Combined production of biofuel precursors, platform chemicals, and catalyst material from the integral processing of rice bran

Abstract

This research reports first-time results regarding the complete processing of rice bran through the combination of extraction, processing hydrothermal, sulfonation, and trans-esterification procedures, generating biofuel precursors – fermentable sugars, bio-oil, hydro-char, and methyl esters – platform chemicals, and a catalyst material. Analyzes of XRD, FTIR, BET, SEM, EDS, calorific power, GC, and HPLC were employed for the product characterizations. Concerning the hydrothermal processing, the “temperature” and “biomass/water mass ratio” demonstrated an interesting influence on the results, where the thermal parameter had a greater impact on directing the process to obtain products resulting from the biomass polysaccharides thermal decomposition. At 260 °C, 11.98 and 11.40 g (100 g biomass)−1 of fermentable sugars and platform chemicals were obtained, respectively. At 300 °C, the production of bio-oil and hydro-char were benefited, yielding 10.48 and 30.19 g (100 g biomass)−1 of each component, respectively. The hydro-char-sulfonated catalyst demonstrated an attractive catalytic capacity in esterifying the free fatty acids of the rice bran oil, while simultaneously presenting some difficulty in transesterifying its triglycerides, indicating limitations in the mass transfer of the heterogeneous reaction. Using 4 wt% of catalyst, 90.1 % of the free fatty acids and 60.3 % of the triglycerides contained in the oil were trans-esterified into methyl esters after 6 h, respectively, with no decrease in its catalytic activity being observed after four reuses. This process combination presents an alternative arrangement for the full processing of lignocellulosic and oily biomasses, in addition to representing an approach matchless for the rice bran.