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Hydrogen Production via a Commercially Ready Inorganic Membrane Reactor Semi-Annual Technical Progress Report: April-September 2004

Description: During the 2nd half of Year I, we continued the development of the microporous ceramic layer as a transition layer for the deposition of the carbon molecular sieve membrane on the stainless steel substrate offered by Pall Corp. Based upon the positive result from the feasibility study conducted in the 1st half of Year I, our activities in this period focused on eliminating the high pore size peak and the minimization of defect. A microporous ceramic layer with 40A pore size and <1% initial flow have been successfully prepared. Further, this modified membrane has demonstrated excellent thermal stability, <1% initial flow after the 5 thermal cycles. In addition we began the CMS layer deposition on the AccuSep with the ceramic transition layer. The CMS membranes fired at the low temperature range demonstrate an excellent hydrogen permeance, up to >5 m{sup 3}/m{sup 2}/hr/bar, with the selectivity of {approx}20 for H{sub 2}/N{sub 2}. The extremely high permeance is indicative of the extremely thin CMS membrane layer, which becomes possible as a result of the uniform and defect free transition layer. This could be an ideal membrane for hydrogen recovery applications where the hydrogen permeance is the primary concern. Presently we are actively pursuing the intermediate temperature firing to enhance the selectivity to above this range without sacrificing too much permeance.
Date: March 8, 2005
Creator: Liu, Paul K. T.

Hydrogen Production via a Commercially Ready Inorganic Membrane Reactor Semi-Annual Technical Progress Report: April-September 2006

Description: In the last report, we covered the experimental verification of the mathematical model we developed for WGS-MR, specifically in the aspect of CO conversion ratio, and the effect of the permeate sweep. Bench-top experimental study has been continuing in this period to verify the remaining aspects of the reactor performance, including hydrogen recovery ratio, hydrogen purity and CO contaminant level. Based upon the comparison of experimental vs simulated results in this period along with the results reported in the last period, we conclude that our mathematical model can predict reliably all aspects of the membrane reactor performance for WGS using typical coal gasifier off-gas as feed under the proposed operating condition. In addition to 250 C, the experimental study at 225 C was performed. As obtained at 250 C, the predicted values match well with the experimental results at this lower temperature. The pretreatment requirement in our proposed WGS-MR process can be streamlined to the particulate removal only. No excess water beyond the stoichiometric requirement for CO conversion is necessary; thus, power generation efficiency can be maximized. PROX will be employed as post-treatment for the elimination of trace CO. Since the CO contaminant level from our WGS-MR is projected to be 20-30 ppm, PROX can be implemented economically and reliably to deliver hydrogen with <10 ppm CO to meet the spec for PEM fuel cell. This would be a more cost effective solution than the production of on-spec hydrogen without the use of prost treatment. WGS reaction in the presence of sulfur can be accomplished with the use of the Co/MoS{sub 2} catalyst. This catalyst has been employed industrially as a sour gas shift catalyst. Our mathematical simulation on WGS-MR based upon the suggested pre- and post-treatment has demonstrated that a nearly complete CO conversion (i.e., 99+%) can be accomplished. …
Date: September 30, 2006
Creator: Liu, Paul K. T.

Hydrogen Production via a Commercially Ready Inorganic Membrane Reactor, Semi-Annual Technical Progress Report: October 200[5] - March 2006

Description: One of the technical barriers for ceramic membranes is its scale up potential. The conventional ceramic membranes/modules originally developed for liquid phase applications are costly and not suitable for high temperature applications. One of the objectives under this project is the development of a ceramic membrane/module, which is economical and suitable for high temperature applications proposed under this project (200-300 C). During this period, we initiated the fabrication of a prototype ceramic membrane module which can be (1) qualified for the proposed application temperature, and (2) cost acceptable for large scale applications. A prototype ceramic membrane bundle (3-inch diameter and 35-inch L) has been prepared, which passes the temperature stability requirement. It also meets the low end of the burst pressure requirement, i.e., 500-750 psi. In the next period, we will continue the improvement of this prototype module to upgrade its burst pressure to 1000 to 1500 psi range. In addition, bench-top experimental study has been conducted in this period to verify satisfactorily the simulated results for the process scheme developed in the last report, which took into the consideration of streamlining the pre- and post-treatment. The sensitivity analysis indicates that membrane surface area requirement is a key operating parameter based upon the criteria of the CO conversion, hydrogen recovery and CO impurity level. A preliminary optimization study has been performed in this period based upon the key operating parameters determined above. Our result shows that at 40 bar feed pressure a nearly complete CO conversion and >95% hydrogen recovery can be achieved with the CO impurity level at {approx}3500 ppm. If the hydrogen recovery ratio is lowered, the CO impurity level can be reduced further. More comprehensive optimization study will be performed in the 2nd half of Yr III to focus on the reduction of the CO impurity level …
Date: May 31, 2006
Creator: Liu, Paul K. T.
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