• Energy Research
• IR close

Co-hydrothermal carbonization (HTC) of livestock manure and biomass might improve the fuel properties of the hydrochar due to the high reactivity of the biomass-derived intermediates with the abundant oxygen-containing functionalities. However, the complicated compositions make it difficult to explicit the specific roles of the individual components of biomass played in the co-HTC process. In this study, cellulose was used for co-HTC with swine manure to investigate the influence on the properties of the hydrochar. The yield of hydrochar obtained from co-HTC reduced gradually with the cellulose proportion increased, and the solid yield was lower than the theoretical value. This was because the cellulose-derived intermediates favored the stability of the fragments from hydrolysis of swine manure. The increased temperature resulted in the reduction of the hydrochar yield whereas the prolonged time enhanced the formation of solid product. The interaction of the co-HTC intermediates facilitated the formation of O-containing species, thus making the solid more oxygen- and hydrogen-rich with a higher volatility. In addition, the co-HTC affected the evolution of functionalities like -OH and CO during the thermal treatment of the hydrochar and altered its morphology by stuffing the pores from swine manure-derived solid with the microspheres from HTC of cellulose. The interaction of the varied intermediates also impacted the formation of amines, ketones, carboxylic acids, esters, aromatics and the polymeric products in distinct ways.

The development of reactors with varied configurations for the pyrolysis of municipal waste is discussed in this review.

Heavy organics in bio-oil generally refer to the sugar oligomers and lignin-derivatives. They are important fractions in bio-oil and their effective conversion in hydrotreatment determines carbon yield from biomass or bio-oil to biofuel. Fates of the heavy organics largely determine intrinsic reaction behaviors of bio-oil during hydrotreatment. The heavy organics in bio-oil have high tendency towards polymerization upon thermal treatment, which is one of the main precursors for coke formation and catalyst deactivation. Furthermore, the heavy organics have some other unique characteristics in hydrotreatment such as the steric hindrance for contacting active sites on surface of catalyst. How to effectively convert the heavy organics has been regarded as the bottle-neck issue in hydrotreatment of bio-oil and the key barrier in the roadmap from biomass to biofuels. Thus, this review particularly focuses on the progress in understanding reaction behaviors of the heavy organics in hydrotreatment of bio-oil, a central challenge to be resolved. The results indicated that coke formation from heavy organics in bio-oil remains main obstacle in hydrotreatment and further fundamental studies are required to develop suitable catalyst and process to stabilize the heavy organics in bio-oil. In particular, the mechanism for coke formation from the heavy species of varied chemical family should be clarified and corresponding measures should be developed to tackle high tendency of coking. Techno-economic feasibility should be considered in the first place in development of catalysts or process for tackling the heavy fractions of bio-oil.

Abstract In this study, the co-pyrolysis of pig manure with cellulose and glucose were investigated at various heating rates. The results demonstrated that potential cross-interaction of the volatiles from the co-pyrolysis facilitated the cracking reaction, resulted in the formation of less charry products and less tarry compounds in the co-pyrolysis. The volatiles interaction also enhanced the evolution of the organics with the π-conjugated ring structures in the bio-oil and remarkably affect the char properties. The dehydration and condensation reactions were promoted during the fast co-pyrolysis of manure with cellulose and glucose, leading to the increased carbon content (from 20.0%–46.5 and 43.0 %), the higher thermal stability, and the enhanced crystallinity of carbon structure in the char formed. In addition, the in-situ Diffuse Reflection Infrared Fourier Transform Spectroscopy (DRIFTS) characterization indicates that the interaction of volatiles in the co-pyrolysis obviously affected the evolution of the functionalities of the char and the reaction network. Additionally, the HHV (37.2 and 37.9 vs 28.0 MJ/Kg) and the energy yield (66.3 and 68.2 vs 66.2 %) of the char from the co-pyrolysis was higher than that of the manure, which was beneficial for the utilize of the char as solid fuel.

Abstract Ionic liquid combined with metal species is considered as a promising catalytic system for biomass liquefaction, which complies with the requirement of green chemistry and promotes utilization of biomass resources. The catalytic systems containing imidazolium-based ionic liquids and nickel chloride were applied to the hydro-liquefaction of major biomass constituents (cellulose, xylan and lignin) in this work. The anion type in ionic liquid played a vital role in the liquefaction of feedstock. The results indicated that the maximum conversion and bio-oil yield were achieved in 1-butyl-3-methylimidazolium bromide ([BMIM]Br)/NiCl2 system, which was attributed to the strong nucleophile and coordinating capacity of bromide ion. The ionic liquid-based catalyst was more effective in the conversion of cellulose and xylan, due to their high reactivity. Additionally, the ionic liquid-based catalyst facilitated the thermal degradation of feedstocks and intermediates, resulting in the increased content of organics with the smaller molecular sizes. The deoxy-hydrogenation reaction was enhanced over ionic liquid-based catalyst, improving the quality of the resulting bio-oils.

Abstract Soybean residue (SR) is a main solid waste produced during the extraction of soybean oil with bulk volume. In addition to the use as vegetable protein feed, SR could also be used as feedstock for producing biofuels and carbon materials via pyrolysis. In this study, the pyrolysis behaviors of SR at varied temperatures and heating rates were investigated. The results show that the pyrolysis of the organic components in SR could reach completion even at 500 °C, due to the lower thermal stability of the organic component than that in the typical biomass. This also leads to the bio-oil with little heavy organics and also low carbon content of the resulting biochar, as the organic components decomposed to a significant extent while the charring reactions were insignificant. This leads to the biochar with low heating value and low energy yield when compared with that in the pyrolysis of typical biomass. In addition, the high content of proteins, amino acids and other nitrogen-containing nutrients make the SR derived bio-oil nitrogen-rich and a significant portion of nitrogen could also be retained in the biochar. These specialties have to be considered during their applications as either biofuels or functional carbon materials.

Bio-oil is a mixture of organics produced from pyrolysis of biomass. The organics in bio-oil serve as the feedstock for the production of hydrogen, chemicals, biofuels and carbon materials. In many...

Abstract Reactive atmosphere significantly affects pyrolysis of biomass, as the gases such as NH3 involves in the reaction network in pyrolysis. In this study, instead of feeding reactive gas, the impacts of co-feeding ethanol or glycol on the pyrolysis of cellulose were investigated at varied pyrolysis temperatures (400 and 600 °C). The results showed that the co-feeding of the alcohols affected yields of bio-char and tar, evolution of light organics and heavy organics, elemental composition, formation of fused ring structures, crystallinity, thermal stability, distribution of functionalities in the bio-char. The co-feeding of both glycol and ethanol enhanced the formation of the heavy components with the π-conjugated ring structures and affected the production of the light organics such as furfural and glycolaldehyde. Glycol or its derivatives cross-polymerized with the organics in bio-char, increasing bio-char yield and made the bio-char more oxygen-rich. Ethanol, however, showed the converse effects. Co-feeding of the alcohols promoted crystallinity but showed distinct effects on thermal stability of the bio-char at the varied pyrolysis temperatures. Both pyrolysis temperature and structures of the alcohols determined their extents of involvement in the pyrolysis of cellulose.