Microwave-assisted synthesis of sulfonic acid-functionalized microporous materials for the catalytic etherification of glycerol with isobutene

Abstract

Commercial Beta, ZSM-5 and mordenite zeolites and commercial montmorillonite K-10 were successfully\ud sulfonated by a one-step simple method using microwaves. Different amounts of the sulfonating agent\ud were required to maximize the incorporation of sulfonic groups for each structure. This has been related\ud to the different dealumination degree suffered by the starting samples during sulfonation together with\ud the different accessibility of the silanols to the sulfonic groups depending on the arrangement and size\ud of their pores. All optimised sulfonated catalysts showed total conversion and very high selectivity\ud (79–91%) to h-GTBE (glycerol di- and tri-ethers), in spite of their microporosity, due to the incorporation\ud of the sulfonic groups that led to a higher number and strength of Brønsted acid sites. Pore size and\ud arrangement together with the external surface area of the catalysts affected the accessibility of the acid\ud sites to the reactants, explaining the evolution of the catalytic results with time for each structure.Postprint (published version

Enhanced production of high octane oxygenates from glycerol etherification using the desilicated BEA zeolite

“…The selectivity to h-GTBE (DTBG + TTBG) was reported to be about 37% on fluorinated BEA while as high as 75-91% selectivity is observed on sulfonic acid functionalized aerogels, BEA, SBA-15 and HBS based catalysts [21][22][23]. The studies of Tuan et al yielded highest glycerol conversion of 90% with 77.7% selectivity to DTBG + TTBG over p-toluenesulfonic acid catalyst while the corresponding values on Amberlyst-35 are 59% and 63.9% respectively [24].…”

Alternative fuel additives from glycerol by etherification with isobutene: Structure–performance relationships in solid catalysts

“…Gonzalez et al modified zeolite Beta by post synthesis sulfonic acid addition via conventional heating and microwave heating [38], and then tested microwave assisted sulfonation on a wider range of zeolites, covering zeolite Beta, ZSM-5 and Mordenite [41]. The sulfonic acid source was 2-(4-chlorosulfonylphenyl) ethyltrimethoxysilane (CSPTMS) (Fig.…”

“…Mesostructured silica functionalized with organo-sulfonic groups have already been used as successful alternatives to conventional solid acid catalysts in fatty acid esterification [127,128] and sugar hydrolysis [129,130]. The properties of sulfonic acid mesoporous silica, such as high surface area, larger pores, narrower pore size distribution, easy access to Brønsted acid sites and strong acidity, favored its applicability also for the etherification [28,36,38,41,45,46] of glycerol.…”

“…Although high glycerol conversion, high desired ether selectivity and low DIB selectivity were obtained with homogenous catalysts, difficulties in catalyst-product separation, corrosion and environmental issues reduced the interest on the commercialization of glycerol ether production. Subsequently, as well as improving the catalytic environment of ion exchange resins [27,29,31,34], different heterogeneous catalysts covering pure or modified wide pore zeolites [25,27,31,34,35,38,40,41,44], functionalized mesostructured materials [28,32,36,46] and other heterogeneous acid catalysts, such as montmorillonite K-10, amorphous microporous mixed oxide [24], sulfonated peanut shell [33], solid heteropolyacids [24,31,39], spherical silica supported Hyflon [37], sulfonated graphene [47], sulfonic acid functionalized aerogels [43], triflic acid supported on gamma alumina [46,48] were elaborated by comparing their performance with acidic ion exchange resins and attempting to understand effects of catalyst structures, such as porosity, surface area, pore size, pore volume, acid capacity, acid strength on catalytic activity, expressed by glycerol conversion, ether selectivity and side product formation.…”

Liquid–liquid–solid mass transfer and phase behavior of heterogeneous etherification of glycerol with isobutene

“…tert ‐Butyl glycerol ethers obtained by etherification of biodiesel‐derived glycerol with isobutene or tert ‐butyl alcohol are considered as promising fuel (gasoline, diesel, and biodiesel) additives which can improve fuel quality and reduce particle emissions . Substantial research has been directed toward identifying catalysts that enhance glycerol conversion and the selectivity of the glycerol ethers . These include acid resins, zeolites, mesoporous silicas, sulfonated catalysts, so forth.…”