氧化镧催化甲烷氧化偶联反应的晶粒尺寸效应的研究  

Study of grain size effect of lanthanum oxide catalyzed methane oxidation coupling reaction

作　　者：张祺 牛鹏宇 贾丽涛[1] 林明桂[1] 李德宝[1,3] ZHANG Qi;NIU Peng-yu;JIA Li-tao;LIN Ming-gui;LI De-bao(State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China;University of Chinese Academy of Sciences,Beijing 100049,China;Dalian National Laboratory of Clean Energy,Dalian 116023,China)

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,山西太原030001 [2]中国科学院大学,北京100049 [3]中国科学院洁净能源创新研究院,辽宁大连116023

出　　处：《燃料化学学报（中英文）》2023年第5期644-655,共12页Journal of Fuel Chemistry and Technology

基　　金：山西省基础研究计划(20210302124466);中国科学院山西煤炭化学研究所创新基金(SCJC-DT-2022-06)资助。

摘　　要：采用水热合成法,制备了不同晶粒尺寸的La_(2)O_(3)催化剂。运用XRD、原位拉曼光谱、原位红外漫反射光谱、H_(2)-TPR和O^(2)-TPD等表征手段研究了不同晶粒尺寸La_(2)O_(3)催化剂的OCM反应性能和催化剂之间的构效关系。结果表明,La_(2)O_(3)催化剂的La-O键会随着温度的升高出现明显的伸长,从而影响La_(2)O_(3)对O2的吸附和动态储存。当晶粒尺寸增大至57.4 nm时,La_(2)O_(3)催化剂的储氧能力开始下降,同时伴随着表面氧物种,特别是超氧物种在催化剂表面富集,导致CH_(4)和产物的过度氧化,降低OCM反应的选择性。晶粒尺寸为52.3 nm的L-La_(2)O_(3)催化剂在750℃时,表面氧物种含量适宜,储氧能力强。在CH_(4)/O_(2)为3,空速为1.6×10^(5)mL/(g·h)的条件下表现出最佳的C2+烃选择性。La_(2)O_(3) catalysts with different grain sizes were prepared under hydrothermal condition.The structure activity relationship of La_(2)O_(3) catalysts with different grain sizes were investigated by using in-situ XRD,Raman,FT-IR and H_(2)-TPR,O_(2)-TPD.The results showed that the La−O bond of the La_(2)O_(3) catalyst showed a significant elongation with increasing temperature,which affected its adsorption and dynamic storage of O2.When increasing the grain size up to 57.4 nm,the oxygen storage capacity of the La_(2)O_(3) catalyst started to decrease,accompanied by the enrichment of surface oxygen species,especially superoxide species,on the catalyst surface,which led to the over-oxidation of CH4 and products and reduced the C_(2+)hydrocarbons selectivity.The L-La_(2)O_(3) catalyst with a grain size of 52.3 nm had a suitable content of surface oxygen species and a high oxygen storage capacity at 750℃.It exhibited the best C2+hydrocarbon selectivity up to a CH_(4)/O_(2) of 3 and a vacancy rate of 1.6×10^(5) mL/(g·h).

关 键 词：甲烷氧化偶联 La_(2)O_(3) 晶粒尺寸 储氧能力 

分 类 号：O643[理学—物理化学]