non-isocratic simulated moving beds; however, applications of such systems have been limited because one must select numerous operating parameters (zone velocities and port velocities). The operating parameters must be selected correctly to achieve high purity, yield, and productivity and depend on a large number of system parameters (feed, material, and equipment parameters). To address this challenge, the Standing-Wave Design method has been developed for three-zone, open-loop, non-isocratic, and non-ideal systems with both linear and non-linear isotherms. This method directly links the operating parameters to the system parameters. The operating parameters can be solved from a set of algebraic equations. In contrast, for non-ideal systems, previous literature design methods require extensive search using rate model simulations, which involve solving partial differential equations at each grid point. Two examples were tested for the effectiveness of the SWD method using rate model simulations. In both examples, sorbent productivity was pressure limited. Higher pressure sorbents or equipment would lead to higher sorbent productivity. In the first example, a 3-zone open-loop simulated moving bed was designed and compared with an optimal batch step-wise elution system. Compared to batch step-wise elution systems, the simulations showed that the 3-zone open-loop SMB could give an order of magnitude higher productivity in systems with weakly competing impurities and two orders of magnitude higher in systems with strongly adsorbing impurities. In the second example, the simulations showed that an SMB designed using the Standing-Wave method could achieve an order of magnitude higher productivity than a system designed using the Triangle Theory.

    更新日期:2019-11-28
  • The potential of polymers of intrinsic microporosity (PIMs) and PIM/graphene composites for pervaporation membranes
    BMC Chem. Eng. Pub Date : 2019-08-08
    Richard A. Kirk; Maia Putintseva; Alexey Volkov; Peter M. Budd

    Pervaporation (PV), a membrane process in which the feed is a liquid mixture and the permeate is removed as a vapour, offers an energy-efficient alternative to conventional separation processes such as distillation, and can be applied to mixtures that are difficult to separate, such as azeotropes. Here the principles of pervaporation and its industrial applications are outlined. Two classes of material that show promise for use in PV membranes are described: Polymers of intrinsic microporosity (PIMs) and 2D materials such as graphene. The literature regarding PV utilizing the prototypical PIM (PIM-1) and it hydrophilic hydrolysed form (cPIM-1) is reviewed. Self-standing PIM-1 membranes give competitive results compared to other membranes reported in the literature for the separation of alcohols and other volatile organic compounds from aqueous solution, and for organic/organic separations such as methanol/ethylene glycol and dimethyl carbonate/methanol mixtures. Blends of cPIM-1 with conventional polymers improve the flux for dehydration of alcohols. The incorporation of fillers, such as functionalised graphene-like fillers, into PIM-1 to form mixed matrix membranes can enhance the separation performance. Thin film composite (TFC) membranes enable very high fluxes to be achieved when a suitable support with high surface porosity is utilised. When functionalised graphene-like fillers are introduced into the selective layer of a TFC membrane, the lateral size of the flakes needs to be carefully controlled. There is a wide range of PIMs and 2D materials yet to be explored for PV applications, which offer potential to create bespoke membranes for a wide variety of organic/aqueous and organic/organic separations.

    更新日期:2019-11-28
  • Optimization-based investigations of a two-phase thermofluidic oscillator for low-grade heat conversion
    BMC Chem. Eng. Pub Date : 2019-08-22
    Yukun Wang; Christos N. Markides; Benoît Chachuat

    The non-inertive-feedback thermofluidic engine (NIFTE) is a two-phase thermofluidic oscillator capable of utilizing heat supplied at a steady temperature to induce persistent thermal-fluid oscillations. The NIFTE is appealing in its simplicity and ability to operate across small temperature differences, reported as low as 30 ∘C in early prototypes. But it is also expected that the NIFTE will exhibit low efficiencies relative to conventional heat recovery technologies that target higher-grade heat conversion. Mathematical modeling can help assess the full potential of the NIFTE technology. Our analysis is based on a nonlinear model of the NIFTE, which we extend to encompass irreversible thermal losses. Both models predict that a NIFTE may exhibit multiple cyclic steady states (CSS) for certain design configurations, either stable or unstable, a behavior that had never been hypothesized. A parametric analysis of the main design parameters of the NIFTE is then performed for both models. The results confirm that failure to include the irreversible thermal losses in the NIFTE model can grossly overpredict its performance, especially over extended parameter domains. Lastly, we use the NIFTE model with irreversible thermal losses to assess the optimization potential of this technology by conducting a multi-objective optimization. Our results reveal that most of the optimization potential is achievable via targeted modifications of three design parameters only. The Pareto frontier between exergetic efficiency and power output is also found to be highly sensitive to these optimized parameters. The NIFTE is of practical relevance to a range of applications, including the development of solar-driven pumps to support small-holder irrigation in the developing world. Given its low capital cost, potential improvements greater than 50% in efficiency or power output are significant for the uptake of this technology. Conventional heat recovery technologies are known to have higher efficiencies than those reported in this work, but they also have more complex designs and operations, higher capital costs, and may not even be feasible for the temperature differences considered herein. Future work should focus on confirming this model-based assessment via dedicated experimental campaigns and on investigating design modifications to mitigate irreversible thermal losses.

    更新日期:2019-11-28
  • Membrane condenser as emerging technology for water recovery and gas pre-treatment: current status and perspectives
    BMC Chem. Eng. Pub Date : 2019-09-12
    Adele Brunetti; Francesca Macedonio; Giuseppe Barbieri; Enrico Drioli

    The recent roadmap of SPIRE initiative includes the development of “new separation, extraction and pre-treatment technologies” as one of the “key actions” for boosting sustainability, enhancing the availability and quality of existing resources. Membrane condenser is an innovative technology that was recently investigated for the recovery of water vapor for waste gaseous streams, such as flue gas, biogas, cooling tower plumes, etc. Recently, it has been also proposed as pre-treatment unit for the reduction and control of contaminants in waste gaseous streams (SOx and NOx, VOCs, H2S, NH3, siloxanes, halides, particulates, organic pollutants). This perspective article reports recent progresses in the applications of the membrane condenser in the treatment of various gaseous streams for water recovery and contaminant control. After an overview of the operating principle, the membranes used, and the main results achieved, the work also proposes the role of this technology as pre-treatment stage to other separation technologies. The potentialities of the technology are also discussed aspiring to pave the way towards the development of an innovative technology where membrane condenser can cover a key role in redesigning the whole upgrading process.

    更新日期:2019-11-28
  • Synthesis and analysis of separation processes for extracellular chemicals generated from microbial conversions
    BMC Chem. Eng. Pub Date : 2019-10-28
    Wenzhao Wu; Kirti M Yenkie; Christos T. Maravelias

    Recent advances in metabolic engineering have enabled the production of chemicals via bio-conversion using microbes. However, downstream separation accounts for 60–80% of the total production cost in many cases. Previous work on microbial production of extracellular chemicals has been mainly restricted to microbiology, biochemistry, metabolomics, or techno-economic analysis for specific product examples such as succinic acid, xanthan gum, lycopene, etc. In these studies, microbial production and separation technologies were selected apriori without considering any competing alternatives. However, technology selection in downstream separation and purification processes can have a major impact on the overall costs, product recovery, and purity. To this end, we apply a superstructure optimization based framework that enables the identification of critical technologies and their associated parameters in the synthesis and analysis of separation processes for extracellular chemicals generated from microbial conversions. We divide extracellular chemicals into three categories based on their physical properties, such as water solubility, physical state, relative density, volatility, etc. We analyze three major extracellular product categories (insoluble light, insoluble heavy and soluble) in detail and provide suggestions for additional product categories through extension of our analysis framework. The proposed analysis and results provide significant insights for technology selection and enable streamlined decision making when faced with any microbial product that is released extracellularly. The parameter variability analysis for the product as well as the associated technologies and comparison with novel alternatives is a key feature which forms the basis for designing better bioseparation strategies that have potential for commercial scalability and can compete with traditional chemical production methods.

    更新日期:2019-11-28
  • Engineering microbial chemical factories using metabolic models
    BMC Chem. Eng. Pub Date : 2019-11-01
    Debolina Sarkar; Costas D. Maranas

    Living organisms in analogy with chemical factories use simple molecules such as sugars to produce a variety of compounds which are necessary for sustaining life and some of which are also commercially valuable. The metabolisms of simple (such as bacteria) and higher organisms (such as plants) alike can be exploited to convert low value inputs into high value outputs. Unlike conventional chemical factories, microbial production chassis are not necessarily tuned for a single product overproduction. Despite the same end goal, metabolic and industrial engineers rely on different techniques for achieving productivity goals. Metabolic engineers cannot affect reaction rates by manipulating pressure and temperature, instead they have at their disposal a range of enzymes and transcriptional and translational processes to optimize accordingly. In this review, we first highlight how various analytical approaches used in metabolic engineering and synthetic biology are related to concepts developed in systems and control engineering. Specifically, how algorithmic concepts derived in operations research can help explain the structure and organization of metabolic networks. Finally, we consider the future directions and challenges faced by the field of metabolic network modeling and the possible contributions of concepts drawn from the classical fields of chemical and control engineering. The aim of the review is to offer a current perspective of metabolic engineering and all that it entails without requiring specialized knowledge of bioinformatics or systems biology.

    更新日期:2019-11-28
  • Effect of ionic liquids as entrainers on the dynamic behavior of ethanol-water extractive columns
    BMC Chem. Eng. Pub Date : 2019-11-18
    Nelly Ramírez-Corona; Andrés Schramm-Flores; Sofía Reyes-Lombardo; Arturo Jiménez-Gutiérrez

    Ionic liquids (ILs) have been recently considered as potential entrainers for extractive distillation. The use of ILs may affect the vapor-liquid properties to aid the separation of azeotropic mixtures. In particular, their effectiveness has been observed for ethanol dehydration, showing promising perspectives for their industrial implementation. However, there is still a lack of information about the effect of ILs on the system controllability. The objective of this work is to explore the dynamic implications of the use of two types of ionic liquids on the ethanol dehydration process. An equimolar feed mixture of ethanol and water was considered, and different IL concentrations were tested. The results show that changing the IL concentration affect the degree of stabilization of the product stream, even when smooth dynamic responses were in many cases observed.

    更新日期:2019-11-28
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