Sukaran Singh Arora, Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, USA

The production of methanol and its subsequent conversion over zeolite and zeo-type materials to producelarge-scale polymer precursors, such as ethylene and propylene, provides a route for the commercial-scale val-orization of unconventional carbon sources such as coal, biomass, and natural gas. The complex network of re-actions governing this chemistry can be summarized by a dual catalytic cycle description where olefins-based chemistries of methylation and scission are interconnected with the aromatics-based chemistries of methylation and dealkylation via hydrogen transfer and cyclization. Transient isotopic labeling studies infer ethylene production to arise predominantly from the aromatics-based cycle, thereby suggesting that process or material parameters that result in selective propagation of the olefinic cycle would, in turn, result in high propylene-to-ethylene ratios. In this talk, the inlet methanol partial pressure will be demonstrated as the key process parameter that allows control over the relative propagation of the two cycles. Varying inlet methanol partial pressure from 52.5 kPa to 0.6 kPa engenders a systematically increasing trend in the propylene-to-ethylene molar ratio or synonymously, in the preferential propagation of the olefinic cycle over its aromatics counterpart during methanol-to-olefins catalysis over H-ZSM-5. This behavior is observed to persist irrespective of variations in contact-time and reaction temperature, and is rationalized as an effect of methanol pressure on the relative rates of transfer dehydrogenation events (which play a critical role in the aromatic cycle) in reference to methylation events involved in carbon chain growth. These mechanistic studies provide guidance for process conditions to significantly alter product distribution during methanol-to-olefins catalysis over zeolite and zeotype materials. I obtained my B.Tech. degree in Chemical Engineering from the Indian Institute of Technology Delhi in 2014 and was advised by Prof. Shantanu Roy during my thesis work. I completed my Masters in 2016 and am currently pursuing my Ph.D. degree in Chemical Engineering from the University of Minnesota under the supervision of Prof. Aditya Bhan. My current research work is broadly focused on the mechanistic understanding of methanol-to-olefins catalysis over zeolite and zeotype materials.