Biomass Feedstock Variability and its Effect on Biocrude Oil Properties

These studies employed similar varieties of switchgrass (Panicum virgatum L.) grown at three different locations and three hybrid poplar clones grown at one location. The feedstocks were pyrolyzed in a fluidized bed reactor at 500 deg. C. The gas products of pyrolysis were analyzed on-line, and the liquid products were analyzed for elemental composition and higher heating values. Apart from smalldifferences in the yield of char, the yields of pyrolysis liquids (biocrude oils) and gases were similar for switchgrass feedstocks grown at all three locations. The char yields ranged from 21.1% to 22.9% by weight; total liquids (organic liquids and water) yields ranged from 59% to 60.5%; and the gas yields ranged from 11% to 12%. The higher heating values (HHVs) of the oils were similar (24.3-24.6 MJ/kg). For the hybrid poplar feedstocks, total liquids (65%-69%), char (10%-11%), and gas yields (15.6%-17%) were similar for all three poplar clones. However, the elemental composition and the HHVs of the biocrude oils had statistically significant differences. The NC5260 biocrude oils had lower HHV (22.0+/-0.5 MJ/kg) compared to the DN17 and DN182 poplar clones (23.2+/-0.3 MJ/kg). Theyields of total liquids and organics for the three poplar clones were higher than those for the switchgrass feedstocks. The gas yields for the hybrid poplar clones alse were higher than those for the switchgrass, but had compositions similar to those of the switchgrass feedstocks. The char yields of the switchgrass were twice those of the hybrid poplar clones.