Characterization of 12-tungstophosphoric acid impregnated on mesoporous silica SBA-15 and its catalytic performance in isopropylation of naphthalene with isopropanol

12-Tungstophosphoric acid catalysts supported on mesoporous silica SBA-15 with various acid loadings were prepared by impregnation, and their physical chemical properties were characterized by XRD, N-2-adsorption, FTIR, DSC and NH3-TPD techniques. Their catalytic performances in the isopropylation of naphthalene with isopropanol were investigated in a batch reactor. It was found that 12-tungstophosphoric acid was highly dispersed on the SBA-15 support when the acid loading was as high as 60%, and meanwhile the Keggin structure of heteropolyanions could be retained. In addition, the thermal stability of the supported acid decreased by approximately 100 K as compared with the pure acid. In isopropylation of naphthalene, SBA-15 supported acid catalysts showed much higher conversion and selectivity to diisopropylnaphthalenes, beta-isopropylnaphthalene, and beta, beta-products than those of pure acid. Furthermore, the catalytic performances of SBA-15 supported catalysts were compared with those supported on other siliceous materials such as MCM-41 and amorphous silica, as well as zeolite catalysts such as USY, H-mordenite and dealuminated H-mordenites. The catalytic behavior has been discussed in relation with the physical chemical properties of catalysts. (C) 2004 Elsevier Inc. All rights reserved.