前驱体结构及Cu含量对CuFe基催化剂CO_(2)加氢制C_(2+)醇性能的影响

Effect of precursor structure and Cu content on performance of CuFe-based catalysts for CO_(2) hydrogenation to C_(2+)alcohol

采用类水滑石(HTLC)的制备方法制备了CuFeMg、CuFeZn和CuFeZnMg催化剂前驱体,考察了前驱体结构以及催化剂碱性强度对CO_(2)加氢制C_(2+)醇性能的影响。结合表征结果和催化剂的活性评价数据发现,相对于类水滑石前驱体结构,碱性强度对CO_(2)加氢性能的影响更为显著,弱碱性位有利于C_(2+)醇的生成。以性能最优的CuFeZn催化剂为基础,考察了活性金属Cu含量(物质的量)对CO_(2)加氢性能的影响。结果表明,改变Cu含量会影响催化剂中活性金属的相互作用、Cu^(0)的晶粒尺寸以及Fe物种的价态。当n(Cu):n(Fe):n(Zn)=0.5:1.0:2.0时,催化剂中各物种分散均匀,Cu^(0)晶粒尺寸适宜,且低价Fe物种较多,因而表现出良好的催化性能,此时CO_(2)转化率为7.70%,总醇选择性为37.78%,C_(2+)醇占比达94.26%,C_(2+)醇的时空收率为46.08 mg/(mL·h)。

CuFeMg,CuFeZn and CuFeZnMg catalyst precursors were prepared by the preparation method of hydrotalcite-like compounds(HTLC),and the effects of precursor structure and catalyst basicity on the performance of CO_(2) hydrogenation to C_(2+)alcohol were investigated.Combined with the characterization results and activity evaluation data,it is found that compared with the structure of HTLC precursor,the effect of basicity on CO_(2) hydrogenation performance is more significant,and weak basic sites are beneficial to the formation of C_(2+)alcohol.Based on the optimum CuFeZn catalyst,the influence of Cu content(amount of substance)on CO_(2) hydrogenation performance was studied.The results show that Cu content affects the interaction of active metals,grain sizes of Cu^(0) and valence of Fe species.When n(Cu):n(Fe):n(Zn)=0.5:1.0:2.0,all species in the catalyst are evenly dispersed,and Cu^(0) grain size is appropriate,and there are more low valence Fe species,so the catalyst shows good catalytic performance.At this time,CO_(2) conversion is 7.70%,and total alcohol selectivity is 37.78%,and C_(2+)alcohol accounts for 94.26%,and space-time yield of C_(2+)alcohol is 46.08 mg/(mL·h).