A techno-economic analysis of catalytic processing of whole algal biomass into aromatics and ammonia.
Wenqin Li.b, Wright M. M.ab, and Brown, R. C.ab
bDepartment of Mechanical Engineering
Iowa State University
The objective of this project is to evaluate the techno-economic costs under process and market price uncertainty for catalytic processing of whole algal biomass into ammonia and hydrocarbons. Algae is a promising resource for biofuel production, and recent experimental results indicate that it could provide a low-cost resource for renewable ammonia production. Bench-scale experiments that pyrolyze whole algal biomass into nitrogen-free hydrocarbons and ammonia in the presence of zeolite catalysts have been conducted at ISU (Wang et al., 2012). In this study, we evaluate the economic cost of catalytic processing of lipid-lean green microalgae (Chlorella vulgaris) over HZSM-5 catalyst at 700 °Celsius and atmospheric pressure in a fluidized bed reactor. Nitrogen derived from C. Vulgaris was found in ammonia, hydrogen cyanide, and the coke residue. Ammonia is recovered from the catalytic pyrolysis oil and sold as fertilizer, while hydrogen cyanide is separated and treated due to its toxicity. The products of upgrading catalytic pyrolysis oil include significant quantities of benzene, toluene, and xylene (BTX), which can be recovered and marketed as high value hydrocarbons. The remaining hydrocarbons can be upgraded and fractionated into gasoline- and diesel-range fuels. Current results indicate that more than 4.44 wt. % of ammonia, 8.79 wt. % of BTX, and 3.18 wt. % of gasoline and diesel fuels could be recovered from algae (dry basis). The outcome of this analysis is an estimate of the commercial potential for ammonia production from algal biomass under process and market uncertainty. Future work would address the sustainability of using algal-based ammonia in agricultural applications instead of petroleum derived fertilizer.
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