This Small Business Innovation Research Phase I project investigates a new series of low-cost non-precious metal catalysts for combustion of volatile organic compounds (VOCs), such as propane, hexane, toluene, ketone, alcohols, phenols, xylene and formaldehyde, for reducing VOC emissions from industry exhausts. Catalytic combustion is an efficient approach for the VOCs destruction at mild temperatures before they are released into atmosphere. This project proposes nano-sized transition metal mixed oxides with spinel and perovskite structures as catalysts for this application. Due to the interactions between the spinels and perovskites, the composite catalysts are expected to exhibit excellent performance in complete oxidation of VOCs to CO2 and H2O at 200-400C, with less cost than traditional precious metal based catalysts. In this project, nano-size powder catalysts will be synthesized with various methods, tested for VOCs combustion, and characterized by physical and chemical methods. The promising catalysts will be scaled up, washcoated in monoliths, and evaluated under real VOCs combustion conditions in Phase II project. The generated information can provide new insights into understanding activation process of O2 and small organic molecules and their interactions on the transition metal oxide catalyst surface. The data will be utilized to understand VOC oxidation behavior and design more active VOC combustion catalysts in the future. The generated information can also be applied to develop active catalysts for combustion of H2, CO, soot, natural gas, light hydrocarbons and other fuels.
The broader impact/commercial potential of this project can help abate the VOCs emissions because the VOCs can be completely oxidized to CO2 and H2O on the catalyst surface before they are released into air. Since VOCs are toxic to human health and contribute to a number of environmental problems (e.g., photochemical smog), environmental legislation has imposed increasingly stringent targets for permitted levels of atmospheric emissions. As compared to the conventional Pd and Pt containing catalysts, the substitution with non-precious metal catalysts could drastically improve the combustion efficiency and also reduce the cost of the combustion system, which allows VOC catalytic combustion technology to be more widely used in the world for reducing air pollution.
In this Phase I SBIR project, NexTech Materials Ltd. conducted preliminary research to establish a new family of spinel/perovskite composite catalysts with excellent performance for abating air pollution by combustion of volatile organic compounds (VOC). VOC are toxic to human health and contribute to the formation of photochemical smog by reacting with nitrogen oxides. The primary sources of VOC are emissions from industrial processes and transportation exhaust. Catalytic combustion is an efficient approach for the VOC destruction at mild temperatures. The testing data indicated that the composite oxide catalysts could oxidize VOC (e.g., propane, butane, hexane, butene, toluene and propanol) to CO2 and H2O at 200-250°C and gas hourly space velocities of 45,000-150,000 ml/g-hr. The temperature for complete conversion of VOC on the composite oxides was 100-150?C lower than that on the conventional precious metal catalysts under the same reaction conditions. The oxide catalysts were also more tolerant to silicon and phosphorous, two common impurities in VOC stream, than the precious metal catalysts. As a result, the replacement of precious metal catalysts to this composite oxide catalyst could save >80% material cost and 30% operation cost. In addition, the catalysts were characterized by BET, XRD, TEM, XPS and TPR. The results suggested that nano-sized oxide particles contributed to the superior combustion activity. The preliminary results of the Phase I effort have demonstrated that the low-cost transition metal oxides are good catalyst candidates for VOC removal.
