制备方法对H2SO4固体酸结构和催化性能的影响

 以溶胶-凝胶法和浸渍法制备了H2SO4固体酸催化剂. FT-IR, XRD和 29Si MAS NMR结果表明,两种方法得到的催化剂结构不同. FT-IR和 29Si MAS NMR结果表明,溶胶-凝胶法制备的固体酸H2SO4-SiO2中H2SO4和载体SiO2间存在相互作用; 1H MAS NMR结果表明,H2SO4-SiO2固体酸的酸强度和液体浓硫酸相当. 通过对柠檬酸与正丁醇的液/固相催化酯化反应比较了溶胶-凝胶法与浸渍法制备的固体酸的催化性能,结果表明,浸渍法得到的固体酸重复使用4次后活性消失; 溶胶-凝胶法制备的H2SO4-SiO2固体酸重复使用6次后仍显示出较高的活性和选择性.

Influence of Preparation Methods on the Structure and Catalytic Performance of H2SO4 Solid Acid

The supported sulfuric acid on silica was prepared by sol gel and impregnation methods. The structure, stability and acidity of as prepared materials were characterized by XRD, FT IR, 29 Si MAS NMR and 1H MAS NMR. Theresults of FT IR and 29 Si MAS NMR confirmed that H 2SO 4 was combined with the amorphous SiO 2 inthe H 2SO 4 SiO 2 catalyst. 1H MAS NMR investigations showed that H 2SO 4 SiO 2 catalyst had high acid strength. The solid acid was applied to the esterification reaction of citric acid and n butanol, showing that the H 2SO 4 SiO 2 catalyst had higher activity,selectivity and stability.