Microvawe pyrolysis of biomass: control of process parameters for high pyrolysis oil yields and enhanced oil quality

The oil yield and quality of pyrolysis oil from microwave heating of biomass was established by studying the behaviour of Larch in microwave processing. This is the first study in biomass pyrolysis to use a microwave processing technique and methodology that is fundamentally scalable, from which the basis of design for a continuous processing system can be derived to maximise oil yield and quality. It is shown systematically that sample size is a vital parameter that has been overlooked by previous work in this field. When sample size is controlled the liquid product yield is comparable to conventional pyrolysis, and can be achieved at an energy input of around 600 kWh/t. The quality of the liquid product is significantly improved compared to conventional pyrolysis processes, which results from the very rapid heating and quenching that can be achieved with microwave processing. The yields of Levoglucosan and phenolic compounds were found to be an order of magnitude higher in microwave pyrolysis when compared with conventional fast pyrolysis. Geometry is a key consideration for the development of a process at scale, and the opportunities and challenges for scale-up are discussed within this paper

Catalytic Pyrolysis of Pinyon–Juniper Using Red Mud and HZSM‑5

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