成型工艺条件对Pt/SO4^(2-)/ZrO2催化剂异构化性能的影响

EFFECT OF EXTRUSION CONDITIONS ON ISOMERIZATION PERFORMANCE OF Pt/SO_4^(2-)/ZrO_2 CATALYST

采用挤条成型法制备Pt/SO_4^(2-)/ZrO_2(Pt SZ)催化剂,考察黏结剂种类、黏结剂含量以及黏结剂引入方式对PtSZ催化剂异构化性能和机械强度的影响,并用XRD和TG手段对催化剂的晶相和硫含量进行表征。结果表明:对于Zr(OH)4粉末先硫酸化后加黏结剂制备的催化剂,以拟薄水铝石作为黏结剂制备的Pt/SO_4^(2-)/ZrO_2-Al_2O_3[PtSZA(a)]催化剂较硅溶胶和铝溶胶为黏结剂制备的催化剂具有更高的异构化活性和机械强度;随着Al_2O_3质量分数从5%提高到30%,Pt SZA(a)的异构化活性明显降低;对于Zr(OH)4粉末先加拟薄水铝石后硫酸化制备的Pt/SO_4^(2-)/ZrO_2-Al_2O_3[PtSZA(b)]催化剂,黏结剂的质量分数提高至20%时,异构化活性基本保持不变,进一步增加Al_2O_3质量分数至30%,异构化活性仅仅表现出轻微下降;无论采用哪种方式引入拟薄水铝石,催化剂上硫含量和机械强度均随Al含量的增加而提高,采用先加拟薄水铝石黏结剂后硫酸化的方法制备的PtSZA(b)催化剂同时具有良好的异构化性能和高的机械强度。

The Pt-sulfated zirconia catalysts （PtSZ） were prepared by extrusion method with the addition of binder. The influence of the binder type, binder content and the addition order of binder on the isomerization performance and mechanical strength of catalyst were studied. The crystalline structure and sulfur content of the catalysts were characterized by XRD and TG techniques. The experimental results demonstrate that the PtSZA（a） catalyst prepared with pseudo bohemite powder as the binder has a higher catalytic activity and higher mechanical strength than that with aluminum sol and silica sol as binder added into sulfated Zr（OH）4 powder. The increase of Al2O3 content （w） from 5% to 30% leads to an obvious decrease in the isomerization activity of PtSZA（a）. However, the isomerization activity of PtSZA（b） catalyst prepared by the addition of pseudo bohemite to Zr（OH）4 powder before sulfation of Zr（OH）4did not change with Al2O3 content increasing up to 20%. And the further increase of theAl2O3 content up to 30% results in a very slight decrease in the activity of PtSZA （b）. Both mechanical strength and sulfur content of catalyst are improved with the increase of Al2O3 whatever the addition order of binder is. The PtSZA（b） catalyst prepared by the addition of pseudo bohemite prior to the sulfation of Zr（OH）4possesses both high activity and high mechanical strength.