均苯三甲酸辅助合成CuZnAlZr催化CO_(2)加氢制甲醇

1,3,5-Benzenetricarboxylic acid assisted synthesis of CuZnAlZr catalysts for CO_(2)hydrogenation to methanol

CO_(2)加氢制甲醇是合成化学增值品的重要途径之一,有助于缓解能源与环境压力。采用共沉淀法合成了用于CO_(2)加氢制甲醇的CuZnAlZr催化剂,并采用X射线衍射(XRD)、N_(2)O-H_(2)滴定、N_(2)吸/脱附、H_(2)程序升温还原(H_(2)-TPR)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等手段对所得催化剂进行了表征,详细考察了均苯三甲酸(BTC)辅助合成对CuZnAlZr催化剂活性Cu物种的分散度及其催化性能的影响。结果表明,在CuZnAlZr催化剂前驱体中引入BTC后,焙烧阶段分解生成气体产物有利于增加催化剂的比表面积并产生更多的孔隙结构,还可减弱Cu与载体氧化物之间的相互作用,有助于Cu物种的分散。当BTC引入量为n(BTC)/n(Cu^(2+))=1/6时,在空气中焙烧所得CuZnAlZr催化剂表面存在更多高度分散的较小Cu晶粒和Zn O晶相,Cu与Zn O物种之间的协同作用增强使其表现出优异的催化性能,CO_(2)转化率和甲醇时空产率分别可达27.81%和278.6 g/(kg·h),说明在前驱体中引入BTC辅助合成可得到Cu分散度高和Cu晶粒较小的高活性加氢催化剂。

CO_(2)hydrogenation to methanol is one of the important ways to synthesize chemical value-added products,which helps to relieve energy and environmental pressure.CuZnAlZr catalysts for CO_(2)hydrogenation to methanol were synthesized by co-precipitation method,and the resulting catalysts were characterized by X-ray diffraction(XRD),N_(2)O-H_(2)titration,N_(2)adsorption/desorption,H_(2) temperature programmed reduction(H_(2)-TPR),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).And the effects of 1,3,5-benzenetricarboxylic acid(BTC)assisted synthesis on the dispersion of active Cu species in CuZnAlZr catalysts and their catalytic performance were investigated in detail.The results show that after the introduction of BTC into the CuZnAlZr catalysts precursor,the gas products generated by the decomposition in the calcining stage,contributes to the increase of the specific surface area of the catalyst and generates more pore structures,and it also weakens the interaction between Cu and the carrier oxide,which contributes to the dispersion of Cu species.When the amount of BTC introduced into the catalyst is n(BTC)/n(Cu^(2+))=1/6,more highly dispersed smaller Cu grains and Zn O crystalline phases existe on the surface of the CuZnAlZr catalysts calcined in air and the enhanced synergy between Cu and ZnO species leds to excellent catalytic performance with CO_(2)conversion rate and methanol space-time yield up to 27.81%and 278.6 g/(kg·h),respectively.This indicates that the introduction of appropriate amount of BTC in the precursor to assist the synthesis can lead to highly active hydrogenation catalysts with high Cu dispersion and small Cu grains.