Biogas upgrading: the role of Ni-based catalysts

Much has been said and written in recent times about possible solutions for CO2 capture, conversion and storage. The role played by CCCS has become crucial and its importance is constantly growing together with the idea of storing surplus renewable energy under the form of green H2. At the same time, biogas upgrading relies on CO2 removal to obtain biomethane with a suitable purity for NG-grid injection [1]. In this picture, biogas upgrading through thermo-catalytic CO2 methanation is every day more appealing, since it avoids the costs associated with the CO2 removal step [2]. This project focus on the use of Ni as active phase. Different metal oxides were used as support, such as Al2O3, SiO2, ZSM-5, TiO2 and CeO2. Both in-house developed and commercial support have been used to synthetize the catalysts through wet-impregnation techniques. Tests have been conducted in two continuous tubular reactors, loaded with 200 mg of catalyst diluted in carborundum, at different GHSV. All the catalysts testes have been characterized through XRD, XPS, SEM, TEM, FT-IR, ICP and N2 physisorption analysis. Several catalysts, among which it is interesting to note 36% Ni/Al2O3 and 36% Ni/CeO2 showed high catalytic activities, approaching thermodynamic equilibrium at about 400°C and 350°C, respectively. Both catalysts, as reported in Figure 1, show near 100% selectivity to methane under the working conditions up to 400°C.