CO₂<span> Valorization into Synthetic Natural Gas (SNG) using a Co-Ni bimetallic Y₂<span>O₃<span> Based Catalysts

Recently, because of the increasing demand for natural gas and the reduction of greenhouse gases, interests have focused on the production of synthetic natural gas (SNG), which is suggested as an important future energy carrier. Hydrogenation of CO₂, the so-called methanation reaction, is a suitable technique for the fixation of CO₂. Nickel supported on yttrium oxide and promoted with cobalt were prepared by the wet-impregnation method respectively and characterized using SBET, XRD, FTIR, XPS, TPR, and HRTEM/EDX. CO₂ hydrogenation over the Ni/Y₂O₃ catalyst was examined and compared with Co-Ni/Y₂O₃ catalysts, Co% = 10 and 15 wt/wt. Carbon dioxide hydrogenation was carried out in a homemade fixed bed tubular reactor operating at atmospheric pressure. The quartz silica reactor was heated in an electric furnace equipped with a programmable temperature controller. 2 gm of the fresh catalyst were diluted with silicon carbide (SiC) to obtain 5cm bed height packed in the middle of the reactor. The temperature was monitored by a K-type thermocouple placed in the center of the catalyst bed. Before the catalytic test, all the samples were activated in situ with a 30 mL/min flow of pure hydrogen at atmospheric pressure for 2 h at 600 °C. After the reduction, the catalysts were cooled down and the flow of premixed gas at a molar ratio CO₂/H₂/Ar = 1/4/5 with GHSV of 6000 ccg^-1h^-1 was gradually introduced through the catalysts. Then, the temperature was increased to 350 °C and the reaction time was 3h. Gaseous reaction products were analyzed on-line by a quantitative gas analysis system (HIDEN ANALYTICAL QGA, England). The selectivity of H₂, CO₂, CH₄ and, CO was detected by the gas analyzer using a matrix equation to correct the overlapped detection values from the m/z of 28 (CO), 44 (CO₂), 2 (H₂), and 16 (CH₄).