Study On Vapor Phase Nitration Of Benzene And Substitution Aromatic Hydrocarbons With Low Boiling Point Over Solid Acid Catalysts

In this paper, vapor-phase nitration of benzene and other substitution aromatic hydrocarbons with low boiling point was studied and many factors that affect vapor-phase nitration of aromatic hydrocarbons were investigated. New solid acid catalysts are effective on the vapor-phase nitration of aromatic hydrocarbons were synthesized by ourselves, which are supported heteropoly acid and supported sulfuric acid.The results show that the molar ratio of benzene and HNO3, 2:1 and the optimum reaction temperature, 150~170癈 and the best support, the silica for the vapor-phase nitration benzene and diluted nitric acid (60~70%).Supported heteropoly acid catalysts give fairly high catalytic activity and selectivity on vapor-phase nitration of benzene and diluted nitric acid and were characterized by ESR. Under conditions of molar ratio of benzene and HNO3, 2:1 and reaction temperature, 170癈 and space velocity, 1200ml/g h and reaction pressure, 0.1 MPa and the catalyst, 15%H3PW12O40/SiO2(by weight), the yield and the space-time yield (STY) of nitrobenzene (NB) are 86% and 0.66 kg NB/(kg cath) respectively. ESR spectrum show that reduced of heteropoly acid was occurred in vapor-phase nitration reaction of benzene. The ESR signals of W5+ are observed, which have g=1.94 and g//=1.95 at room temperature and have g=1.989 and g//=1.974 at 77K. And ESR of O2 with g1=2.026, g2=2.0 19 and g3=2.0 14 were observed simultaneously.Supported sulfuric acid catalyst exhibits also very high catalytic activity and selectivity on vapor-phase nitration ofbenzene and diluted nitric acid. Under conditions of molar ratio of benzene and HNO3, 2:1 and reaction temperature, 160 癈 and space velocity, 1200ml/g h and reaction pressure, 0.1 MPa and the catalyst, 10%H2SO4/SiO2(by weight), the yield and the space-time yield (STY) of nitrobenzene (NB) are 98% and 0.75 kg NB/(kg cath) respectively.