Direct catalytic production of sorbitol from waste cellulosic materials

- Materials ball-milling disrupted their crystallinity, easing the direct conversion.
- Sorbitol was directly obtained from cotton wool, cotton textile and tissue paper.
- Mix-milling greatly enhanced the rate of conversion of cellulosic biomass.
- Sorbitol amounts higher than 0.5 g could be obtained from 1 g of cellulosic biomass.
- Printing paper (white and recycled) was not converted to sugar alcohols.

Cotton wool, cotton textile, tissue paper and printing paper, all potential waste cellulosic materials, were directly converted to sorbitol using a Ru/CNT catalyst in the presence of H2 and using only water as solvent, without any acids. Conversions up to 38% were attained for the raw substrates, with sorbitol yields below 10%. Ball-milling of the materials disrupted their crystallinity, allowing reaching 100% conversion of cotton wool, cotton textile and tissue paper after 4 h, with sorbitol yields around 50%. Mix-milling these materials with the catalyst greatly enhanced their conversion rate, and the materials were efficiently converted to sorbitol with a yield around 50% in 2 h. However, ball- and mix-milled printing paper presented a conversion of only 50% after 5 h, with sorbitol yields of 7%. Amounts of sorbitol of 0.525, 0.511 and 0.559 g could be obtained from 1 g of cotton wool, cotton textile and tissue paper, respectively.

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