Vapor phase nitration of benzene over solid acid catalysts - II. Nitrationwith nitric acid (1); montmorillonite and mixed metal oxide catalysts

Vapor phase nitration of benzene over acidic catalysts is expected to be a clean process without sulfuric acid waste. We investigated this process ove r 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 contai ning TiO2 or ZrO2 exhibited such high activities as 80-90% yields of nitrob enzene (STY=0.6 g/g cat h) for more than 480 h on-streams. We have estimate d that the strong Bronsted acidity is the active site for the vapor phase n itration with nitric acid. (C) 1998 Elsevier Science B.V. All rights reserv ed.