Integrating molten carbonates pyrolysis and catalytic reforming with modified HZSM-5 for monophenols produced from digestate

Digestate (DE), the residue following anaerobic digestion , has been well utilized as a potential feedstock of molten carbonates pyrolysis and catalytic reforming . The lignin of DE was converted into phenolics, guaiacols and furfural with molten carbonates pyrolysis, and further upgraded to bio-based monophenols by coupling with modified HZSM-5 catalyst. The maximum monophenols yield could achieve 7.22 g/100 g of digestate, and 81.34% of the organic phase of bio-oil at the optimum reaction conditions. The alkali-treated and Fe-loaded on HZSM-5 catalyst, with enhanced pore diameter distinctly and mild acidity, has an outstanding selectivity for monophenols and preferable anti-coking ability in integrated pyrolysis system, while with quite a low catalyst coke yield of 3.97%. The results indicated that the formation of mesopores might minimize the diffusion hindrance of the reactant molecules and reduce coke accumulation. In addition, according to the experiment conducted on a self-designed thermogravimetric analysis device, the kinetic study of the digestate with molten carbonates certificated that the reaction rate of pyrolysis had been promoted by both decreasing activation energy and intensification of heat transfer.