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Enzymatic/Mild Acidolysis Lignin (EMAL) was isolated from Cunninghamia lanceolata and eucalyptus woods. The chemical structure and thermochemical properties were characterized by means of elemental analysis, Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TG), and pyrolysis-gas chromatography combined with mass spectrometry (Py-GC/MS). The EMAL isolated from Cunninghamia lanceolata (C-EMAL) had larger HHV (higher heat value) in comparison to the EMAL isolated from eucalyptus (E-EMAL) due to the greater carbon content of the C-EMAL. The E-EMAL had more syringyl units, whereas the C-EMAL contained more guaiacyl units. It was observed that thermal decomposition occurred over a wide temperature range, and that at a given starting temperature, within the same sample, a higher heating rate produced a higher temperature at which maximum weight loss peaked. The pyrolysis products were mainly composed of carboxylic acids, alcohols, ketones, aldehydes, olefins, alkanes, esters, ethers, and phenols. At all pyrolysis temperatures, the largest components of the pyrolysis products obtained from C-EMAL were the phenols. [ABSTRACT FROM AUTHOR]

To investigate the effect of organic bound Na groups on pyrolysis and gasification behaviors of alkali lignin, an experimental study was carried out by Thermogravimetric Analyzer coupled with Fourier Transform Infrared Spectrometry (TG-FTIR). Acid precipitated lignin (APL) and Alkali soluble lignin (ASL) were selected as the testing samples, and physiochemical properties were studied by FTIR, ¹H NMR, and SEM analyses. The research results showed that the pyrolysis and gasification characteristics of alkali lignin depended on phenolic sodium (-CONa) and carboxylate sodium (-COONa) groups (PCSG). In pyrolysis stage, PCSG improved the yields of alcohols and hydrocarbons but inhibited benzenes. During gasification stage, in the present of PCSG, the peak value of gasification rate increased, yet the initial gasification temperature decreased. Meanwhile, CO releasing was relatively concentrated and intensively increased from 37 min (740 °C) to 42 min (840 °C). [ABSTRACT FROM AUTHOR]

In order to study the thermal decomposition characteristics of hemicellulose, a highly efficient procedure was carried out to extract hemicellulose from corn stalk. Several different sugar units were observed by 13C NMR spectra to show the presence and species of hemicellulose. Following isolation of the hemicellulose, experimental research on its thermal behavior were carried out with a thermogravimetric analyzer under inert atmosphere at heating rates ranging from 10 to 50°C/min, and the kinetic parameters were calculated by the Kissinger and Ozawa methods, respectively. It was found that the thermal degradation of hemicellulose mainly occurred in the temperature range 180-340°C with a final residue yield of 24% at 700°C. An increase of the heating rate could slightly increase both the temperatures at which the peak weight loss rate was observed and the maximum value of weight loss rate. The activation energy (E) and the pre-exponential factor (lnA) obtained by the Kissinger and Ozawa methods were 213.3kJ mol-1, 211.6kJ mol-1 and 46.2min-1, 45.9min-1, respectively. Even though the data showed little difference, the fitting degree of the Ozawa method was better than that of the Kissinger method. The experimental results and kinetic parameters may provide useful data for effective design and improvement of thermochemical conversion units. [ABSTRACT FROM AUTHOR]

Pyrolysis characteristics and mechanism of tobacco stem were studied by pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS), thermogravimetric analyzer coupled with Fourier transform infrared spectrometry, and mass spectrometry (TG-FTIR and TG-MS) techniques. The composition of evolved volatiles from fast pyrolysis of tobacco stem was determined by Py-GC/MS analysis, and the evolution patterns of the major products were investigated by TG-FTIR and TG-MS. Py-GC/MS data indicated that furfural and phenol were the major products in low temperature pyrolysis, and these were generated from depolymerization of cellulose. Indene and naphthalene were the major products in high temperature pyrolysis. TG-FTIR and TG-MS results showed that CO, CO2, phenols, aldehydes, and ketones were released between 167°C and 500°C; at temperatures >500°C, CO and CO2 were the main gaseous products. [ABSTRACT FROM AUTHOR]