在NiSO_4表面上激光促进CO＋H_2合成乙烯反应机理

Study on the Mechanism of Laser Stimulated CO+H_2 Surface Reaction to form C_2H_4

利用红外光谱、程序升温脱附、程序升温表面反应和激光表面反应技术研究了固体ＮｉＳＯ_４表面上ＣＯ、Ｈ_２和Ｃ_２Ｈ_４的化学吸附性能及激光促进ＣＯ加氢合成乙烯的反应机理。实验结果表明：在硫酸镍固体表面上卧式吸附于Ｓ－Ｏ－Ｎｉ键Ｓ位和Ｎｉ位的ＣＯ是激光合成乙烯的有效吸附态；解离吸附于硫氧双键氧位上的Ｈ参与ＣＯ加氢反应；激光选择激发表面Ｓ－Ｏ键，通过能量传递和驰豫使卧式吸附态Ｃ＝Ｏ键活化并与吸附态Ｈ反应生成ＣＨ_２物种和Ｈ_２Ｏ，继而邻近的ＣＨ_２结合形成产物Ｃ_２Ｈ_４。

The title reaction on the surface of nickel sulfate has been studied using the techniques of TPD,TPSR,IR and Laser stimulated surface rcaction(ISSR).The experimental results show that under the conditions of ordinary pressure and 200℃with 1047 cm-1 laser exciting the surface of nickel sulfate for 1000 times, the CO conversion of 30.7%and the C2H4 selectivity of 100%are obatined;The Co- adsorbed lying down on the surface is a reactive one and the H-adsorbed dissociatively on the surface oxygen sites takes part in the reaction of CO hydrogenaton. The 1047cm-1 laser photon excites selectively the surface S-O band and the energy transfers immediately to the adsorbed C=O band by V-V energy transfer and relaxation, then the activated C=O reacts with the adsorbed H to form CH2 and H2O,finally the CH2 species combine to produce C2Hr4.Temperature is believed to supplement the energy density provided by the laser photon, and promote the dissociation of CO-adsorbed lying down and the desorption of the products of C2H4 and H2O.