Study On The Preparation Of Ru-based Catalysts And Their Catalytic Performance For Hydrogenation Of NO To NH₃

This thesis mainly studies the ammonia synthesis by the coupling of methanol steam reforming reaction with NO hydrogenation reaction over Ru-based catalyst.In this paper,methanol is used as a hydrogen source to convert harmful NO into valuable NH₃in order to find a new way for ammonia synthesis,which is because that NH₃is an important chemical raw material and NO is one of the main pollutants in the atmosphere on the one hand,and methanol has the advantages of high hydrogen content,low cost,and easy availability on the other hand.Firstly,preparing Ru catalysts used for hydrogenation of NO to NH₃has been investigated to screen out moderate support and reduction temperature.The physical and chemical properties of the materials are characterized by X-ray powder diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,and N₂adsorption-desorption（BET）techniques.The results demonstrated that CeO₂is the optimal carrier and desired reduction temperature is 500℃,moreover Ru catalyst with nanorod-shaped CeO₂as support has better catalytic performance toward NH₃synthesis than Ru catalysts with particulate CeO₂or cubic CeO₂as support.Secondly,the effects of Ru loading and catalytic reaction conditions on the ammonia synthesis from NO hydrogenation have been investigated.X-ray powder diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and N₂adsorption-desorption（BET）techniques were performed to determine the physical and chemical properties of the as-prepared Ru/r-CeO₂catalysts.The concentration of NO,reaction pressure,reaction temperature,and the ratio of methanol to water were investigated to obtain better catalytic performance for ammonia synthesis from NO hydrogenation over Ru/r-CeO₂catalysts.The results showed that the desired Ru loading for ammonia formation was 3%,and higher concentration of NO is beneficial to increase the NH₃synthesis rate and lower concentration of NO is beneficial to improve the selectivity of NH₃.When the concentration of NO in Ar was10%,the optimized pressure,reaction temperature,the ratio of methanol to water and reaction time were 0.5 MPa,200℃,5 ml:5 ml,and 1 h,respectively.When the concentration of NO in Ar was 2%,the optimized pressure,reaction temperature,the ratio of methanol to water and reaction time were 0.5 MPa,200℃,2 ml:8 ml,and 3 h,respectively.