Synthesis of titanium-aluminum binary oxides stabilized by polyvinylpyrrolidone and their application for catalytic nitration of arenes

A series of titanium-aluminum binary oxides are prepared through co-precipitation of metal salts with polyvinylpyrrolidone (PVP) in alkaline solution, along with dehydration. Most of synthetic oxides are composed of micro- or nano-sized blocks, while one of them shows an interesting two-dimensional morphology. Furthermore, loading of aluminum into co-precipitation would increase product porosity compared with the non-loaded case, while addition of PVP shows influences on building micropores of synthetic oxide. In catalysis, the synthetic oxides usually show high activities for nitration of various arenes. The key factors affecting catalytic outputs are carefully discussed, and the matching relation between shape of substrate and pore distribution of catalyst may affect catalytic efficiency too. Moreover, the binary oxide featuring PVP shows more durable recycling behavior than the non-doped one. On the other hand, nitration reactions of naphthalene and benzene halides show better stereoselectivities than those of alkylbenzenes. In general, this study may contribute to the catalytic progress of new oxide materials.