Cold plasma pretreatment mediated structural engineering of cellulose for enhancing anhydrosugars production

CP pretreatment reduced cellulose crystallinity and pyrolysis E a. • O 2 -CP introduced oxygen-containing groups and H 2 -CP modulated C-C/C-O bonds. • Multiple characterization reveals plasma-induced pathway reconstruction. • Plasma atmospheres uniquely reconstruct pyrolysis pathways. Anhydrosugars, mainly derived from cellulose fast pyrolysis, serve as versatile platform molecules for the sustainable synthesis of advanced biofuels and high-performance polymeric materials. Efficient pretreatment can enhance the potential for anhydrosugars generation by fast pyrolysis. The present study proposed a cold plasma (CP) pretreatment method to treat cellulose and enhance anhydrosugars production and revealed its effect in different plasma atmospheres (oxidizing O 2 , reducing H 2 , and inert He) on cellulose structural. Multi-dimensional characterization indicated that O 2 and H 2 plasma pretreatment significantly reduced the crystallinity (from 73.41% to 48.96%) of cellulose and promoted particle fragmentation through surface etching and redox reactions. The effect of He was insignificant. Kinetic analysis and fixed-bed fast pyrolysis experiments of cellulose after pretreatment were performed. Kinetic analysis of cellulose pyrolysis after pretreatment revealed a substantial decrease in the E a in O 2 -cold plasma (O 2 -CP) (from 222 to 195 kJ/mol). It indicated that the O 2 -CP pretreatment facilitated the thermal decomposition of cellulose. The pyrolysis volatile was evaluated by real-time tracking to analyze pyrolysis behaviors. The results showed that the liquid product yield increased to 62% under both O 2 –80 kV-20 min and H 2 –80 kV-10 min, and the corresponding anhydrosugars yields were 54.32% and 50.82%, respectively. These results are attributed to distinct active species from oxygen and hydrogen plasmas influencing the structure of key intermediates for anhydrosugars formation. The present study elucidated the directional reconstruction effect of plasma atmosphere on cellulose structure, influencing the subsequently preferred pyrolysis pathway, providing a theoretical basis and technical support to facilitate the high-value conversion of biomass. Download: Download high-res image (149KB) Download: Download full-size image