BaF_2/La_2O_3催化剂上甲烷氧化偶联反应活性氧物种的原位红外光谱  

In Situ Infrared Spectroscopy of Active Oxygen Species for Oxidative Coupling of Methane over BaF_2/La_2O_3 Catalyst

作　　者：王丽华[1] 伊晓东[1] 翁维正[1] 万惠霖[1] 

机构地区：[1]厦门大学固体表面物理化学国家重点实验室化学化工学院化学系

出　　处：《催化学报》2007年第9期789-793,共5页

基　　金：国家重点基础研究发展计划(973计划;2005CB221408);国家自然科学基金(20433030;20423002);福建省科技重大专项基金(2005HZ01-3)

摘　　要：用原位红外光谱研究了BaF2/La2O3催化剂上甲烷氧化偶联反应的活性氧物种.结果表明,催化剂经O2预吸附后,在1 108-1 118 cm^-1处出现超氧物种O2^-的O-O键伸缩振动峰.经18O2同位素交换实验后,原1 108-1 118 cm^-1处谱峰的强度减弱,同时在1 086和1 051 cm^-1处出现（O^18O）-物种和^18O2-物种的吸收峰.同位素交换实验进一步确证了1 108-1 118cm^-1处谱峰确为O2^-物种的吸收峰.在700℃下,O2^-物种能够活化CH4生成C2H4,而且O2^-物种的消耗量和C2H4的生成量呈很好的消长对应关系.超氧物种O^2-是BaF2/La2O3催化剂上甲烷氧化偶联反应的活性氧物种.In situ IR spectroscopy was used to study the superoxide spectes （O2^- ） Ior oxtoattve coupling, methane （OCM） over the BaF2/La2O3 catalyst. After the pretreatment of the catalyst with O2, the IR peak at 1108-1118 cm^-1 appeared, which was assigned to O-O bond stretching vibration in O2^-species. After the introduction of 18↑O2 isotope, the IR peak at 1108-1118 cm^-1 was weakened, and the absorption peaks appeared at 1 086 and 1 051 cm^-1, which was consistent with the assignment of the O^-18↑O bond and 18↑O-18↑O bond stretching vibrations in the superoxide species, respectively. At 700℃ , the superoxide species could react with CH4, accompanied by the formation of gas phase C2H4. A good correlation between the rate of O2^- consumption and the rate of C2H4 formation was observed, so the superoxide species was believed to be responsible for the OCM reaction over the BaF2/La2O3 catalyst.

关 键 词：同位素交换 超氧物种 红外光谱 氧化偶联 甲烷 氟化钡 氧化镧 

分 类 号：O643.32[理学—物理化学]