Optimization of levulinic acid production from heterogeneous catalytic pretreatment of rice straw using Dowex 50 W in aqueous ferric chloride solution

A major lignocellulosic biomass, rice straw (RS) generated from agricultural waste, has an immense potential to produce platform chemicals, levulinic acid (LA). The effectiveness of Dowex 50 W (X8 hydrogen form) catalyst for the production of LA from RS in the three mediums namely liquid water, dilute sulfuric acid and aqueous ferric chloride solution have been studied. For optimization, the temperature range of 150–190 °C with 5–15 min reaction and 10–30 % ( w /w) catalyst loading have been used. Two Pathways for the production of LA from RS in the presence Dowex 50 W were described. The yield of LA yield (g of LA per kg of RS) at 190 °C and 10 min reaction time using Dowex 50 W (20 % loading) in liquid water, diluted sulfuric acid (0.1 M) and ferric chloride (0.1 M) solution were determined as 7.83, 17.89 and 72.45 respectively. Using Design expert software (version−11), a 3-level, 3-factor Box-Behnken statistical design in response surface methodology (RSM) was used to predict the optimum yield of LA. The optimum LA yield for model prediction and experimental was achieved as 91.02 and 90.37 g of LA per kg of RS at 179.9 °C for 14.4 min with 20.1 % Dowex loading in 0.2 M ferric chloride solution. At optimum condition, the degradation of xylan and cellulose were determined as 99.43 % and 54.31 %, respectively. A comprehensive mass balance flow sheet for LA production has been illustrated and described. • Levulinic acid (LA) production from rice straw (RS) using Dowex 50W has been investigated for the first time ever. • LA yields in liquid water, dilute sulfuric acid, and ferric chloride solution with/ without Dowex 50W have been determined. • Two Pathways for the production of LA were proposed. • At optimum condition (179.9 °C, 14.4 min. 20.1 % catalyst-loading) the yield of LA is 90.37 (g of LA per kg of RS). • At optimum condition, the degradation of xylan and cellulose were 99.43 % and 54.31 %.