甲烷无氧芳构化反应中Co助剂对Mo/HZSM-5催化剂积炭行为的影响  

Effect of Co Additive on Formation of Coke Deposits in Methane Dehydro-Aromatization over Mo/HZSM-5 Catalyst

作　　者：刘红梅[1] 田丙伦[1] 李永刚[1] 包信和[1] 徐奕德[1] 

机构地区：[1]中国科学院大连化学物理研究所催化基础国家重点实验室,辽宁大连116023

出　　处：《催化学报》2003年第2期123-128,共6页

基　　金：国家 973重大基础研究项目 (G19990 2 2 40 0 )

摘　　要：甲烷在Co Mo/HZSM 5催化剂上进行无氧芳构化反应的评价结果表明 ,Co的添加大大提高了Mo/HZSM 5催化剂在反应过程中的稳定性 .BET实验证明 ,反应后的积炭对Co Mo/HZSM 5催化剂孔道堵塞的程度较小 .对积炭催化剂进行的一系列程序升温表面反应 (如TPH ,TPCO2 和TPO)结果表明 ,TPO谱上有两个峰温明显不同的烧炭峰 ,Co的添加明显抑制了高温积炭的生成 .H2 主要与高温积炭发生反应 ,这部分积炭是催化剂失活的主要原因 ;CO2 对低温积炭的影响则尤为明显 .TEM结果表明 ,积炭催化剂上存在丝状积炭物种 .碳丝不能与H2 反应 ,但能被CO2 除去 .Co的添加促进了丝状积炭物种的生成 。Methane dehydro-aromatization (MDA) in the absence of gas-phase oxygen is one of the promising routes for direct conversion of methane into fuels and chemicals, particularly into aromatics such as benzene and toluene. MDA under non-oxidative conditions was carried out over Co-Mo/HZSM-5 catalyst, and the result suggested that the addition of Co dramatically improved the stability of Mo/HZSM-5 catalyst. Furthermore, the chemical nature and physical properties of the coke deposits formed on Co-Mo/HZSM-5 catalyst were studied by various temperature-programmed surface reactions (TPSR), such as TPH, TPCO_2 and TPO, combining with TGA and TEM. The results were compared with those obtained over Mo/HZSM-5 catalyst. The TPO profiles recorded during the procedure of coke burning-off showed two peaks. The TPH experiments had effect on the coke burning-off only at high temperature. However, TPCO_2 mainly resulted in the diminishing of the coke burning-off at low temperature. The TEM pictures gave evidence that a lot of filamentous carbon formed on the surface of coked catalysts during the course of TPSR, and this kind of coke deposits was not a contributor to the deactivation of catalyst. Hydrogen had no ability to react with carbon filaments, but TPCO_2 experiment could eliminate them completely.

关 键 词：甲烷 无氧芳构化反应 Co助剂 MO/HZSM-5 钼 分子筛 负载型催化剂 钴 积炭 程序升温表面反应 

分 类 号：O643.3[理学—物理化学]