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以H3 PW12 O4 0 (PW12 )作为固体表面材料 ,用IR ,TPD和激光促进表面反应 (LSSR)技术等手段考察了PW12的表面构造、化学吸附性能和激光促进CH4 部分氧化合成CH3 OH的反应规律 .PW12 表面上存在着Lewis碱位 (W=O和W O W键中的氧位 )和Lewis酸位 ( W6+ ) .CH4 在PW12 表面的Lewis碱位上发生化学吸附 ,主要吸附位是W =O键 .采用 980cm-1的激光激发PW12 表面的W =O键 ,在 10 0℃以上和常压下 ,CH4 的部分氧化反应顺利进行 .CH3 OH是CH4 氧化的直接产物 ,HCHO ,CH3 OCH3 和烃类是CH3 OH进一步反应的产物 .H2 O分子在反应中的作用可能为 :通过激光参与下H2 O分子与PW12 表面发生相互作用 ,能产生有利于CH4 吸附和CH3 OH生成的表面活性位W6+ O-,同时产生有利于气相分子氧补充反应消耗晶格氧的表面氧缺位 ,从而提高光能的有效利用并加速CH4 直接氧化反应的进行 .根据实验结果 ,探讨了LSSR机理
The surface structure, chemisorption properties of PW12 and the reaction rule of CH4 partial oxidation to CH3OH by laser were investigated by using H3 PW12 O4 0 (PW12) as solid surface material and by means of IR, TPD and laser induced surface reaction (LSSR) Lewis bases (W = O and WOW bonds) and Lewis acid sites (W6 +) exist on the surface of PW 12. CH4 chemisorbed on the Lewis base of PW12 with the main adsorption site being the W = O bond The partial oxidation of CH4 was carried out at a temperature of more than 10 ℃ and atmospheric pressure by using 980cm-1 laser to excite the W = O bond on the surface of PW 12. CH 3 OH is the direct product of CH 4 oxidation, HCHO, CH 3 OCH 3 and hydrocarbons Is the product of the further reaction of CH3OH.The possible role of H2O in the reaction may be as follows: the interaction of H2O molecules with the surface of PW12 under laser-induced interaction can generate surface active sites W6 + O- , And at the same time produce surface oxygen vacancies which are conducive to the consumption of lattice oxygen by oxygen molecular oxygen replenishment reaction so as to increase the effective utilization of light energy and accelerate the direct oxidation reaction of CH 4.According to the experimental results,