CO₂ methanation characteristics over ni catalyst in a pressurized bubbling fluidized bed reactor

Storing the surplus energy from renewable energy resource is one of the challenges related to intermittent and fluctuating nature of renewable energy electricity production. CO₂ methanation is well known reaction that as a renewable energy storage system. CO₂ methanation requires a catalyst to be active at relatively low temperatures (250-500 ^oC) and selectivity towards methane. In this study, the catalytic performance test was conducted using a pressurized bubbling fluidized bed reactor (Diameter: 0.025 m and Height: 0.35 m) with Ni/γ-Al₂O₃ (Ni70%, and γ-Al₂O₃30%) catalyst. The range of the reaction conditions were H₂/CO₂ mole ratio range of 4.0-6.0, temperature of 300-420 ^oC, pressure of 1-9 bar, and gas velocity (U₀/U_mf) of 1-5. As the H₂/CO₂ mole ratio, temperature and pressure increased, CO₂ conversion increases at the experimental temperature range. However, CO₂ conversion decreases with increasing gas velocity due to poor mixing characteristics in the fluidized bed. The maximum CO₂ conversion of 99.6% was obtained with the operating condition as follows; H₂/CO₂ ratio of 5, temperature of 400 ^oC, pressure of 9 bar, and U₀/U_mf of 1.4-3.