Vapor phase nitration of benzene over solid acid catalysts: II. Nitration with nitric acid (1); montmorillonite and mixed metal oxide catalysts Original Research Article

Vapor phase nitration of benzene over acidic catalysts is expected to be a clean process without sulfuric acid waste. We investigated this process over acidic catalysts utilizing diluted nitric acid (dil. HNO3) as a nitrating agent and found that several solid acid catalysts such as montmorillonite ion-exchanged with a multivalent metal cation and mixed metal oxides containing TiO2 or ZrO2 exhibited such high activities as 80–90% yields of nitrobenzene (STY=0.6 g/g cat h) for more than 480 h on-streams. We have estimated that the strong Brønsted acidity is the active site for the vapor phase nitration with nitric acid.