激光促进锂铋磷酸盐表面异丁烷选择氧化反应

Laser Stimulated Isobutane Selective Oxidation Reaction on the Surface of Li and Bi Mixed Phosphate

用共沉淀法制备了 5％ Li3PO4· BiPO4固体材料 .运用 XRD、 IR、 TPD和 LSSR技术研究了其晶体结构、表面构造、化学吸附特性和激光促进异丁烷选择氧化表面反应性能 .结果表明 ,复合盐的主体晶相为简单单斜晶型的 BiPO4， Li3PO4以分子分散态掺杂主体相中；其表面存在 Lewis碱位 P=O和 P－ O－ Bi键中的 O2－及 Lewis酸位 Bi3＋和 Li＋；异丁烷的两个甲基中的 H分别吸附在两个相邻的 Lewis碱位 P=O上，形成双位分子吸附态；在常压和 200℃下，用一定频率的激光激发 P=O键 1000次，异丁烷的转化率为 11.3％，甲基丙烯酸的选择性为 72％ .根据实验结果，探讨了激光促进异丁烷选择氧化为 MAA的表面反应机理 .

The mixed phosphate Li3PO4 . BiPO4 was prepared from coprecipitation method. The crystal structure, chemisorption properties and LSSR behaviors of this material have been investigated by the techniques of XRD, IR, TPD and LSSR. The main phase is monoclinic BiPO4 and Li3PO4 dispersed in molecular state in the BiPO4. There are the Lewis basic sites O2- in the P = O or P - O - Bi bonds and Lewis acid site Bi3+ or Li+ appeared on the surface of mixed phosphate. Two methyl hydrogen in isobutane molecule can be chemisorbed on the terminal oxygen of neighboring P = O-. bonds on the surface of mixed phosphate. Under the conditions of 0. 1 MPa and 200 degreesC with the 1050 cm(-1) laser photons excited the P = O bonds 1000 times, the conversion of isobutane is about 11. 3% with the selectivity of the product MAA over 72%. Based on the experiment results,a mechanism of LSSR has been proposed for the isobutane selective oxidation to MAA.