新型K/αMoC 1－x 催化剂CO加氢合成低碳混合醇的研究
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摘要: 制备K改性的αMoC1－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αMoC1－x催化剂的CO加氢选择性发生显著变化。αMoC1－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αMoC1－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K/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）。αMoC1－x催化剂上醇烃产物符合线性A-S-F分布曲线，K改性αMoC1－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αMoC1－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/αMoC1－x催化剂表面“K-Mo-C”新相的生成有关。
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关键词:
- αMoC1－x催化剂 /
- K改性 /
- CO加氢 /
- 低碳混合醇
Abstract: αMoC1－xpromoted by K2CO3, was studied as catalysts for carbon monoxide hydrogenation reactions under conditions of 573, 8.0MPa, GHSV=2000h-1,n(H2)/n(CO)=1.0. Unpromoted αMoC１－xproduced mainly CO2 and light hydrocarbons, addition of K2CO3 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 αMoC１－xwith higher selectivity of C2+OH. The investigations of the effects of the loadings of K2CO3 in αMoC１－xrevealed that the maximum yield of alcohols was obtained at K/Mo (mol ratio) =0.1. However, there was no significant difference between αMoC１－xand K/αMoC１－xcatalysts 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/αMoC１－xcatalysts, which was considered to be the active sites for the alcohols synthesis.-
Key words:
- αMoC1－x /
- potassium /
- CO hydrogenation /
- mixed alcohols synthesis
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