No abstract

No abstract

Due to intensive feedlots operations, the role of cattle manure has changed from a cheap fertilizer to an agricultural waste. Hydrothermal conversion (HTC) is a potential technology of converting cattle manure waste to biooil. In this paper, HTC of cattle manure was studied with regards to the effects of conversion temperature, pressure, residence time, process gas and mass ratios of cattle manure to water on yields and properties of biooil. Results showed that within the temperature range of 260 ∼ 360 °C, biooil yield first increased and then decreased. The maximum biooil yield was obtained at 310 °C. The biooil yield was not further improved by higher initial operating pressure. In contrast, it decreased biooil yields from 38.49% under 0 psig to 6.51% under 150 psig. Longer residence times also reduced biooil yield. Compared with 38.49% of biooil produced with 15-minute residence time, only 12.95% of biooil remained after 40-minute residence time. Process gases also had important impacts on biooil yield. When N2 was replaced with CO, the maximum biooil yield increased to 48.76%. But, when air was used as process gas, the biooil yield decreased to 27.97%. Also, biooil yield decreased with larger mass ratios of cattle manure to water. When the ratio was 2, biooil yield was only 1.46% much less than 48.76% with ratio of 0.25. Therefore, biooil yield from HTC of cattle manure largely depended on the conversion temperatures and process gases. Higher conversion pressures, longer residence time and larger mass ratios of cattle manure to water had negative impacts on biooil yield. The mean high heating value of biooil from HTC of cattle manure was 37.0 MJ/kg.

Hydrothermal gasification is a promising technology for the treatment of wet organic biomass, and as such, has been subject to significant research effort. It is well known that two groups of catalysts exhibit high activity for hydrothermal gasification—broadly classified as platinum group metals and alkali salts. In the present work, this effect is further investigated through a study of the synergistic effects of sodium carbonate and Pt/Al2O3 on gas yield from cellulose at 315°C. Results indicate that dilute alkali appears far more efficient in promoting gasification reactions in the presence of Pt/Al2O3. Potential mechanisms and a comparison with the alkaline degradation pathways of glucose are discussed.

A number of researchers have reported that biooil was produced through hydrothermal conversion of different types of biomass. However, it is difficult to evaluate and compare these biooils in terms of yields and chemical properties. They applied different organic solvents to extract biooil from products after hydrothermal conversion of biomass. The purpose of this study is to assess the impact of extraction solvents on the quantity and chemical structure of biooil. Cattle manure was used as one type of biomass feedstock for biooil production. And dichloromethane (CH2Cl2), chloroform (CHCl3) and diethyl ether (C4H10O) were used for biooil extraction. Results showed that extraction solvents influenced biooil yields. The highest biooil yield of 48.78 wt% of volatile content of cattle manure was obtained when using CH2Cl2 solvent. The main components of biooil extracted by CH2Cl2 and CHCl3 were ketones and carboxylic acids, while those extracted by C4H10O were aromatic chemicals. In terms of elemental compositions and high heating values of biooil, no statistically apparent differences were caused by different solvents. The mean elemental compositions (by weight) of biooils were carbon of 73.79%, hydrogen of 8.18%, nitrogen of 4.38% and oxygen of 13.65%. And the mean high heating value of biooil was 36.74 MJ/kg.