关键词: 杏壳, 半纤维素, 结构表征, 热重红外, 热解特性

Abstract: [Objective] In order to study the complex pyrolysis behavior based on biomass components, the structure composition and micromorphology of the hemicellulose of apricot shell were analyzed, and its pyrolysis properties and product formation rule might be expected to provide theoretical basis for its thermal chemical utilization.[Method] Apricot shell hemicellulose were separation by the alkali extraction and ethanol purification method. The composition, structure and microstructure were characterized by infrared spectrometer, nuclear magnetic resonance imaging, scanning electron microscope. The pyrolysis properties of apricot shell hemicellulose were investigated by thermogravimetric analysis and thermal infrared continuous analysis.[Result] The hemicellulose was isolated from apricot shell at a rate of 29.44%, and the FTIR spectrum characteristic absorption peaks were mainly concentrated in 1 620-600 cm^-1 which showed that the main components of hemicellulose were xylose of pyran ring structure. ¹H-NMR showed that apricot shell hemicellulose was the main chain of xylan composed of β-D-pyran xylose, which connected 4-O-methyl-α-D-glucuronic acid in xylose C-2 and α-L-furan arabinose in C-3. The SEM showed that hemicellulose was reuniting, the microstructure was approximate spherical structure, and the hemicellulose structure had some damage. Apricot shell hemicellulose main pyrolysis temperature ranged in 210-380℃, there were a shoulder peak at 240℃and a weightlessness peak at 308℃. The weightlessness process was at the end of the 600℃, the pyrolytic carbon residue content was 25.33% at 800℃. The pyrolysis product of apricot shell hemicellulose reached the highest at 310℃, small molecule gas products mainly include CO₂, CO, and CH₄, and CO, CO₂ were far higher than CH₄.[Conclusion] The content of hemicellulose in apricot shell was 29.44%, which was the main chain of β-D-pyran xylose xylan, and had an approximate spherical structure. Pyrolysis products were mainly CO₂, CO and acetic acid, furfural and acetone. The result of this study would provide a theoretical reference for the thermochemical transformation of the apricot shell hemicellulose.

Key words: apricot shell, hemicellulose, structure characterization, TGA-FTIR, pyrolysis properties