A recent advancement in the conversion of methanol or dimethyl ether to hydrocarbon fuels is the development of a Cu-modified beta zeolite catalyst (Cu/BEA) that exhibits a higher yield than the parent H-form BEA zeolite catalyst in the production of branched C<sub>4</sub>-C<sub>8 </sub>hydrocarbons. The Cu/BEA catalyst activates co-fed hydrogen, and shifts the paraffin-to-olefin (P/O) ratio of the products to favor paraffins. The P/O ratio in gasoline fuel is a critical metric affecting fuel properties and engine efficiency. Control over the P/O ratio would enable the ability to tune the resulting product fuel properties toward high-value, high-octane hydrocarbons, and would contribute to the flexibility of a market-responsive biorefinery centered around bio-derived DME. Towards that end, we utilized catalyst design and materials chemistry to install targeted active sites in bimetallic catalysts that balance the net hydrogenation and dehydrogenation activity during DME homologation. The Cu-Zn/BEA catalyst exhibited greater relative dehydrogenation activity attributed to higher ionic site density, resulting in a lower P/O ratio (6.6) versus the benchmark Cu/BEA (9.4). The Cu-Ni/BEA catalyst exhibited increased hydrogenation due to reduced Ni species, resulting in a higher P/O ratio (19). The product fuel properties were estimated with an efficiency merit function and compared against finished gasolines and a typical alkylate blendstock. Merit values for the hydrocarbon product from all three BEA catalysts exceeded those of the comparison fuels (0-5.3), with the product from Cu-Zn/BEA exhibiting the highest merit value (9.7).

Catalyst design to direct renewable high-octane gasoline fuel properties for improved engine efficiency

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.