Dale M. Taylor

Ion transport membrane technology for oxygen separation and syngas production

Abstract Ion transport membranes (ITMs) are made from ceramic materials that conduct oxygen ions at elevated temperatures. Successful application of ITM technology will allow significant improvement in the performance of several large-scale industrial processes. The ITM Oxygen process, in which ITMs are used to separate high-purity oxygen from air, has the potential for significant advantages when integrated with power generation cycles. The ITM Syngas process, by combining air separation and high-temperature syngas generation processes into a single compact ceramic membrane reactor, has the potential for substantially reducing the capital investment for gas-to-liquid (GTL) plants and for distributed hydrogen. The development efforts are major, long-term and high risk, and place severe demands on the performance and property requirements of the ITM materials. Air Products and Chemicals has joined with the U.S. Department of Energy, Ceramatec and other partners to develop, scale-up and commercialize these technologies. In addition, Air Products and Ceramatec are developing the SEOS™ Oxygen Generator, an electrically-driven, small scale, oxygen generation and removal technology using ITMs, which could have a significant impact in the global market for distributed oxygen and inert gases. This paper describes the stages of development of these three related technologies, their industrial applications, and the technical hurdles that must be overcome before successful commercialization.

Reference electrode placement and seals in electrochemical oxygen generators

We report measurements and numerical calculations of the potential distribution within a thin solid electrolyte near active (current-bearing) electrodes. These studies demonstrate two principles: (1) In a flat-plate geometry, the electrolyte is approximately equipotential beyond a distance of about three electrolyte thicknesses from the edge of the active electrodes. (2) If one of the active electrodes on one side of the electrolyte extends beyond the other, it strongly biases the potential of the electrolyte far from the active region. We show that these effects make it challenging to measure electrode overpotential accurately on thin cells. However, we also show that these effects can be useful for protecting glass-ceramic seals in an oxygen generator stack against electrochemical degradation/delamination.

Electrochemical Oxygen Separation Using Solid Electrolyte Ion Transport Membranes

A novel process employing solid electrolyte-based ion-transport membranes enables the production of high-purity oxygen at elevated pressure from a feed stream of ambient pressure air. This technology exploits the theoretically infinite selectivity of oxygen ion migration through a dense ceramic electrolyte membrane under the influence of an externally applied electrical potential. The solid electrolyte is derived from cerium oxides with dopants added to enhance both ion transport and membrane processability. The oxidation and reduction reactions are promoted by the use of porous perovskite electrodes, which together with the electrolyte form an electrochemical cell. Stacks comprising multiple cells in a planar configuration have demonstrated excellent electrochemical performance and stability, mechanical integrity. and the capacity to produce high-purity oxygen over thousands of hours. An oxygen generator based on this technology must incorporate an integrated thermal management system air mover, power supply, and control systems.

ITM Syngas ceramic membrane technology for synthesis gas production

Publisher Summary The ITM Syngas process is a breakthrough technology that combines air separation and high-temperature synthesis gas generation processes into a single ceramic membrane reactor, with significant savings in the capital cost of synthesis gas production. Because synthesis gas is a feedstock for a range of different processes, ITM Syngas represents a technology platform that has numerous applications, such as gas-to-liquids; hydrogen; clean fuels, including liquid transportation fuels; and chemicals. The basic fabrication methods used to construct ITM Syngas wafers are—tape casting, laser cutting, lamination, and co-sintering. Although these processes are each practiced commercially, the sub-surface open channels found in these wafers required the development of new lamination techniques to prevent collapse of the ribs separating adjacent channels while assuring adequate contact pressure to prevent de-bonding during co-sintering. The ITM Syngas process places severe demands on the membrane material. The membrane must simultaneously meet the criteria of being thermodynamically stable in the high-pressure, reducing, natural gas feed and intermediate synthesis gas; being thermodynamically stable in the low-pressure, oxidizing air feed; having sufficient mixed electronic and oxygen ion conductivity to achieve economically attractive oxygen fluxes; and having the requisite mechanical properties to meet lifetime and reliability criteria.