Combustion of Coal Using Chemical Looping Oxygen Carriers

Slide presentation only - No abstract supplie

A modified relation between the intraocular and intracranial pressures

A modified relation between the intraocular and intracranial pressures is presented by employing the least square method to fit the existing experiments. Relative analysis here indicates that this modified relation not only is better than the previous relation by comparing with the existing experimental data but also overcomes the induced singularity in applying the existing mechanical models to compute the mechanical properties of the lamina cribrosa. The present study will be a beneficial help to understanding the relationship between the intraocular and intracranial pressures and even glaucomatous developing

Comparison of UV and visible Raman spectroscopy of bulk metal molybdate and metal vanadate catalysts

The visible (532 and 442 nm) and UV (325 nm) Raman spectra of bulk mixed metal oxides (metal molybdates and metal vanadates) were compared on the same spectrometer, for the first time, to allow examination of how varying the excitation energy from visible to UV affects the resulting Raman spectra. The quality of the Raman spectra was found to be a strong function of the absorption properties of the bulk mixed oxide. For bulk mixed metal oxides that absorb weakly in the visible and UV regions, both the visible and UV Raman spectra were of high quality and exhibit identical vibrational bands, but with slightly different relative intensities. For bulk mixed metal oxides that absorb strongly in the UV and visible regions and/or strongly in the UV and weakly in the visible regions, the visible Raman spectra are much richer in structural information and of higher resolution than the corresponding UV Raman spectra. This is a consequence of the strong UV absorption that significantly reduces the sampling volume and number of scatterers giving rise to the Raman signal. The shallower escape depth of UV Raman, however, was not sufficient to detect vibrations from the surface metal oxide species that are present on the outermost surface layer of these crystalline mixed metal oxide phases as previously suggested. It was also demonstrated that there is no sample damage by the more energetic UV excitation when very low laser powers and fast detectors are employed, thus avoiding the need of complicated fluidized bed sample arrangements sometimes used for UV Raman investigations. The current comparative Raman investigation carefully documents, for the first time, the advantages and disadvantages of applying different excitation energies in collecting Raman spectra of bulk mixed metal oxide materials. © 2005 American Chemical Society.Fil: Tian, Hanjing. Lehigh University; Estados UnidosFil: Wachs, Israel E.. Lehigh University; Estados UnidosFil: Briand, Laura Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentin

Metal modified hexaaluminates for syngas generation and CO2 utilization via chemical looping

Chemical looping CH4-CO2 reforming (CLDR) is an emerging technology for the generation of Fischer-Tropsch ready syngas and CO2 utilization, which is strongly dependent upon the improvement in the design of efficient oxygen carriers (OCs). In this present work, different metal additives (Si, Zr and Ce ions) were introduced into Fe-based hexaaluminates and used OCs for CLDR. The microstructure and reactivity of BaFe2.8M0.2Al9O19 (M = Fe, Si, Zr, and Ce) OCs were found greatly influenced by the metal additives and CH4/CO2 redox treatment. Pure Fe and Ce doped OCs showed the co-existence of both beta-Al2O3 and MP hexaaluminate phases, while the introduction of Si and Zr in the hexaaluminate structure led to the phase transformation from beta-Al2O3 into MP. During the CH4/CO2 redox process, large amounts of Fe species in both BaFe2.8Si0.2Al9O19 and BaFe2.8Zr0.2Al9O19 OCs were gradually stabilized in sintering FeAl2O4 with low oxygen-storage capacity, which resulted in low CH4 reactivity and weak cyclic stability. However, Ce-doped BaFe2.8Ce0.2Al9O19 OC showed good reactivity and stability during the 10 redox cycles with CH4 conversion of 93%, H-2/CO ratio of similar to 2, high syngas yield of 2.2 mmol/g, and high CO2 activation ability of 0.95 mmol/g, which was associated with the preservation of hexaaluminate main phase, the formation of CeFexAl1-xO3 and the abundant oxygen vacancies. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Computational design of novel sorbent materials for IGCC H2S removal and process intensification

The high efficiency Integrated Gas Combined Cycle (IGCC) offers potential low-cost energy production via conversion of coal into syngas. Possible gasification byproducts contaminating the syngas can include species like H S, AsH , H Se, and HgCl. A low cost high uptake sorbent is needed to capture these species simultaneously. Zn TiO (henceforth \u27ZTO\u27) has been proposed as this sorbent. In the work presented we have used Density Functional Theory (DFT) calculations to examine the dissociative adsorption of H S on ZTO. We first calculated the low energy bulk and then low energy surface structures of ZTO. Comparison of quantitative data for atomic-scale structure of bulk ZTO between theory and experiment is shown to be good. We then probed adsorption sites of H, S, and H2S on the ZTO(010) surface. Finally, we have used the NEB method implemented in DFT calculations to probe the decomposition pathway of H S to 2H+S on the ZTO(010) surface. 2 3 2 2 4 2

Characterization of bulk structure in zinc orthotitanate: A density functional theory and EXAFS investigation

Development of high-efficiency multicontaminant sorbents is critical for commercialization of power plants utilizing integrated gasification combined cycle technologies. A known prototypical sorbent for this application is the compound zinc orthotitanate, Zn TiO (ZTO). Previous work has not completely resolved the atomic-level structure of ZTO. Results from both experimental X-ray absorption fine structure measurements and density functional theory (DFT) calculations are presented and are in quantitative agreement. The DFT calculations identify the octahedral site occupation of Zn and Ti atoms that give the lowest energy ground state structure. We have supplemented our DFT calculations with a cluster expansion model used to parameterize Monte Carlo (MC) simulations. The results of the MC simulations reveal the temperature dependence of the equilibrium octahedral site occupation in Zn TiO . © 2007 The American Ceramic Society. 2 4 2

Microstructure and electrical contact behavior of the nano-yttria-modified Cu-Al2O3/30Mo/3SiC composite

With the rapid development of the copper-based composite in the field of electrical contact material industry, the problem of poor arc erosion resistance of the copper-based material becomes more and more prominent. Improving the arc erosion resistance of the copper-based composite is an urgent problem to be solved. Cu-Al2O3/30Mo/3SiC and 0.5Y2O3/Cu-Al2O3/30Mo/3SiC electrical contact composites were prepared in a fast-hot-pressing sintering furnace. The microstructure and phase structure of the composites were analyzed by using a scanning electron microscope, transmission electron microscope, and X-ray diffraction meter, respectively. The arc erosion properties of the composites at 25 V, DC and 10-30 A were investigated by using a JF04C electric contact tester. The mass loss of the composites was reduced by 77.8%, and the arc erosion rate was reduced by 79.6% after the addition of nano-yttrium oxide under the experimental conditions of 25 V, DC and 30 A. At the same time, the arc energy and welding force of the composite after switching operations decreased, indicating that the addition of nano-yttria improved the arc erosion resistance of the composite. This work provides a new method for improving the arc erosion resistance of the copper-based composite contact material