Microwave‐assisted synthesis of levulinic acid from low‐cost, sustainable feedstocks using organic acids as green catalysts

Abstract

BACKGROUNDModern day scientific endeavour strives towards global sustainability through the smart utilisation of renewable resources as base materials for chemicals. Until now, the most common commercial process to produce levulinic acid (a mass‐produced platform chemical) depends on a two‐stage mineral acid‐catalysed reaction, which generates harmful environmental waste. In this work, an environmentally friendly levulinic acid production route using less harmful organic acids assisted by microwave heating from biomass feedstocks is reported for the first time.RESULTSUsing aluminum sulfate as a green Lewis acid catalyst and seven organic acids, levulinic acid was successfully produced from barley straw under microwave heating, with maleic acid giving the highest catalytic conversion. A Response Surface Methodology (RSM) approach was used to rapidly and effectively examine the effect of five reaction variables on the productivity of the levulinic acid. A wide range of different biomass wastes (barley straw, brewery waste, olive cake, spent tea leaves and potato, tomato, and mandarin peels) were subsequently screened to produce the levulinic acid. The highest yield of 86 wt% based on cellulose content from mandarin peel (a value comparable to a lengthier ‘non‐green’ route) was achieved under the following optimized reaction conditions: 180 °C, 38 min, 2 M maleic acid concentration, 0.1 g Al2(SO4)3 and 1:22 biomass: maleic acid ratio (g mL−1).CONCLUSIONSThe proposed method is a promising new route towards the green, high yield production of levulinic acid from a variety of agricultural and household lignocellulosic biomass wastes, without the need for pre‐treatment. © 2020 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Hybridization of Synthetic Humins with a Metal–Organic Framework for Precious Metal Recovery and Reuse

“…For instance, HMF was heated at 120 °C in a solution containing FeCl 3 , which enabled us to explore the effects of the Lewis acidic Fe 3+ sites in Fe-BTC without the presence of the porous MOF template. In this reaction, HMF was partially converted to levulinic acid (conversion of ∼10%, Figure S13), demonstrating that the Fe 3+ sites of the MOF can catalyze the ring opening of HMF and hence drive the elimination of the furan functionality. Also, in addition to levulinic acid, there was the formation of a high MW polymer that is insoluble in DMF, ethanol, and DMSO.…”

Statistical approach for the optimization of levulinic acid production from orange peel as agricultural waste

“…By contrast, the maximum FF yield was achieved in water‐DMSO 3 . Aliko et al 23 . reported the microwave‐assisted synthesis of LA from mandarin peel using organic acids.…”

“…By contrast, in the conditions employing H 2 SO 4 as a catalyst, a decrease in furan production and an increase in LA production were achieved. Aliko et al 23 reported that this is because of enhanced cellulose decomposition at higher temperatures and higher acid concentrations.…”

“…Shao et al 1 obtained the highest 5-HMF yield (3.8%) from watermelon peel with HCl as catalyst by microwave hydrothermal liquefaction. Aliko et al 23 reported the microwave-assisted synthesis of LA (9 wt%) from mandarin peels using a combined catalytic system of maleic acid and Al 2 (SO 4 ) 3 . However, Licursi et al 24 reported a 22% LA yield from lemon peel using HCl-salt solution as the catalyst.…”

“…28,29 In this study, an acid-catalyzed hydrothermal conversion of orange peel to platform chemicals was carried out using sulfuric acid as the catalyst. The reaction was optimized using RSM, which has been proven to be a useful and reliable statistical approach for the rapid and efficient determination of the optimal reaction conditions for the production of LA, 23,29 and the reciprocal interactions of reaction variables were explored and assessed. The catalytic efficiency was also evaluated in comparison with the combined severity (CS) values and LA yields.…”