Effect of Co/Ce ratio on NO reduction by petroleum gas over Co-Ce-Ti oxide catalyst

Co-Ce-Ti composite oxide catalysts with TiO 2 as support and different loadings and molar ratios of Co/Ce were prepared by a sol–gel method. The conversion efficiency of NOx was inspected on a fixed bed with liquefied petroleum gas as reducing agent, and decoupling experiments were performed in a simulated rotary reactor to investigate the adsorption and reduction efficiency of NOx. The experiments founded that CeTi, Co 0.5 CeTi, and CoCe 0.5 Ti had poor nitrogen oxide conversion efficiency, and the effects of CoTi and CoCeTi above 300 °C were relatively good and acceptable. The CoCeTi catalyst showed excellent NO adsorption performance in the simulated rotary reactor, and the removal rate of NO exceeded 95% above 300 °C. Through characterization methods such as BET, TPR, XPS, XRD, and in situ DRIFT, it could be known that Co element in the catalyst was the main factor for NO reduction and Ce element played an important role in the adsorption process, but it had little effect when acting alone. In the case of proper metal ratio, the interaction of two elements reduce the surface oxygen vacancy formation energy and change the pore structure of the catalyst surface. The formed surface synergetic oxygen vacancies promoted the reaction rate for NO removal by liquefied petroleum gas, and effectively improved the catalytic reduction efficiency.