Catalytic characteristics of massive and loaded sulfonic resins in the synthesis of ethyl tert-butyl ether at atmospheric and increased pressure

Abstract

The catalytic characteristics of massive and loaded sulfonic resins in the synthesis of ethyl tert-butyl ether at atmospheric and increased pressures have been compared. It has been established that massive sulfonic resins are more active than loaded resins at atmospheric pressure. At higher pressures, on the other hand, the activity and selectivity of catalysts are greater the lower the content of polymer as a result of the increased effectiveness of the acid centers.Recently alkyl tert-butyl ethers have been obtained industrially by the use of sulfonic resin catalysts of various types [1,2]. Structurally they may be gels or macroporous. The gel cation exchangers are deprived of porosity and most of their acid centers are used for adsorption (and consequently for catalytic reactions) only on swelling in polar media, while the macroporous catalysts have developed surfaces thanks to their porosity and their acid centers are available in both the swollen and unswollen states. The catalytic activity and selectivity of the organic sulfonic resins is determined by the presence of the sulfonic acid groups, located both on the surface and within the porous structure of the granules. The basic drawback of such materials is, in particular, the low mass-exchange characteristic, which is an important limitation to the use of massive sulfonic resins [3].To avoid the drawbacks of the massive sulfonic resins hybrid mineral-organic acid catalysts have been created, in which the organic sulfonic resin phase is distributed in the porous structure of the inorganic carrier (Al 2 O 3 , SiO 2 , zeolites, clays, ceramics, graphite). These catalysts, in contrast to ion exchange resins, are characterized by the rapid establishment of the adsorption equilibrium, which is not limited by internal diffusion.Mineral-organic sulfonic resins based on silica have been known for a long time and have been used as the basis of adsorption processes because of their high mass-exchange characteristics. Information on the use of such materials as catalysts is scattered, unsystematic and limited in character [4][5][6][7][8][9][10]. For example aluminosilicate with a loaded thermostable sulfonic