Comparative Study of the Structure of Hydroproducts Derived from Loblolly Pine and Straw Grass

The structural characteristics of products derived from the hydrothermal carbonization (HTC) of loblolly pine (LP) and straw grass (SG) were investigated via solid-state cross-polarization/magic angle spinning nuclear magnetic resonance (CP/MAS ¹³C NMR), heteronuclear single-quantum correlation nuclear magnetic resonance (HSQC-NMR), and solution ¹³C NMR and ³¹P NMR techniques. Results revealed that after HTC, hydrochars from both LP and SG mainly consisted of a combination of lignin, furfural, and condensed polyaromatic structures with a high level of fixed carbon content and higher heating value (HHV). Hydrochar from LP exhibited a higher aryl to furan ratio, and those from SG contained more aliphatic functional groups. Solution ¹³C NMR and HSQC revealed that both liquid chemicals were condensed polyphenolic structures with aliphatic groups that exist mainly in the form of side chains. Although the LP products exhibited a higher proportion of aromatic structures, the types of polyphenol and aliphatic C–H were more diverse in the SG products. Results also indicated that reactions such as chain scission and condensation occurred during hydrothermal carbonization processes. Overall, HTC was found to be an effective refinery treatment for converting different waste biomass into valuable energy materials and chemicals

Liquid Hydrocarbon Fuels from Catalytic Cracking of Waste Cooking Oils Using Basic Mesoporous Molecular Sieves K₂O/Ba-MCM-41 as Catalysts

Mesoporous molecular sieves K₂O/Ba-MCM-41, which feature base sites, were prepared under hydrothermal conditions. The structure, base properties, and catalytic activity of the mesoporous molecular sieves as heterogeneous catalysts for the cracking of waste cooking oil (WCO) were then studied in detail. K₂O/Ba-MCM-41 exhibited higher catalytic performance for the cracking of WCO than traditional base catalysts such as Na₂CO₃ and K₂CO₃. Moreover, the cracking of WCO generates fuels (main composition is C₁₂∼C₁₇ alkane or olefin) that have similar chemical compositions to diesel-based fuels, and K₂O/Ba-MCM-41 is of excellent stability. The catalyst could be recycled and reused with negligible loss in activity for four cycles. K₂O/Ba-MCM-41 is an environmentally benign heterogeneous basic catalyst for the production of liquid hydrocarbon fuels from low quality feed stocks