Heterogeneous catalysts for the extraction of arabinoxylans from wheat bran


The conversion of biomass within biorefineries into chemicals and energy is seen as a real possibility for the substitution of fossil resources. Raw materials of high lignocellulosic content are an interesting option. Nowadays wheat bran is gaining interest as raw material for biorefineries due to its high content in polysaccharides. In this sense, arabinoxylans (AX), which are the most abundant valuable components in wheat bran, are seen as suitable compounds for the production of sugar alcohols.

In general terms, the conversion of these hemicellulosic components from biomass into sugar alcohols is a two‑step reaction: 1) extraction and hydrolysis of AX and 2) hydrogenation of these hemicelluloses into polyols (Fig. 2).

Fig 2. Overview of the polyols production process from wheat bran

In this work, the extraction-hydrolysis process of arabinoxylans from wheat bran has been studied using heterogeneous ruthenium supported catalysts. Dissolution and hydrolysis of the AX into sugars were performed by pressurized hot water (PHW) and the acid sites of ruthenium catalysts. Different parameters, such as time (10‑30 minutes), temperature (140‑180 °C) and the presence of ruthenium catalysts were studied in this extraction process in terms of (1) matter solubilization, (2) content in total and free monosaccharides and (3) degradation products. The highest AX yield was achieved at 180 °C and 10 minutes using 500 mg of Ru/Al-MCM-48. The yield under these conditions was about 78%, compared to the 55% when no catalyst was used (Fig. 3).

Fig 3. Comparison of the effect of Ru/Al-MCM-48 catalysts on AX extraction yield from wheat bran

Nuria Sánchez – FPU (Cod: FPU14/00812) & project BIOFRAHYNERY

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