Influence of Brønsted and Lewis acidity on the selective synthesis of BPMF from 5-HMF using zeolite-based catalysts

Abstract

5-Hydroxymethyl furfural (5-HMF), a bio-platform molecule, can effectively convert to 2,5-bis(propoxymethyl) furan (BPMF) via reductive etherification in the presence of a catalyst. BPMF is considered an important bio-based fuel/fuel additive candidate. However, producing it selectively is challenging, as Meerwein–Ponndorf–Verley (MPV) and etherification reactions occur simultaneously. Sufficient Brønsted acidic sites (BAS) and abundant Lewis acidic sites (LAS) favour the etherification reaction, whereas the MPV reaction is favoured by LAS only. Therefore, the presence of both BAS and LAS on the catalyst surface is a crucial factor affecting BPMF selectivity. Hence, developing a highly selective catalyst is very important. In this study, highly selective BPMF was obtained via 5-HMF reductive etherification through a one-pot pathway using 2-propanol as a hydrogen source with Sn-HZSM-5 and Zr-HZSM-5. The excellent collaborative effect of BAS and LAS provided higher selectivity towards BPMF using Sn-HZSM-5. The prepared catalysts were characterized using various techniques, such as PXRD, TEM, BET, Py-IR spectroscopy, and NH₃-TPD. Sn-HZSM-5 exhibited excellent catalytic activity at 160 °C and 4 h reaction time with 0.20 g and 1 g of catalyst and 5-HMF, respectively, with 96% 5-HMF conversion and 99% BPMF selectivity.