co2 Selective Ceramic Membrane for Water-Gas-Shift Reaction With Concomitant Recovery of CO2

A high temperature membrane reactor (MR) has been developed to enhance the water-gas-shift (WGS) reaction efficiency with concomitant CO{sub 2} removal for sequestration. This improved WGS-MR with CO{sub 2} recovery capability is ideally suitable for integration into the Integrated Gasification Combined-Cycle (IGCC) power generation system. Two different CO{sub 2}-affinity materials were selected in this study. The Mg-Al-CO{sub 3}-layered double hydroxide (LDH) was investigated as an adsorbent or a membrane for CO{sub 2} separation. The adsorption isotherm and intraparticle diffusivity for the LDH-based adsorbent were experimentally determined, and suitable for low temperature shift (LTS) of WGS. The LDH-based membranes were synthesized using our commercial ceramic membranes as substrate. These experimental membranes were characterized comprehensively in terms of their morphology, and CO{sub 2} permeance and selectivity to demonstrate the technical feasibility. In parallel, an alternative material-base membrane, carbonaceous membrane developed by us, was characterized, which also demonstrated enhanced CO{sub 2} selectivity at the LTS-WGS condition. With optimization on membrane defect reduction, these two types of membrane could be used commercially as CO{sub 2}-affinity membranes for the proposed application. Based upon the unique CO{sub 2} affinity of the LDHs at the LTS/WGS environment, we developed an innovative membrane reactor, Hybrid Adsorption and Membrane Reactor (HAMR), to achieve {approx}100% CO conversion, produce a high purity hydrogen product and deliver a concentrated CO{sub 2} stream for disposal. A mathematical model was developed to simulate this unique one -step process. Finally a benchtop reactor was employed to generate experimental data, which were consistent with the prediction from the HAMR mathematical model. In summary, the project objective, enhancing WGS efficiency for hydrogen production with concomitant CO{sub 2} removal for sequestration, has been theoretically and experimentally demonstrated via the developed one-step reactor, HAMR. Future development on reactor scale up and field testing is recommended

Quarterly Report For the period April 1, 2004 to June 30, 2004

For the purpose of process simulation and economic analysis of the proposed CO{sub 2} selective membrane process, we began to generate the equilibrium and rate data at the operating condition interested to our applications. In this quarter, we have concentrated on the experiments at 200 C and CO{sub 2} pressure of 0 to 1 bar. In this report we present the equilibrium isotherm and transport rate data and the mathematical treatment using the commonly accepted Langmuir and linear driving force equations. The results from this analysis were then compared with the literature published data. In general, our equilibrium capacity is higher than the literature reported data while the linear driving force model is adequate to describe the rate data obtained from 0 to 1 bar CO{sub 2} pressure. In the next month, we will begin the experimental study at higher temperatures (i.e., 300 and 400 C) to complete our thermodynamic and kinetic database for process simulation

Quarterly Report for the Period January 1, 2005 to March 31, 2005

In this quarter, we have focused on the completion of the loose ends of the experimental study. A series of CO{sub 2}-affinity membranes (carbonaceous base) prepared previously were characterized and evaluated for their suitability for the proposed application The CO{sub 2} permeance and selectivity are 0.5 to >3 m{sup 3}/m{sub 2}/hr/bar and 4 to 10 for CO{sub 2} over nitrogen respectively. Based upon its performance dependence on temperature and pore size, we conclude that this type of CO{sub 2} affinity membrane shows significant surface affinity to CO{sub 2} over nitrogen even at the temperature as high as 220 C, which is within the typical operating condition for LTS-WGS. Future study should focus on mixture separations for CO/CO{sub 2}/H{sub 2} to establish the selectivity of CO{sub 2} over CO and H{sub 2} which are present in the WGS reaction of the coal gasifier off-gas

SiC-BASED HYDROGEN SELECTIVE MEMBRANES FOR WATER-GAS-SHIFT REACTION

This technical report summarizes our activities conducted in Yr II. In Yr I we successfully demonstrated the feasibility of preparing the hydrogen selective SiC membrane with a chemical vapor deposition (CVD) technique. In addition, a SiC macroporous membrane was fabricated as a substrate candidate for the proposed SiC membrane. In Yr II we have focused on the development of a microporous SiC membrane as an intermediate layer between the substrate and the final membrane layer prepared from CVD. Powders and supported thin silicon carbide films (membranes) were prepared by a sol-gel technique using silica sol precursors as the source of silicon, and phenolic resin as the source of carbon. The powders and films were prepared by the carbothermal reduction reaction between the silica and the carbon source. The XRD analysis indicates that the powders and films consist of SiC, while the surface area measurement indicates that they contain micropores. SEM and AFM studies of the same films also validate this observation. The powders and membranes were also stable under different corrosive and harsh environments. The effects of these different treatments on the internal surface area, pore size distribution, and transport properties, were studied for both the powders and the membranes using the aforementioned techniques and XPS. Finally the SiC membrane materials are shown to have satisfactory hydrothermal stability for the proposed application. In Yr III, we will focus on the demonstration of the potential benefit using the SiC membrane developed from Yr I and II for the water-gas-shift (WGS) reaction

Quarterly Report for the Period January 01, 2003 to March 31, 2003

Hydrotalcite material properties, specifically its CO{sub 2} reversibility, are critical to the performance of the proposed hydrotalcite-based membrane. In this report, we summarize the fundamental study we have performed using TGA, TGA/MS, and DRIFTS to quantify the degree of CO{sub 2} reversibility for the temperature range from 200 to 300 C. Results from these three separate studies consistently exhibit the CO{sub 2} reversibility. In addition, water effect appears negligible. Finally a high-pressure experimental study was performed to determine the reversibility under the actual operating condition. The results from this high-pressure (CO{sub 2}) study also demonstrate the CO{sub 2} reversibility. In the next quarter, we will continue the high-pressure experiment in the presence of high-pressure steam to quantify its effect under the actual WGS environment. The quantitative information obtained from this study will then be incorporated in a mathematical model describing the CO{sub 2} permeance as a function of the membrane layer thickness

CO2 SELECTIVE CERAMIC MEMBRANE FOR WATER-GAS SHIFT REACTION WITH CONCOMITANT FOR THE RECOVERY OF CO2

In this quarter we focus on the membrane synthesis via interphase impregnation and slip casting. The slip casting method shows very promising. A well-organized hydrotalcite layer has been deposited on the porous ceramic substrate. Under SEM examination, few defects were recognized. In addition, its particle size in the range of {approx}500{angstrom} is comparable to our existing Al{sub 2}O{sub 3} membrane with 100{angstrom} pore size. This membrane could be qualified for post-treatment with CVD/I to seal the opening to become a CO{sub 2}-affinity membrane. On the other hand, the hydrotalcite membrane prepared via impregnation requires further refinement. After 4th impregnation defects in the range of 0.2 micron were observed under SEM examination, likely due to the incomplete coverage. In the next quarter, we will improve the in-situ technique to overcome this problem

Non-linear stability in photogravitational non-planar restricted three body problem with oblate smaller primary

We have discussed non-linear stability in photogravitational non-planar restricted three body problem with oblate smaller primary. By photogravitational we mean that both primaries are radiating. We normalised the Hamiltonian using Lie transform as in Coppola and Rand (1989). We transformed the system into Birkhoff's normal form. Lie transforms reduce the system to an equivalent simpler system which is immediately solvable. Applying Arnold's theorem, we have found non-linear stability criteria. We conclude that $L_6$ is stable. We plotted graphs for $(\omega_1, D_2).$ They are rectangular hyperbola.Comment: Accepted for publication in Astrophysics & Space Scienc

Properties of Al-doped ZnS films grown by chemical bath deposition

Zinc sulphide (ZnS) buffer layers are a cadmium free, wider energy band gap, alternative to the cadmium sulphide(CdS) buffer layers commonly used in copper indium gallium diselenide (CuInGaSe2)-based solar cells. However extrinsic doping of the ZnS is important to lower the resistivity of the layers and to improve flexibility of device design. In this work, Al-doped ZnS nanocrystalline films have been produced on glass substrates using a chemical bath deposition (CBD) method. The Al- concentration was varied from 0 at. % to 10 at. %, keeping other deposition parameters constant. The elemental composition of a typical sample with 6 at. % ‘Al’ in ZnS was Zn=44.9 at. %, S=49.8 at. % and Al=5.3 at.%. The X-ray diffraction data taken on these samples showed a broad peak corresponding to the (111) plane of ZnS while the crystallite size varied in the range, 8 – 15 nm, depending on the concentration of Al in the layers. The films with a Al-doping content of 6 at. % had an optical transmittance of 75 % in the visible range and the energy band gap evaluated from the data was 3.66 eV. The films n-type electrical conductivities and the electrical resistivity varied in the range, 107-103 Ωcm, it decreasing with an increase of the Al-concentration in the solution

Investigation into the effect of beam shape on melt pool characteristics using analytical modelling

An established analytical model is used to simulate an extended laser beam. Multiple Gaussian sources are superimposed to form a rectangular beam and results are compared with a single circular Gaussian source model as well as experimental results from a high power diode laser with a rectangular beam. Melt depth, and melt pool profile and progression have been predicted by modelling which are compared with experimental results from melting of Inconel 625. The model produced is shown to give a reasonable prediction of melt pool shape and can be usefully employed to help optimise overlap required for laser surface processing applications. The value of absorptivity used in the model can be used as a fitting parameter to optimise the match between experimental and predicted results