Novelties of eclectically engineered sulfated zirconia and carbon molecular sieve catalysts in cyclisation of citronellal to isopulegol

Cyclization of citronellal over zeolites and mesoporous materials for production of isopulegol

“…It was, however, stated that the catalysts exhibiting residual Zn(II) sites were the most active in the cyclization of (+)-citronellal. The ene cyclization of (+)-citronellal proceeds very fast over sulfated zirconia, but the stereoselectivity toward (−)-isopulegol was maximally 61% [8]. High selectivities to isopulegol (72%) accompanied with high reaction rates were obtained over hydrous zirconia [7].…”

“…Additionally the use of heterogeneous catalysts allows more environmentally friendly processes than homogeneous catalysts. There exist some publications on the cyclization of (+)-citronellal over heterogeneous catalysts, like zeolites [6], sil- ica and mixed cogels [2], hydrous zirconia [7], sulfated zirconia [8], supported ZnBr 2 [9], and cation-exchanged montmorillonite [10].…”

Friedel‐crafts alkylation of diphenyl oxide with 1‐decene over sulfated zirconia as catalyst

“…Several heterogeneous catalysts have been reported and among the non-zeolitic catalysts, sulfated zirconia has a better scope for industrial applications (Tanabe et al, 1979;Tanabe, 1981;Song and Sayari, 1996;Yadav and Nair, 2000). We have evaluated the prowess of sulfated zirconia and clay-based non-zeolitic catalysts for a number of reactions of industrial importance, such as condensation (Kumbhar and Yadav, 1989), esterification (Kumbhar et al ., 1989;Yadav and Mehta, 1994;Yadav and Krishnan, 1998a;Thorat et al, 1992), alkylation (Dixit and Yadav, 1996a, b;Yadav and Thorat, 1996a, b;Yadav and Doshi, 1999a, b), etherification (Yadav and Kirthivasan, 1995;Yadav and Bokade, 1995;Yadav and Krishnan,l998b;Yadav and Kirthivasan, 1999), dehydration (Yadav and Kirthivasan, 1999;Yadav and Kirthivasan, 1997), acylation (Yadav and Pujari, 1999a;Yadav and Krishnan, 1999), isomerisation (Yadav and Satoskar, 1997;Yadav and Nair, 1998), nitration (Yadav and Nair, 1999a) and acetalization (Yadav and Pujari, 1999b) by using sulfated zirconia, clays, pillared clays, ion exchange resins, supported heteroployacids, and zeolites. Among these catalysts, sulfated zirconia has gained a considerable attention due to its very high acidity under certain conditions (Yadav and Nair, 1999b) and this catalyst can be modified or doped with other cations/anions, even incorporating sieving behaviour, for specific reactions (Yadav and Nair, 1999b;Yadav and Pujari, 1999a).…”

Current advances in catalysis toward sustainable biodiesel production

“…Moreover, the efficiency of zeolites in transesterification is highly dependent on strength of acid sites and hydrophobicity. Other properties such as adsorption characteristics, geometrical factors, dimensionality of the channel system [85] and aluminum content of the zeolite framework [86] affect the catalytic activity and performance for esterification.…”