Improved Hydrogen Purification

Industrial hydrogen production relies primarily on natural gas and hydrocarbon feedstocks to drive the various reaction chemistries that lead to hydrogen generation. Carbon dioxide, the ultimate co- product when such feedstocks and processes are employed, necessarily becomes a major contaminant of the generated hydrogen. Thus, carbon dioxide isolation and removal is an important process step in the efficient, low cost purification and recovery of hydrogen from the intermediate reformed and synthesis gases. A new proprietary, chemically resistant and highly durable membrane being developed in this project will improve the separation efficiency and dramatically reduce energy requirements for the separation of carbon dioxide and hydrogen. In the Phase I program, membranes with CO2/H2 selectivities as high as 15 were developed. When compared to both amine scrubbers and pressure swing absorption processes, the CMS membrane process has dramatically lower capital and operating costs. Costs for a typical CMS membrane system is $58/MM SCF H2 while PSA and amine scrubber costs are between $162 and $1,072 MM SCF H2 for the same 99% H2 purity. In the Phase II program CO2/H2 selectivities up to 40 have been achieved. While membranes with more than adequate selectivity have been demonstrated, there is still significant room for improvement in CO2 permeance. This program will develop a high performance (both high selectivity and high permeance), robust membrane for the purification of hydrogen. The proposed membrane will employ a novel material with a high permeability for CO2. While this material can easily be formed into a membrane, making the material thin enough to provide high CO2 permeance is much more difficult. CMS has identified a means of forming this material into a thin, high permeance membrane. This membrane fabrication method will be developed to enable fabrication of prototype membranes for pilot tests. Besides the hydrogen generation processes mentioned already, the new membrane promises to have broad application in the hydrogen economy, hydrogen processing, synthesis gas production, hydrotreating, and sulfur removal processes. Improvements in hydrogen purification and separation efficiencies and the ready isolation of a concentrated carbon dioxide co-product will have direct benefits in emissions reductions, energy independence, and carbon management.