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The kinetics of the absorption of CO2 into two nonaqueous CO2-binding organic liquid (CO2 BOL) solvents were measured at T=35, 45, and 55 °C with a wetted-wall column. Selected CO2 loadings were run with a so-called "first-generation" CO2 BOL, comprising an independent base and alcohol, and a "second-generation" CO2 BOL, in which the base and alcohol were conjoined. Liquid-film mass-transfer coefficient (k'g ) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of the k'g value was also observed, which suggests that the physical solubility of CO2 in organic liquids may be making CO2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO2 BOL solvents. Previous work established the thermodynamic properties related to CO2 capture. The present paper quantitatively studies the kinetics of CO2 capture and develops a rate-based model.

The Department of Energy Bioenergy Technologies Office (BETO) invests in research and development of new pathways for commercially viable conversion of biomass into drop-in ready transportation fuels, fuel blendstocks and products. The primary emphasis has been on terrestrial and algae feedstocks, but more recently BETO has begun to explore the potential of wet wastes for biofuel production, with focus on wastewater residuals, manure, food waste, and fats, oils and grease. A recent resource analysis estimates that 77 million dry tons per year of these wastes are generated annually, 65% of which are underutilized for any beneficial purpose. 1 Approximately 14 million dry tons of the total resource is wastewater residuals (sludge and biosolids) generated at the nation's wastewater treatment plants (WWTPs). 2 Conversion of this resource into transportation fuels could significantly contribute to the creation of a new domestic bioenergy and bioproduct industry, while providing an economically and environmentally sustainable alternative for current waste disposal practices.

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