镧掺杂硫酸钛的酸性及催化缩酮活性

以La2O3为镧源,硫酸钛掺杂镧后经高温焙烧制得一类稀土改性固体酸.用DTA,XRD表征催化剂结构,用吸附吡啶的FT-IR表征其表面酸性,由Hammett指示剂来测定酸强度,以正丁胺定量分析催化剂表面Bronsted酸和Lewis酸酸量;用环己酮与乙二醇缩酮化反应表征其酸催化性能.结果表明:催化剂表面同时存在B酸和L酸中心,且B/L酸量比与焙烧温度、镧的含量呈现较好的线性关系;在缩酮化反应中具有良好的催化活性,在300～600℃的实验范围内,催化活性随灼烧温度的升高而降低,随镧含量的增加而升高,兼有B酸和L酸的催化剂具有更好的催化活性.催化剂易回收和再生,反应后处理简单,无废酸排放,可重复使用多次,该固体酸是一种环境友好催化剂.

The Acid Property of Titanium Sulfate Doped Lanthanum Oxide and its Catalytic Activity in Ketal Synthesis

A new type of solid acid catalysts was prepared by calcination of Titanium Sulfate doped Lanthanum Oxide. The structure of catalyst was characterized by DTA and XRD. The acid property was characterized by FT-IR spectra of pyridine adsorbed on the catalyst surface. The acid intensity was estimated with Hammett indictor. The amount of B-acid and L-acid on the catalyst surface was quantitatively analyzed with n-butylamine. The catalytic activity was determined by ketalization of cyclohexanone with glycol. The results showed that the catalysts had Brnsted and Lewis acid centers; more satisfactory linear relation between ratio of B/L and calcination temperature, as well as between ratio of L/B and content of Lanthanum was obtained in terms of the peak heights of FT-IR spectra; the catalytic activity decreased with the increasing of calcination temperature, and increased with the rising of content of Lanthanum. The catalyst with B-acid and L-acid center had better catalytic activity to ketalization. The catalyst could be recovered and regenerated easily, and reused for many times. It is simple of the after-treatment of ketalization with it as catalyst. No waste acid was discharged. Titanium sulfate doped Lanthanum Oxide was an environmentally friend catalyst.