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Interfacial Structure-Determined Reaction Pathway and Selectivity for 5-(Hydroxymethyl)furfural Hydrogenation over Cu-Based Catalysts
ACS Catalysis ( IF 12.9 ) Pub Date : 2020-01-03 , DOI: 10.1021/acscatal.9b03630
Qian Wang 1 , Junting Feng 1 , Lirong Zheng 2 , Bin Wang 3 , Ruxia Bi 1 , Yufei He 1 , Haichao Liu 4 , Dianqing Li 1
Affiliation  

The catalytic upgrading of biomass-derived feedstocks to valuable chemicals generally requires catalysts with integrated active sites and tuned structures for selective activation of their multifunctional groups. Herein, we fabricated different Cu-based catalysts with multiple interfaces by facile reduction of layered double hydroxides (LDHs), aimed at controlling the reaction pathway and product selectivity in the hydrogenation of 5-(hydroxymethyl)furfural (HMF), an important biomass-based platform molecule. These Cu catalysts were characterized by XRD, Raman, TPR, HAADF-STEM, and in situ XAFS. For Cu/MgAlOx, derived from CuMg5Al2-LDHs, Cu particles were partially encapsulated by a MgAlOx support, thus forming highly intimate Cu–MgAlOx interfaces. On [email protected]/CoAlOx, derived from CuCoxAl2-LDHs, together with a Cu–CoAlOx interface, partially reduced ultrasmall Co clusters were mounted around Cu particles to form a metallic Co–Cu interface, which is tunable by varying the Cu/Co ratio. As expected, Cu/MgAlOx was only active in C═O hydrogenation to produce 2,5-bis(hydroxymethyl)furan (DHMF) in a 92.7% yield, while [email protected]/3CoAlOx sequentially catalyzed the C═O hydrogenation and C–OH hydrogenolysis to yield as high as 98.5% 2,5-dimethylfuran (DMF), in sharp contrast to [email protected]/5CoAlOx, which further broke the C═C bonds of DMF to yield 83.6% 2,5-dimethyltetrahydrofuran (DMTHF). The dependence of the reaction pathway and product selectivity on the composition and properties of the interface was revealed by identifying various intermediates using in situ IR. Specifically, HMF transformed into an O-bound intermediate on the Cu sites over the Cu–MgAlOx, while the unsaturated interfacial Cu–CoAlOx structure served as dual active sites to form a C,O-bound intermediate, thus leading to different products. In addition, the tunable Cu–Co interfacial sites remarkably influenced the adsorption modes of C═C bonds in the furan ring. This work provides a rationale for controlling the reaction pathway and product selectivity for complicated biomass reactions via the controllable construction of multiple interfaces.

中文翻译:

铜基催化剂上界面结构决定的5-(羟甲基)糠醛加氢反应路径和选择性

将生物质衍生的原料催化提纯成有价值的化学物质通常需要具有集成活性位点和调整结构的催化剂,以选择性活化其多功能基团。在此,我们通过方便地还原层状双氢氧化物(LDHs)来制备具有多个界面的不同Cu基催化剂,旨在控制重要生物量的5-(羟甲基)糠醛(HMF)加氢中的反应途径和产物选择性。基于平台的分子。这些铜催化剂的特征在于XRD,拉曼,TPR,HAADF-STEM和原位XAFS。对于源自CuMg 5 Al 2 -LDHs的Cu / MgAlO x,Cu颗粒被MgAlO x部分包封支持,从而形成高度亲密的Cu–MgAlO x界面。在源自CuCo x Al 2 -LDHs的[受电子邮件保护] / CoAlO x以及Cu–CoAlO x界面上,部分还原的超小Co簇安装在Cu颗粒周围,形成金属Co–Cu界面,该界面可通过改变铜/钴比。如预期的那样,Cu / MgAlO x仅在C = O氢化中具有活性,以92.7%的产率生产2,5-双(羟甲基)呋喃(DHMF),而[电子邮件保护] / 3CoAlO x依次催化C = O氢化和C–OH氢解可产生高达98.5%的2,5-二甲基呋喃(DMF),与[受电子邮件保护] / 5CoAlO x形成鲜明对比,这进一步破坏了DMF的C═C键,生成83.6%的2,5-二甲基四氢呋喃(DMTHF)。通过使用原位红外鉴定各种中间体,揭示了反应途径和产物选择性对界面组成和性质的依赖性。具体而言,HMF在Cu–MgAlO x上的Cu位上转变为O结合中间体,而不饱和界面Cu–CoAlO x结构充当双重活性位点以形成C,O结合的中间体,从而产生不同的产物。另外,可调的Cu-Co界面位显着影响了呋喃环中C═C键的吸附方式。这项工作为通过可控的多个界面结构控制复杂生物质反应的反应途径和产物选择性提供了理论依据。
更新日期:2020-01-04
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