Zeolite-Based Catalysis For Phenol Production

Phenol is an important chemical commodity utilized for several applications (e.g., polycarbonate, epoxy-resins, phenolic resins, nylon). Its conventional production starts from benzene and propylene and is based on a series of reaction steps most of which are catalyzed by acid catalysts. Besides this technology other ones have been considered during the last decades, starting from other reactants and catalysts. Looking at the catalyst types both already in use or under evaluation, it is interesting to note that zeolites, as acidic catalysts or red-ox catalysts, were widely investigated. Therefore, the production of phenol represents a fascinating example of how zeolite catalysis contributes to improving the sustainability of these chemical processes by displacing the previous large use of corrosive and dangerous liquid acids and improving overall selectivity, which reduces the side production of wastes. Aromatic alkylation, transalkylation, and disproportionation, oxidations, rearrangements, oligomerization, and cracking are the reactions occurring in phenol production technologies, but also key unit operations in refineries and the chemical industry. A review of the zeolite catalysts utilized and proposed by major licensors and research groups in these technologies is provided as well as a discussion of key process differences and recent advances.