摘要
用Na_4P_2O_7做为Na+添加剂制备Na_4P_2O_7/CaO催化剂。在5.5×10^(_2)的Na_4P_2O_7/CaO上及760℃,w/F=0.0.9g·s·mL^(-1)条件下可以获得23.4×10^(-2)的CH_4转化率和66.8×10^(-2)的C_2烃选择率。催化剂表面Na^+的富集有利于表面活性中心的形成。催化剂表面存在CO_2的碳酸化与脱碳酸化平衡。表面Na^+的流失会引起催化剂活性的下降。
Na_4P_2O_7 doped CaO as a catalyst for the reaction of methane oxidative coupling was re-ported in this paper. Experimental results show that the relationship of activity of the catalyst becomes as a 'voleanol type' and the CH_4 conversion and C_2H_4 selectivity were maximum and CO_2 selectivity was mini-mum when the Na_4P_2O_7 content is about 6.6×10^(-2). The XRD analysis indicates that the fresh catalyst con-taines mainly Na_4P_2O_7 and CaO crystal phase. Since the radii of Na^+ and Ca^(2+) are very close, the Na^+ can easily plunge into the lattice of CaO to form [Na^+O^-].active centers. The XPS analysis shows that. the Na^+ is enriched on the surface of the catalyst. Combined with the reaction results we can concluded that the Na^+ on the catalyst surface can easily form active centers to act upon methane. Reaction test shows that at 760℃,CH_4/air=1:1.83 and W/F=0.09g.s.mL^(-1), a C_2 yield of 18.2×10^(-2) can be reached. Stability test shows that the activity of the catalyst losed slowly at 10 hours reaction. The experiment and XPS analy-sis demonstrates that the reason of deactivation of the catalyst is the losing of the surface Na^+ other than the formation'of carboanate
出处
《合成化学》
CAS
CSCD
1993年第1期45-52,共8页
Chinese Journal of Synthetic Chemistry
基金
国家自然科学基金
关键词
甲烷
氧化偶联
乙烯
催化剂
氧化钙
Methane, Oxidative coupling, Ethylene, Na_4P_2O_7/CaO, Catalyst
