ENHANCED HYDROGEN PRODUCTION FROM ACID GAS
El-Melih, Ahmed Mahmoud
Gupta, Ashwani K
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Hydrogen sulfide is a colorless, corrosive, toxic and flammable gas that is notorious for its nuisance rotten egg odor. Hydrogen sulfide endangers environment, human health and industrial equipment. Despite its high heating value, utilization of hydrogen sulfide as fuel is strictly prohibited using conventional combustion technologies. This malignant gas naturally exists in crude oil and natural gas wells. The separated-out hydrogen sulfide from crude oil and gas has other impurities that include: carbon dioxide, nitrogen, ammonia, carbonyl sulfide, carbon disulfide as well as benzene, toluene and xylene (commonly referred to as BTX). With the increase in energy demand, there will be reliance on utilization of sourer feedstock. Consequently, hydrogen sulfide stream needs to be efficiently treated. On the other hand, hydrogen sulfide is considered a hydrogen rich feedstock. In addition, the hydrogen-constituted impurities, such as: methane, ammonia and BTX in the separated-out hydrogen sulfide stream from crude oil and gas furtherly enrich the hydrogen feedstock of this stream. Hydrogen can be produced from the decomposition of hydrogen sulfide into its two valuable constituents: hydrogen and sulfur. Thermal decomposition of hydrogen sulfide was studied in this work. Experimental examination of wide range of several key parameters that affect the amounts of hydrogen produced and destructed hydrogen sulfide was conducted. Effect of inlet acid gas composition as well as role of different contaminant gases naturally accompanying H2S on the chemistry, production of hydrogen and destruction of hydrogen sulfide were studied. A chemical reaction mechanism that characterizes hydrogen sulfide thermal decomposition as well as decomposition of a mixture of hydrogen sulfide with methane over wide range of conditions was developed. The developed mechanism addresses the chemical kinetics and possible pathways. The difference in dominant reaction pathways between the two cases of presence and absence of impurities facilitated the identification of the role played by the contaminants.