Shape-selective isopropylation of naphthalene over dealuminated mordenites. Increasing?-substitution selectivity by adding water

C2–C4 light olefins from bioethanol catalyzed by Ce-modified nanocrystalline HZSM-5 zeolite catalysts

“…However, other factors such as the Lewis acid sites, the function of metal cation on dehydrogenation, the effect of shape selectivity and the crystal size of CeO 2 should not be neglected [16,52,[56][57][58][59][60][61], especially for the Lewis acid sites [25,30,62], as the introduction of metal cation to the surface of HZSM-5 zeolite could result in the formation of both Brönsted acid sites and Lewis acid sites [30,32,34,54]. The results of XPS (Figs.…”

“…It can be calculated that compared with nano-HZSM-5 after calcination at 520 • C, the amount of acid sites on nano-HZSM-5 after calcinations at 620 • C remained 62.4%, and that was only 32.8% at 720 • C; while compared with 5.0 Ce-nano-HZSM-5 calcined at the 520 • C, the amount of acid sites on 5.0 Ce-nano-HZSM-5 after calcinations at 620 • C remained 81.9%, and that was 50.7% at 720 • C. This indicates that cerium modification could enhance thermal stability of HZSM-5 zeolite catalyst comparatively. The loss of acid sites could be attributed to dealumination in the HZSM-5 framework and dehydroxylation of Brönsted sites arising from the higher calcination temperature [25,37]. Furthermore, from Fig.…”

“…As the stability of zeolite catalysts could be enhanced by modification with rare earth metals [22,24], most of the tested nanocrystalline HZSM-5 catalysts were modified with cerium in this paper. Considering the effect of water on the acid properties and coke resistance of zeolite catalysts [17,25,26], a ethanol/water ratio of 20/80 (vol%) was used as the bioethanol feedstock.…”

Shape-selective synthesis of 2,6-diisopropylnaphthalene on H-mordenite catalysts

“…[33] but using high-silica mordenites as catalysts. The last test seems important because a positive influence of water addition or using isopropanol as alkylating agent on shape-selective formation of 2,6-DIPN can be found in the literature [16,36]. Also, a positive effect of cyclohexane or decalin solvent on 2,6-DIPN selectivity in alkylation of naphthalene with isopropanol is reported [37].…”

Regioselective Electrophilic Aromatic Substitution Reactions over Reusable Zeolites

“…Isopropylation of naphthalene with propene [79], isopropyl alcohol [80][81][82][83][84] and isopropyl bromide [85] as reagents, had been studied using a variety of zeolites. In this case, β,β-selectivities of over 75%, with a 2,6/2,7 ratio of approximately 2, have been reported using HM [86], and the best isopropylation procedure gave a 54% yield of 2,6-di-isopropylnaphthalene with a 2,6/2,7 ratio of 4 [86].…”