posted on 2022-12-29, 13:39authored byAyush Vasishta, Hitesh S. Pawar
5-Hydroxymethyl furfural
(5-HMF) is a potential platform molecule
with multidimensional applications and can be produced from biomass-based
hexose sugars. In the present article, polyethyleneimine (PEI)-functionalized
polymeric Bronsted acid ionic liquid (PolyE-IL) catalyst has been
explored for fructose dehydration in the presence of isopropyl alcohol
(IPA) as a green and low-boiling-point (LBP) organic solvent. The
use of homogeneous PolyE-IL catalyst provides several specific advantages
in terms of high yield, conversion, selectivity, ease of catalyst
separation, recycle and reuse, and so forth. PEI with various Bronsted
acid counterions such as H2SO4, H3PO4, TsOH, TfOH, and TFA provides the corresponding variables
of PolyE-IL such as [PEI]+[HSO3]−, [PEI]+[H2PO4]−, [PEI]+[CF3CO2]−, [PEI]+[TfO]−, and [PEI]+[TsO]−, which are tested for fructose dehydration
in the presence of IPA. Of the tested catalysts, only PolyE-IL with
[HSO4]−, [CF3CO2]−, [TfO]−, and [TsO]− counterions showed the formation of 5-HMF. [PEI]+[HSO4]− showed the maximum yield of 5-HMF (61%)
and selectivity (70%) with (87%) fructose conversion. Thus, further
process optimization study was conducted to obtain the maximum yield,
conversion, and selectivity. The intensified process provides a maximum
yield of 5-HMF of 75% with 85% fructose conversion and 90% selectivity.
The catalyst recyclability study showed the consistency in 5-HMF yield
(75%), conversion (85%), and selectivity (90%) for five consecutive
recycle runs. However, the study of reaction kinetics showed the first-order
kinetics with an activation energy of 12.4 kJ/mole by using [PEI]+[HSO4]− catalyst. Thus, the use
of an easily recyclable and robust catalyst provides an efficient
route for production of 5-HMF in the presence of a green solvent.