摘要
本文考察了以Li、Mn等金属氧化物为活性组分时,载体的酸碱性对甲烷氧化偶联反应的影响。发现随着载体的碱性增强,生成C_2(C_2H_4,C_2H_6)的选择性提高;增强酸性,反应则向非选择氧化生成CO_x(CO_2,CO)方向进行。用碱金属Na对Li/MgO进行处理,在反应开始的一小时左右产物中无CO_x生成,即生成C_2的选择性为100%。ESR谱图表明,Na的存在增强了催化剂表面氧物种[O^-]的相对强度,从而使生成C_2的选择性大大提高。
The effect of the acidity and basicity of supports on the oxidative coupling of methane using oxides of Li and Mn etc. as active components has been investigated. It was shown that the selectivity of C_2(C_2H_4 and C_2H_6) increased with the increase of the basicity of supports, and higher acidity results in non-selective oxidation to CO_x(CO, CO_2). Doping Li/MgO with Na achieved a 100% C_2 selectivity at 23.7% conversion of CH_4 in the first hour. ESR results indicate that there are three kinds of oxygen species on the surface of catalysts, O^-, O_2^- and O_(?)^- O^- was the active species which abstracts H from CH_4 to produce CH_(3.) and then C_(2.) O_2^- and O_.^- are the species which oxidize the CH_(3.) deeply to produce CO_x. When the catalyst is doped with Na, the selectivity of C_2 is increased owing to more O^-.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
1990年第3期234-239,共6页
Journal of Fuel Chemistry and Technology
关键词
甲烷
氧化偶联
固体碱
催化剂
oxidative coupling
methane
acicity
basidity
support
