Comparative Evaluation of Hydrothermal Carbonization and Low Temperature Pyrolysis of Eucommia ulmoides Oliver for the Production of Solid Biofuel

Abstract

This study evaluates the feasibility of two thermal pretreatments including hydrothermal carbonization (HTC) and low temperature pyrolysis (LTP) on the production of Eucommia ulmoides biochar. The waste wood of Eucommia ulmoides Oliver was pretreated and characterized for fuel applications. The results confirm that both LTP and HTC are promising processes for improving fuel properties. However, for the same char yield, the required temperature for HTC is lower than LTP, as the char yields of H 200 and L 300 were quite close (66.50% vs. 66.74%). The surface morphology is significantly different between the pyrolytic carbon and the hydrochar. In addition, it was found that the H/C and O/C ratios of H 300 were 0.82 and 0.21, respectively, and the H/C and O/C ratios of L 340 were 0.77 and 0.22, respectively. They were similar to that of sub-bituminous. Moreover, under the same reaction temperature, hydrochar showed better grindability, hydrophobicity, and reduction in inorganic content. Comparing the integrated combustion characteristic index ( S ), LTP process had the better performance within the lower temperature under 220 °C while HTC process performed better at temperature higher than 300 °C. The results reveal that HTC has the potential to produce solid carbonized products with better fuel quality.

Biomass‐derived Carbon Quantum Dots – A Review. Part 1: Preparation and Characterization

“…to generate pores during carbonization 155. Both HTC and pyrolysis are promising technologies for the preparation of CQDs from biomass wastes 156. However, HTC requires low temperature compared to the pyrolysis process.…”

“…However, HTC requires low temperature compared to the pyrolysis process. In addition, HTC has advantages over pyrolysis since the moisture content of the biomass is considered as a feedstock and accordingly, the formation of toxic gases during processing is limited and the auto‐ignition of solids is low due to the presence of many surface groups 156, 157. Carbon produced from HTC has the stronger hydrophobicity than the carbon prepared by pyrolysis 156.…”

“…In addition, HTC has advantages over pyrolysis since the moisture content of the biomass is considered as a feedstock and accordingly, the formation of toxic gases during processing is limited and the auto‐ignition of solids is low due to the presence of many surface groups 156, 157. Carbon produced from HTC has the stronger hydrophobicity than the carbon prepared by pyrolysis 156. HTC is the best option to produce CQDs with many functional groups and also exhibits excellent physicochemical properties.…”

Hydrothermal Carbonization and Pellet Production from Egeria densa and Lemna minor

“…Although this value is higher, it was achieved at a higher temperature of 340 • C. Other authors have studied the viability of converting biomass into biofuels through HTC. Wang et al [34] calculated the HHV of Eucommia ulmoides and their results ranged from 20.00 MJ/kg at 180 • C to 29.61 MJ/kg at 320 • C. Krylova and Zaitchenko [35] calculated the heating value of plant biomass, such as softwood, hardwood, and pine bark, and found values between 18.50 and 21.00 MJ/kg. Saba et al [36] also calculated the HHV of miscanthus at 230 • C, obtaining a value of 24.60 MJ/kg.…”

Syntrophic interactions in anaerobic digestion: how biochar properties affect them?

“…It is favoured if the feedstock has a higher moisture content as no drying process is required (Y. Wang et al, 2019b;ZHOU et al, 2020). Compared to the above methods, gasification produces syngas as the main product, while biochar is the by-product with less yield.…”