The oligomerization of light olefins to longer chain olefins including gasoline and distillate fuels has been practiced industrially since Ipatieff’s initial discovery of solid phosphoric acid (SPA) and improved catalysts are still sought to optimize production of specific olefin properties.[1] We have shown that MTW zeolite based catalysts are attractive for the oligomerization of propene and butenes to gasoline and utilize, along with corroborating characterization data, multiple NMR techniques to better understand catalyst and product properties. The C8 fraction of liquid products obtained from oligomerization of light olefins over SPA and MTW zeolite were investigated with 1H and 13C NMR including DEPT and two-dimensional techniques to understand and quantify the differences in branching pattern and olefin location observed. The product obtained over MTW catalyst showed higher quantities of quaternary olefins, likely from type V tetrasubstituted olefins, compared to that produced over SPA catalyst.[2] Phosphorous treatment of these Al2O3 bound MTW zeolite catalysts allows significant enhancement of the selectivity to gasoline product during oligomerization. Using solid state NMR techniques, amongst other characterization methods, allows a better understanding of the effects of phosphorus treatment. Along with conversion of the binding matrix from Al2O3 to aluminophosphates coating the surface of the MTW zeolite crystals, the interaction of P with zeolite framework Al, observed via XRD, TEM and 31P {27Al} TRAPDOR NMR correlation experiments, is a major effect reducing acidity of the zeolite and thus affecting the catalytic results. Via this modification, we attain catalytic performance similar to traditional solid phosphoric acid catalyst, but with a significant yield of triisobutylenes.[3]

Developing an understanding of the oligomerization of light olefins over MTW zeolite based catalysts using NMR

255th National Meeting (2018)

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