Active phase transition in VPO catalysts during condensation reaction

Acrylic acid (AA) is a key industrial monomer used to produce various acrylic esters. A promising alternative to the conventional propylene-based production route is the one-step condensation of formaldehyde and acetic acid—both of which can be derived from coal-based methanol. This approach utilizes abundant methanol resources and reduces reliance on petroleum. Vanadium phosphorus oxide (VPO) catalysts show high selectivity for AA in this reaction, but their active phases are complex and change dynamically during operation. This ambiguity has long obscured the true active sites, slowing the development of more efficient catalysts.

Recently, a research team led by Prof. Feng Wang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences hassystematically unraveled the active phase evolution and driving mechanisms of VPO catalysts under formaldehyde-acetic acid condensationreaction conditions. They clearlydefined the distinct contributions of different phasesto catalytic activity and selectivity.Theseresults offer a crucial theoretical foundation for designing high-performance, selective, and stable FA-HAc condensation catalysts through precise control of catalyst phase composition and stability.The results were published in Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(25)64844-3).

The study revealed that under reaction conditions, the V⁴⁺ phase (VO)₂P₂O₇ remained highly stable in its bulk structure. In contrast, carbonaceous species within the reaction system induced the loss of lattice oxygen from V⁵⁺ phases, triggering their rapid transformation. Specifically, V⁵⁺ phases such as δ-VOPO₄ and ω-VOPO₄ first transformed into another V⁵⁺ phase, αII-VOPO₄, which then reversibly converted back into the V⁴⁺ phase R1-VOHPO₄. Most critically, a clear “phase-performance” relationship was established. VPO catalysts rich in V⁴⁺ phase (VO)₂P₂O₇showed higher selectivity toward acrylic acid, while those containing V⁵⁺ phases exhibited a higher acetic acid conversion rate.

About the Journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

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