This work attempts to utilize sodium chlorite to clean up NO x and SO 2 gases simultaneously from flue gas in a novel swirl scrubber system. Experiments were carried out to evaluate the effects of various operating parameters such as initial SO 2 concentration, scrubbing medium pH, sodium chlorite concentration, and liquid and gas volumetric flow rates at 35 °C. In addition, reaction mechanisms of simultaneous denitrification and desulfurization using sodium chlorite in acidic and basic solutions are proposed. Complete oxidation of NO into NO 2 occurred using 0.2 M sodium chlorite solution as the scrubbing medium. Complete (100%) SO 2 and 81% NO x removal efficiencies were achieved under optimized conditions. The NO x removal increased with decreasing pH. Input SO 2 enhanced the NO x absorption. The effect of the SO 2 concentration on NO x removal was more intense at higher pH values. Using sodium chlorite as the scrubbing medium in the novel swirl scrubber was found to be quite promising for the simultaneous removal of NO x and SO 2 .

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Efficient separation of hydrogen under steam reforming conditions is important for the development of clean energy sources. Although high-temperature and steam-stable membranes with high fluxes and large separation factors would be valuable for such an application, their fabrication remains a challenge. Silicon-based ceramic membranes are particularly promising due to their high temperature resistance and excellent chemical stability. In this study, we propose a new synthetic route for fabricating nanoporous, asymmetric membranes via the pyrolysis of silicon-containing polymer films deposited by initiated chemical vapor deposition (iCVD) on macroporous silicon carbide supports. Specifically, we systematically investigated the change in the chemical structure of poly­(2,4,6,8-tetravinyl-2,4,6,8-tetramethyl cyclotetrasiloxane) films at different pyrolysis temperatures and found that the complete transition to a silica membrane occurred at ∼1100 °C. Three different supports composed of silicon carbide powders of varying sizes were tested for membrane preparation. It was found that membranes formed with our process were microporous with separation factors several times above the corresponding Knudsen factors. Our synthetic route, therefore, offers a scalable and solventless method for producing silicon-based ceramic membranes for high-temperature separation and sensor applications.

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The goal of this research was to determine the feasibility of employing the catalytic steam reforming of biogas to increase its energy content by converting the methane it contains into a hydrogen-rich syngas mixture and using this reformate product intermixed with raw biogas in a lean-burn gas engine in order to enhance combustion stability and to reduce NOX emissions. The field-testing component of the project involved catalytically reforming a side stream of biomethane from a landfill gas collection system at a California landfill via a waste energy chemical recuperation process, in which waste heat from a gas engine was used to promote the reforming reaction of biogas. In the study, the total flow of raw biogas diverted to the engine remained constant. A fraction of that biogas was, however, separated and directed to the aforementioned catalytic reactor. The reformer exit stream was then dried, blended with the remaining biogas, and burned in an internal combustion engine to produce electricity. When operating on the blended biogas mixture, combustion stability was enhanced, and the engine ran smoothly at the full speed of 3600 rpm with a 60 Hz output frequency. On the other hand, when burning raw biogas without any reformate gas blended, the test engine ran poorly, sputtering and never reaching 3600 rpm. Also, when operating at various loads under fuel-lean (excess-air) conditions, NOX emissions were significantly reduced when compared to the engine operating on propane under the same load conditions. Similar comparative testing could not be performed on raw landfill gas alone because the engine would not operate at full speed, as noted above. The research presented here has validated the technical and economic feasibility of using reforming products during biogas combustion in a lean-burn gas engine in order to reduce NOX emissions and to enhance combustion stability. This, in our opinion, is an important contribution to the scientific/technical literature and a significant advance for the field of biogas utilization.