Stabilization of Fast Pyrolysis Liquids from Biomass by Mild Catalytic Hydrotreatment: Model Compound Study

Depeng Han,Tongrui Liu,Wang Yin,Shuqian Xia,Ali Arslan,Yan Zheng

doi:10.3390/catal10040402

Depeng Han, Tongrui Liu + Show 4 more

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https://doi.org/10.3390/catal10040402

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Abstract

Repolymerization is a huge problem in the storage and processing of biomass pyrolysis liquid (PL). Herein, to solve the problem of repolymerization, mild catalytic hydrotreatment of PL was conducted to convert unstable PL model compounds (hydroxyacetone, furfural, and phenol) into stable alcohols. An Ni/SiO2 catalyst was synthesized by the deposition-precipitation method and used in a mild hydrotreatment process. The mild hydrotreatment of the single model compound was studied to determine the reaction pathways, which provided guidance for improving the selectivity of stable intermediate alcohols through the control of reaction conditions. More importantly, the mild hydrotreatment of mixed model compounds was evaluated to simulate the PL more factually. In addition, the effect of the interaction between hydroxyacetone, furfural, and phenol during the catalytic hydrotreatment was also explored. There was a strange phenomenon observed in that phenol was not converted in the initial stage of the hydrotreatment of mixed model compounds. Thermogravimetric analysis (TGA), Ultraviolet-Raman (UV-Raman), and Brunauer−Emmett−Teller (BET) characterization of catalysts used in the hydrotreatment of single and mixed model compounds demonstrated that this phenomenon did not mainly arise from the irreversible deactivation of catalysts caused by carbon deposition, but the competitive adsorption among hydroxyacetone, furfural, and phenol during the mild hydrotreatment of mixed model compounds.

Highlights

Pyrolysis liquids (PL), obtained from biomass fast pyrolysis, are considered potential liquid energy carriers for the production of renewable fuels and bio-based chemicals from lignocellulosic biomass [1].They have a volumetric energy density that is 5 to 20 times higher than that of mother solid biomass [2], which favors storage and transport
No obvious carbon deposition on the catalyst used in the hydrotreatment of mixed model compounds was observed, which further certificated that it did not originate from the irreversible deactivation of catalysts caused by carbon deposition and that the conversion of phenol was inhibited in the initial stage of hydrogenation
An Ni/SiO2 catalyst was synthesized by the deposition-precipitation method and used in the mild hydrotreatment of single and mixed model compounds

Summary

Introduction

Pyrolysis liquids (PL), obtained from biomass fast pyrolysis, are considered potential liquid energy carriers for the production of renewable fuels and bio-based chemicals from lignocellulosic biomass [1]. They have a volumetric energy density that is 5 to 20 times higher than that of mother solid biomass [2], which favors storage and transport. The composition of biomass PL is complex [4] and varies with the biomass feed [5] Some components, such as aldehyde, ketones, carbohydrates, and phenols [6], are chemically and thermally unstable as the fast pyrolysis process occurs too rapidly to reach the equilibrium [7]. All of the above undesired properties limit the use of PL as fuel or for bio-based chemical production [4]

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