期刊
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
卷 5, 期 12, 页码 11761-11769出版社
AMER CHEMICAL SOC
DOI: 10.1021/acssuschemeng.7b03344
关键词
CFP aqueous stream; Wastewater treatment; HZSM-S; BTX; Coke formation
资金
- U.S. Department of Energy's Bioenergy Technologies Office [DE-AC36-08GO28308]
- National Renewable Energy Laboratory (NREL)
Catalytic fast pyrolysis (CFP) of biomass produces a liquid product consisting of organic and aqueous streams. The organic stream is typically slated for hydrotreating to produce hydrocarbon biofuels, while the aqueous stream is considered a waste stream, resulting in the loss of residual biogenic carbon. Here, we report the detailed characterization and catalytic conversion of a CFP wastewater stream with the ultimate aim to improve overall biomass utilization within a thermochemical biorefinery. An aqueous stream derived from CFP of beech wood was comprehensively characterized, quantifying 53 organic compounds to a total of 17 wt % organics. The most abundant classes of compounds were acids, aldehydes, and alcohols. The most abundant components identified in the aqueous stream were C1-C2 organics, comprising 6.40% acetic acid, 2.16% methanol, and 1.84% formaldehyde on wet basis. The CFP aqueous stream was catalytically upgraded to olefins and aromatic hydrocarbons using a Ga/HZSM-5 catalyst at 500 degrees C. When the conversion yield of the upgraded products was measured with fresh, active catalyst, 33% of the carbon in the aqueous stream was recovered as aromatic hydrocarbons and 29% as olefins. The majority of the experiments were conducted using a molecular beam mass spectrometer, and separate GC-MS/FID experiments were used to confirm the assignments and quantification of products with fresh excess catalyst. The recovered 62% carbon in the form of olefins and aromatics can be used to make coproducts and/or fuels potentially improving biorefinery economics and sustainability. Spent catalysts were collected after exposure to varying amounts of the feed, and were characterized using multipoint-Brunauer-Emmett-Teller (BET) adsorption, ammonia temperature-programmed desorption (TPD), and thermogravimetric analysis (TGA) to monitor deactivation of Ga/HZSM-5. These characterization data revealed that deactivation was caused by coke deposits, which blocked access to active sites of the catalyst, and spent catalysts regained total activity after regeneration.
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