Hydrogenolysis of cellulose combining mineral acids and hydrogenation catalysts

Abstract

A catalytic system capable of reaching high performance in the hydrogenolysis of cellulose at low reaction temperature and short reaction times has been developed. Therefore, supported noble metal catalysts based on Pt, Pd and Ru have been combined with dilute mineral acids. A broad variable set in terms of type of noble metal, type of acid, acid concentration and reaction time could be evaluated based on chemical interpretation and supported by a Design of Experiment (DoE) approach. The variables significantly influenced conversion of cellulose, product range and selectivity towards sugar alcohol formation. Thus, at 160 • C, above 60% yield in sugars and sugar alcohols with 84% selectivity at a cellulose conversion of 72% could be reached. Besides, glycerol, propylene glycol, ethylene glycol and methanol were formed as additional valuable by-products leading to an overall carbon utilization above 89%. Furthermore, the concept was successfully transferred to real feedstocks in the form of spruce reaching close to 60% conversion in only one hour reaction time.

Exergetical Evaluation of Biobased Synthesis Pathways

“…This process is currently in an early stage of development, and especially, conversion and selectivity achieved by the catalyst are low. According to Palkovits et al, conversion of glucose of 72%, and selectivity to 1,2-ethanediol of only 6% have been reached [36]. Besides 1,2-ethanediol, further by-products occur like glycerol, xylitol or sorbitol.…”

Combining Bio- and Chemo-catalysis for the Sustainable Production of Chemicals

“…Apart from acid sites from solid acid, water with high temperature and pressure, mineral acids like phosphoric acid and sulfuric acid were also introduced into cellulose hydrogenation under the catalysis of supported noble metal catalysts based on Pt, Ru, and Pd at relatively low temperature and short reaction time [21,[39][40][41]. The reaction network of cellulose hydrogenolysis is shown in Fig.…”

Efficient Conversion of Maltose into Sorbitol over Magnetic Catalyst in Extremely Low Acid

“…For glucose hydrogenation, the yield and selectivity of sorbitol can reach above 90% under the catalyzing of Ru-based catalysts (Zhang et al 2011). However, the selectivity to sorbitol decreased markedly during the hydrolytic hydrogenation of cellulose, and downstream molecules such as ethylene glycol and propylene glycol were produced at the same time (Palkovits et al 2010). Furthermore, the formation of these lower alcohols was hard to avoid during the hydrogenation process at temperatures of about 473 K. In previous work, Ru/C catalyst combined with extremely low acid was developed for direct conversion of cellobiose into sorbitol, and an optimized sorbitol yield of 87.1% was attained at 458 K and 3 MPa H 2 (Zhang et al 2012).…”