硅铝比对Cu-Co/ZSM-5-Al_2O_3催化剂性能的影响

The Influence of Si/Al on Cu-Co/ZSM-5-Al_2O_3 Catalyst Performance

采用物理混合法制备了不同硅铝比的ZSM-5与Al_2O_3的混合载体,并采用浸渍法制备Cu-Co基催化剂,考查其对合成气制混合醇性能的影响,并用Ar物理吸-脱附、H2程序升温还原(H2-TPR)、X射线光电子能谱(XPS)等手段对其结构性能进行了表征。结果表明:当混合载体中ZSM-5硅铝比为50时,载体形成了新的孔道结构,有利于消除载体的堆积现象,促进载体活性物种的分散,更有利于表面活性物种的还原,同时改变了表面活性物中的化学状态,从而使合成气制备低碳混合醇具有较高的反应活性和选择性。在5.0MPa,300℃,V(H2)∶V(CO)∶V(N2)=4∶2∶1,GHSV=7200m L·h^(-1)反应条件下,不同硅铝比的混合载体催化剂表现出不同的催化活性,其中当混合载体中ZSM-5硅铝比为50时,CO转化率和C^(2+)醇类选择性分别达到21.31%和41.80%。

ZSM-5 zeolite with different Si/Al ratio and Al2O3 were used to prepare hybrid supported Cu-Co based catalysts. The properties of lower carbon mixed alcohols synthesis from syngas were studied. The textual and structural properties of the catalysts were studied using Ar physics-stripping in low temperature, H2-temperature programmed reduction （H2-TPR）, X-ray photoelectron spectroscopy（ XPS ）. The results indicate that when the hybrid supported with Si/Al ratio of 50 would form the new channel structure and beneficial to eliminate the phenomenon of the accumulation of carrier, the hybrid supported contributed to high metal dispersion, be beneficial to the reduction of surface active species, changed the chemical state of the surface activity at the same time , thus improve the conversion and selectivity of the reaction. In 5.0MPa, 300℃, V （HE） ： V （CO） ： V （N2）=4 ： 2 ： 1 ,GHSV=7200mL .h-1 reaction conditions,hybrid supported catalysts with different Si/Al ratio showed different catalytic activity. When the Si/Al ratio of ZSM-5 zeolite to 50 of ZSM-5/Al2O3, the CO conversion was 21. 31% and the C2＋ alcohol selectivity was 41.80%.