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Hypercrosslinked microporous polymer sorbents for the efficient recycling of a soluble acid catalyst in cellulose hydrolysis
- Woodward, Robert T., Kessler, Martin, Lima, Sérgio, Rinaldi, Roberto
- Green chemistry 2018 v.20 no.10 pp. 2374-2381
- adsorbents, aqueous solutions, batch systems, biorefining, biotransformation, catalysts, cellulose, furfural, green chemistry, hydrolysis, hydroxymethylfurfural, lignocellulose, methanol, polymers, porous media, saccharification, solvents, sugars, sulfuric acid, washing, yeasts
- Difficulties in the recycling of soluble acid catalysts within the lignocellulosic biorefinery constitute a serious issue to the sustainability of cellulose hydrolysis and several other transformations. Herein, we demonstrate a simple and effective method for the removal and recovery of p-toluenesulfonic acid (p-TSA) employed as a replacement of H₂SO₄ in the saccharification of cellulose by a mechanocatalytic route. p-TSA is recovered from its diluted aqueous solutions using a non-expensive hypercrosslinked polymer adsorbent. In a batch process, around 97% p-TSA acid was removed from a 5 mM solution after exposure to the hypercrosslinked polymer. Notably, a flow-through process was able to selectively remove the catalyst completely from even lower initial concentrations. Importantly, the efficient recovery of the p-TSA is achieved by washing the spent polymer with methanol. In the purification of a stream derived from the saccharification of cellulose, the extraction of p-TSA catalyst in addition to 5-hydroxymethylfurfural (HMF) and furfural was also achieved. With the rational choice of solvents, p-TSA and furfurals were separately recovered. In the broader context, the current findings represent a step forward towards the acid management from the acid-catalyzed saccharification of cellulose. Moreover, this approach is conducive for the purification of sugars for bioconversion in which even low levels of furfurals may exert a strong inhibitory effect upon yeast cultures.