第二组分改性Ga/HZSM-5催化剂芳构化性能研究  

STUDY ON AROMATIZATION OVER Ga/HZSM-5 CATALYSTS MODIFIED BY SECOND COMPONENTS

作　　者：朱华青[1] 翟效珍[1] 王建国[1] 

机构地区：[1]中国科学院山西煤炭化学研究所煤转化国家重点实验室,太原030001

出　　处：《燃料化学学报》1999年第S1期75-79,共5页Journal of Fuel Chemistry and Technology

摘　　要：对La、Pd、Ag第二组分改性Ga/HZSM-5催化剂的丙烷芳构化反应进行了考察,结合NH3-TPD表面酸表征、电镜(TEM)形貌观察和表面微区能谱(EDAX)分析结果,解释第二组分的改性作用。研究结果表明,添加第二组分后,催化剂的表面酸特别是强酸性质减弱,使得丙烷芳构化过程中裂解产物CH4和氢转移产物C02减少,催化剂稳定性不同程度提高。EDAX分析结果表明,Ga/HZSM-5中Ga在催化剂表面富集,La的加入没有改变Ga的分散状态,Pd和Ag的加入使Ga在催化剂中的分布均匀,La、Pd、Ag在催化剂中的分散状态也各不相同。La的加入同时抑制了Ga的脱氢作用,使芳烃选择性降低,产氢量减少,催化剂活性降低;Pd改性催化剂由于Pd具有较强的脱氢活性,丙烷转化活性明显改善;Ag的加入增强了Ga的脱氢芳构化功能,促进了C03的活化和中间产物的进一步转化,提高了齐聚物的脱氢芳构化活性,使得丙烷转化率大为提高,显示出良好的催化稳定性。The aromatization of C 0 3 over Ga/HZSM-5 catalysts modified by La, Pd, Ag was studied. The surface acidic properties of the catalysts obtained by NH 3-TPD showed: the acidity, especially the strong acidity was reduced because of the addition of the second components, which led the yields of methane and ethane were reduced and the stability of the catalysts was improved. The TEM and EDAX analysis gave the results that the dispersing degree of Ga in zeolites was promoted by Pd, Ag while it was decreased by La. The addition of La inhibited not only the hydrocracking and hydrogen transfer activity on acid sites but also the dehydrogenation of Ga so that the yields of aromatics and hydrogen were reduced as well. For the Ga/HZSM-5 catalyst modified by Pd, the conversion of propane and the yields of hydrogen and aromatics were increased due to the strong dehydrogenation of Pd. For GaAg/HZSM-5 catalyst, the yields of C = 2、C 0 2、C = 3、C + 4 were reduced when those of aromatics and hydrogen were increased. So it could be concluded that Ag improved the dehydrogenation of Ga.and it was a more efficient component for Ga/HZSM-5 on propane conversion activity and stability.

关 键 词：Ga/HZSM-5 第二组分改性 丙烷 芳构化 

分 类 号：TQ426.94[化学工程]