Propylene is a major petrochemical building block used to generate a variety of important chemicals. Historically, propylene has been produced as a byproduct of steam cracking. With an increase in shale gas production, however, steam cracking processes are switching to lighter feedstocks that produce less propylene. Thus, there is a need for the development of “on-purpose” methods for producing propylene. The direct conversion of ethylene to propylene (ETP) through simultaneous ethylene dimerization and olefin metathesis is a promising method for propylene production that is currently in development. In ethylene dimerization, two ethylene molecules dimerize to form butene molecules and through olefin metathesis, ethylene and 2-butene form two propylene molecules. Many catalysts have been proposed for this reaction. One method for designing a catalyst for ETP is to combine elements of catalysts for ethylene dimerization and catalysts for olefin metathesis. Ethylene dimerization catalysts are typically Ni-based and olefin metathesis catalysts are typically Mo-, W-, or Re-based. In the present study, a supported NiSO4/ReO4/γ-Al2O3 catalyst was synthesized for the direct conversion of ethylene to propylene, in which NiSO4 performs ethylene dimerization to butenes and ReO4 performs olefin metathesis to propylene. The catalyst was extensively characterization at the molecular level with in situ IR spectroscopy, in situ UV-vis spectroscopy, C2=-TPSR spectroscopy, and ammonia adsorption to probe the nature of the surface acid sites. Preliminary findings at 60°C achieved an ethylene conversion of 63% and a selectivity towards propylene of 76%. The structure-activity relationships of this catalytic system will be discussed during the presentation.

Direct conversion of ethylene to propylene through simultaneous ethylene dimerization and olefin metathesis with 8%NiSO4/8%ReO4/γ-Al2O3 catalyst

ACS Spring Meeting 2021

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