Methane emissions from coal mining contribute significantly to the greenhouse effect but at the same time represent a potentially economic source of energy. One factor that prohibits economic utilization is the lack of a cost-effective system for removing contaminant gases such as carbon dioxide, nitrogen, and oxygen from diluted sources of methane, particularly when these resources are too small or remote to justify installation of traditional gas processing plants. Preliminary testing suggests that a variety of clinoptilolite. a natural zeolite found in Wyoming, would be successful in separating nitrogen and carbon dioxide from methane using a pressure swing adsorption process. This process could be the first economic means of separating nitrogen and methane in a small capacity plant, and in addition, the cost of this natural zeolite would be a small fraction of that of the synthetic zeolites currently being used in other gas separation processes. This research is determining the capacity of the natural zeolite to adsorb and desorb gases under different pressure conditions. The Phase I effort includes determining adsorption/desorption isotherms for carbon dioxide, nitrogen, oxygen, and methane; (2) testing will be done to determine how adsorption of the gases is affected when these gases are mixed in various combinations and proportions; (3) testing to determine the ability of the zeolite to perform gas separation in a laboratory-scale pressure swing apparatus; (4) finally, the study of performance of the system by adding moisture to a gas mixture.Anticipated Results/Potential Commercial Applications as described by the awardee:If a low cost process can be developed to separate nitrogen, carbon dioxide, and oxygen from methane, the U.S. ability to recover methane from low grade resources and reduce methane emissions to the atmosphere will be greatly enhanced. Many countries have similar problems, so there is a substantial opportunity for export of this technology, if successful. Potential commercial applications are as follows in (1) the coal mining industry, to recover methane currently being vented to the atmosphere; (2) the gas industry, to improve the economics of remote, small, or substandard natural gas or coalbed methane fields; and (3) landfills, where low grade methane is usually flared or simply allowed to vent to the atmosphere.
