A review of C_1 chemistry synthesis using yttrium-stabilized zirconia catalyst

C1 chemistry based on synthesis gas, methane, and carbon dioxide offers many routes to industrial chemicals. The reactions related to the synthesis of gas can be classified into direct and indirect approach for making such products, such as acetic acid, dimethyl ether, and alcohol. Catalytic syngas processing is currently done at high temperatures and pressures, conditions that could be unfavorable for the life of the catalyst. Another issue of C1 chemistry is related to the methane-initiated process. It has been known that direct methane conversions are still suffering from low yields and selectivity of products resulting in unprofitable ways to produce products, such as higher hydrocarbons, methanol, and so on. However, many experts and researchers are still trying to find the best method to overcome these barriers, for example, by finding the best catalyst to reduce the high-energy barrier of the reactions and conduct only selective catalyst-surface reactions. The appli- cation of Yttria-Stabilized Zirconia （YSZ） and its combination with other metals for catalyzing purposes are increasing. The existence of an interesting site that acts as oxygen store could be the main reason for it. Moreover, formation of intermediate species on the surface of YSZ also contributes significantly in increasing the production of some specific products. Understanding the phenomena happening inside could be necessary. In this article, the use of YSZ for some C1 chemistry reactions was discussed and reviewed.

Preliminary Synthesis and Characterization of Mesoporous Nanocrystalline Zirconia

A novel method to prepare mesoporous nano-zirconia was developed. Thesynthesis was carried out in the presence of PEO surfactants via a solid-state reaction. Thematerials exhibit a strong diffraction peak at low 2θ angle and their nitrogenadsorption/desorption isotherms are typical of type IV with H1 hysteresis loops. The pore structureimaged by TEM can be described as wormhole domains. The tetragonal zirconia nanocrystals are uniformin size (around 1.5 nm) and their mesopores focus on around 4.6 nm. The zirconia nanocrystal growthis tentatively postulated to be the result of an aggregation mechanism. This study also revealsthat the PEO surfactants can interact with the Zr-O-Zr framework to reinforce the thermal stabilityof zirconia. The ratio of NaOH to ZrOCl_2, crystallization and calcination temperature play animportant role in the synthesis of mesoporous nano-zirconia.

Corrosion Resistance Mechanism of Magnesia Zirconia Brick to RH Furnace Slag

Magnesia zirconia brick containing 11 wt% zirconia was prepared with magnesia and monoclinic zirconia as starting materials in order to replace the chrome-containing materials for Rtt furnace. The corrosion resistance of magnesia zirconia brick and fused rebonded magnesia chrome brick （short for magnesia chrome brick） to high, and low basicity slag of RH fitrnace was comparatively researched by rotary slag method and their slag resistance mechanisms were analyzed. The results show that： （1） because the reaction layer containing CaZrO3 forms in magnesia zirconia brick, it has better corrosion resistance to high basicity slag than magnesia chrome brick, however, it has worse corrosion resistance to low basicity slag than magnesia chrome brick; （2） ZrO2 in the magnesia zirconia brick can absorb CaO in the slag, which decrea- ses the basicity of slag and inereases the viscosity of slag, so the degree of slag penetration in magnesia zircon.ia brick decreases ; （ 3 ） there is little zirconia in the slag layer of residual nutgnesia zirconia brick;from working face to original brick layer, the residual magnesia zirconia brick shows three layers： obviotasly deteriorative layer, slightly deteriorative layer, and original brick layer, but the residual magnesia chrome brick only shows two layers ： obviously deteriorative layer and original brick layer; the SiO2 content of residual magnesia zirconia brick is the highest in the slightly deteriorative layer, however, the SiO2 content of residual magnesia chrome brick gradually decreases front working face to original brick layer.

One-pot Green Synthesis of Pyrrole Derivatives Catalyzed by Nano Sulfated Zirconia as a Solid Acid Catalyst

A new and efficient method for the preparation of N-substituted pyrroles from one-pot Paal-Knorr condensation has been accomplished using nano-crystalline sulfated zirconia （SZ） as the catalyst in ethanol at moderate temperature. This new protocol has the advantages of easy availability, stability, reusability and eco-friendliness of the catalyst, high to excellent yields, simple experimental and work-up procedure. The synthesized compounds were confirmed through spectral characterization using IR, 1H NMR, 13C NMR and mass spectra.

Role of Nanosized Zirconia on the Properties of Cu/Ga2O3/ZrO2 Catalysts for Methanol Synthesis

The introduction of mesoporous nanosize zirconia to the catalyst for methanol synthesis dedicates the nanosized catalyst and mesoporous duplicated properties. The catalyst bears the larger surface area, larger mesoporous volume and more uniform diameter, more surface metal atoms and oxygen vacancies than the catalyst prepared with the conventional coprecipitation method. The modification of microstructure and electronic effect could result in the change of the reduced chemical state and decrease of reducuction temperature of copper, donating the higher activity and methanol selectivity to the catalyst. The results of methanol synthesis demonstrate that the Cu^＋ is the optimum active site. Also, the interaction between the copper and zirconia shows the synergistic effect to fulfil the methanol synthesis.

Thermogravimetric Analysis of Zirconia-Doped Ceria for Thermochemical Production of Solar Fuel

Developing an efficient redox material is crucial for thermochemical cycles that produce solar fuels (e.g. H2 and CO), enabling a sustainable energy supply. In this study, zirconia-doped cerium oxide (Ce1-xZrxO2) was tested in CO2-splitting cycles for the production of CO. The impact of the Zr-content on the splitting performance was investigated within the range 0 ≤ x < 0.4. The materials were synthesized via a citrate nitrate auto combustion route and subjected to thermogravimetric experiments. The results indicate that there is an optimal zirconium content, x = 0.15, improving the specific CO2-splitting performance by 50% compared to pure ceria. Significantly enhanced performance is observed for 0.15 ≤ x ≤ 0.225. Outside this range, the performance decreases to values of pure ceria. These results agree with theoretical studies attributing the improvements to lattice modification. Introducing Zr4+ into the fluorite structure of ceria compensates for the expansion of the crystal lattice caused by the reduction of Ce4+ to Ce3+. Regarding the reaction conditions, the most efficient composition Ce0.85Zr0.15O2 enhances the required conditions by a temperature of 60 K or one order of magnitude of the partial pressure of oxygen p(O2) compared to pure ceria. The optimal composition was tested in long-term experiments of one hundred cycles, which revealed declining splitting kinetics.

Preparation and sintering properties of zirconia-mullite-corundum composites using fly ash and zircon

Zirconia-mullite-corundum composites were successfully prepared from fly ash,zircon and alumina powder by a reaction sintering process.The phase and microstructure evolutions of the composite synthesized at desired temperatures of 1 400,1 500 and 1 600°C for 4 h were characterized by X-ray diffractometry and scanning electronic microscopy,respectively.The influences of sintering temperature on shrinkage ratio,apparent porosity and bulk density of the synthesized composite were investigated.The formation process of the composites was discussed in detail.The results show that the zirconia-mullite-corundum composites with good sintering properties can be prepared at 1 600°C for 4 h.Zirconia particles can be homogeneously distributed in mullite matrix,and the zirconia particles are around 5μm.The formation process of zirconia-mullite-corundum composites consists of decomposition of zircon and mullitization process.

Influence of Impurities of Zircon Sand on the Microstructure of Fused Zirconia Grains for Continuous Casting of Steel Refractories

Certain impurities of zircon sands, especially alumina, titania, calcia and yttria cannot be completely re- moved in the production of fused zirconia and may have an influence on the corrosion resistance and other product properties of refractories for continuous casting of steel. In this paper, we present our findings on how impurities in raw materials end up in different stabilised zirconia refractory grains, in particular calcia-, magnesia- and yttria-stabilised zirconia. The microstructure （and phase composition） is affected by both the raw materials and the fusion conditions （furnace type and cooling technology）.

Optimizing the Preparation Parameters of Nanocrystalline Zirconia for Catalytic Applications

Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparation temperature and calcinations＇ temperature are optimized.Crystallite size, specific surface area, tetragonal phase percentage and the thermal stability of the prepared samples are identified by diferent characterization tools such as X-ray difraction（XRD）, thermo gravimetric analysis（TGA）, diferential scanning calorimetry（DSC）, BET surface area, scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The optimum preparation parameters for obtaining nanocrystalline zirconia with high percentage of tetragonal phase and high surface area are pH 9, preparation temperature of 80℃ and calcinations＇ temperature of 400℃. The sample prepared under optimized conditions showed a high specific surface area of 179.2 m2/g, high tetragonal phase percentage of 81% and high catalytic activity（60%） for synthesis of butyl acetate ester.

Fabrication of β-Sialon/ZrN/ZrON composites using fly ash and zircon

β-Sialon/ZrN/ZrON composites were successfully fabricated by an in-situ carbothermal reduction？nitridation process with fly ash, zircon and active carbon as raw materials. The effects of raw materials composition and holding time on synthesis process were investigated, and the formation process of the composites was also discussed. The phase composition and microstructure of the composites were characterized by means of XRD and SEM. It was found that increasing carbon content in a sample and holding time could promote the formation of β-Sialon, ZrN and ZrON. The proper processing parameters to synthesize β-Sialon/ZrN/ZrON composites were mass ratio of zircon to fly ash to active carbon of 49：100：100, synthesis temperature of 1550 °C and holding time of 15 h. The average grain size ofβ-Sialon and ZrN（ZrON） synthesized at 1550 °C for 15 h reached about 2 and 1μm, respectively. The fabrication process ofβ-Sialon/ZrN/ZrON composites included the formation ofβ-Sialon and ZrO2 as well as the conversion of ZrO2 to ZrN and ZrON.

Synthesis Mechanism and High Temperature Chemical Stability of CaZrO3

CaZrO3 powder was prepared using CaO,CaCO3 and Ca(OH)2 as calcium source,nano m-ZrO2 powder,micron m-ZrO2 powder,micron CaO partially stabilized ZrO2(Ca-PSZ)powder as zircon source,through high temperature solid reaction.Effect of the calcination temperature(800,900,1000,1100,1200,1300,1400,1500,and 1600℃)and the holding time(3,4,and 5 h)on the phase composition change was studied to research the synthesis mechanism.The synthesized CaZrO3 powder was mixed with CaO,MgO,Al2O3,Cr2O3,SiO2,and ZrO2 powder separately and fired at 1500℃for 3 h to prepare specimens to research the high temperature chemical stability of CaZrO3 with different reaction mediums.The results show that during the synthesis process,the CaZrO3 content does not always increase with the increasing calcination temperature or the prolonging holding time,CaZrO3 decomposes resulting from the diffusion of Ca2+and O2-in CaZrO3 to m-ZrO2 or c-ZrO2.At high temperatures,when CaZrO3 is in alkaline environment(such as environment containing CaO or MgO),the high temperature chemical stability is high,but when CaZrO3 is not in alkaline environment(such as environment containing Al2O3,Cr2O3,SiO2 or ZrO2),the high temperature chemical stability is low.

Poriferan chitin as a template for hydrothermal zirconia deposition

Chitin is a thermostable biopolymer found in various inorganic-organic skeletal structures of numerous invertebrates including sponges （Porifera）. The occurrence of chitin within calcium- and silica-based biominerals in organisms living in extreme natural conditions has inspired development of new （extreme biomimetic） synthesis route of chitin-based hybrid materials in vitro. Here, we show for the first time that 3D-a-chitin scaffolds isolated from skeletons of the marine sponge Aplysina aerophoba can be effectively mineralized under hydrothermal conditions （150℃） using ammonium zirconium（IV） carbonate as a precursor of zirconia. Obtained chitin-ZrO2 hybrid materials were characterized by FT-IR, SEM, HRTEM, as well as light and confocal laser microscopy. We suggest that formation of chitin-ZrO2 hybrids occurs due to hydrogen bonds between chitin and ZrO2.

Microwave-induced synthesis and characterization of nanometer Ce_(0.5)Zr_(0.5)O_2 solid solution for the acidic catalytic reaction

Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce0.5Zr0.5O2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce0.5Zr0.5O2 solid solution.

CO_2 Reforming of CH_4 over Ni/CeO_2-ZrO_2-Al_2O_3 Prepared by Hydrothermal Synthesis Method

The Ni/CeO_2-ZrO_2-Al_2O_3 catalyst with different Al_2O_3 and NiO contentswere prepared by hydrothermal synthesis method. The catalytic performance for CO_2 reforming of CH_4reaction, the interaction among components and the relation between Ni content and catalyst surfacebasicity were investigated. Results show that the interaction between NiO and Al_2O_3 is strongerthan that between NiO and CeO_2-ZrO_2. The addition of Al_2O_3 can prevent the formation of largemetallic Ni ensembles, increase the dispersion of Ni, and improve catalytic activity, but excessAl_2O_3 causes the catalyst to deactivate easily. The interaction between NiO and CeO_2 results inmore facile reduction of surface CeO_2. The existence of a small amount of metallic Ni can increasethe number of basic sites. As metallic Ni may preferentially reside on the strong basic sites,increasing Ni content can weaken the catalyst basicity.

Nanocrystalline Growth Activation Energy of Zirconia Polymorphs Synthesized by Mechanochemical Technique

The synthesis of ZrO2 by mechanochemical reaction using ZrCI4 and CaO as raw materials and subsequent annealing of the products were investigated. The effect of thermal treatment on the structural evolution and morphological characteristics of the nanopowders was studied by X-ray diffractometry, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, differential thermal analysis and Rietveld refinement. The results showed that the average crystallite size of Zr02 was less than 100 nm up to around 1100 ℃. The activation energy for ZrO2 nanocrystallite growth during calcination was calculated to be about 13,715 and 27,333 J/too Mechanism of the nanocrysta for tetragonal （t-ZrO2） and monoclinic （m-Zr02） polymorphs, respectively. ite growth of the ZrO2 polymorphs during annealing is primarily investigated.

Microstructure and application of mesoporous nanosize zirconia

The mesoporous nanoscale zircoina zeolite was firstly synthesized via solid state —— Structure directing method without addition of any stabilizer. The sample bears lamellar or worm pore structures, relatively high surface area compared with that reported. The mesoporous nanosize structure can also resist higher calcination temperature. The introduction of above zirconia to the catalyst of methanol synthesis dedicates the nanosize particle size to the catalyst, which significantly changes the physical structure and elec-tronic effect of the catalyst. The catalyst shows higher catalytic activity and selectivity to methanol. The active sites for methanol synthesis are demonstrated over various cata-lysts in this paper.

Effect of Zircon Addition on Properties of Low Carbon AL_2O_3-C Refractories

Using tabular alumina as aggregate,tabular alumina fines,reactive alumina ultra-fines,aluminum powders,silicon powders,carbon black,flake graphite,B4 C and zircon fines as matrix,low carbon Al2O3-C refractories were prepared.Influences of zircon powders additions （0,3%,5% and 7%,in mass,the same hereinafter） on properties,phase composition and microstructure were investigated.The results show that the ZrO2-nitride can be in-situ formed through carbothermal reduction and nitridation in Al2O3-C refractories.With the increase of zircon powder,the oxidation resistance of the Al2O3-C refractories improves obviously,the oxidized layer thickness decreases from 7.94 mm without zircon to 2.71 mm with 5% zircon.HMOR at 1 400 ℃ of the Al2O3-C refractories reaches the maximum 14.9 MPa when zircon addition is 5%.With the increase of zircon powder,the apparent porosity and bulk density change a little,CMOR and CCS increase.

Simultaneous Al2O3 Doping and Sulfation in Hierarchically Porous ZrO2 Solid Acids by an One-pot Synthesis for Enhanced Recycling Catalytic Performances

Alumina doping and sulfation in hierarchically porous zirconia solid acids have been achieved simultaneously via one-pot and bi-surfactant-assisted self-assembly process, using aluminum sulfate as both Al and SO^2- sources. The prepared composite solid acids showed much enhanced acidity and recycling catalytic activity for an esterification reaction compared with sulfated zirconia without alumina doping and Al-doped sulfated zirconia without hierarchically porous structure.

预合成镁锆砂和煅烧温度对镁锆质材料性能的影响

为了改善镁锆质材料的高温使用性能,以岫岩二级菱镁矿、脱硅锆为原料制备的预合成镁锆砂和电熔镁砂为原料,经混合、成型、烘干、煅烧制备了镁锆质材料。研究了预合成镁锆砂加入量(质量分数分别为10%、20%、30%)和煅烧温度(1500、1600、1700℃)对镁锆质材料体积密度、显气孔率、烧后线收缩率、常温抗折强度、抗热震性、抗渣性的影响,并分析了其物相组成和显微结构。结果表明:1)随着预合成镁锆砂加入量和煅烧温度的提高,试样体积密度和常温抗折强度增大,显气孔率减小;2)试样线收缩率随预合成镁锆砂加入量的增加而减小,随煅烧温度的升高而增大;3)当预合成镁锆砂加入量为20%(w),煅烧温度为1600℃时,试样的抗热震性最优,这是由于预合成镁锆砂引起的微裂纹增韧提高了抗热震性;4)当预合成镁锆砂加入量为20%(w),煅烧温度为1700℃时,试样的抗渣性最优,主要原因在于ZrO_(2)与渣反应生成CaZrO_(3)和尖晶石,阻碍了钢渣的进一步侵蚀与渗透。

Thermite assisted synthesis of ZrB2 and ZrB2-SiC through B4C reduction of ZrO2 and ZrSiO4 in air

ZrB2 and ZrB2-SiC powders have been produced by reducing ZrO2 and ZrSiO4 with B4C without using any furnace.Magnesium was added to the mixtures of (ZrO2+B4C) and (ZrSiO4+B4C).The reaction has been assisted by a floral thermite packed around the compacts.By introducing elemental Si into (ZrO2+B4C) mixture,composite powders of ZrB2-SiC formed.After leaching out MgO with suitable HCl water solution,the product was analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The effect of Si,B4C,and Mg on the extent of formation of ZrB2,ZrB2-SiC,and other phases has been studied.Formation of nano-sized ZrB2 and ZrB2-SiC composite powders was identified.The adaptability of the process for bulk production was examined.