Fractional catalytic pyrolysis is a selective in situ conversion of biopolymers into desired products. Fractional catalytic pyrolysis was used to convert the lignin fraction of hybrid poplar wood into high yields of cresols and phenols while the carbohydrate fraction was selectively converted into gaseous products. Ground air-dried biomass was fractionally pyrolyzed at 450−500 °C in a 2-in fluidized bed reactor. The total liquid, gas, and char/coke yields were 33%, 53%, and 12.5%, respectively. The low viscosity liquid products consisted of almost pure phenolics with minor carbohydrate decomposition products. The major liquid components were phenol, cresols, methyl substituted phenols, and small fractions of indene and substituted naphthalenes. The carbon and oxygen contents and high heating value (HHV) of the oil were 71%, 21%, and 30.5 MJ/kg, respectively. About 90 wt % of the gaseous products was carbon monoxide and carbon dioxide, and the rest was a mixture of hydrocarbons.

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Pinyon and juniper are invasive woody species in the western United States that occupy over 30 million hectares of land. The U.S. Bureau of Land Management (BLM) has embarked on harvesting these woody species to make room for range grasses for grazing. The major application of harvested pinyon–juniper (PJ) is low-value firewood. Thus, there is a need to develop new high value products from this woody biomass to reduce the cost of harvesting. We investigated the fractional catalytic pyrolysis of PJ using both HZSM-5 catalyst and red mud at 475 °C in a fluidized bed reactor at atmospheric pressure. Both the HZSM-5 and the red mud were effective catalysts for producing low-viscosity pyrolysis oils. Oils that were catalyzed with red mud had a lower viscosity (96 cP @40 °C) than oils that were catalyzed with HZSM-5 (213 cP @40 °C). In both cases, the yields of liquids ranged from 42 wt % to 49 wt %. The mechanisms of catalysis by the two catalysts were quite different. The HZSM-5 rejected oxygen mostly as carbon monoxide (CO) and produced lower amounts of carbon dioxide (CO2); in contrast, the red mud produced more CO2 and less CO. However, both catalysts produced similar amounts of water. The char/coke yields from both catalysts were similar but the total gas yields were slightly different. The higher heating value of the red mud catalyzed oil (HHV = 29.46 MJ/kg) was slightly higher than that catalyzed by HZSM-5 (HHV = 28.55 MJ/kg). Thus, red mud can be used to achieve similar catalytic pyrolysis results as HZSM-5 catalysts.

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Microalgae is being investigated as a renewable transportation fuel feedstock based on various advantages that include high annual yields, utilization of poor quality land, does not compete with food, and can be integrated with various waste streams. This study focuses on directly assessing the environmental impact of two different thermochemical conversion technologies for the microalgae-to-biofuel process through life cycle assessment. A system boundary of "well to pump" (WTP) is defined and includes sub-process models of the growth, dewatering, thermochemical bio-oil recovery, bio-oil stabilization, conversion to renewable diesel, and transport to the pump. Models were validated with experimental and literature data and are representative of an industrial-scale microalgae-to-biofuel process. Two different thermochemical bio-oil conversion systems are modeled and compared on a systems level, hydrothermal liquefaction (HTL) and pyrolysis. The environmental impact of the two pathways were quantified on the metrics of net energy ratio (NER), defined here as energy consumed over energy produced, and greenhouse gas (GHG) emissions. Results for WTP biofuel production through the HTL pathway were determined to be 1.23 for the NER and GHG emissions of-11.4 g CO 2-eq (MJ renewable diesel)-1. WTP biofuel production through the pyrolysis pathway results in a NER of 2.27 and GHG emissions of 210 g CO 2-eq (MJ renewable diesel)-1. The large environmental impact associated with the pyrolysis pathway is attributed to feedstock drying requirements and combustion of co-products to improve system energetics. Discussion focuses on a detailed breakdown of the overall process energetics and GHGs, impact of modeling at laboratory-scale compared to industrial-scale, environmental impact sensitivity to systems engineering input parameters for future focused research and development, and a comparison of results to literature.