Study of ethylene/2-butene cross-metathesis over W-H/Al₂O₃ for propylene production: Effect of the temperature and reactant ratios on the productivity and deactivation

Mazoyer, Etienne; Szeto, Kai C.; Merle, Nicolas; Norsic, Sebastien; Boyron, Olivier; Basset, Jean-Marie; Taoufik, Mostafa; Nicholas, Christopher P.

Study of ethylene/2-butene cross-metathesis over W-H/Al₂O₃ for propylene production: Effect of the temperature and reactant ratios on the productivity and deactivation

2013

A highly active and selective catalyst based on supported tungsten hydride for the cross-metathesis between ethylene and 2-butenes yielding propylene has been investigated at low pressure with various temperatures and feed ratios. At low temperature (120°C), the catalyst deactivates notably with time on stream. This phenomenon was extensively examined by DRIFTS, TGA, DSC, and solid-state NMR techniques. It was found that a large amount of carbonaceous species were formed due to a side-reaction such as olefin polymerization which took place simultaneously with the metathesis reaction. However, at 150°C, the catalyst was stable with time and thereby gave a high productivity in propylene. Importantly, the slight increase in temperature clearly disfavored the side reaction. The ratio of ethylene to trans-2-butene was also studied, and surprisingly, the W-H/Al₂O₃ catalyst is stable and highly selective to propylene even at substoichiometric ethylene ratios.

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