新型K/α-MoC_(1-x)催化剂CO加氢合成低碳混合醇的研究

K/α-MoC_(1-x): A novel catalyst for mixed alcohols synthesis from CO hydrogenation

制备K改性的α-MoC1-x催化剂并对其CO加氢合成低碳混合醇性能进行了考察。结果表明，K改性使α-MoC1-x催化剂的CO加氢选择性发生显著变化。α-MoC1-x，催化剂CO加氢的产物主要为CO2和C1～4烷烃，同时有少量醇产物生成；经K改性后α-MoC1-x，催化剂产物中烷烃选择性明显降低，而C1～5低碳醇选择性显著提高。通过对碱金属质量分数的考察发现，当K1／Mo（摩尔比）为0．1时，总醇选择性达到极大值，低碳醇的时空收率达到28．6g／（L·h）。α-MoC1-x催化剂上醇烃产物符合线性A-S-F分布曲线，K改性α-MoC1-x催化剂上醇烃产物也有类似A-S-F分布曲线，但K助剂的加入有效促进了低碳醇的形成及其链增长能力。结合XRD、SEM及XPS表征，K助剂与α-MoC1-x催化剂主体之间的电子作用导致其CO加氢产物选择性发生显著变化，这与K／α-MoC1-x催化剂表面“K-Mo-C”新相的生成有关。

α-MoC1-x, promoted by K2CO3, was studied as catalysts for carbon monoxide hydrogenation reactions under conditions of 573 K, 8.0 MPa, GHSV = 2 000 h^-1, n （ HE ）/n （CO） = 1.0. Unpromoted α-MoC1-x produced mainly CO2 and light hydrocarbons, addition of KECO3 as a promoter, however, resulted in remarkable selectivity shift from hydrocarbons to alcohols. Moreover, the promoter of potassium enhanced the ability of chain propagation of α-MoC1-x with higher selectivity of C2 ＋OH. The investigations of the effects of the loadings of KECO3 in α-MoC1-x revealed that the maximum yield of alcohols was obtained at K/Mo （mol ratio） =0.1. However, there was no significant difference between α-MoC1-x and K/α-MoC1-x catalysts in the distributions of alcohols and hydrocarbons ; they both have similar linear A-S-F plots. Though, the promotion effects of potassium on the formation of higher alcohols could be attributed to the formation of ＂ K-Mo-C＂ phase in K/α-MoC1-x catalysts, which was considered to be the active sites for the alcohols synthesis.