Elucidating metal composition–coking relationships and coke formation pathways during gas-phase oxydehydration of glycerol over clay mineral-supported Mo-V-O catalysts

• Published in: Applied catalysis. B, Environmental Environmental, 2024-06, Vol.347, Article 123766
• Main Authors: Kurniawan, Alfin, Yin, Shu Tian, Jian Li, Da, Li, Ke Jin, Chen, Xiao Lan, Huang, Wei Jun, Zhao, Peng Yang, Liu, Jia Hui, Zhou, Chun Hui
• Format: Article
• Language: English
• Subjects: Catalyst deactivation; Coke; Glycerol; Molybdenum-vanadium; Oxydehydration; Polycyclic aromatic compounds
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2024.123766

Catalyst deactivation by carbon deposition (coking) remains a major obstacle in many important industrial processes, such as catalytic gas-phase oxydehydration of glycerol. Understanding the chemical nature and development of coke species during the time-on-stream (TOS) of the catalytic solids is therefore crucial for mitigating the extent of coking and in the design of regeneration process of the coked catalysts. In this study, multiple analytical techniques, including SEM, XRD, FTIR, Raman, GC-MS, XPS, and 13C solid-state MAS NMR were employed to gain insights into the coking behavior of acid-activated montmorillonite (HMMT) supported Mo-V-O catalysts with modulated metal ratios, along with soluble and insoluble coke compositions and their evolution over time. Insoluble coke was comprised of polycyclic aromatic compounds with 5 or more fused-benzene rings containing different types of oxygen-bonded groups, such as −OCH3, −COOH, −CHO, and −OH. The major chemical constituents of soluble coke were mononuclear aromatic derivatives (i.e., xylenes, 2,4-di-tert-butylphenol, and 1-hydroxycyclohexyl phenyl ketone) and paraffinic hydrocarbons with 12–18 carbon atoms. The latter coke species is thought to be formed via the deoxygenation of linear oligoglycerols. The insights presented in this study may aid in understanding the carbon deposition process during gas-phase oxydehydration of glycerol for improved design of supported Mo-V-O catalyst materials with high coking resistance. •Quantitative metal composition–coking relationships of Mo-V/HMMT catalysts for gas-phase glycerol oxydehydration.•Structural and compositional studies of soluble and insoluble cokes with time-on-stream.•Linear oligoglycerols are precursors to long-chain paraffins in soluble coke.•Aromatic cluster size in the insoluble coke is comprised of 5-7 fused ring structures.•Polycyclic aromatic compounds in the insoluble coke contain various carbon-oxygen groups.