Design of stable and selective solid acid catalysts is crucial due to the recent abundance of shale gas derived hydrocarbons. Ethylene is a major commodity chemical that can be catalytically converted to C4 (butene) hydrocarbons via dimerization process on solid acids. Heterogeneous active catalysts can potentially substitute for currently industrially utilized homogeneous organometallic catalysts to improve the overall process efficiency via simplifying product separation and catalyst handling. The challenge with heterogeneous catalysis is in designing a catalyst with uniform active and selective surface sites. Nickel based heterogeneous catalysts for ethylene coupling have been shown to be promising and very recent attempts have in general focused on designing (a) solid acids via sulfate modification of nickel compounds (e.g. NiSO4-ZrO2) and (b) pure oxide based NiO-ZrO2/WO3. Zirconia sulfation by either SOx adsorption or sulfate ion impregnation of zirconia supports can produce the same spectra with a surface tridentate monooxo configuration. Most of the studies were performed at relatively low, or unspecified loadings of the sulfate groups. The application of spectroscopic characterization is significant for an understanding of the formation of sulfate groups at higher loadings. We utilized multimodal operando spectroscopy to systematically investigate solid acid catalyst surface site molecular and electronic structures via controlled environment Raman, UV-vis and DRIFT spectroscopies. Coverage dependent changes in surface site structure were unraveled and will be presented.

Multimodal characterization of solid acid catalyst active sites for hydrocarbon upgrading

254th National Meeting (2017)

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