Propylene is a starting material for many important industrial processes and is classically derived as a side product of petroleum cracking; however, increased consumption is driving the development of on-demand methods like olefin metathesis. The cross-metathesis reaction between ethylene and 2-butenes[ii] to form propylene is a method of significant industrial interest.1A To access metathesis pathways to propene, we supported W(Np)3(≡Np) onto a dehydroxylated Al2O3 support and then utilized hydrogenolysis to yield W-H/Al2O3, which proceeds as a “tri-functional single site” catalyst for conversion of ethylene by dimerizing ethylene to 1-butene, isomerizing 1-butene to 2-butenes and then cross-metathesis between 2-butenes and ethylene leading to propylene.[iii] However, this system suffers from catalyst deactivation, leading to low total yields of propylene.[iv] We then utilized the W-H/Al2O3 system to selectively produce propylene from various butene feeds. Cross-metathesis of ethylene and 2-butene was investigated and surprisingly, the W-H/Al2O3 catalyst is stable and highly selective to propylene even at substoichiometric ethylene ratios.[v] Likewise, the autometathesis reactions of 1-butene and 2-butene have been studied and found to yield good selectivity to propylene, [vi] unlike what should result from a classical Chauvin mechanism. In this lecture, we’ll discuss the mechanistic pathways for the above reactions, deactivation routes and the application of Surface Organometallic Chemistry to the synthesis of precursors to bridge the divide between the aforementioned hydride catalysts and the traditionally A) Mol, J. C. J. Mol. Catal. A: Chem. 2004, 213, 39– 45. B) Tullo, A. H. Chem. Eng. News 2003, 81, 15– 16. [ii] A) Engelhardt, J. J. Mol. Catal. 1980, 8, 119– 125. B) Amigues, P.; Chauvin, Y.; Commereuc, D.; Hong, C. T.; Lai, C. C.; Liu, Y. H. J. Mol. Catal. 1991, 65, 39– 50. C) Pillai, S. M.; Tembe, G. L.; Ravindranathan, M. Appl. Catal., A 1992, 81, 273– 278. [iii] Taoufik, et.al. Angew. Chem., Int. Ed. 2007, 46, 7202– 7205. [iv] Mazoyer, et.al. J. Mol. Catal. A 2014, 385, 125-32. [v] Mazoyer, et.al. J. Catal. 2013, 301, 1-7. [vi] a) Mazoyer, et.al. ACS Catal, 2011, 1, 1643-6. b) Mazoyer, et.al. Chem. Commun. 2012, 48, 3611-3.

High selectivity production of propylene via olefin metathesis over surface organometallic chemistry derived catalysts

251st National Meeting (2016)

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