To more efficiently utilize natural resources, low value components of the oil refinement stream can be advantageously redirected for the on-purpose synthesis of high demand commodity chemicals, such as propylene. The demand for propylene is expected to outpace the quantity produced through conventional cracking processes. Thus, the on-purpose synthesis of this valuable commodity chemical via metathesis from underutilized feedstocks, such as 2-butene, would be a valuable and efficiency enhancing process. Current methods for the on-purpose synthesis of propylene rely on the cross metathesis of 2-butene with ethylene, which is itself a highly desired commodity chemical. In order to eliminate the need for ethylene in the synthesis of propylene, catalysts that can produce propylene selectively using a feed stream of exclusively 2-butene are currently being explored.<br/>Industrial and academic development of heterogeneous catalysts for olefin metathesis reactions has focused on improving the dispersion of catalytic centers on support materials. Techniques, such as wet impregnation, incipient wetness impregnation, aerosol, sol-gel, and grafting of well-defined catalysts, have been used in the past to produce catalysts with varying specific activities.<br/>The objective of this work is to utilize a single step aerosol synthesis technique to deposit well-dispersed tungsten oxide onto a support surface to optimize catalytic activity. In this high temperature aerosol process, a silica support is synthesized in one temperature zone and tungsten oxide is deposited in a second temperature zone in one continuous step, yielding well-dispersed metal centers that show high activity towards olefin metathesis at low catalyst loadings (1-2%). Using the materials synthesized by this method, we will demonstrate the formation of highly active olefin metathesis catalyst sites whereby, compared to conventional methods, only a fraction of the amount of active species is required to achieve similar activity. Using aberration-corrected TEM/STEM, x-ray photoelectron spectroscopy (XPS), Raman, and temperature programmed reduction (TPR), the nature of the active catalyst is interrogated, and the results comparing the physical properties and dispersion of the catalytic material will be presented. Ultimately, this work will accelerate the further development of novel catalysts that use costly metal centers more efficiently for catalysis and for improving the economics of catalytic processes.<br/>

Refinement of aerosol processes to generate highly dispersed catalytic centers for metathesis on silica supports

255th National Meeting (2018)

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