Ni-CaO Combined Sorbent-Catalyst Materials usage for Sorption Enhanced Steam Methane Reforming

摘要

In the aim to develop new low carbon power generation processes, energy efficiency can be improved by associating carbon dioxide capture. Our work concerns SE-SMR (Sorption Enhanced Steam Methane Reforming) looping cycle. It is based on solid particles of CSCMs (Combined Sorbent Catalyst Materials) constituted by CaO — for sorbent function — and a reforming catalyst (metallic state) on the same support. Main reactions are [1]: Methane Steam Reforming (MSR) CH_4(g) + H_2O_(v) → CO_(g) + 3H_(2(g)) □ H_(298K)~0 = 206.2 kJ/mol Water-gas shift (WGS) CO(g) + H_2O(v) □ CO_2(g) + H_(2(g)) □ H_(298K)~0=-41.2 kJ/mol CO_2 sorption CO_2(g) + CaO_(s)□ CaCO_(3(s)) □H_(298K)~0= - 178.2 kJ/mol The last reaction shifts to the right WGS equilibrium by removing gaseous CO_2, so H_2 gas fraction increases. All reactions occur on the same solid particle and the global process in nearly auto-thermal. The hypothesized process works with this sequence: SE-SMR proceeds by CSCM particles (650°C, 1 atm [2]); these are then regenerated by calcination (reverse of CO_2 sorption, 800-900 °C, 1 atm); regenerated particles then return to SEMSR conditions, starting a new cycle; high purity H_2 here produced can be converted in power by fuel cells.