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6. Development of Passive HC/NOx Trap Catalysts for Low Temperature Gasoline Applications

Author

Crocker, Mark, primary, Bell, Alex, additional, Van der Mynsbrugge, Jeroen, additional, Kim, Paul, additional, Gounder, Raj, additional, Lardinois, Trevor, additional, Bates, Jason, additional, Pace, Robert, additional, Ji, Yaying, additional, Lambert, Christine, additional, Theis, Joseph, additional, Getsoian, Andrew, additional, Ura, Justin, additional, Lupescu, Jason, additional, Prikhodko, Vitaly, additional, and Wei, Xinyi, additional

Published
2021
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7. Towards an Integrated Process for CO2 Capture and Utilization: Cultivation of Scenedesmus acutus Using Gaseous CO2 and NH3.

Author

Vorisek, Fritz E., Ji, Yaying, Hillis, Maya H., Parker, Julia, Thompson, Jesse, Liu, Kunlei, and Crocker, Mark

Subjects
*SCENEDESMUS, *POISONS, *ALGAL growth, *CARBON sequestration, *FLUE gases, *TOXIC algae
Abstract

Integrating CO2 scrubbing from flue gas with its utilization in algae cultivation represents a potential means of lowering the cost of CO2 capture. Towards this goal, this study sought to assess the feasibility of using gaseous a CO2/NH3 stream, derived from CO2 capture using aqueous ammonia, as a C- and N-source for algae cultivation. Scenedesmus acutus was cultured in 800 mL photobioreactors using gaseous CO2/NH3 in mole ratios varying from 7 to 18. Excellent growth of Scenedesmus acutus was observed, the average growth rate for CO2/NH3 = 10 of 0.171 ± 0.015 g/L·day exceeding that obtained using 1% CO2/N2 and urea as the N-source (0.099 ± 0.28 g/L·day). Under optimal growth conditions (CO2/NH3 mole ratio of 10), CO2 utilization ranged from 57 to 72%, while the NH3 utilization was >90%. The CO2/NH3 feed rate was also found to exert a significant effect on algae productivity, with excessive feed rates leading to the accumulation of NH3 in the culture at concentrations that were toxic to the algae. Consequently, to avoid the toxic effects of high NH3 concentrations (>2.0 mM), it proved necessary to balance the NH3 supply with the algae growth rate so that excessive NH3 accumulation was prevented. This indicates that for practical applications, a CO2/NH3 feed control strategy would be required that takes into account the ammonium ion concentration in solution and the pH so as to avoid significant concentrations of free NH3. Analysis of the harvested biomass revealed a high protein (≥ 47 wt%) and a low ash content (< 3.6 wt%), suggesting it would be well suited for use as animal feed or as a feedstock for the production of bioplastics. [ABSTRACT FROM AUTHOR]

Published
2023
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8. Towards an Integrated Process for CO2 Capture and Utilization: Cultivation of Scenedesmus acutus Using Gaseous CO2 and NH3.

Author

Vorisek, Fritz E., Ji, Yaying, Hillis, Maya H., Parker, Julia, Thompson, Jesse, Liu, Kunlei, and Crocker, Mark

Subjects
SCENEDESMUS, POISONS, ALGAL growth, CARBON sequestration, FLUE gases, TOXIC algae
Abstract

Integrating CO2 scrubbing from flue gas with its utilization in algae cultivation represents a potential means of lowering the cost of CO2 capture. Towards this goal, this study sought to assess the feasibility of using gaseous a CO2/NH3 stream, derived from CO2 capture using aqueous ammonia, as a C- and N-source for algae cultivation. Scenedesmus acutus was cultured in 800 mL photobioreactors using gaseous CO2/NH3 in mole ratios varying from 7 to 18. Excellent growth of Scenedesmus acutus was observed, the average growth rate for CO2/NH3 = 10 of 0.171 ± 0.015 g/L·day exceeding that obtained using 1% CO2/N2 and urea as the N-source (0.099 ± 0.28 g/L·day). Under optimal growth conditions (CO2/NH3 mole ratio of 10), CO2 utilization ranged from 57 to 72%, while the NH3 utilization was >90%. The CO2/NH3 feed rate was also found to exert a significant effect on algae productivity, with excessive feed rates leading to the accumulation of NH3 in the culture at concentrations that were toxic to the algae. Consequently, to avoid the toxic effects of high NH3 concentrations (>2.0 mM), it proved necessary to balance the NH3 supply with the algae growth rate so that excessive NH3 accumulation was prevented. This indicates that for practical applications, a CO2/NH3 feed control strategy would be required that takes into account the ammonium ion concentration in solution and the pH so as to avoid significant concentrations of free NH3. Analysis of the harvested biomass revealed a high protein (≥ 47 wt%) and a low ash content (< 3.6 wt%), suggesting it would be well suited for use as animal feed or as a feedstock for the production of bioplastics. [ABSTRACT FROM AUTHOR]

Published
2023
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49. Mn-based mixed oxides for low temperature NOx adsorber applications

Author

Universidad de Alicante. Departamento de Química Inorgánica, Ji, Yaying, Xu, Dongyan, Crocker, Mark, Theis, Joseph R., Lambert, Christine, Bueno López, Agustín, Harris, Deb, Scapens, Dave, Universidad de Alicante. Departamento de Química Inorgánica, Ji, Yaying, Xu, Dongyan, Crocker, Mark, Theis, Joseph R., Lambert, Christine, Bueno López, Agustín, Harris, Deb, and Scapens, Dave

Abstract

Pd-promoted ternary oxides of the type Mn-Ce-Zr and Mn-Pr-Zr were characterized and evaluated for low temperature NOx storage applications such as diesel vehicle cold starts. While X-ray diffraction data were in all cases consistent with the formation of solid solutions, Mn/Zr and Mn/Ce(Pr) ratios found by XPS were consistently higher than the bulk values, indicative of an enrichment of Mn at the surface of the solids. Both sets of Pd-promoted mixed oxides showed remarkably high NOx storage efficiency in the range 80–160 °C, while a 1.8% Pd/Mn(27)-Ce(7)-Zr catalyst showed excellent NOx storage in simulated cold start experiments. Moreover, ramping the temperature to 370 °C in these experiments, simulating higher speed operation, resulted in near complete purging of stored NOx from the catalyst. NOx storage efficiency in isothermal storage experiments was found to improve with increasing Mn content for the 1%Pd/Mn(x)-Ce(7)-Zr series (x = 9, 18, 27 wt.%), DRIFTS measurements showing that relative to Ce-Zr mixed oxides, Mn incorporation favored NOx storage as nitrate. During temperature programmed desorption (TPD) two main desorption events were observed, corresponding to decomposition of nitrites (up to 200 °C), followed by loss of nitrates (⁓200–400 °C). Nitrates stored on Pd/Mn-Ce(Pr)-Zr mixed oxides desorbed during TPD at lower temperatures than for CeO2-ZrO2 mixed oxides, a finding attributed to the lower basicity of Mn compared to Ce. Hydrothermal aging of 1.8%Pd/Mn(27)-Ce(7)-Zr at 700 °C reduced NOx storage efficiency, although the catalyst was still able to store significant amounts of NOx. However, catalyst sulfation led to a large decrease in NOx storage efficiency and the efficiency could not be completely recovered with lean or rich desulfations at high temperatures.

Published
2018

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