Progress and recent novelties in naphtha reforming catalysts

Abstract

High octane gasoline and aromatics, such as benzene, toluene, and xylenes, are both produced by the catalytic reforming of naphtha, being aromatics crucial building blocks in the chemical industry. Competing reactions occurring concurrently and catalyst deactivation under specific operating conditions make catalytic reforming of naphtha a very complicated process. This review focuses on the catalytic naphtha reforming process for aromatics production and makes special emphasis on reforming catalysts (evolution and recent novelties, as well as their deactivation, regeneration, and reactivation processes). Various aspects of the catalytic reforming process, such as the major reforming reactions carried out during the reforming process, types of industrial reforming processes, characteristics of the reviewed reforming processes, and the reaction parameters and their effect on the catalytic reforming process, are also considered in order to establish the context. Reforming catalysts are bifunctional, while some reactions just require the Pt site or the acid function to complete, others require both of these types of sites. Platinum is generally combined with one or two metals, such as Re, Ir, Sn, or Ge. The catalyst's acidic function is determined by chlorine, which also contributes to a high dispersion of the metallic phase. Research into naphtha reforming catalysts is looking for ways to improve aromatics yield and catalyst life. It has been noted that low dehydrogenating capacity and high hydrogenolytic capacity, both of which are provided by Pt, as well as low polymerization capacity, which is provided by the strong acid sites in the support, are the characteristics that make a catalyst stable as a result of the lesser formation of coke. Significant differences in the catalysts' basic composition have not been documented because bi- and trimetallic catalysts are still actively researched due to the complexity of their chemistry, with the identification of the wide variety of sites present within them and the understanding of their chemistry being of utmost importance. Even so, some innovation has occurred in recent years, among which are: non-noble metal reforming catalysts based on metal carbides, metal zeolite composite catalysts, the use of metals (In and Ga) other than those commonly used, and Ce3+-modified zeolites as support.