Effect of some preparation variables on the activity of the mathanation catalyst

Abstract

Nickel catalysts find widespread industrial application in hydrogenation, hydrotreating, and steam reforming reactions. Recently considerable interest has developed in the application of nickel catalysts for methanation of coal synthesis gas. Before starting experimental work, extensive literature studies were carried out on this topic and it was found that despite this widespread use very little work had been done on the co-precipitated nickel catalyst. The scope of the work under this project was to study the effect of composition and calcination temperature on the structure and activity of methanation catalyst. Nickel catalyst supported by alumina and promoted by chromium prepared by co-precipitation method was used for this purpose. The whole work was divided into three groups. These are : (1) To study the effect of composition on the structure of the catalyst, . (2) To investigate the effect of composition on the activity of the catalysts, . and (3) To assess the effect of calcination temperature on the structure and activity of the catalysts. A set of four catalysts of different composition was prepared to study the effect of composition on structure. Temperature Programmed Reduction (TPR), Hydrogen Chemisorption and X-ray Diffraction (XRD) methods were used to study the structure of the catalysts. Methanation reaction was 11 carried out on these catalysts to established their suitability for this reaction. Free NiO, CrZ03 and fixed compounds were found to be present in most of the catalysts. From XRD patterns it is evident that the position and intensity of the peaks varied due to different structural orientation. In the second section of this work, the space velocity of the feed was increased to assess the effect of composition on the performance of the prepared catalysts. XRD patterns were used to find out the relationship between structure and activity. Conversions of carbon oxides varied inversely with the space velocity. Conversion and selectivity of methanation reaction did not show any trend with weight loading. In the third section of this work, one catalyst without promoter was calcined at different temperatures. The impact of calcination temperature on the activity and structure was studied. For the same catalyst calcined at different temperatures, highest conversion (21.87%/gm cat.) was found for the lowest calcination temperature. The conversion decreased markedly with increasing temperature. Most of the catalysts showed very good performance in respect of activity. It has been found that the catalyst preparation variables have. significant influence on the structure and activity ofthe catalysts.