This invention describes a novel catalytic method combined with a chemical looping process to produce a hydrogen (H2)-rich synthesis gas (syngas) stream free of the nitrogen from coal. The catalytic process uses reduced metal oxide/coal/steam to produce a H2-rich syngas stream that is free of nitrogen (N2) from coal while the chemical looping combustion (CLC) of fuel with the metal oxide is used for production of the heat required for the catalytic process. CLC processes also produce a concentrated stream of carbon dioxide (CO2) that is ready for sequestration. This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy’s National Energy Technology Laboratory.
Challenge
Traditional coal gasification requires an expensive air separation unit to produce N2-free syngas. However, NETL’s novel catalytic process using reduced metal oxide/coal/steam does not require an air separation unit for production of nitrogen free syngas stream. Heat is traditionally produced via fuel combustion, which generates a CO2 stream mixed with N2. This stream requires expensive separation technologies for CO2 sequestration. The novel catalytic process uses the heat from CLC of fuel, which generates a sequestration ready CO2 stream. Integration of the processes, addressing contaminant issues and scaling up the technology for commercialization are necessary.
Researchers at NETL have developed a catalytic process to produce H2-rich syngas from coal that does not require an air separation unit. Syngas and H2 production from coal is commercially conducted via coal gasification process. The goal is to get a concentrated syngas stream that has a higher energy value and that can be used for many applications, including production of pure H2. Typically, the gasification process involves partial coal combustion with either oxygen (O2) or air. When air is used, N2 can enter the syngas, diluting the syngas and making syngas extraction difficult. When O2 is used, expensive oxygen production units are needed that tend to generate high parasitic losses.
Using steam for coal gasification can avoid the need for an expensive air separation unit to produce nitrogen-free syngas. A novel catalytic process using reduced metal oxide with coal/steam will produce H2/syngas at a high rate and address the issues encountered during coal gasification process.
Additionally, the heat required for traditional gasification is generated by combusting some type of fuel in air. This results in flue gas containing CO2 and N2. CO2 must be separated from N2 prior to any sequestration, further adding to the cost of CO2 mitigation. CLC is a combustion process that utilizes oxygen from an oxygen carrier such as a metal oxide for fuel combustion. Significantly, the CO2 that is produced via CLC is sequestration-ready and does not require any further processing or incur associated costs prior to storage.
In the novel catalytic process, reduced metal oxide is used as the catalyst for H2-rich syngas production from coal/steam while using the same metal oxide as an oxygen carrier for the CLC to produce heat for the process.
This NETL CLC process for producing hydrogen from coal offers multiple advantages over conventional technologies.
Advantages
Syngas is the precursor for production of many chemicals and products we sue every day. It is also used for hydrogen production. Hydrogen is used in oil refineries, to make ammonia, for methanol production, and in fuel cells.
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