论文部分内容阅读
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%。
The SnOx / γ-Al2O3 catalysts with different SnOx loadings were prepared by impregnation precipitation method using γ-Al2O3 as support. X-ray photoelectron spectroscopy (XPS) and Pyridine-IR Center and surface acidity were investigated. The effect of SnOx / γ-Al2O3 catalysts with different loadings and SnOx loadings on the catalytic activity and product distribution of microcrystalline cellulose was investigated. The results showed that the catalyst activity and product distribution were related to the surface acidity of the catalyst and the SnOx loading. The stronger B acid sites on the surface of the supported catalyst promoted the alcoholysis of microcrystalline cellulose to methyl levulinate, while the moderate L acid sites Is conducive to the formation of methyl lactate. When SnOx / γ-Al2O3 was used as catalyst, the catalytic activity and the amount of methyl lactate increased with the increase of SnOx loading. When the loading of Sn was 6.75wt%, the conversion of microcrystalline cellulose The rate of 82%, the yield of methyl lactate reached 28.1%.