58 research outputs found
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 (CO<sub>2</sub>); in contrast, the red mud produced more CO<sub>2</sub> 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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Catalyst and Feedstock Effects in the Thermochemical Conversion of Biomass to Liquid Transportation Fuels
The thermochemical conversion of biomass feedstocks to liquid transportation fuels can be accomplished by three processes, namely gasification, high-pressure liquefaction, and pyrolysis. In this study, the pyrolysis option is selected which is followed by the catalytic upgrading of pyrolysis vapors to aromatic and olefinic hydrocarbons (PYROCAT process). The aromatics constitute a high-octane gasoline blend, while the olefins can be utilized as feedstocks for various chemicals. The PYROCAT process has been studied in a laboratory-scale fixed-bed catalytic reactor. Consecutive biomass samples were pyrolyzed rapidly in steam at 550{degree}C and atmospheric pressure, and then the pyrolysis vapors were passed over a zeolite catalyst. The catalytic upgrading products were monitored in real-time using molecular-beam mass-spectrometry (MBMS). The yields of major products were estimated from mass-spectral data. Several zeolite catalysts were screened in the upgrading process and promising catalysts with high yields were identified. Feedstocks studied included: the woody biomass species aspen (Populus tremuloides), basswood (Tilia americana), and willow (Salix alba); the three isolated components of wood lignin, xylan and cellulose; and the herbaceous species bagasse (Saccharum spp. hybrid), wheat straw (Triticum aestivum), and Sericea lespedeza (Lespedeza cuneata). 17 refs
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