Conversion of cellulose into platform chemicals is essential for sustainable development of the chemical industry. With this aim, single step hydrothermal conversion of cellulose to industrially important levulinic acid using zirconium dioxide as a catalyst has been investigated. A remarkably high yield (53.9 mol %) of levulinic acid with excellent accountability and total conversion of cellulose has been achieved at 180 °C reaction temperature and reaction time of 3 h with 2 wt % of catalyst and 2 g of cellulose. The major products identified were levulinic acid (LA), formic acid (FA), 5-hydroxymethylfurfural (5-HMF), furfural, and humins. Formation of humins during cellulose hydrolysis and dehydration was observed and is also confirmed by NMR and FTIR analysis. The effect of various reaction parameters such as temperature, time, substrate concentration, and catalyst loading on conversion and selectivity has been studied. The catalyst has been regenerated and recycled several times without any loss of activity and selectivity.
Sustainable process
and efficient heterogeneous acid catalyst for the preparation of platform
chemicals like 5-hydroxymethyl furfural (5-HMF) from renewable source
is much in demand in the context of heterogeneous catalysis. Commercially
available solid acid catalyst, H-USY zeolite was modified by treating
with aqueous solution of H3PO4 and H2SO4 (10–30 wt %). Modified H-USY was completely
characterized by XRD, NH3-TPD, energy dispersive analysis
X-ray (EDAX), FT-IR, pyridine-IR, and NMR. Its catalytic performance
was evaluated for the fructose conversion to 5-HMF in methyl isobutyl
ketone (MIBK)–water system. Modified H-USY zeolite was identified
to have potential in enhancement of 5-HMF yield up to 65% from 32%
(parent H-USY) with minimum formation of furfural (8%). H-USY modified
with 10 wt % H3PO4 (10P–Y) was found
to be the best compared to other studied catalysts, namely, H-USY
modified with 20 and 30 wt % H3PO4 (20 and 30P–Y)
or 10–30 wt % H2SO4 (10- to 30S–Y).
Best performance of 10P–Y is associated with the optimum combination
of moderate acidity (both weak as well as strong), moderate dealumination
of Al from extra-framework sites as well as from framework sites of
H-USY, formation of new Al–O–P bonds between framework
Al and elemental monomeric phosphorus, presence of Brønsted as
well as Lewis acidity, and creation of mesopores. This gives new insight
on a potential heterogeneous acid catalyst for the synthesis of 5-HMF.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.