微波水热改性制备S_2O_8~(2-)/Fe_2O_3-SiO_2固体酸及催化性能

对共沉淀法得到的Fe2O3-SiO2混合氧化物前驱物进行微波水热改性处理,经浸渍(NH4)2S2O8后再焙烧得S2O82-/Fe2O3-SiO2固体酸催化剂。用XRD、TEM、N2气吸附/脱附及化学分析方法对其进行了表征,用乙酸/丁醇酯化催化反应评估固体酸的催化性能,并与通常条件下制得的催化剂进行了比较。结果显示,引入SiO2会延迟Fe2O3晶体的形成与长大;对前驱物用250W的微波水热改性处理1.5h,制得的固体酸具有适中的比表面积、均匀的孔径分布,含硫量为6.02%,比表面积为37.1m2/g。该固体酸对乙酸丁醇酯化反应有很高的催化活性,催化酯化反应3h,乙酸的转化率高达97.7%。

Preparation of S_2O_8~(2-)/Fe_2O_3-SiO_2 Solid Acid by Microwave Hydrothermal Treatment and Its Catalytic Activity

The precursors of S_2O~(2-)_8/Fe_2O_3-SiO_2 solid acids prepared via co-precipitation method were modified by microwave hydrothermal treatment. After being impregnated in a (NH_4)_2S_2O_8 solution and calcined at a certain temperature, solid acid catalysts were formed. The samples were characterized by XRD, TEM, N_2 gas adsorption/desorption and chemical analysis. The catalytic activities of the solid acids were evaluated by esterification of acetic acid and butanol. In addition, the solid acid catalysts were compared with other (catalysts) prepared under normal conditions. The results show that adding SiO_2 retards the formation and growth of Fe_2O_3 crystals. After the precursors were modified via 250 W microwave hydrothermal treatment, the solid acids had a moderate specific area(37.1 m~(2)/g) and a narrow pore size distribution, and the sulphur content was 6.02%. The solid acid showed a high catalytic activity. At 3 h reaction time, the convertion of acetic acid reached 97.7%.