Publications

The use of Ion Mobility Spectrometry (IMS)in the Detection of Contraband Sandia researchers use ion mobility spectrometers for trace chemical detection and analysis in a variety of projects and applications. Products developed in recent years based on IMS-technology include explosives detection personnel portals, the Material Area Access (MAA) checkpoint of the future, an explosives detection vehicle portal, hand-held detection systems such as the Hound and Hound II (all 6400), micro-IMS sensors (1700), ordnance detection (2500), and Fourier Transform IMS technology (8700). The emphasis to date has been on explosives detection, but the detection of chemical agents has also been pursued (8100 and 6400).

The use of Ion Mobility Spectrometry (IMS) in the Detection of Contraband Sandia researchers use ion mobility spectrometers for trace chemical detection and analysis in a variety of projects and applications. Products developed in recent years based on IMS-technology include explosives detection personnel portals, the Material Area Access (MAA) checkpoint of the future, an explosives detection vehicle portal, hand-held detection systems such as the Hound and Hound II (all 6400), micro-IMS sensors (1700), ordnance detection (2500), and Fourier Transform IMS technology (8700). The emphasis to date has been on explosives detection, but the detection of chemical agents has also been pursued (8100 and 6400). Combining Ion Mobility Spectrometry (IMS) with Mass Spectrometry (MS) is described. The IMS-MS combination overcomes several limitations present in simple IMS systems. Ion mobility alone is insufficient to identify an unknown chemical agent. Collision cross section, upon which mobility is based, is not sufficiently unique or predictable a priori to be able to make a confident peak assignment unless the compounds present are already identified. Molecular mass, on the other hand, is much more readily interpreted and related to compounds. For a given compound, the molecular mass can be determined using a pocket calculator (or in one's head) while a reasonable value of the cross-section might require hours of computation time. Thus a mass spectrum provides chemical specificity and identity not accessible in the mobility spectrum alone. In addition, several advanced mass spectrometric methods, such as tandem MS, have been extensively developed for the purpose of molecular identification. With an appropriate mass spectrometer connected to an ion mobility spectrometer, these advanced identification methods become available, providing greater characterization capability.

There is a great need for robust, defect-free, highly selective molecular sieve (zeolite) thin film membranes for light gas molecule separations in hydrogen fuel production from CH{sub 4} or H{sub 2}O sources. In particular, we are interested in (1) separating and isolating H{sub 2} from H{sub 2}O and CH{sub 4}, CO, CO{sub 2}, O{sub 2}, N{sub 2} gases; (2) water management in PEMs and (3) as a replacement for expensive Pt catalysts needed for PEMs. Current hydrogen separation membranes are based on Pd alloys or on chemically and mechanically unstable organic polymer membranes. The use of molecular sieves brings a stable (chemically and mechanically stable) inorganic matrix to the membrane [1-3]. The crystalline frameworks have 'tunable' pores that are capable of size exclusion separations. The frameworks are made of inorganic oxides (e.g., silicates, aluminosilicates, and phosphates) that bring different charge and electrostatic attraction forces to the separation media. The resultant materials have high separation abilities plus inherent thermal stability over 600 C and chemical stability. Furthermore, the crystallographically defined (<1 {angstrom} deviation) pore sizes and shapes allow for size exclusion of very similarly sized molecules. In contrast, organic polymer membranes are successful based on diffusion separations, not size exclusion. We envision the impact of positive results from this project in the near term with hydrocarbon fuels, and long term with biomass fuels. There is a great need for robust, defect-free, highly selective molecular sieve (zeolite) thin film membranes for light gas molecule separations in hydrogen fuel production from CH{sub 4} or H{sub 2}O sources. They contain an inherent chemical, thermal and mechanical stability not found in conventional membrane materials. Our goal is to utilize those zeolitic qualities in membranes for the separation of light gases, and to eventually partner with industry to commercialize the membranes. To date, we have successfully: (1) Demonstrated (through synthesis, characterization and permeation testing) both the ability to synthesize defect-free zeolitic membranes and use them as size selective gas separation membranes; these include aluminosilicates and silicates; (2) Built and operated our in-house light gas permeation unit; we have amended it to enable testing of H{sub 2}S gases, mixed gases and at high temperatures. We are initiating further modification by designing and building an upgraded unit that will allow for temperatures up to 500 C, steady-state vs. pressure driven permeation, and mixed gas resolution through GC/MS analysis; (3) Have shown in preliminary experiments high selectivity for H{sub 2} from binary and industrially-relevant mixed gas streams under low operating pressures of 16 psig; (4) Synthesized membranes on commercially available oxide and composite disks (this is in addition to successes we have in synthesizing zeolitic membranes to tubular supports [9]); and (5) Signed a non-disclosure agreement with industrial partner G. E. Dolbear & Associates, Inc., and have ongoing agreements with Pall Corporation for in-kind support supplies and interest in scale-up for commercialization.

Abstract not provided.