Work

Understanding the relationship between catalytic pyrolysis conditions and hydrogen production by aqueous phase reforming of the water-soluble fractions of bio-oils

Year: 2024

Type: article

Abstract: • Severe catalytic pyrolysis conditions increase H 2 production in APR of AFB. • Higher H 2 production for levoglucosan-rich AFBs with low acid and ketone proportion. • 40 % H 2 production increases by adding 0.04 wt% formic acid to AFB. • The catalyst was reasonably stable over three consecutive reaction cycles. • Cumulative adsorption of heavy compounds and oligomers on the catalyst surface. The valorization to H 2 of real aqueous fractions of bio-oil (AFBs) from catalytic pyrolysis of woodchips was carried out by aqueous phase reforming (APR). Notable gas yield (23 mmol/gTOC o ) and H 2 concentration (46 mol%) were achieved, with values among the best published for the APR of real biorefinery streams. The reforming of AFBs was favoured by a high concentration of levoglucosan and low proportion of acids and ketones, with acetone and acetic acid being the most refractory compounds to APR. Relationships between the pyrolysis conditions and the H 2 production obtained by APR were assessed, with more favourable results when the pyrolysis was carried out under the most severe conditions of those studied, i.e. 0.30 catalyst/biomass ratio and 500 °C in the catalytic step. H 2 production increased to 32 mmol/gTOC o when 0.04 wt% formic acid was added to the reaction medium, showing that this strategy can overcome the low reforming ability of some AFB components. The Pt catalyst showed good stability after 3 consecutive reaction cycles, displaying only a slight decrease in TOC conversion and CCgas, but a moderate decrease in H 2 production and gas concentration. The loss of activity was ascribed to cumulative adsorption of high molecular weight compounds and oligomers on the catalyst surface.

Source: Energy Conversion and Management

DOI: 10.1016/j.enconman.2024.118999