Pyrolysis

About: Pyrolysis is a research topic. Over the lifetime, 34918 publications have been published within this topic receiving 833524 citations.

Effects of slow and fast pyrolysis biochar on soil C and N turnover dynamics

Abstract: This study compared the effect of two principal pyrolysis methods on the chemical characteristics of biochar and the impact on C and N dynamics after soil incorporation. Biochar was produced from wheat straw that was thermally decomposed at 525 °C by slow pyrolysis (SP) in a nitrogen flushed oven and by fast pyrolysis (FP) using a Pyrolysis Centrifuge Reactor (PCR). After 65 days of soil incubation, 2.9% and 5.5% of the SP- and FP-biochar C, respectively, was lost as CO 2 , significantly less than the 53% C-loss observed when un-pyrolyzed feedstock straw was incubated. Whereas the SP-biochar appeared completely pyrolyzed, an un-pyrolyzed carbohydrate fraction (8.8% as determined by acid released C6 and C5 sugars) remained in the FP-biochar. This labile fraction possibly supported the higher CO 2 emission and larger microbial biomass (SMB-C) in the FP-biochar soil. Application of fresh FP-biochar to soil immobilized mineral N (43%) during the 65 days of incubation, while application of SP-biochar led to net N mineralization (7%). In addition to the carbohydrate contents, the two pyrolysis methods resulted in different pH (10.1 and 6.8), particle sizes (113 and 23 μm), and BET surface areas (0.6 and 1.6 m 2 g −1 ) of the SP- and FP-biochars, respectively. The study showed that independently of pyrolysis method, soil application of the biochar materials had the potential to sequester C, while the pyrolysis method did have a large influence on the mineralization-immobilization of soil N.

Thermal degradation of cellulose in air and nitrogen at low temperatures

Abstract: Thermal analysis and kinetic studies have shown that oxidative reactions are responsible for acceleration in the rates of weight loss and depolymerization of cellulose on pyrolysis in air at temperatures below 300°C. The oxidative reactions include production of hydroperoxide, carbonyl, and carboxyl groups, which have been investigated at lower temperatures along with the rates of depolymerization and production of carbon monoxide and carbon dioxide. The experimental results are consistent with an autoxidation mechanism involving initiation, propagation, and decomposition reactions. At temperatures above 300°, the rate of pyrolysis is essentially the same in both air and nitrogen, indicating that thermal degradation is independent of the oxidative reactions.

Transformation of Oxygenate Components of Biomass Pyrolysis Oil on a HZSM-5 Zeolite. I. Alcohols and Phenols

Abstract: The effects of temperature and space time on the transformation over a HZSM-5 zeolite catalyst of several model components of the liquid product obtained by the flash pyrolysis of vegetable biomass (1-propanol, 2-propanol, 1-butanol, 2-butanol, phenol, and 2-methoxyphenol) have been studied. The transformation of alcohols follows a route similar to that of methanol and ethanol toward the formation of hydrocarbon constituents of the lumps of gasoline and light olefins. Phenol and 2-methoxyphenol have a low reactivities to hydrocarbons, and the deposition of coke of thermal origin caused by the condensation of 2-methoxyphenol is noticeable. The generation of catalytic coke and the deactivation by this cause attenuate as the space time and water content in the feed are increased. To avoid the irreversible deactivation of the HZSM-5 zeolite, operations must be carried out at a temperature below 400 °C. Above this temperature, the increase in product aromaticity is also significant.