Sn-BEA zeolites prepared by two-step postsynthesis method: Physicochemical properties and catalytic activity in processes based on MPV reduction

Abstract

Sn0.5SiBEA and Sn2.0SiBEA zeolites obtained by two-step postsynthesis method were characterized by several physicochemical techniques (namely, NMR, Mössbauer, XPS, DR UV-vis and IR spectroscopies) and used in the study of Meerwein–Ponndorf–Verley (MPV) reduction as well as with the subsequent reaction of etherification, that is, conversion of (i) cyclohexanone with 2-propanol, (ii) 4-methoxybenzaldehyde with 2-butanol, and (iii) HMF with butyl alcohols (1-butanol, 2-butanol or isobutanol). The results have shown that in the case of cyclohexanone, MPV reduction to cyclohexanol occurs on both Sn0.5SiBEA and Sn2.0SiBEA zeolite catalysts with a higher degree of conversion in the presence of Sn2.0SiBEA. For 4-methoxybenzaldehyde a tandem process was observed consisting of MPV reduction with 2-butanol to 4-methoxybenzylalcohol followed by its etherification with 2-butanol to 4-methoxybenzyl sec-butyl ether. Higher conversion of aldehyde was achieved on the catalyst with higher amount of tin. The zeolites were active in HMF conversion with butyl alcohols. However, a tandem process including MPV reduction with the next formation of furanic diether was achieved only in the presence of secondary alcohol at test conditions.