The homologation of dimethyl ether (DME) over catalysts like copper on beta zeolite (Cu/BEA) opens a potential new market for bio-gas, bio-methanol, methanol, and natural gas by enabling the production of non-aromatic high-octane gasoline blendstocks like 2,2,3-trimethylbutane (triptane, research octane value 112), for which there is significant demand. Process and economic models suggest that the yield of high-octane paraffins is a key driver of market viability for this process. We have recently conducted pilot-scale studies of triptane production over Cu/BEA, starting with bio-methanol, and have observed a shift in naphthene/paraffin selectivity as the catalyst is operated over hundreds of hours, without a marked change in activity. This is a new observation made possible by increased scale, as naphthene concentrations are small and undetectable in the lab. In this presentation we will highlight some of the potential advantages and disadvantages in operating a Cu/BEA catalyst to produce triptane at short vs. long times on stream in the context of product yield and fuel properties. We will also provide our hypotheses on why the product selectivity changes with time, an assessment on whether this is due to “deactivation,” and potential strategies to maximize profits by taking advantage of a transient product selectivity.

Changes in product selectivity with time: Producing high octane fuels from biomethanol at the pilot scale

2019 Spring National Meeting

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