Effects of ammonia and amines on propylene disproportionation over a tungsten oxide silica catalyst

Gangwal, S.K.; Wills, G. B.

doi:10.1016/0021-9517(78)90361-5

Cited by 8 publications

(1 citation statement)

References 6 publications

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“…This trend also matches that of promotional ability (table S3), highlighting the importance of Brønsted acidic silanols in modulating the dynamic balance between site renewal and decay. Indeed, early experiments demonstrated that steady-state propylene metathesis rates can be increased by poisoning these acidic sites, whether reversibly by co-feeding ammonia [28][29] or irreversibly by introducing a silylating agent 30 .…”

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confidence: 99%

Universal promotion of heterogeneous olefin metathesis catalysts by controlling dynamic active site renewal

Gani

Berkson

Zhu

et al. 2021

Preprint

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Olefin metathesis is a versatile strategy for large-scale olefin interconversion, yet mechanistic details over industrial heterogeneous catalysts have remained ambiguous for decades. Here, from rigorous kinetic measurements, spectroscopic studies, and computational modeling of propylene metathesis over model and industrial WOx/SiO2 catalysts, we identify a hitherto unknown site renewal and decay cycle, mediated by proton transfers involving proximal Brønsted acidic OH groups, which operates concurrently with the classical Chauvin cycle. We show how this cycle can be manipulated using small quantities of promoter olefins to drastically increase steady-state propylene metathesis rates by up to 30-fold at 250oC with negligible promoter consumption. The increase in activity and considerable reduction of operating temperature requirements were also observed on MoOx/SiO2 catalysts, showing that this strategy is general and can address major roadblocks associated with industrial metathesis processes.

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confidence: 99%