Hongyou Yuan

Effects of chemical form of sodium on the product characteristics of alkali lignin pyrolysis.

The effects of Na as organic bound form or as inorganic salts form on the pyrolysis products characteristics of alkali lignin were investigated by using thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TG-FTIR), tube furnace and thermo-gravimetric analyzer (TGA). Results of TG-FTIR and tube furnace indicated that the two chemical forms Na reduced the releasing peak temperature of CO and phenols leading to the peak temperature of the maximum mass loss rate shifted to low temperature zone. Furthermore, organic bound Na obviously improved the elimination of alkyl substituent leading to the yields of phenol and guaiacol increased, while inorganic Na increased the elimination of phenolic hydroxyl groups promoting the formation of ethers. It was also found the two chemical forms Na had different effects on the gasification reactivity of chars. For inorganic Na, the char conversion decreased with increasing the char forming temperature, while organic bound Na was opposite.

Characteristics of NO x precursors and their formation mechanism during pyrolysis of herb residues

Abstract Based on two herb residues-herbal tea waste (HTW) and penicillin mycelial waste (PMW), characteristics of NOx precursors during their pyrolysis were investigated in a horizontal tubular reactor with the help of XPS and TGA technologies. Effects of thermal conditions and physicochemical properties of fuels were discussed and compared. The results demonstrate that protein-N is the main nitrogen form for both HTW and PMW, determining the dominance of NH3 among NOx precursors at any operational conditions. Thermal conditions would still change the ratio and total yield by intrinsically influencing their formation pathways. Subsequently, the effects could be sequenced as follows: high temperatures with rapid pyrolysis > high temperatures with slow pyrolysis > low temperatures with rapid pyrolysis ≈ low temperatures with slow pyrolysis. Moreover, at high temperatures with rapid pyrolysis, increase in particle size or decrease in moisture content would result in reduction of total yield by 5%–11% and 4%–6%, respectively. In addition, NH3 yield is produced at low temperatures or slow pyrolysis with sequence of PMW > HTW and vice versa, depending on components in the fuels. Consequently, analyses on nitrogen forms in char and nitrogen distribution indicate that total yield of 20%–45% is observed to be independent of fuel type under typical pyrolysis conditions, which may provide helpful guidance for the clean reutilization of herb residues.

Relevance between chemical structure and pyrolysis behavior of palm kernel shell lignin

Palm kernel shell (PKS) lignin obtained by enzymatic/mild acid hydrolysis (EMAL) was thoroughly elucidated by FTIR (fourier transform infrared), 13C-1H 2D-NMR (nuclear magnetic resonance), quantitative 31P NMR combined with DFRC (derivatization followed by reductive cleavage), and Py-GC/MS (pyrolysis-gas chromatography/mass spectrometry) with and without TMAH (tetramethylammonium hydroxide). Pyrolysis behavior was then characterized by TG-FTIR-MS (thermo-gravimetric-FTIR-mass spectrometry) and Py-GC/MS. The PKS lignin is demonstrated to be a p-hydroxyphenyl-guaiacyl-syringyl (H-G-S) lignin with abundances of p-hydrobenzoates and low S/G ratio of 0.15. 2D-NMR indicated that the main substructures are β-O-4-ethers (~85%), and 31P NMR/DFRC quantified the total β-O-4 content of 2295μmol/g. Py-GC/MS with and without TMAH confirmed that phenol mainly originated from p-hydroxybenzoates units. Thermal-stability, evolution behavior of typical volatiles, and selectivity of phenolic compounds (H-, G-, S-, C-type) during PKS lignin pyrolysis were explored. Relationship between chemical structure and pyrolysis behavior are also obtained. This work will provide a deep insight to the effective utilization of PKS.