(696b) Promoted Perovskites for Low-Temperature Chemical Looping Reforming

Reforming of methane to syngas is an important but energy intensive step in the synthesis of chemicals and liquid fuels from natural gas. Steam reforming (SMR) does not give an ideal H₂ to CO ratio for liquid fuel or chemical synthesis, and conventional methane partial oxidation/auto-thermal reforming (POx/ATR) approaches require costly air separation. These processes are, therefore, difficult to implement economically at intermediate and distributed, modular scales. Chemical looping reforming (CLR), which partially oxidizes methane into H₂ and CO in the absence of steam or gaseous oxygen, offers a simpler and potentially more efficient route for syngas generation. This is achieved by cyclic removal and replenishment of active lattice oxygen in oxygen carrier particles (also known as redox catalysts). Elimination of water-gas shift reactors and oxygen plants make CLR attractive for small scale gas-to-liquids (GTL).

Selecting a redox catalyst particle with high selectivity and facile oxygen transport is very important for CLR. Although the system is dynamic due to the continuous change in oxidation state, carful study of the oxidation state vs. selectivity and activity of the catalyst can help probe the nature of the active surface species. Substituting the metals into the perovskite structure also allows tuning the thermodynamics of available oxygen. Surface promotion with platinum group metals, or substituting reforming active metals in the perovskite also allows independent modification of surface activity. The heats of reaction can also be tuned to optimize reactor heat integration. In the work presented, high performance redox catalyst for low-temperature conversion of methane to syngas are presented. The combined use of CLR with integrated CO₂ splitting to enhance CO yields is also discussed. Process modeling indicating high energy efficiency to chemicals is shown.