Effect of torrefaction temperature and O2 concentration on the pyrolysis behaviour of moso bamboo

Five-year-old moso bamboo was torrefied under nitrogen and different oxygen concentrations of 3% to 9% and torrefaction temperatures of 200 °C to 300 °C. Mass yields of 31.7% to 96.6%, energy yields of 30.8% to 98.9%, and higher heating values (HHVs) in the range 18.8 to 27.1 MJ/kg were obtained. The torrefied sample was characterized by Fourier transform infrared spectrometry (FTIR). Under the different torrefaction temperatures and oxygen concentrations, hemicellulose and cellulose were thermally decomposed, which led to significant changes in the chemical functional groups of the raw and torrefied bamboo. The pyrolysis experiments on raw and torrefied bamboo were conducted using the pyrolyzer coupled with a gas chromatography/mass spectrometer (Py-GC/MS). According to the Py-GC/MS analysis, the pyrolytic bio-oil were mainly composed of acids, furans, phenols, ketones, aldehydes, esters, alcohols, and hydrocarbons. Higher torrefaction temperature reduced the relative contents of acids, ketones, furans, and aldehydes. However, lower torrefaction temperatures and moderate oxygen concentrations were optimal for the production of phenols and hydrocarbons.

Kinetic study on the slow pyrolysis of nonmetal fraction of waste printed circuit boards (NMF-WPCBs)

In this study, the pyrolysis behaviour of nonmetal fraction of waste printed circuit boards (NMF-WPCBs) was studied based on five model-free methods and distributed activation energy model (DAEM). The possible decomposition mechanism was further probed using the Criado method. Thermogravimetric analysis indicated that the NMF-WPCBs pyrolysis process could be divided into three stages with temperatures of 37–330°C, 330–380°C and 380–1000°C. The mass loss at different heating rate was determined as 26.85–29.98%, 13.47–24.21% and 20.43–23.36% for these stages, respectively. The activation energy ( Eα) from various model-free methods first increased with degree of conversion ( α) increasing from 0.05 to 0.275, and then decreased beyond this range. The coefficient ( R) from the Flynn–Wall–Ozawa (FWO) method was higher, and the resulting Eα fell into the range of 214.947–565.660 kJ mol−1. For the DAEM method, the average Eα value was determined as 337.044 kJ mol−1, comparable with 329.664 kJ mol−1 from the FWO method. The thermal decomposition kinetics of NMF-WPCBs could be better described by the second-order reaction.

Operating Conditions Affecting the Behavior of Wheat Straw Pellets During Slow Pyrolysis Process: a Full Insight

A deep study on the effects of absolute pressure, peak temperature, gas residence time and gas atmosphere on the pyrolysis behaviour of wheat straw pellets in a bench-scale fixed-bed reactor has been carried out.