Critical Role of CUS in the Au/MOF-808(Zr) Catalyst for Reaction of CO2 with Amine/H2 via N-Methylation and N-Formylation
Critical Role of CUS in the Au/MOF-808(Zr) Catalyst for Reaction of CO2 with Amine/H2 via N-Methylation and N-Formylation
复制标题
CUS 在 Au/MOF-808(Zr) 催化剂中对 CO2 与胺/H2 通过 N-甲基化和 N-甲酰化反应的关键作用
DOI：
10.1021/acs.iecr.0c00242
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发表时间：
2020-04-08
影响因子：
4.2
通讯作者：
Ji, Shengfu
中科院分区：
文献类型：
--
作者：
Mu, Jincheng;Liu, Jianfang;Ji, Shengfu
采用热回流法合成了具有不饱和（CUS）Zr 4+配位中心的MOF-808（Zr），并采用浸渍-还原法制备了一系列不同Au负载量的Au/MOF-808（Zr）催化剂。采用X射线衍射、傅里叶变换红外光谱、高分辨透射电子显微镜、X射线光电子能谱、N2吸附-脱附、电感耦合等离子体质谱和NH3程序升温脱附等表征手段对催化剂的结构进行了表征。在间歇式反应器中研究了苯胺/H-2在CO2中催化N-甲基化和N-甲基化反应的活性。结果表明，催化剂中的MOF-808（Zr）结构质量好，无损伤。Au纳米颗粒（NP）高度分散在M0 F-808（Zr）笼的表面上，平均尺寸为2-20 nm。同时，该催化剂还能高效催化CO2与苯胺/H2反应生成N-甲基化和N-甲基化产物。在3.0wt%的Au/MOF-808（Zr）催化剂上，苯胺的转化率为18.4%，N-甲基苯胺的选择性为80.9%，N，N-二甲基苯胺的选择性为19.1%。初步探讨了反应机理和催化剂的关键作用。确定H-2在Au NPs上被吸附和活化。CO2被吸附在CUS的Zr 4+酸性位和O2-碱性位上。伯胺和仲胺被吸附在CUS Zr 4+酸性位点上，在那里它们与CO2和H-2反应形成N-甲酰胺。随后，N-甲酰胺与活化的H-2反应以产生N-甲胺。
MOF-808(Zr) with the coordinated unsaturated (CUS) Zr4+ centers was synthesized by the thermal reflux method, and a series of Au/MOF-808(Zr) catalysts with different Au loading percentages have been prepared by the impregnation-reduction method. The related X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, N-2 adsorption-desorption, Inductively coupled plasma-mass spectrometry, and NH3 temperature-programmed desorption characterizations have been undertaken to understand the structure of catalysts. The catalytic activity in CO2 with aniline/H-2 to N-methylation and N-formylation has been studied in a batch reactor. Results show that the MOF-808(Zr) structures in catalysts are of high quality and damage-free. The Au nanoparticles (NPs) are highly dispersed on the surface of the MOF-808(Zr) cage with a mean size of 2-20 nm. Also, the catalysts could catalyze the conversion of CO2 with aniline/H-2 to N-methylation and N-formylation products with a high efficiency. With a 3.0 wt % Au/MOF-808(Zr) catalyst, the conversion of aniline is 18.4%, and the selectivity of N-methylaniline is 80.9% and that of N,N-dimethylaniline is 19.1%. The preliminary reaction mechanism and the critical role of CUS were also studied. It is determined that H-2 is adsorbed and activated on Au NPs. CO2 is adsorbed on the CUS Zr4+ acidic sites and O2- basic sites. The primary and secondary amines are adsorbed on the CUS Zr4+ acidic sites, where they react with CO2 and H-2 to form N-formamide. Subsequently, N-formamide reacts with activated H-2 to yield N-methylamine.