Hydrocarbon Liquid Production from Biomass via Hot-Vapor-Filtered Fast Pyrolysis and Catalytic Hydroprocessing of the Bio-Oil

Hot-vapor-filtered bio-oils were produced from two different biomass feedstocks, oak and switchgrass, and the oils were evaluated in hydroprocessing tests for the production of liquid hydrocarbon products. Hot-vapor filtering reduced bio-oil yields and increased gas yields. The yields of fuel carbon as bio-oil were reduced by 10% by hot-vapor filtering for both feedstocks. The unfiltered bio-oils were evaluated alongside the filtered bio-oils using a fixed-bed catalytic hydrotreating test. These tests showed good processing results using a two-stage catalytic hydroprocessing strategy. Equal-sized catalyst beds, sulfided Ru on a C catalyst bed operated at 220 °C and sulfided CoMo on an Al₂O₃ catalyst bed operated at 400 °C were used with the entire reactor at 10 MPa operating pressure. The products from the four tests were similar. The light-oil-phase product was fully hydrotreated, so that nitrogen and sulfur were below the level of detection, while the residual oxygen ranged from 0.3 to 2.0%. The density of the products varied from 0.80 to 0.86 g/mL over the period of the test with a correlated change of the hydrogen/carbon atomic ratio from 1.79 to 1.57, suggesting some loss of catalyst activity through the test. These tests provided the data needed to assess the suite of liquid fuel products from the process and the activity of the catalyst in the relationship to the existing catalyst lifetime barrier for the technology.