Bio: M. Steinberg is an academic researcher from Hebrew University of Jerusalem. The author has contributed to research in topics: Thermal decomposition & Oxalate. The author has an hindex of 15, co-authored 43 publications receiving 608 citations.
TL;DR: In this paper, the adsorption and the thermal stability of the organo-clay complexes were studied by IR thermospectrometry, and it was concluded that the hydrophobicity of the clays increases and their thermal stability decreases as a result of the adorption of the organic bases.
TL;DR: Anhydrous lanthanum oxalate is stable at 320°C and at higher temperatures intermediates are produced which appear to correspond to definite compositions, but they are contaminated with finely dispersed carbon as discussed by the authors.
TL;DR: The presence of paramagnetic species on the surface of cerium(IV) oxide prepared by the thermal decomposition of the oxalate at low temperatures (375°) was shown by ESR.
TL;DR: In this paper, a number of mixed-metal oxides have been reduced in situby H2 and NH3 at pressures in the range 5×10−5to 1 mbar and temperatures of around 520 K. The surface composition was monitored before and after reduction using X-ray photoelectron spectroscopy.
TL;DR: A survey of the use of cerium oxide and CeO2-containing materials as oxidation and reduction catalysts is presented in this paper, with a special focus on catalytic interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide.
Abstract: Over the past several years, cerium oxide and CeO2-containing materials have come under intense scrutiny as catalysts and as structural and electronic promoters of heterogeneous catalytic reactions. Recent developments regarding the characterization of ceria and CeO2-containing catalysts are critically reviewed with a special focus towards catalyst interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide. Relevant catalytic and technological applications such as the use of ceria in automotive exhaust emission control and in the formulation of SO x reduction catalysts is described. A survey of the use of CeO2-containing materials as oxidation and reduction catalysts is also presented.
TL;DR: In this article, the advances achieved during the past few years in the development of catalytic materials for hydrogen generation through fuel reforming, 1 water-gas shift and carbon monoxide preferential oxidation, as used or aimed to be of use in fuel processing for PEM fuel cell systems.
Abstract: The rapid development in recent years of the proton-exchange membrane (PEM) fuel cell technology has stimulated research in all areas of fuel processor catalysts for hydrogen generation. The principal aim is to develop more active catalytic systems that allow for the reduction in size and increase the efficiency of fuel processors. The overall selectivity in generating a low CO content hydrogen stream as needed by the PEM fuel cell catalyst is dependent on the efficiency of the catalysts in each segment of the fuel processor. This article reviews the advances achieved during the past few years in the development of catalytic materials for hydrogen generation through fuel reforming, 1 water-gas shift and carbon monoxide preferential oxidation, as used or aimed to be of use in fuel processing for PEM fuel cell systems.
TL;DR: In this paper, the reduction of CeO2 by hydrogen has been studied from 300-1200 K by several complementary techniques: temperature-programmed reduction (TPR), magnetic susceptibility measurements, Fourier transform infrared (FTIR), UV-VIS diffuse reflectance and X-ray photoelectron (XP) spectroscopy.
Abstract: The reduction of CeO2 by hydrogen has been studied from 300–1200 K by several complementary techniques: temperature-programmed reduction (TPR) and magnetic susceptibility measurements, Fourier-transform infrared (FTIR), UV–VIS diffuse reflectance and X-ray photoelectron (XP) spectroscopy. Two CeO2 samples were used with B.E.T. surface areas of 115 and 5 m2 g–1, respectively. The concentration of Ce3+ was determined in situ by measuring the magnetic susceptibility and the CeIII photoemission line. The reduction began at 473 K, irrespective of the initial surface area of the ceria. In the case of the low-surface-area sample, an intermediate reduction step was observed between 573 and 623 K, corresponding to the reduction of the surface. This intermediate step was less easily observed in the case of the high-surface-area ceria. In both cases, the reduction led to a stabilised state with the formal composition CeO1.83. Temperatures higher than 923 K were required to reduce the ceria further. The surface CeIII content determined by XPS was close to that determined by magnetic susceptibility measurements. The intensity of the 17 000 cm–1 band in the UV–VIS reflectance spectrum also varied with the degree of reduction. Finally, the evolution of the surface species observed by IR spectroscopy was in good agreement with the results from the other techniques. The IR results indicated large changes in the concentration and nature of both the hydroxyl and the polydentate carbonate species during the reduction process. The adsorption of oxygen on samples previously reduced to the composition CeO1.83 led to almost complete reoxidation at room temperature. The state of the initial B.E.T. surface did not influence the oxidation process. A slight excess adsorption of oxygen was evident on the surface. This was thermodesorbed at 380 K under vacuum.
TL;DR: In this article, the atomic structures of nanocrystalline powders of ceria, CeO2, and ceria-zirconia solid solution, (Ce,Zr)O2 were studied by the pulsed neutron diffraction technique.
Abstract: The atomic structures of nanocrystalline powders of ceria, CeO2, and ceria-zirconia solid solution, (Ce,Zr)O2, were studied by the pulsed neutron diffraction technique. Ceria is used as an oxygen storage component in automotive exhaust emission control systems, but the degradation of its oxygen storage capacity (OSC) after extended use at high temperatures has been a problem. Our results for the first time establish a direct correlation between the concentration of vacancy-interstitial oxygen defects and OSC. The surface area, on the other hand, exhibits much less correlation with OSC. The results also show that zirconia, which is known to retard the degradation when incorporated into ceria, reduces ceria and preserves oxygen defects. It is suggested that oxygen defects are the source of OSC in ceria-based catalyst supports, and the preservation of oxygen defects is critical for the stability of OSC against thermal aging.
TL;DR: In this article, the authors summarize literature data on thermal decomposition of ammonium perchlorate and discuss the mechanism of the decomposition and various factors that influence the thermal decompositions of perchlorates.