Chemical Looping For Syngas And Hydrogen Production With Parallel CO2 Activation.

The anticipated rise in global population and the rapidly growing economies of the developing world will dramatically increase the demand for consumer products¬, which are derived mostly from commodity chemicals. While the abundant natural gas (>95% CH4) reserves can potentially enable bulk chemical production, all commercial routes for methane (CH4) upgrading require its conversion to syngas (mixture of CO+H2) as a first step. Not only are current syngas production technologies highly energy and capital intensive, but they also result in large CO2 emissions. Overall, rising environmental concerns, increase demand for bulk chemicals and availability of abundant natural gas reserves together motivate the need to develop alternative processes for syngas production with CO2 utilization. \ud ‘Chemical Looping Combustion’ is a clean combustion technology, which enables fossil fuel combustion with inherent CO2 capture based on the cyclic oxidation and reduction of an oxygen carrier. While most efforts in chemical looping (CL) are focused on combustion, we demonstrate the application of the “CL principle”—the periodic oxidation and reduction of a metal oxide to couple two independent redox reactions—to the activation of CO2 via reduction to CO (a chemical feedstock) and upgrading of CH4 to syngas or hydrogen.\ud In this work, we investigate and compare CO2 activation via CL in two different operating modes: In the first scheme, CO2 reduction is coupled with CH4 oxidation by using mixtures of Fe and Ni (as alloys or simple physical mixtures) to produce CO and syngas product streams. In the second operating scheme, monometallic Ni carriers are utilized to catalytically crack CH4, producing pure H2 streams. The solid carbon deposits are then burnt off with CO2, overall producing separate CO and H2 product streams. Our investigations demonstrate the potential of CO2 as a “soft” oxidant which enables selective oxidation reactions in all the configurations, and thereby establish the potential of chemical looping processes for efficient syngas production with CO2 utilization