K改性β-Mo2C催化剂CO加氢合成低碳混合醇的研究

制备系列K改性的β-Mo2C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β-Mo2C催化剂的CO加氢选择性发生显著变化。β-Mo2C催化剂CO加氢的产物主要为C1～C4烷烃,经K改性后β-Mo2C催化剂上产物主要为C1～C5低碳醇，其中高级醇(C2+OH)选择性可达到33.78%。通过对碱金属质量分数的考察发现，当K/Mo（原子比）为0.2时，总醇选择性达到最大值，低碳醇的时空收率达到0.12 g/（mL·h－１）。β-Mo2C催化剂上醇烃产物均符合线性Anderson-Schultz-Flory（A-S-F）分布曲线，而K改性β-Mo2C催化剂上醇产物为独特的甲醇负偏离A-S-F分布。可见，K助剂的加入有效促进了低碳醇的形成，尤其是促进了C1OH到C2OH的链增长步骤。

Mixed alcohols synthesis from CO hydrogenation over potassium-promotedβ-Mo2C catalysts

The modification effects of K2CO3 on β-Mo2C catalysts for mixed alcohols synthesis from CO hydrogenation were studied. Un-prompted β-Mo2C produced mainly hydrocarbons of C1-C4 under the reaction conditions of 573 K, 8.0 MPa, H2/CO=1.0, GHSV=2 000 h－1. Addition of K2CO3 to β-Mo2C resulted in remarkable selectivity shift from hydrocarbons to alcohols. Moreover, the promoter of potassium enhanced the ability of chain propagation of β-Mo2C with the higher selectivity of C2+ alcohols. The investigations of the loadings of K2CO3 in β-Mo2C revealed that the maximum of alcohol yield obtained at K/Mo (molar ratio) =0.2. On K/β-Mo2C catalysts, the distribution of hydrocarbons obeyed the traditional linear Anderson-Schultz-Flory equation, while the distribution of alcohols gave a unique linear Anderson-Schultz-Flory with remarkable deviation of methanol. Thus, potassium promoter exerted a prominent function on the whole chain propagation to produce alcohols especially for the stage of methanol to ethanol.