Catalyst Study for the Conversion of Greenhouse Gases into Useful Products

Dry reforming reactions have important environmental and economical implications, since they can utilize both methane & carbon dioxide which are considered as greenhouse gases that cause global warming and produce useful chemical products such as H2 and CO commonly known as synthesis gases. These gases can be used as feedstock for numerous chemicals and fuels besides, being sources for pure hydrogen and carbon monoxide. An experimental investigation was carried out to prepare suitable catalysts for dry reforming reaction using Nickel based catalyst prepared by impregnation method. Alumina (-Al2O3 low surface area, γ-Al2O3 high surface area} were used as supports. The study investigated the effect of activating the catalysts with different gas-media and temperatures while maintaining the applied calcination temperature at 900˚C. The prepared catalyst were tested in a micro reactor at atmospheric pressure, flow rate of 33 ml/min and various reaction temperatures in the range of 500-800˚C. The effluents were analyzed using an online gas chromatograph equipped with a TCD. Influence of catalyst activity, carbon yield, stability, coke deposition and synthesis gas ratio (H2/CO) were studied. Spent and fresh catalysts were characterized by XRD, SEM and TGA techniques. It was observed that, calcination followed by activation of catalyst is essential for the process of reforming. The highest performances were achieved activating both 3 wt% Ni/-Al2O3 and 1 wt% Ni/-Al2O3 catalysts at 700C for 2 hr. The % conversions of CH4 and CO2 obtained were 86.8 and 87.7 respectively for 3 wt% Ni/-Al2O3. While for 1 wt% Ni/-Al2O3, the % conversions of CH4 and CO2 obtained were 84.6 and 89.4 respectively. On the other hand, nickel chloride precursor provided less activation performance than nickel nitrate precursor in the preparation of 1 wt% Ni/-Al2O3. The % conversions of CH4 and CO2 obtained at 700C reaction temperature were 49.0 and 50.0 respectively using nickel chloride precursor, while the % conversions of CH4 and CO2 obtained at 700C reaction temperature using nickel nitrate gave 62.9 and 72.3 respectively. It was also found using 1 wt% Ni/-Al2O3 catalyst that activation media with H2 gas gave better performance than CH4. The % conversions of CH4 and CO2 obtained at 800C reaction temperature were 84.6 and 89.4 respectively using H2 and 65.6 and 70.7 respectively using CH4.Yeme