(57d) Catalytic Oxygen Removal from Pressurized Oxy-Combustion Flue Gases Using a Reverse Flow Fixed-Bed Reactor

Pressurized oxy-combustion (OC) is regarded as an energy-efficient alternative to atmospheric OC. To utilize the captured CO₂ from pressurized OC for enhanced oil recovery or store it in geological formations, the CO₂ stream must meet the required purity specifications. One major impurity in OC flue gases is residual O₂ (e.g., 3 vol%). The O₂ limit is typically required to be below 100 ppmv to lessen corrosion effects on pipelines, avoid reactions with oil and overheating injection points in oil wells, and mitigate the oxidation of caprock species in sequestration applications.

In this study, a catalytic approach was investigated to remove O₂ impurity in CO₂ streams from pressurized OC systems. The flue gas entered a laboratory high-pressure reverse flow fixed-bed (RFFB) reactor, where O₂ residue was removed through a catalytic reduction reaction with injected natural gas (CH₄). With the reverse-flow reactor operation, an autothermal operation (wherein the heat generated by the CH₄ oxidation reaction was sufficient to maintain essentially complete conversion) was achieved without preheating the feed gas. Non-precious metal catalysts synthesized using wet chemistry methods were investigated in the experiments.

This presentation will first provide an overview of the OC technology and RFFB reactor process for catalytic O₂ removal. Then, the focus will be on the test results of O₂ removal using the RFFB reactor system with a simulated 15 bar OC flue gas at different temperature, O₂/CH₄, and space velocity conditions. The performances of the selected catalysts and the effects of the RFFB operating conditions will be compared and discussed to provide insights to the process development.