Strategic way for valorization of manure into chemicals and fuels

Abstract

Animal manure contains a variety of organic materials that can be used for synthesis of value-added biofuels and chemicals. To maximize the carbon recovery from animal manure waste, this study focused on consecutive valorization of horse manure into furfural and syngas (H-2 and CO). Acid hydrolysis/dehydration of horse manure was employed to extract furfural, and the residue after furfural extraction was valorized into syngas and bio-oil through CO2-assisted pyrolysis. In acid treatment process, the levulinic acid and furfural were produced from horse manure, and the maximum yield (3.68 wt%) of furfural was achieved at 0.5 M H2SO4 (40 wt% based on hemicellulose content). Horse manure residue was further converted into bio-oil and syngas under N-2/CO2 environments. Under CO2 atmosphere, gas phase homogeneous reactions were occurred, which simultaneously reduced CO2 and oxidized bio-oil showing enhanced CO formation (18 times higher comparing to pyrolysis under N-2). The homogeneous reaction also resulted in decrease of aromaticity in bio-oil. To enhance the reaction kinetics of the homogeneous reaction and thermal cracking of bio-oil under CO2, catalytic pyrolysis was performed in the presence of Ni/SiO2 catalysts. The catalytic pyrolysis improved syngas (H-2 and CO) production more than one order of magnitude higher, comparing to pyrolysis without Ni catalyst. All the experimental findings suggested that horse manure and CO2 could be used as raw materials for production of value-added chemicals and syngas.