(379e) The Upgrading of Biomass-Derived Dimethyl Ether to High-Octane Hydrocarbons: The Effect of Process Conditions on Catalyst Performance

Nash, C., National Renewable Energy Laboratory
Behl, M., National Renewable Energy Laboratory
Christensen, E., National Renewable Energy Laboratory
Schaidle, J. A., National Renewable Energy Laboratory
Hensley, J. E., National Renewable Energy Laboratory
Ruddy, D. A., National Renewable Energy Laboratory
Dimethyl ether (DME) and/or methanol can be converted into C5+ branched hydrocarbons at low temperatures and pressures over large-pore acidic zeolites. Recently, we have demonstrated that Cu-modification of the existing commercial catalyst (H-BEA) resulted in a 2-fold increase in total hydrocarbon productivity at 200 °C with co-fed H2.1 The Cu/H-BEA catalyst incorporated H2 with DME into the desired branched hydrocarbons, while maintaining the high C5+ selectivity of the parent H-BEA. Here, we compare the performance of Cu/H-BEA and the parent H-BEA at 175, 200 and 225 °C, and at weight-hourly space velocities (WHSV) for DME ranging from 0.43-1.4 h-1. The productivity of C5+ products increased with temperature over H-BEA, with no significant changes over Cu/H-BEA due to a decrease in C5+ selectivity at elevated temperature, which was observed for both catalysts. Operation at 175 °C resulted in a significant increase in C5+ selectivity (75-85% for Cu/H-BEA), but lower productivity than at 200 °C due to lower reactant conversion. Lower space velocities increased reactant conversion over both catalysts, but significantly decreased the C5+ productivity over Cu/H-BEA. The Cu/H-BEA catalyst was stable for 100 h at 200 °C after an initial 40 h break-in period. In previous research, we demonstrated that C4-C8 olefins produced in the DME homologation reaction can be oligomerized to C12-C22 branched hydrocarbons with properties that align with a synthetic paraffinic kerosene product.2 Following a simple vacuum distillation, the fuel properties of the distillate-range product align well with a jet fuel blend when compared with 5 ASTM methods. This DME-to-hydrocarbons reaction represents a promising route to transform renewable biomass sources into commercially viable, high-performance biofuels.3

1Schaidle, J. A.; Ruddy, D. A.; Habas, S. E.; Pan, M.; Zhang, G.; Miller, J. T.; Hensley, J. E. ACS Catal. 2015, 5, 1794.

2Behl, M.; Schaidle, J. A.; Christensen, E.; Hensley, J. E. Energy & Fuels 2015, 29, 6078.

3Tan, E. C.; Talmadge, M.; Dutta, A.; Hensley, J.; Snowden-Swan, L. J.; Humbird, D.; Schaidle, J.; Biddy, M. Biofuels, Bioproducts and Biorefining 2016, 10, 17.