微晶纤维素在SnOx/γ-Al_2O_3催化剂上的催化醇解反应研究

The Studies on Catalytic Alcoholysis of Microcrystalline Cellulose over the Catalysts of SnOx / γ-Al_2O_3

以γ-Al2O3为载体,采用浸渍沉淀法,制备了不同SnOx负载量的SnOx/γ-Al2O3催化剂,采用X射线光电子能谱法(XPS)和吡啶吸附红外(Py-IR)光谱法对催化剂活性中心和表面酸性进行了表征,考察了不同载体和SnOx不同负载量的SnOx/γ-Al2O3催化剂对微晶纤维素催化醇解活性和产物分布的影响规律。结果表明,催化剂活性及产物分布与催化剂的表面酸性及SnOx负载量有关,载体表面较强的B酸中心有利于促进微晶纤维素催化醇解生成乙酰丙酸甲酯,而中等强度L酸中心有利于生成乳酸甲酯。以SnOx/γ-Al2O3为催化剂时,催化剂活性和乳酸甲酯生成量随SnOx负载量增加而增加,当Sn的负载量为6.75wt%时,在240℃反应10 h,微晶纤维素的转化率达82%,乳酸甲酯的收率达到28.1%。

A series of SnOx/γ-Al2O3 catalysts with different Sn loadings were prepared ny impregnation catalysts were beneficial to the alcoholysis reaction, while moderate Lewis acid sites were preferred for the generation of methyl lactate. The catalytic activity and the yield of methyl lactate were increased with an increase of Sn loading in the catalyst. A conversion of 82% of microcrystalline cellulose with 28.1% yield of methyl lactate could be obtained at 240℃ for 10 hours over the SnOx/γ-Al2O3 catalyst with 6.75% （m/m） of the Sn loading.