Simple and Efficient Way of Molybdenum Oxide-Based Catalyst Activation for Olefins Metathesis by Methane Pretreatment

Abstract

An efficient method for activation of MoO3-based catalysts obtained by incipient wetness impregnation was elaborated. It has been found that a short (30 min) pretreatment of the catalyst in pure methane atmosphere above 600 °C enhances an initial specific activity in propene metathesis by 1–2 orders of magnitude compared with the pretreatment in inert gas. A two-step activation process including carbide-like species formation, similar to dehydroaromatization, and metathetically active carbene-like species generation via interaction of Mo sites with ethene is proposed.

Computational Insights into Active Site Formation during Alkene Metathesis over a MoOx/SiO2 Catalyst: The Role of Surface Silanols

“…Olefin metathesis has found wide applications in the synthesis of a variety of organic compounds, both basic and fine chemicals. − Metathesis of light alkenes, which enables for regulation of olefin stocks in petrochemical industry, is of great industrial importance. , Large-scale processes involving olefin metathesis are based on ill-defined heterogeneous catalysts, that is, supported tungsten or molybdenum oxides. − In the OCT (olefins conversion technology) process for propene production, a WO x /SiO 2 catalyst is used, operating at relatively high temperatures, above 300 °C. − On the other hand, a MoO x /SiO 2 system can be very effective for alkene metathesis at mild conditions, even at room temperature, provided that appropriate methods for its preparation and activation are applied. − …”

Room-Temperature Metathesis of Ethylene with 2-Butene to Propene Over MoOx-Based Catalysts: Mixed Oxides as Perspective Support Materials

“…Apparently, Brønsted acidic sites in close vicinity to MoO x species are relevant for high propene production at temperatures above 100 °C. The activity can also be enhanced after thermal catalyst pretreatment in inert gas [15], propene, ethylene, methane [16], methanol [13] or after photoreductive treatment in CO or H 2 . [17] The influence of co-catalysts such as CaO, Al 2 O 3 or SiO 2 -Al 2 O 3 on the metathesis of ethylene and 2-butene to propene over MoO x /Al x Si y O z was investigated by Goelden et al [8].…”

Propane to olefins tandem catalysis: a selective route towards light olefins production

“…127 MoO x catalysts were activated by CH 4 atmosphere at 600 1C or above for 30 min. 128 From the above list, it is clear that the PDH product mixture should be actually beneficial for Met catalysts (e.g., H 2 and propylene, CH 4 produced by cracking,) and that much more should be studied in terms of activation and regeneration of Met catalysts. For instance, pre-reduced WO x catalysts were recently shown to be active for PDH themselves.…”