Cited by 169
Universiti Putra Malaysia
ORCID: 0000-0001-8868-5048Publishes on Polyoxometalates: Synthesis and Applications, Catalysis for Biomass Conversion, Chemical Synthesis and Reactions. 45 papers and 4k citations.
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A series of heteropolyacid (HPA) ionic liquids [C4H6N2(CH2)3SO3H]3−nHnPW12O40 ([MIMPSH]nH3−nPW12O40, n = 1, 2 3, abbreviated as [MIMPSH]nH3−nPW) was used to catalyze one-pot depolymerization of cellulose into glucose. Their performances were much better than those of the previously reported HPAs, such as H3PW12O40, Cs2.5H0.5PW12O40. Besides cellulose, the HPA ionic liquids were able to catalyze the conversion of sucrose and starch into glucose. In addition, one-pot synthesis of levulinic acid (LA) directly from cellulose was realized using these HPA ionic liquid catalysts in a water–methyl isobutyl ketone (MIBK) biphasic system. The separation of the products and catalysts was easy, and the retrieved [MIMPSH]nH3−nPW could be repeatedly used without appreciable loss of performance.
A new series of heteropolyacids [(CH<sub>3</sub>)<sub>3</sub>NCH<sub>2</sub>CH<sub>2</sub>OH]<sub>n</sub>H<sub>5−n</sub>AlW<sub>12</sub>O<sub>40</sub> are used to catalyse the single step conversion of cellulose into levulinic acid (LA). The highest reported yield of LA directly from cellulose was achieved with 74.8% yield and 98.9% conversion in one pot.
A series of acid–base bifunctional heteropolyacids (HPAs) (C6H15O2N2)3−xHxPW12O40 (abbreviated as Ly3−xHxPW) have been designed using different ratios of HPAs with amino acid lysine in order to control their acid–base properties. The amino acid group facilitated the HPAs forming micellar assemblies in choline chloride–fructose deep eutectic solvents. In the dehydration of fructose to 5-hydroxymethylfurfural (HMF), Ly3−xHxPW exhibited different catalytic activities because of their different acid–base properties. Among all the HPA catalysts, Ly2HPW gave the best results with 93.3% conversion and 92.3% HMF yield within a very short time, i.e. 1 min under the conventional temperature of 110 °C using choline chloride (ChCl) as solvent, and this was almost the best result by far. The highest activity and selectivity of Ly2HPW came from the synergistic effect between certain acidic and basic capacities, which provides ready accessibility to the nucleophilic (–NH2) and electrophilic (H) sites. Moreover, this catalyst was tolerant to highly concentrated feedstock (∼66.7 wt%) with the additive ChCl. Ly2HPW performed as a heterogeneous catalyst in the ChCl system and could be recycled by simple washing treatment.