不同pH铝溶胶对二甲醚羰基化成型丝光沸石催化剂性能的影响

Influence of aluminum sol with different pH on performance of shaped mordenite catalyst for dimethyl ether carbonylation

由合成气生产二甲醚(DME),然后DME羰基化生产乙酸甲酯(MA),MA加氢生成乙醇是一条转化率和选择性高、反应条件温和、分离能耗低的绿色工艺路线。其中二甲醚羰基化反应作为重要的中间反应已经受到了广大学者的高度关注。本文主要针对DME羰基化制MA反应,使用具有高活性和高稳定性的丝光沸石(MOR)制备成型催化剂,为进一步工业化奠定基础。通过使用不同pH的铝溶胶作黏结剂制备一系列丝光沸石成型催化剂,并与使用拟薄水铝石作黏结剂的成型催化剂进行比较。通过强度测试以及Weibull函数统计分析,探究了黏结剂对成型MOR的强度以及强度可靠性的影响;X射线衍射、N_(2)物理吸附、^(29)Si MAS NMR、吡啶吸附原位红外等表征结合活性评价,探究了黏结剂对MOR的物理结构、酸性以及催化性能的作用。结果表明,铝溶胶的pH对丝光沸石成型催化剂的孔道结构、力学性能和催化性能都有十分重要的影响。铝溶胶的pH在4.9时,成型催化剂介孔比表面积和体积最大(70 m^(2)/g和0.20 cm^(3)/g),机械强度最高(110.7 N/cm),单位分子筛上Brønsted酸量下降幅度最小。因此,单位分子筛上DME转化率和时空收率最高。

The production of dimethyl ether(DME)from syngas,followed by the carbonylation of DME to produce methyl acetate(MA),and the hydrogenation of MA to ethanol is a green process route with high conversion and selectivity,mild reaction conditions,and low separation energy consumption.Among them,the dimethyl ether carbonylation reaction,as an important intermediate reaction,has attracted great attention from scholars.The present work focuses on the reaction of carbonylation of DME to MA,using mordenite(MOR)with high carbonylation activity and stability to prepare shaped catalysts,which lays a foundation for further industrialization.A series of extruded MOR catalysts were prepared by using aluminum sol with different pH as binder and compared with shaped catalysts using pseudo-boehmite as binder.The effect of the binder on the strength of the shaped catalysts was investigated by strength tests as well as statistical analysis of the Weibull function.The role of the binder on the physical structure,acidity and catalytic performance of the MOR was investigated by characterization such as X-ray diffraction,N_(2)physical adsorption,^(29)Si MAS NMR,and in-situ pyridine adsorption infrared in combination with the evaluation of catalytic properties.The results showed that the pH of the aluminum sol had a very important effect on the pore structure,mechanical properties and catalytic performance of the shaped catalyst.When the pH of the aluminum sol is 4.9,the extruded catalyst had the largest mesoporous specific surface area and volume(70 m^(2)/g and 0.20 cm^(3)/g),the highest mechanical strength(110.7 N/cm)and the smallest decrease in the amount of Brønsted acid by unit mass of zeolite.Therefore,the extruded catalyst had the highest DME conversion and space-time yield by unit mass of zeolite.