Zeitschriftenartikel: „Zr oxidation ratio“

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Lun, Huilin, Yi Zeng, Xiang Xiong, Ziming Ye, Zhongwei Zhang, Xingchao Li, Haikun Chen und Yufeng Liu. „Oxidation behavior of non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution powders in air“. Journal of Advanced Ceramics 10, Nr. 4 (13.07.2021): 741–57. http://dx.doi.org/10.1007/s40145-021-0469-y.

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AbstractMulti-component solid solutions with non-stoichiometric compositions are characteristics of ultra-high temperature carbides as promising materials for hypersonic vehicles. However, for group IV transition-metal carbides, the oxidation behavior of multi-component non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution has not been clarified yet. The present work fabricated four kinds of (Zr,Hf,Ti)Cx carbide solid solution powders by free-pressureless spark plasma sintering to investigate the oxidation behavior of (Zr,Hf,Ti)Cx in air. The effects of metallic atom composition on oxidation resistance were examined. The results indicate that the oxidation kinetics of (Zr,Hf,Ti)Cx are composition dependent. A high Hf content in (Zr,Hf,Ti)Cx was beneficial to form an amorphous Zr-Hf-Ti-C-O oxycarbide layer as an oxygen barrier to enhance the initial oxidation resistance. Meanwhile, an equiatomic ratio of metallic atoms reduced the growth rate of (Zr,Hf,Ti)O2 oxide, increasing its phase stability at high temperatures, which improved the oxidation activation energy of (Zr, Hf, Ti)Cx.

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Yoon, C. H., S. H. Cho, S. H. Kim und S. R. Ha. „Catalytic wet air oxidation of p-nitrophenol (PNP) aqueous solution using multi-component heterogeneous catalysts“. Water Science and Technology 43, Nr. 2 (01.01.2001): 229–36. http://dx.doi.org/10.2166/wst.2001.0094.

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This study investigated the decomposition of high strength p-nitrophenol (PNP) of 2,000 mg/l (3,400 mg of COD/1,250 mg of TOC) by catalytic wet air oxidation. Multi-component heterogeneous catalysts were used as catalysts for this purpose. The study results using a batch reactor showed that catalyst “D” (Mn-Ce-Zr 22.4 g plus CuSO4 1.0 g; Mn-Ce-Zr-Cu [CuSO4]) was more effective (56˜74%) than catalyst “A” (Mn-Ce-Zr 22.4 g) under the given conditions (O2 partial pressure of 1.0 MPa; temperature of 170˜190°C; 30 min of reaction time). The best result was obtained when 2 g of Mn-Ce-Zr-Cu [CuSO4] was used per 1L of PNP aqueous solution. COD and TOC removal efficiencies were 18% and 23% without catalysts during 20 min of reaction at 190°C. They were improved to 79% and 71% with 2 g/L of Mn-Ce-Zr-Cu [CuSO4] under the same conditions. The ratio of BOD5/COD was measured to evaluate biodegradability. It was 0.05 without catalyst and increased to 0.33 with 2 g/L of Mn-Ce-Zr-Cu [CuSO4] for 20 min of reaction.

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Ramos, Jesús Miguel, Jin An Wang, Sergio Odin Flores, Lifang Chen, Ulises Arellano, Luis Enrique Noreña, Julio González und Juan Navarrete. „Ultrasound-Assisted Hydrothermal Synthesis of V2O5/Zr-SBA-15 Catalysts for Production of Ultralow Sulfur Fuel“. Catalysts 11, Nr. 4 (24.03.2021): 408. http://dx.doi.org/10.3390/catal11040408.

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This work reports the results of the ultrasound-assisted hydrothermal synthesis of two sets of V2O5 dispersed on SBA-15 and Zr doped SBA-15 catalysts used for the oxidation of dibenzothiophene (DBT) in a model diesel via the combination of oxidation, catalysis, and extraction technical route. These catalysts contained Lewis acidity as major and Brønsted acidity as minor. The amount of acidity varied with the content of vanadia and zirconium doping. It was found that DBT conversion is very sensitive to the Lewis acidity. DBT conversion increased by increasing the vanadium content and correlated well with the amount of surface Lewis acidity. Under the optimal experimental condition (Reaction temperature: 60 °C, reaction time 40 min, catalyst concentration: 1 g/L oil; H2O2/DBT mole ratio = 10), the 30% V2O5/SBA-15 and 30% V2O5/Zr-SBA-15 catalysts could convert more than 99% of DBT. Two reaction pathways of DBT oxidation involving vanadia surface structure, Lewis acidity, and peroxometallic complexes were proposed. When the vanadia loading V2O5 ≤ 10 wt%, the oxidative desulfurization (ODS) went through the Pathway I; in the catalysts with moderate vanadia content (V2O5 = 20–30 wt%), ODS proceeded via the Pathways II or/and the Pathway I.

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Jeong, Gu Beom, Pyung Woo Shin und Sun Ig Hong. „Effect of Scrap: Sponge Ratio on Mechanical and Corrosion Properties of Zr-1Nb-0.7Sn-0.1Fe Alloy“. Advanced Materials Research 977 (Juni 2014): 94–98. http://dx.doi.org/10.4028/www.scientific.net/amr.977.94.

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In this study, the effect of scrap ratio on the mechanical and corrosion properties of Zr-1Nb-0.7Sn-0.1Fe alloy was studied. Oxygen content in the ingot cake increased rapidly with increasing fraction of scrap, which can be attributed to the surface oxide of scrap cake made of small pieces of turning, chips, etc. Iron content was not changed much, suggesting scrap materials was well reserved in the iron-free container. As-cast structure of Zr-1Nb-0.7Sn-0.1Fe alloy with the scrap:sponge ratio displayed basket-weave α phase and no appreciable change of the cast structure was observed with change of scrap fraction. The strength increases with increasing fraction of scrap, which can be attributed to the increase of oxygen content. The ductility decreased slightly with increase of scrap fraction. The increase of oxidation resistance with increasing fraction of scrap also can be linked to the increase of oxygen content.

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Hattori, Masatomo, Masaaki Haneda und Masakuni Ozawa. „Influence of Ce/Zr ratio on CO oxidation activity of ceria–zirconia supported Cu catalyst“. Japanese Journal of Applied Physics 55, Nr. 1S (05.11.2015): 01AE05. http://dx.doi.org/10.7567/jjap.55.01ae05.

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Kundozerova, Tatyana, und Genrikch Stefanovich. „Resistance Switching in Metal Oxide Thin Films and its Memory Application“. Applied Mechanics and Materials 346 (August 2013): 29–34. http://dx.doi.org/10.4028/www.scientific.net/amm.346.29.

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We explore the unipolar resistance switching effect in sandwich structures based on Nb, Ta and Zr oxide thin films. The structures were fabricated by pulsed laser deposition and low temperature anodic oxidation methods. After electroforming process memory cells demonstrate reproducible switching between low and high resistance states with a resistance ratio around 102. Nonvolatile resistance storage was traced within 40 days. The low-temperature anodic oxidation of Nb was found to be suitable to fabricate flexible nonvolatile memory elements. The parameters of resistive switching are not degraded after 100000 flexing.

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Sato, Nobuaki, Akira Krishima und Takayuki Sasaki. „Behavior of Fuel and Structural Materials in Severely Damaged Reactors“. Advances in Science and Technology 94 (Oktober 2014): 93–96. http://dx.doi.org/10.4028/www.scientific.net/ast.94.93.

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To study the fuel debris treatment at Fukushima Daiichi NPP, information on the behaviour of fuel and structural materials in severely damaged reactors, i.e., oxides and metals of uranium and zirconium is essential. Since sea water was introduced to the reactors, situation of fuel debris became different from that for TMI case. In this paper, phase relations of uranium and zirconium oxides were analyzed by powder XRD method at high temperatures. By the heat-treatment of the mixture of UO2 and ZrO2 (U:Zr=1:1) under 10 torr air, UO2 was oxidized to U3O8 over 800 oC, The UO2 like phase appeared again at 1350 oC which may be caused by the decomposition of U3O8. The oxidation behavior of the UO2-ZrO2 system was also investigated by using solid solution sample with different U/Zr ratios under different steam and oxygen pressures. The oxidation of the UO2-ZrO2 mixture seemed to be suppressed with decreasing U/Zr ratio. The behavior of fuel materials in the presence of seawater was also discussed as well as that for other structural materials.

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Silva, P. P., F. A. Silva, L. S. Portela, L. V. Mattos, F. B. Noronha und C. E. Hori. „Effect of Ce/Zr ratio on the performance of Pt/CeZrO2/Al2O3 catalysts for methane partial oxidation“. Catalysis Today 107-108 (Oktober 2005): 734–40. http://dx.doi.org/10.1016/j.cattod.2005.07.004.

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Zazhigalov, V. O., und O. V. Kiziun. „The obtaining of the anhydride products by oxidation of n-pentane on the VPO catalysts“. Catalysis and petrochemistry, Nr. 30 (2020): 19–37. http://dx.doi.org/10.15407/kataliz2020.30.019.

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It was investigated VPMeO catalysts (Me=Fe, Mo, Te, W, Ni, Ti, La, Bi, Zr і Ag) in oxidation of n-pentane. On these catalytic samples the main products of reaction are maleic (MA), phthalic (PhA), citraconic (CA) anhydrides, carbon oxides and in-significant quantity of acetic and of acrylic acids. It was established that a change of physical-chemical properties of the VPMeO catalysts affects a course of reaction of n-pentane oxidation. It was determined that the introduction of additives into the basic VPO composition and its content influences a phase composition, a morphol-ogy, acidic properties of catalyst surface, a crystallization temperature of active component and a oxidation degree of vanadium in it. It was established that addi-tives in the VPO sample may be distributed in two ways: a) evenly, high disperse (Fe, Te, Ni, Ag ions), b) with formation of X-ray amorphous additive phosphate phase (Ti, Bi, La, W, Zr ions). Additives that decrease temperature of the active phase formation of a catalyst and increase temperature of its oxidation (Fe, Ti, Bi, Zr ions) positively influence the life of exploitation of catalytic pattern without losing its se-lectivity in the n-pentane oxidation. Additives that reduce the O 1s-electrons energy and increase an oxygen content (O/(V+P+Me)) on the VPO composition surface en-hance the specific rate of the hydrocarbon oxidation. A growth of phosphorous con-tent on the surface of synthesized compositions also contributes to the increase of the time of their stable work. The influence of ratio of Bronsted and Lewis acid cen-ters on surface of the VPМеO pattern on a selectivity of anhydrides production was established. The growth of acidic centers content on the surface of patterns increas-es the CA selectivity. The rise of quantity of Lewis centers favors the PhA formation while the MA selectivity reduces in the reaction products. According to experimental data the modification of the VPO catalyst is affect its physical-chemical and cata-lytic properties. The change of defined physical-chemical properties allows to regu-late a process of the n-pentane oxidation in the direction of formation of one of the anhydrides.

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Shakshooki, S. K., F. A. El-Akari und Najat A. Abozaid. „Synthesis and Characterization of Novel -Type Zirconium Phosphate-Crystalline Cerium Phosphate/ Polyaniline, Polyindole, Polycarbazole, Polyaniline-co-Polyindole, and Polyaniline-co-Polycarbazole Composites“. Academic Journal of Chemistry, Nr. 62 (30.05.2021): 45–59. http://dx.doi.org/10.32861/ajc.62.45.59.

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-Type zirconium phosphate,-Zr(HPO4)2-.1.77H2O (-ZrP), crystalline cerium phosphate, Ce(HPO4)2.1.33 H2O (CePc), and [-Zr(HPO4)2]0.30 [Ce (HPO4)2]0.70 .2H2O composite were prepared and characterized by chemical, XRD, TGA, FT-IR and scanning electron microscopy(SEM). [-Zr(HPO4)2]0.30[Ce(HPO4)2]0.70/polyaniline, polyindole, polycarbazole, polyaniline-co-polyindole, polyaniline-co-polycarbazole composites were prepared via in-situ chemical oxidation of the monomers aniline, indole , carbazole, and (1:1moler ratio) of co-monomers aniline-indole, aniline- carbazole, respectively, that was promoted by the reduction of part of Ce(IV) ions present in the inorganic matrix. A possible explanation is part of CePc is attacked by the monomers, and the co-monomers, respectively, converted to cerium (III) orthophosphate (CePO4). The resultant novel composites were characterized by elemental (C,H,N) analysis, FT-IR, and (SEM). From elemental (C,H,N) analysis ,the amount of organic materials present in [-Zr(HPO4)2]0.30 [Ce (HPO4)2]0.70/ polyaniline, polyindole, polycarbazole composites were (23.44, 5.24 and 33.02 % in wt. ), respectively. The amount of resultant copolymers were (Pani 5.92, PIn 7.48 % in wt) and (Pani 1.42, PCz 2.48 % in wt ) These composites can be considered as novel conducting inorganic-organic composites, ion exchangers , solid acid catalysts and sensors.

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Fei, Zhaoyang, Xingxing Xie, Yong Dai, Haoyue Liu, Xian Chen, Jihai Tang, Mifen Cui und Xu Qiao. „HCl Oxidation for Sustainable Cl2 Recycle over the CexZr1–xO2 Catalysts: Effects of Ce/Zr Ratio on Activity and Stability“. Industrial & Engineering Chemistry Research 53, Nr. 50 (08.12.2014): 19438–45. http://dx.doi.org/10.1021/ie503297k.

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Guo, Bin, Liqing Yang, Weijie Hu, Wenlong Li und Haojing Wang. „Effect of nano-sized cerium–zirconium oxide solid solution on far-infrared emission properties of tourmaline powders“. Modern Physics Letters B 29, Nr. 30 (04.11.2015): 1550183. http://dx.doi.org/10.1142/s0217984915501833.

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Far-infrared functional nanocomposites were prepared by the co-precipitation method using natural tourmaline [Formula: see text], where [Formula: see text] is [Formula: see text], [Formula: see text], [Formula: see text], or vacancy; [Formula: see text] is [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], or [Formula: see text]; [Formula: see text] is [Formula: see text], [Formula: see text], [Formula: see text], or [Formula: see text]; [Formula: see text] is [Formula: see text], [Formula: see text]; and [Formula: see text] is [Formula: see text], [Formula: see text], or [Formula: see text] powders, ammonium cerium(IV) nitrate and zirconium(IV) nitrate pentahydrate as raw materials. The reference sample, tourmaline modified with ammonium cerium(IV) nitrate alone was also prepared by a similar precipitation route. The results of Fourier transform infrared spectroscopy show that tourmaline modified with Ce and Zr has a better far-infrared emission property than tourmaline modified with Ce alone. Through characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the mechanism for oxygen evolution during the heat process in the two composite materials was systematically studied. The XPS spectra show that [Formula: see text] ratio inside tourmaline modified with Ce alone can be raised by doping Zr. Moreover, it is showed that there is a higher [Formula: see text] ratio inside the tourmaline modified with Ce and Zr than tourmaline modified with Ce alone. In addition, XRD results indicate the formation of [Formula: see text] and [Formula: see text] crystallites during the heat treatment and further TEM observations show they exist as nanoparticles on the surface of tourmaline powders. Based on these results, we attribute the improved far-infrared emission properties of Ce–Zr doped tourmaline to the enhanced unit cell shrinkage of the tourmaline arisen from much more oxidation of [Formula: see text] to [Formula: see text] inside the tourmaline caused by the change in the catalyst redox properties of [Formula: see text] brought about by doping with [Formula: see text]. In all samples, tourmaline modified with 7.14 wt.% Ce and 1.86 wt.% Zr calcined at 800[Formula: see text]C for 5 h has the best far-infrared emission property with the maximum emissivity value of 98%.

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Zhao, Jing, Ming Qiao Zhu, Jia Jing Chen, Yang Yang Yang, Yue Tang, Zhen Yu Cai, Yang Yi Shen und Chao Hong He. „Cyclohexane Oxidation Catalyzed by Au/MxOyAl₂O₃ Using Molecular Oxygen“. Advanced Materials Research 233-235 (Mai 2011): 254–59. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.254.

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Alumina was modified by doping with metal oxide and then used as the support for depositing gold by an impregnation-ammonia washing method to obtain Au/MxOy/Al2O3(M=Co, Zr and Ce) catalysts. These samples were characterized by inductively coupled plasma-atomic emission spectrometry (ICP-AES), transmission electron microscope (TEM) and X-ray diffraction (XRD). The effects of Co3O4content, metal oxide and mixed metal oxides on the catalytic activity for the selective oxidation of cyclohexane to cyclohexanone and cyclohexanol using molecular oxygen as oxidant were studied. The results showed that better catalytic performance was obtained over Au/MxOy/Al2O3catalysts compared with over Au/Al2O3catalysts. 9.69% conversion of cyclohexane and 93.31% selectivity to cyclohexanone, cyclohexanol and cyclohexyl hydroperoxide, with 1.02 ratio of cyclohexanone to cyclohexanol were obtained over the Au/MxOy/Al2O3catalyst at 150 , 1.5 MPa for 3 h. Moreover, according to the recycling test, the catalyst could be reused four times without remarkable loss of activity.

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Cecilia, Juan, M. Soriano, Alejandro Natoli, Enrique Rodríguez-Castellón und José López Nieto. „Selective Oxidation of Hydrogen Sulfide to Sulfur Using Vanadium Oxide Supported on Porous Clay Heterostructures (PCHs) Formed by Pillars Silica, Silica-Zirconia or Silica-Titania“. Materials 11, Nr. 9 (30.08.2018): 1562. http://dx.doi.org/10.3390/ma11091562.

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Vanadium oxide (V2O5) species has been supported on different porous clay heterostructures (with silica pillars, silica-zirconia with a molar ratio Si/Zr = 5 and silica-titania with a molar ratio Si/Ti = 5) by wetness incipient method. All catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption at −196 °C, NH3 thermoprogrammed desorption (NH3-TPD), Raman spectroscopy, diffuse reflectance UV-Vis and X-ray photoelectron spectroscopy (XPS). After that, the catalytic activity of the vanadium-based catalysts was evaluated in the selective oxidation of H2S to elemental sulfur. The catalytic data show that both the activity and the catalytic stability increase with the vanadium content, obtaining the highest conversion values and sulfur yield for the catalysts with vanadium content of 16 wt.%. The comparison among all supports reveals that the incorporation of TiO2 species in the pillars of the PCH improves the resistance to the deactivation, attaining as best results a H2S conversion of 89% for SiTi-PCH-16V catalyst and elemental sulfur is the only compound detected by gas chromatography.

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Zhu, Han, Haiyong Liu, Feng Huang, Jun Yi und Fangfang Ge. „Effect of Cr/Al Atomic Ratio on the Oxidation Resistance in 1200°C Steam for the CrAlSiN Coatings Deposited on Zr Alloy Substrates“. JOM 71, Nr. 12 (15.10.2019): 4839–47. http://dx.doi.org/10.1007/s11837-019-03839-4.

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Wei, Ning, Jia Zhang, Hexiang Zhong, Liwei Pan, Zeyu Wang, Juan Wang und Yi Zhou. „Methane Steam Reforming Over NiO/CexZryO2-Sil-1 Catalyst Prepared by In-Situ Self-Assembly“. Journal of Nanoscience and Nanotechnology 19, Nr. 11 (01.11.2019): 7416–20. http://dx.doi.org/10.1166/jnn.2019.16620.

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NiO/CexZryO2-Sil-1 catalysts were prepared using an In-Situ self-assembly approach by coupling silicalite-1 and CexZryO2. This one-step synthesis method utilized the high surface area and hydrothermal stability of silicalite-1 and the good oxidation-reduction ability of the CexZryO2, and hence offered high synthesis efficiency. The catalyst structure was examined by N2-physisorption, temperature-programmed reduction, transmission electron microscopy, and X-ray diffraction. All the results showed that silicalite-1 was well-encapsulated by NiO/Ce0.5Zr0.5O2. Furthermore, the effect of the Ce/Zr molar ratio on the performance of the catalysts was investigated in detail. The catalysts were subjected to methane steam reforming at high temperatures to evaluate their catalytic performance. The result showed that the NiO/Ce0.5Zr0.5O2-Sil-1 catalyst exhibited the best performance and its methane conversion efficiency reached up to 99.5%. Even after 16 h of continuous stability test, this catalyst could retain a methane conversion efficiency of 97.8%.

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Wu, Gang, Ke Tang, Deng Wu, Yuelin Li und Yuqiang Li. „Experimental Evaluation on the Catalytic Activity of a Novel CeZrK/rGO Nanocomposite for Soot Oxidation in Catalyzed Diesel Particulate Filter“. Processes 9, Nr. 4 (12.04.2021): 674. http://dx.doi.org/10.3390/pr9040674.

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A nanostructured solid solution catalyst CeZrK/rGO for soot oxidation in catalyzed diesel particulate filter was synthesized using the dipping method. The reduced graphene oxide (rGO) was used as the catalyst carrier, and CeO2, ZrO2, and K2O were mixed with the molar ratio of 5:1:1, 5:2:2 and 5:3:3, which were referred to as Ce5Zr1K1/rGO, Ce5Zr2K2/rGO, and Ce5Zr3K3/rGO, respectively. The structure, morphology and catalytic activity of the CeZrK/rGO nanocomposites were thoroughly investigated and the results show that the CeZrK/rGO nanocomposites have nanoscale pore structure (36.1–36.9 nm), high-dispersion quality, large specific surface area (117.2–152.4 m2/g), small crystallite size (6.7–8.3 nm), abundant oxygen vacancies and superior redox capacity. The 50% soot conversion temperatures of Ce5Zr1K1/rGO, Ce5Zr2K2/rGO, and Ce5Zr3K3/rGO under tight contact condition were decreased to 352 °C, 339 °C and 358 °C respectively. The high catalytic activity of CeZrK/rGO nanocomposites can be ascribed to the following factors: the doping of Zr and K ions causes the nanocrystalline phase formation in CeZrK solid solutions, reduces the crystallite size, generates abundant oxygen vacancies and improves redox capacity; the rGO as a carrier provides a large specific surface area, thereby improving the contact between soot and catalyst.

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Goyal, Sonam, Maizatul Shima Shaharun, Ganaga Suriya Jayabal, Chong Fai Kait, Bawadi Abdullah und Lim Jun Wei. „Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework“. Catalysts 11, Nr. 3 (08.03.2021): 346. http://dx.doi.org/10.3390/catal11030346.

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A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

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Omata, Takahisa, Haruo Kishimoto, Shinya Otsuka-Yao-Matsuo, Norikazu Ohtori und Norimasa Umesaki. „Vibrational Spectroscopic and X-Ray Diffraction Studies of Cerium Zirconium Oxides with Ce/Zr Composition Ratio=1 Prepared by Reduction and Successive Oxidation of t′-(Ce0.5Zr0.5)O2 Phase“. Journal of Solid State Chemistry 147, Nr. 2 (November 1999): 573–83. http://dx.doi.org/10.1006/jssc.1999.8420.

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Vazquez, M. I. Sosa, J. Salinas Gutierrez, D. Delgado Vigil, V. Collins-Martinez und A. Lopez Ortiz. „Synthesis Gas Production by Methane Partial Oxidation on Ni/Fe₃O₄-Ce_0.75Zr_0.25O₂ Catalysts: Kinetic Study“. Journal of New Materials for Electrochemical Systems 14, Nr. 2 (06.04.2011): 133–39. http://dx.doi.org/10.14447/jnmes.v14i2.122.

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Fe3O4-Ce0.75Zr0.25O2 (FeCZ) is an oxygen carrier material aimed to produce syngas through methane partial oxidation in absence of oxygen gas feed. The objective of the present research is to study the catalytic effect of Ni on FeCZ using an evaluation of the global kinetics (activation energy, reaction rate, order and constant) of its reaction with methane for syngas production. FeCZ and 0.05NiFeCZ (Ni/Fe = 0.05 molar ratio) were synthesized through co-precipitation of their precursor nitrate salts, while 2NiFeCZ was prepared by impregnation of FeCZ with a nickel nitrate solution to obtain a 2 %W Ni material. Samples were calcined at 950°C during 4 hours in air. Kinetic study of oxygen carriers (FeCZ, 0.05NiFeCZ and 2NiFeCZ) reduction with methane was followed through thermogravimetric analysis (TGA) at 5, 7.5 and 10% CH4/Ar and 600, 650 and 700°C. Initial reaction rate was obtained from the slope of the linear region of the weight change signal as a function of time. Results indicate a first order global reaction rate for all materials. Activation energies for samples FeCZ, 0.05NiFeCZ and 2NiFeCZ were 52.2, 39.5 and 28.3 Kcal/mol, respectively. Thus, reflecting the catalytic effect of Ni over the FeCZ global reaction rate.

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MIKHAILOVSKAYA, T. P., R. KURMAKYZY, D. K. TOLEMISOVA und K. A. KADIRBEKOV. „OXIDATIVE AMMONOLYSIS OF 4-METHYLPYRIDINE ON OXIDE VANADIUM-TITANIUM-ZIRCONIUM CATALYST MODIFIED BY TIN AND TUNGSTEN OXIDES“. Chemical Journal of Kazakhstan 73, Nr. 1 (14.03.2021): 196–203. http://dx.doi.org/10.51580/2021-1/2710-1185.21.

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Catalysts based on vanadium pentoxide modified by Ti, Sn, Zr and W oxides were tested in the oxidative ammonolysis of 4-methylpyridine. The role of the main process parameters such as temperature, the ratio of the initial components in the conversion of the methyl group to the nitrile one, and the optimal conditions for the oxidative ammonolysis of 4-methylpyridine were determined. It is determined that the V-Ti-Zr-O-catalyst and the sample containing 9% of tungsten oxide are superior in catalytic activity to the V-Ti-Zr-Sn-O contact. Conditions that ensure a high selectivity for the formation of 4-cyanopyridine were found. The highest yield of the target product (85-86%) was obtained on V-Ti-Zr-W-O at 270 °C, and the yield of 4-cyanopyridine was 87.5% at 310° C on the V-Ti-Zr-Sn-O catalyst. The phase composition and structural changes occurring in modified vanadium oxide catalysts have been studied. It is determined that mixed V-Ti-Zr-Sn-O and V-Ti-Zr-W-O catalysts contain ZrV2O7, the monoclinic modification of ZrO2 (baddeleyite), TiO2 (anatase), SnO2, WO3, and V2O5. In catalysts, it can exist in small amounts as a separate VO2 phase. The V-Ti-Zr-W-O catalyst showed the best catalytic properties. It has highactivity and selectivity towards 4-cyanopyridine.

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Kang, K. H., C. H. Lee, M. K. Jeon, S. Y. Han, G. I. Park und S. M. Hwang. „Characterization Of Cladding Hull Wastes From Used Nuclear Fuels“. Archives of Metallurgy and Materials 60, Nr. 2 (01.06.2015): 1199–203. http://dx.doi.org/10.1515/amm-2015-0097.

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Abstract Used cladding hulls from pressurized water reactor (PWR) are characterized to provide useful information for the treatment and disposal of cladding hull wastes. The radioactivity and the mass of gamma emitting nuclides increases with an increase in the fuel burn-up and their removal ratios are found to be more than 99 wt.% except Co-60 and Cs-137. In the result of measuring the concentrations of U and Pu included in the cladding hull wastes, most of the residues are remained on the surface and the removal ratio of U and Pu are revealed to be over 99.98 wt.% for the fuel burn-up of 35,000 MWd/tU. An electron probe micro-analyzer (EPMA) line scanning shows that radioactive fission products are penetrated into the Zr oxide layer, which is proportional to the fuel burn-up. The oxidative decladding process exhibits more efficient removal ratio of radionuclides.

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Jaques, A. Lynton, Frank Brink und Jiang Chen. „Magmatic haggertyite in olivine lamproites of the West Kimberley region, Western Australia“. American Mineralogist 105, Nr. 11 (01.11.2020): 1724–33. http://dx.doi.org/10.2138/am-2020-7456.

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Abstract We report the first occurrence of magmatic haggertyite (BaFe6Ti5MgO19) from the Miocene lamproites of the West Kimberley region of Western Australia. This contrasts with the metasomatic formation reported in an olivine lamproite host at the type locality, Prairie Creek, Arkansas. Haggertyite occurs in the groundmass of a diamondiferous olivine lamproite pipe in the Ellendale field, and within the large zoned Walgidee Hills lamproite where it forms part of an extensive suite of Ba- and K-bearing titanate and Ti-rich silicate minerals. The haggertyite co-exists with chromian spinel, perovskite, and ilmenite in the Ellendale lamproite, and with priderite and perovskite and, in one locality, with priderite, jeppeite, ilmenite, and perovskite, in the Walgidee Hills lamproite. Unlike priderite and perovskite, which are common groundmass phases in the Ellendale olivine lamproites and present throughout the Walgidee Hills lamproite, haggertyite appears restricted in its occurrence and crystallization interval, with sparse ilmenite apparently mostly crystallizing as an alternative phase. In the Walgidee Hills lamproite the haggertyite-bearing assemblage is succeeded by the Ba-titanate assemblage priderite plus jeppeite in the evolved central part of the body. The haggertyite in the main zone of the Walgidee Hills lamproite has an average composition of (Ba0.7K0.3)1.0(Ti5.0Fe2.13+Cr0.1Fe3.82+Mn0.2Mg0.6Na0.1)12O19 and is thus very similar to the original haggertyite described from xenoliths in the Prairie Creek lamproite apart from being poorer in Cr and Ni. Haggertyite in the groundmass of the Ellendale olivine lamproite and the central zone of the Walgidee Hills lamproite, in addition to variations in Mg and Cr, show significant variation in Ti and Fe contents and in calculated Fe3+ and Fe2+. A linear inverse relationship between Ti and Fe, and Ti and Fe3+, indicates that Fe3+ is accommodated by the coupled substitution Ti4+ + Fe2+ ⇆ 2 Fe3+. A marked trend to higher Fe3+ in the haggertyite in Ellendale 9 olivine lamproite is ascribed to increasing oxidation during crystallization, with fO2 estimated from the olivine-spinel thermometer and oxygen barometer at Dlog FMQ = –1 to +3 at temperatures of 790–660 °C. The haggertyite in the central zone of the Walgidee Hills lamproite, in contrast, shows a marked trend to Fe2+ enrichment, which is associated with decreasing Fe in perovskite. This is inferred to indicate formation under more reducing conditions, but sufficiently oxidized to permit Fe3+ in co-existing priderite and jeppeite. Trace-element analysis by LA-ICP-MS shows the Walgidee Hills haggertyite contains minor amounts of Na, Si, Ca, V, Co, Zn, Sr, Zr, Nb, and Pb, and only traces of Al, P, Sc, Rb, REE, Hf, and Ta. Moreover, the haggertyite is preferentially enriched in certain lithophile (Ba, Sr), siderophile (Mn, Fe, Co, Ni), and chalcophile (Zn, Pb) elements relative to co-existing priderite. Haggertyite crystallization appears to be a consequence not only of the very high Ba, Ti, and K contents of the lamproite, but of relatively high-Fe concentrations and low temperatures in evolved olivine lamproite magma with the Fe3+/Fe2+ ratio determined by the prevailing fO2. The new data suggest that haggertyite might also be present but previously unrecognized in the evolved groundmass of other olivine lamproites. Haggertyite is one of an increasing number of new minerals in upper mantle rocks and volcanics derived from the upper mantle hosting large-ion-lithophile and high field strength cations.

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Delir Kheyrollahi Nezhad, Parastoo, Mohammad Haghighi, Naimeh Jodeiri und Farhad Rahmani. „Sol–gel preparation of NiO/ZrO2(x)–MgO(100−x) nanocatalyst used in CO2/O2 oxidative dehydrogenation of ethane to ethylene: influence of Mg/Zr ratio on catalytic performance“. Journal of Sol-Gel Science and Technology 80, Nr. 2 (20.06.2016): 436–50. http://dx.doi.org/10.1007/s10971-016-4120-2.

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Fazliakhmetov, A. M. „Geochemical features and formation conditions of Early-Devonian cherty-argillaceous shales and the underlying basalts in the Ishkildino section (eastern slope of the Southern Urals)“. LITOSFERA, Nr. 1 (17.03.2019): 30–47. http://dx.doi.org/10.24930/1681-9004-2019-19-1-30-47.

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Research subject.The West Magnitogorsk zone of the Southern Urals in the vicinity of the Ishkildino village features a subaerially exposed basaltic sequence superposed by cherts and siliceous-clay shales. The basalts and the overlying shales are assumed to have formed during the Ordovician and Silurian (?)–Early Devonian (up to the conodont zone excavates inclusive) periods, respectively. The aim of this research was to reconstruct, using geochemical data, the conditions under which the rocks present in this geological location were formed.Materials and methods. Five samples of the basalts (XRD and ICP-MS methods), 27 samples of the siliceous-clay shales and 10 samples of the cherts (XRD and ICP-AES methods) were analyzed.Results.According to the ratio of SiO2, Na2O and K2O, the volcanic rocks from the lower part of the section are represented by basalts and trachybasalts. Their geochemical composition corresponds to the N-MORB and is established to be similar to that of the basalts in the Polyakovskaya formation (the Middle–Upper Ordovician). In terms of main elements, the shales under study consist of quartz and illite with a slight admixture of organic matter, goethite, quartzfeldspar fragments, etc. The degree of the sedimentary material weathering according to the CIA, CIW and ICV index values is shown to be moderate. The values of Strakhov’s and Boström’s moduli correspond to sediments without the admixture of underwater hydrothermal vent products. The values of Cr/Al, V/Al and Zr/Al correspond to those characteristic of deposits in deep-water zones remote from the coasts of passive and active continental margins, basalt islands and areas adjacent to mid-ocean ridges. For most samples, the values of Ni/Co, V/Cr, Mo/Mn are typical of deposits formed under oxidative conditions. However, several samples from the upper part of the section, which is comparable to the kitabicus and excavatus conodont zones, demonstrate the Ni/Co, V/Cr, and Mo/Mn values corresponding to deposits formed under reducing atmospheres. An assumption is made that the existence of these deposits can be associated with the Bazal Zlichov event.Conclusion.The investigated pre-Emsian shales have shown no signs of volcanic activity in the adjacent areas. The studied deposits are established to correspond to the central part of the Ural Paleoocean.

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Horita, Susumu, und Makoto Shoga. „Influence of Pre-Oxidation of an Ir Film on Chemical Composition and Crystal Property of a PZT Film Deposited on the Ir Film by Sputtering“. MRS Proceedings 811 (2004). http://dx.doi.org/10.1557/proc-811-d3.18.

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ABSTRACTWe investigated the influence of pre-oxidation of an Ir film as a bottom electrode on the chemical composition and crystal property of the PZT film deposited on it by RF sputtering, changing the sputtering target composition ratio Zr/Ti to be 20/80, 52/48 or 80/20. The Ir film deposited on a thermally oxidized Si substrate was pre-oxidized at 600°C for 20 min in the O2 gas of 10 Pa. The XRD patterns showed a strong PbO(101) peak from the PZT film on the oxidized Ir film for Zr/Ti = 52/48, but no PbO peak from the film on a no oxidized Ir film. The RBS measurement showed that the film composition ratio of Pb/(Zr+Ti) on the pre-oxidized Ir film was much larger than that on the no oxidized Ir film. For Zr/Ti=20/80, the same tendency was observed. However, for Zr/Ti=80/20, the chemical composition of the PZT film on the pre-oxidized Ir film was almost equal to that without oxidation.

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„Dehalogenation of chlorobromophenol by ozonation using heterogeneous catalyst“. Issue 2 18, Nr. 2 (14.04.2016): 242–50. http://dx.doi.org/10.30955/gnj.001866.

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<div> Ozone initiated oxidation of 2-chloro,4-bromophenol, (CBP) in aqueous system catalyzed by 1, 2.5 and 5% loadings of 1:1 molar ratio of Ce-Zr oxide on TiO2 were studied. The synthesized catalysts were characterized via BET, ICP, PXRD, TPD, TEM, SEM, and FT-IR analysis. The powder XRD data revealed that Ce-Zr exists in three different phases on titania. SEM and SEM-EDX confirmed well dispersed metal oxides on titania surface. 1H NMR, IR and GC-MS positively confirm hydroxyfumaric acid (HFA) and oxalic acid (OA) as reaction products. 5% Ce-Zr/TiO2 showed best performance with100 % conversion in 4 h.  </div>

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Lad, R. J., D. M. Stewart, R. T. Fryer, J. C. Sell, D. J. Frankel, G. P. Bernhardt und R. W. Meulenberg. „Electrically Conductive Pt-Zr-B and Pt-Si Thin Films for Use in High Temperature Harsh Environments“. MRS Proceedings 1746 (2015). http://dx.doi.org/10.1557/opl.2015.400.

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ABSTRACTStable, electrically conductive, thin film materials are key components for high temperature sensors operating in harsh environments. In this work, nanocomposite Pt-Zr-B and Pt-Si thin film materials were grown to a nominal thickness of 200 nm on both r-cut sapphire (α-Al2O3) substrates using e-beam evaporation, and their structure, morphology, and chemical composition was characterized following thermal treatments in an air laboratory furnace up to 1300°C. In the Pt-Zr-B system, oxidation of a nanolaminate architecture consisting of ZrB2 and pure Pt layers leads to boron oxide evaporation and the formation of Pt grains decorated by tetragonal-ZrO2 nanocrystallites at high temperature. Electrical conductivity measurements with a 4-point probe show that this nanocomposite film structure can maintain a film conductivity > 1x106 S/m up to 1300°C, depending on the Pt/ZrB2 layer thickness ratio. In the Pt-Si system, film compositions were varied to yield either nanocrystalline Pt3Si, Pt2Si, or PtSi phases depending on the Pt-Si ratio, or an amorphous phase at high Si content. Above 1000°C in air, Pt-oxide and Si-oxide phases form and coexist with the Pt-Si phases, and some Pt-Si film conductivities remain as high as 1x106 S/m after annealing at 1000°C for 6 hours. It was found that a 100 nm thick amorphous alumina capping layer grown by atomic layer deposition (ALD) aids in limiting film oxidation, but film stress leads to regions of delamination.

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Azzi, H., L. Chérif und S. Siffert. „Gold catalysts supported on cerium-modified mesoporous zirconia for total toluene oxidation. Effect of Ce/Zr molar ratio“. Research on Chemical Intermediates, 04.11.2020. http://dx.doi.org/10.1007/s11164-020-04313-6.

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Sakuda, Masahiro, Hiroyasu Yamahara, Hitoshi Tabata und Munetoshi Seki. „Control of Magnetic Properties of Barium Ferrite Thin Films With Unusual Valence Fe“. Frontiers in Materials 8 (09.09.2021). http://dx.doi.org/10.3389/fmats.2021.732676.

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Thin films of BaFe1-xMxO3 (M = Hf, Zr, and Ce; 0.0 ≤ x ≤ 0.75) were fabricated using pulsed laser deposition and their magnetic properties were investigated. X-ray diffraction analysis indicated that oxygen-deficient BaFeOx (x < 3.0) with a monoclinic structure was formed when the deposition was conducted using a non-substituted target (x = 0.0). The as-grown BaFeOx films were converted into fully oxidized BaFeO3 with a perovskite structure by low-temperature oxidation in an ozone atmosphere. In contrast, the as-deposited films of Hf, Zr, and Ce-substituted films exhibited a perovskite structure, and their crystallinity did not change after low-temperature ozone annealing. The magnetic transition temperature Tc of the BaFeO3 film was 115 K, whereas the substituted BaFeO3 films showed ferromagnetic behavior even at 300 K. These results can be attributed to the weakening of the antiferromagnetic super-exchange coupling among Fe ions owing to the lattice expansion in the substituted BaFeO3. In addition, the magnetization of the films was found to increase with the decreasing ionic ratio of Fe4+/Fe3+, suggesting that the inherent carrier-induced ferromagnetic interaction is dominant in the films.

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Grandjean, Stephane, Chapelet-Arab Bénédicte, Lemonnier Stéphane, Robisson Anne-Charlotte und Vigier Nicolas. „Innovative Synthesis Methods of Mixed Actinides Compounds with Control of the Composition Homogeneity at a Molecular or Nanometric Scale“. MRS Proceedings 893 (2005). http://dx.doi.org/10.1557/proc-0893-jj08-03.

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AbstractActinides contained in the used nuclear fuel need to be managed in the future fuel cycles for the sustainability of this source of energy. The major ones such as uranium or plutonium are very valuable for energy production within a new fuel. The minor ones such as neptunium, americium or curium are responsible for the long-term radiotoxicity of the ultimate waste if not separated and transmuted within new fuels or dedicated targets. Whatever the choice of management in the present or future, innovative synthesis methods are studied in many research institutions to elaborate new actinides based materials.Innovative concepts for future fuels or transmutation targets focus on mixed actinides or mixed actinide-inert element materials. For their synthesis, wet methods fulfill very useful requirements such as flexibility, compatibility with a hydrometallurgical fuel processing, less dissemination of radioactive dusts during processing, and above all a better accessibility to very homogeneous compounds and interesting nanostructures. When dealing with plutonium or minor actinides, this last characteristic is of great importance in order to avoid the so-called “hot spots” and to limit macroscopic defects in the fuel material.In this communication, experimental results are given to illustrate interesting achievements to control the composition or the structure of mixed actinides compounds at a molecular or at a nanometric scale using co-precipitating techniques or sol-gel methods.The first illustration describes the flexibility of the oxalate ligand to modulate the nanostructure of actinides-based solid precursors and obtain mixed actinides oxide following a thermal treatment of the oxalate precursor. New mixed oxalate structures which present original features such as accepting in the same crystallographic site either a tetravalent actinide or a trivalent one are noticeably detailed. Monocharged cations equilibrate the charge in the 3D structure depending on the molar ratio of trivalent to tetravalent actinides. These oxalate compounds are particularly suitable precursors of oxide solid solutions for various actinides systems.The second illustration deals with the control of inorganic condensation reactions of tri- and tetravalent cations in solution by using suitable ligands with a view to obtaining homogeneous oxy-hydroxyde mixtures. The results obtained using Zr(IV), Y(III) and Am(III) or Nd(III) are quite original: a very stable colloidal sol is obtained at pH 5-6 and a nanostructured mixed oxy-hydroxide phase is formed by adapting the sol-gel transition conditions. The initial interactions between the oxy-hydroxide Zr nanoparticles, the ligand and the trivalent cations at a nanometric scale in the sol give access, after gel formation and thermal treatment, to a crystallized phase (Am-bearing cubic Y-stabilized Zirconia) at comparatively low temperatures.In both cases, the simultaneous co-precipitation or co-gelation of the involved actinides remains a challenge because of the specific properties of each actinide, properties which moreover differ according to various possible oxidation states.

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