摘要
以Na_2SnO_3系甲烷氧化偶联催化剂中性能较好的5%Li_2SO_4-Na_2SnO_3样品为主要研究对象,用电子顺磁共振(EPR)方法对表面吸附氧及其与甲烷的作用进行了研究,实验表明:样品在氧气氛中处理后,得到可归属为表面吸附超氧负离子O_2^(?)的顺磁信号,在300℃以上温度条件下吸附氧后,可产生这种表面氧物种,该物种在室温、1.33×10^(-2)Pa 真空条件下能稳定存在,700℃与甲烷作用后顺磁信号显著减弱,因而催化剂表面的O_2^(?)物种可能起着活化甲烷的作用.
According to the results of investigation in a series of Na_2SnO_3 catalysts for oxidative couplingof methane,a sample(5mol%Li_2 SO_4-Na2SnO3)with good catalytic properties was selected asthe main research object.By using electron paramagentic resonance(EPR)method,the form ofsurface adsorbed oxygen has been investigated.The EPR results confirm that a signal with 9 valueof 2.013 is from the species of surface adsorbed oxygen,and that it can be assigned to adsorbedsuperoxide species o_2^-.At 300℃ or the above this type of oxygen species can form on that catalystsample.The species o_2^- is stable under conditions of room temperature and vacuum of 1.33×10^(-2)pa.But at 700℃ the reaction between O_2^- and CH_4 occured,and at the same time the intensityof O_2^- signal considerably decreased.The results show that the surface species o_2^- might play animportant role in activating CH_4 molecules in the oxidative coupling reaction of methane.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1993年第6期746-751,共6页
Acta Physico-Chimica Sinica
基金
国家自然科学基金
关键词
甲烷
氧化偶联
偏锡酸钠
催化剂
Superoxide ion Oxidative coupling of methane Na_2SnO_3
