Date of Award

January 2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

First Advisor

Steven A. Benson

Abstract

In order to facilitate the use of hydrogen in integrated gasification combined-cycle (IGCC) applications or as a transportation fuel, hydrogen-from-coal technologies that are capable of managing carbon will be needed. Many technologies are under development for the separation of hydrogen from coal-derived syngas, and among the most promising are hydrogen separation membranes. Studies indicate a significant IGCC plant efficiency increase can be realized if warm-gas cleanup and hydrogen separation membranes are used in place of conventional technologies. These membranes provide the potential to produce hydrogen while simultaneously separating CO2 at system pressure. Membrane development to date has primarily occurred on bottle-derived syngas, and the impact of coal-derived impurities is largely unknown. Gasification syngas typically has many impurities that, if not removed, will poison most hydrogen separation materials. In order to commercialize this promising technology, scale-up to bench- and pilot-scale gasifiers is required so that the impact of impurities can be evaluated.

Sulfur and other coal derived impurities such as chlorine, sodium, mercury, and arsenic have the potential to deteriorate the performance of hydrogen separation membranes. It is unknown if species such as mercury will have an impact on the membrane performance, but mercury does remain in the gas phase and can cause environmental concerns. Commercially available technologies exist today to remove the contaminants from the syngas prior to exposure to the membranes. The goal of this work was to determine if the warm gas clean up techniques available today are adequate to protect hydrogen separation membranes from performance degradations caused by the impurities found in coal. To test this hypothesis, pilot-scale gasifiers at the Energy & Environmental Research Center (EERC) were used to produce coal-derived syngas, and solid sorbents were used for warm-gas cleanup and water-gas shift. Three hydrogen separation membranes were exposed to coal-derived syngas for several hundred hours. Membrane materials that were exposed to coal derived syngas during the testing were acquired and analyzed for contaminants. This work explores whether the warm gas cleanup techniques employed were adequate to prevent performance degradation of hydrogen separation membranes. The U.S. Department of Energy's National Energy Technology Laboratory and the State of Wyoming funded the experimental effort.

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