Abstract: 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℃ 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.

Key words: Laser stimulated surface reaction, Selective oxidation, Isobutane, 　Methacrylic acid, Mixed phosphate