Composition Of Mixed Oxides Research Articles

Unraveling the Beneficial Electrochemistry of IrO2/MoO3 Hybrid as a Highly Stable and Efficient Oxygen Evolution Reaction Catalyst

Minimization of noble metal contents along with enhancement in electrochemical properties with high durability is a major challenge to be overcome for commercializing water electrolyzers and cheap energy storage devices. Sluggish kinetics of the oxygen evolution reaction (OER) within the electrolytic cell and high energy demand to form O═O bonds have attracted more responsiveness to this area. We report the OER beneficial mixed oxide composite of molybdenum and iridium oxides by a facile hydrothermal method. Adhered IrO2 nanoparticles on MoO3 large particles synergistically possessed a robust nature toward harsh acidic water electrolysis as compared to an alkaline environment. Mass specific OER activity of iridium active centers was greatly enhanced by 7-fold, twice the current density, and was attributed to electronic modulation of noble metal. Enhanced surface area and the existence of highly oxidative species in the O(1s) spectrum of IrO2 and two doublet regions in the X-ray photoelectron spectrum of m...

Acidity of co-precipitated SiO2-ZrO2 mixed oxides in the acid-catalyzed dehydrations of iso-propanol and formic acid

SiO2-ZrO2 is an interesting class of binary mixed oxide systems, but its acidity has not been intensively linked to the catalytic activity in the dehydration reactions. Thus, SiO2-ZrO2 mixed oxides with the Si/(Si + Zr) ratio ranging from 0 to 1 were synthesized via a coprecipitation method and their physicochemical properties including acid characteristics were investigated. As a result of pyridine adsorbed FT-IR and iso-propanol (IPA)-TPD, the type, quantity, concentration, and strength of acid site were largely dependent on the molar composition of SiO2-ZrO2 mixed oxides, where they reached maximum at the Si/(Si + Zr) molar ratio of 0.7. Furthermore, it was found that the catalytic activity was proportional to the acid strength in the decomposition of IPA, while the quantity of Brønsted acid sites was a principal contributor to the activity in the decomposition of formic acid.

Efficiency evaluation of arsenic(III) adsorption of novel graphene oxide@iron-aluminium oxide composite for the contaminated water purification

Abstract Prolong consumption of arsenic-rich drinking water causes serious health problem. Aiming to minimize the problem, it is attempted to develop cheap and advanced materials for arsenic extraction from the contaminated water. Thus, multifunctional graphene oxide (GO)-incorporated iron-aluminium mixed oxide (GIAMO) composite has been prepared with five different GO content, and evaluated by batch method for the arsenic(III) removal efficiency. Among the as-prepared GIAMO samples, three samples consisting 1.0, 2.0 and 3.0 g of GO show equally good (92–95%) arsenic(III) removal efficiency, which is 30–35% higher than pristine iron-aluminium oxide (IAMO) from an aqueous solution (5.0 mg AsIII·L−1) at pH 7.0 (± 0.2) and 303 K. Thus, 1.0 g GO-inserted GIAMO (GIAMO-1) sample was characterized as microcrystalline (10–15 nm) with BET surface area about 1.45 times higher than IAMO and investigated for the arsenic(III) adsorption. Optimized pH for arsenic(III) adsorption is 6.0–8.0. The kinetic data agree more closely with pseudo-first order equation (R2 = 0.98–0.99) than pseudo-second order equation (R2 = 0.92–0.93). The equilibrium data describe the Langmuir isotherm (R2 = 0.97–0.98) better than the Freundlich isotherm (R2 = 0.91–0.92), showing the Langmuir monolayer capacity 42.2836 mg·g−1 at 293 K which drops to 24.9170 mg·g−1 at 313 K. High negative enthalpy change (ΔH° ∼ −224 kJ. mol−1) is responsible for the spontaneous reaction (ΔG° = negative) despite unfavorable entropy change (ΔS° = −0.71 kJ. mol−1). The order of competitive effect of PO43−, SO42− and HCO3− on arsenic(III) removal efficiency is PO43− > SO42− > HCO3−. However, the high HCO3− (> 200 mg·L−1) enhances the arsenic(III) removal efficiency of this material. 2.0 M NaOH can regenerate arsenic adsorbed GIAMO-1 only up to 50–60%. 0.65 g. of composite per L of high arsenic (Astotal: 0.115 mg L−1) groundwater can upgrade to potable standard, encouraging possible safe use for high arsenic water treatment. Highly negative enthalpy change, poor regeneration, FTIR, XRD and CV analyses of arsenic-rich solid suggested that arsenic(III) is stabilized over the solid surface without oxidation by surface complex formation.

Influence of Mg–Al Mixed Oxide Compositions on Their Properties and Performance in Aldol Condensation

The influence of chemical composition of Mg–Al mixed oxides on their properties and catalytic performance in aldol condensation of furfural and acetone was studied. Pure alumina, Mg–Al layered double hydroxides with a wide range of Mg/Al molar ratios from 0.5 to 15, and pure magnesia were prepared by the same synthesis method, and corresponding oxides were produced by calcination of the as-prepared samples at T = 450 °C. The physicochemical properties of the samples were investigated by XRD, N2 physisorption, SEM, CO2-TPD, and NH3-TPD, and their catalytic performance was evaluated in aldol condensation of furfural and acetone. SEM images revealed that the Al content in the samples influenced the size and the morphology of both large agglomerates and plate-like crystals. The CO2-TPD measurements proved that the concentration of basic sites and the distribution of their strengths was determined by the Mg/Al molar ratio in the Mg–Al mixed oxides. However, over the whole range of Mg/Al compositions studied he...

Nanosheet-structured NiCoO2/carbon nanotubes hybrid composite as a novel bifunctional oxygen electrocatalyst

Synthesis of novel bifunctional catalysts based on earth-abundant elements with high catalytic activities for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) becomes a main strategy to promote the development of metal-air batteries and fuel cells. Herein, a novel Co2+-based mixed transition metal oxide composite, the three-dimensional (3D) nanosheet-structured NiCoO2/carbon nanotubes (CNTs) composite, was successfully synthesized through a facile one-pot method. The better electrocatalytic activities of NiCoO2/CNTs for both ORR and OER than those of pure NiCoO2, CNTs, physically mixed NiCoO2 and CNTs, and Co3O4/CNTs are proved. The comparison of local ORR and OER electrocatalytic activities of NiCoO2/CNTs to other catalysts are obtained by scanning electrochemical microscopy (SECM) characterizations. The closed oxygen reduction peak and half-wave potentials, nearly four-electron dominated process, better methanol tolerance and electrochemical stability confirm the comparable electrocatalytic performance and better stability of NiCoO2/CNTs to the commercial Pt/C catalyst for ORR. The similar stability of NiCoO2/CNTs demonstrates its comparable electrocatalytic performance to the state-of-the-art RuO2 catalyst for OER. The as-prepared NiCoO2/CNTs composite presents as a promising bifunctional oxygen electrocatalyst in alkaline solution for potential applications.

Acid-Stable, Low-Noble-Metal Content Oxygen Evolution Electrocatalysts Via Rapid Plasma Synthesis

One outstanding research challenge in water-splitting electrocatalysis is that few known materials have both high catalytic activity and extended stability for the oxygen evolution reaction in acidic electrolytes, and these have primarily been limited to noble metal oxides. A rapid and scalable novel plasma synthesis technique has been employed to fabricate mixed metal oxide compositions of homogeneously phase-pure catalysts with an aim toward the development of acid-stable OER catalysts of low noble metal content. In particular, a composition of W0.9Ir0.1Ox has been characterized and shows high activity and stability at pH 0 following a standardized benchmarking protocol. A high-throughput plasma reactor nanoparticle printer has been developed to enable the rapid search for acid-stable OER catalysts with minimal to no platinum-group-metal elements. Such materials could improve the sustainability and economic competitiveness of proton exchange membrane electrolyzers.

Different Strategies for Modification of Titanium Dioxide as Heterogeneous Cata lyst in Chemical Transformations

It is now extensively established that the ideal way to achieve the development in heterogeneous catalysis is to utilize semiconducting titanium dioxide (TiO2) based particles with high surface area as well as mesoporous structure. This can efficiently accommodate substrates on its surface to interact with each other. Most of the reduction-oxidation type organic transformations, degradation of hazardous organic moieties are feasible at moderate reaction conditions with the help of TiO2 nanoparticles due to their ability to form composites with enhanced performance, better metal support interactions, chemical stability, selectivity and presence of reactive acid-base sites on its surface. This review article provides a balanced and comprehensive analysis of some innovative and ambitious strategies for modification of TiO2 host material for heterogeneous catalysis: a) making its composites with other materials; and b) doping by metal or non-metal. Keywords: Titanium dioxide, heterogeneous catalysis, mixed oxide composites, metal support, organic transformation.

Effects of Ti loading on activity and redox behavior of metals in PtCeTi/KIT-6 catalysts for CH4 and CO oxidation

Ti-KIT-6 materials having different TiO2 loadings (5%, 10%, 30%) were synthesized, modified by Ce and Pt immobilization, characterized by N2-adsorption/desorption, XRD, SEM, EDX, TEM, XPS and TPR analysis techniques and tested in CH4 combustion and CO oxidation reactions. The mesoporous ordered structure of KIT-6 support was preserved in regard to surface area and pore volume. The average pore size was decreasing due to the effect of titania loading and other metals immobilization. The effects of TiO2 content and immobilization of CeO2 on Pt were studied in view of the catalytic properties. XPS showed the increase in electron density on Pt owing to contribution of TiO2, but on the other hand it was decreasing as result of CeO2 effect. The metal–support interaction, under conditions of varying TiO2–CeO2 mixed oxide composition, as evidenced by XRD and TPR, was correlated with the catalytic results. The highest conversion degree of CH4 was observed with the PtTi-KIT-6 samples within the temperature range 250–400°C and the highest activity was displayed by the PT5K6 sample in both reactions. The slight decrease in activity was observed at the highest Pt0 concentration on samples with 30%TiO2. This can be due to highest dispersion degree of Pt metal and lower surface area of the catalyst. All the samples with supported titania and ceria were active in CH4 and CO oxidation reactions and the selectivity to CO2 varied with temperature.

(Invited) Photocurrent Spectroscopy in Corrosion and Passivity Studies: A Critical Assessment

Photocurrent Spectroscopy (PCS) is currently employed for the characterization of solid-state properties of semiconducting and insulating materials, since the knowledge of their band gap is a prerequisite to any possible application in different fields such as: solar energy conversion (photoelectrochemical and photovoltaic solar cells, photocatalysis) and microelectronics (high-k, high band-gap materials) (1-2). In the last 20-30 years an increasing number of scientists working in the area of corrosion has been attracted by this technique owing to its versatility and ability to scrutinize in situ corrosion layers and passive films having semiconducting or insulating behaviour. In previous works (3-4) we have shown that PCS is able to provide detailed information on characteristic energy levels of passive film/electrolyte junctions (flat band potential: Ufb; internal photoemission threshold: Eth; band gap value: Eg), which control the mechanism of charge transfer (electrons and ions) at the metal/corrosion layer/ electrolyte interface. Further advantages stem out from the fact that PCS does not require particular surface finishing control and can be used both in large area as well as in microscopic region of the electrode, and can reach high sensitivity by using a lock-in amplifier coupled to a mechanical light chopper. According to this, numerous experimental studies have shown how it is possible to scrutinize corrosion layer and passive films of very limited thickness grown on metals and alloys (Fe, Cr, Ni and SS) of relevant industrial interest (3-4 and refs. therein). In an attempt to make more quantitative the characterization of corrosion layer and passive by PCS, in previous works (3-4) we have shown that it is possible to correlate semi-empirically the band gap values of numerous binary oxides to their composition by using the Pauling’s equation for the average bond energy, i.e.: Eg =2[EI(χM -χO)2 +Ξ] (1) where χM and χO are the electronegativities, in the Pauling’s scale, of metal and oxygen respectively, and the remaining terms have been defined in the original work (5). Apart few noticeably exceptions, eq. (1) assumed, for sp-metal and d-metal oxides the following expression: Eg - ΔEam (eV) = 2.17(χM−χO)2 − 2.71 for sp metal (1b) Eg - ΔEam(eV) = 1.35(χM −χO)2 − 1.49 for d metal (1c) where ΔEam = 0 for crystalline oxides, whilst increasing ΔEam values have been suggested with a decreasing crystallinity degree. Moreover in several successive works (see refs. in 3-4), we have been able to show that in the case of ternary oxides by using of an average electronegativity parameter defined as the atomic % average between electronegativities of partner metals, eqs. (1b) and (1c) were able to correlate the band gap values measured by PCS with the mixed oxide composition. In this work, in order to test the validity of eq.1 for ternary oxides, we will carry out a comparison between several experimental Eg values of ternary oxides and the Eg values obtained by using eq.1 with the average electronegativity value for ternary oxide given by: χav = x1χcat1 + x2χcat2 where χ cat1,cat2 and x1,2 are the electronegativity parameter and atomic fraction of cations 1,2 in the ternary oxides, respectively. Moreover, some very recently publishes Eg values of mixed d-d metal oxides, of large interest in corrosion studies, theoretically derived from Density Functional Theory will be compared with PCS measured data and with those estimated according to eq. (1). Possible explanations of the difference in experimental and theoretical data will be presented and discussed. References 1- L. Peter, in "Comprehensive Chemical Kinetics", vol.29, p.382, Ed. by R.G. Compton, Elsevier Science, Oxford (1989). 2- V. Afanas'ev, A. Stesmans, Andre, Journal of Applied Physics, 102 (2007) 1 3- F. Di Quarto, M. Santamaria, and C. Sunseri, in “Analytical Methods in Corrosion Science and Technology”, P. Marcus and F. Mansfeld, Editors, p. 697, Taylor and Francis, Boca Raton, FL (2005) 4- F. Di Quarto, F. La Mantia, M. Santamaria, in "Modern Aspects of Electrochemistry, No. 46: Progress in Corrosion Science and Engineering I", Ed. by Su-Il Pyun and Jomg-Won Lee, Ch. 4, p. 231, New York: Springer (UNITED STATES), 2009. 5- F. Di Quarto, C. Sunseri, S. Piazza, M.C. Romano, J.Phys. Chem. B, 101, 2519 (1997)

Effect of in situ generated nascent magnesia and alumina from nitrate precursor on reaction sintered magnesium aluminate spinel

Synthesis of dense magnesium aluminate spinel using a single stage solid oxide reaction is difficult owing to volume expansion associated with spinel formation. In the present work, reaction sintered magnesium aluminate spinel was prepared using commercial grade oxide in a single stage solid oxide reaction reactants. The effect of incorporation of nascent MgO and Al2O3 from nitrate precursor additives was studied. Aluminium nitrate nonahydrate and magnesium hexahydrate were used up to 2wt.% as a source of nascent Al2O3 and MgO respectively. Sintering of the mixed oxide compositions was done in the temperature range 1200–1600°C after compaction under a uniaxial pressure of 150MPa. The dilatometry study was used as a tool to observe the spinel formation reaction. Sintered products were characterised by densification study, flexural strength, thermal shock resistance measurement, phase analysis and microstructural development. The presence of excess MgO and Al2O3 enhanced the spinel formation reaction and densification of spinel at a higher temperature. The template mechanism of spinel formation was observed in the microstructures. The addition of excess alumina and magnesia was found to increase strength values. Also, much higher strength retainment even after 6–8cycles of thermal shock was observed in additive contained batches.

Mixed oxide compositions and process for preparing isoolefins

Mixed oxide compositions and process for preparing isoolefins

A comparative study on the effect of different additives on the formation and densification of magnesium aluminate spinel

Commercially available fused magnesia and sintered alumina sources were used to form reaction sintered spinel by solid oxide reaction route in a single firing. The effect of the addition of four different additives, namely MgCl2, LiF, AlCl3, and MnO2, at 2wt% level was studied. Mixed oxide compositions were compacted under a uniaxial pressure of 150MPa and then sintered between 1200 and 1600°C. The dilatometric study and phase analysis was done to observe the spinel formation reaction. Densification study of the sintered product was done to understand the effect of additives. Cold Crushing strength and thermal shock resistance of 1600° sintered pellets were studied. Microstructural study using field emission scattered electron microscopy (FESEM) was also done to understand the grain development on sintering in the compositions and the effect of different additives on sintering. LiF and MgCl2 were found to strongly enhance the spinel formation reaction. Bulk density values were found to be lower for the additive containing batches at 1200°C due to enhanced spinel formation but higher at 1600°C due to greater sintering. Strength values were strongly enhanced by LiF and MnO2 due to the development of dense, compact microstructure. Also, additives containing compositions showed much higher strength retainment even after 6 cycles of thermal shock.

Effect of ZrO2 addition on MgAl2O4 spinel from commercial grade oxide reactants

Dense stoichiometric magnesium aluminate spinel was developed from commercially available fused magnesia and sintered alumina sources by solid oxide reaction in a single firing. Mixed oxide compositions were compacted under a uniaxial pressure of 150MPa and then fired in the temperature range of 1200–1600°C. Effect of addition of ZrO2 up to 2wt% was also studied. The dilatometric study was done to study the spinel formation with varying amount of ZrO2. Sintered products were characterized for densification and phase analysis study. 1600°C sintered products were also characterized for bending strength and thermal shock resistance properties. Microstructural study with EDAX was also done to understand the grain development on sintering in the compositions and effect of zirconia in the sintered products. ZrO2 was found to enhance the spinel formation reaction and densification of spinel. Dense compact microstructure was observed with increased strength values for compositions containing ZrO2. Also, ZrO2 containing compositions showed much higher retained strength values till 6 thermal cycles after thermal shock.

Spectral characterization of mechanically synthesized MoO3-CuO nanocomposite

In this work, MoO3-CuO metal oxide composite nanopowders are prepared by simple mechanochemical assisted synthesis technique with the stoichiometric weight ratios of MoO3 and CuO as 2.3:1 and 3.3:1, respectively. The structural and spectroscopic properties of the as-synthesised samples are characterised by XRD, SEM with EDS, FT-IR, Raman spectroscopy and TGA/DTA. X-ray diffraction pattern demonstrates the peaks correspond to orthorhombic phase of α-MoO3 and monoclinic phase of β-CuO. The average crystalline sizes of the 2.3:1 and 3.3:1 samples were found to be 16 and 24 nm, respectively, which are supported by Williamson–Hall (W–H) calculations. The correlations between the milling rotational speeds with morphological characteristics are revealed by the SEM images. The fundamental modes of Mo=O and Cu–O were analysed by FT-IR. Raman analysis has provided the qualitative information about the structure of the mixed oxide composite. Thermogravimetry analysis and Differential Thermal Analysis (DTA) of MoO3-CuO have revealed that the dual phase mixed oxide composite is stable up to 709 °C with a negligible weight loss. Based on the above, it can be inferred that the synthesised mixed lubricous oxide nanocomposite could be used as a solid lubricant at elevated temperatures.

New Development of Anodic Electro-catalyst for Chlor-alkali Industry

Anodic electro catalysts are developed by using a titanium substrate coated with different compositions of mixed oxides, as it follows: ruthenium-titanium mixed oxides; ruthenium-titanium-tin mixed oxides; and ruthenium-titanium-iridium mixed oxides. The performance of electro catalysts was further evaluated by measuring coating thickness, studying coating morphology with microscope, identifying the presence of RuO2, TiO2, IrO2 and SnO2 in coating film, analyzing shape of individual crystal by XRD, performing accelerated life test and current efficiency test of the selected anode. The coating composition of 15% RuO2, 15% IrO2 and 70% TiO2 exhibited premium properties among the studied anodes.

Spectral Investigation of Structural and Optical Properties of Mechanically Synthesized TiO2-V2O5 Nanocomposite Powders

TiO2-V2O5 nanocomposite powders are prepared by simple ball milling process at room temperature. The structural and optical properties of the synthesised sample powders are characterised by Powder X-Ray diffraction (PXRD), SEM with EDS, Fourier Transform Infrared (FT-IR) Spectroscopy, UV Vis, Raman spectroscopy, TGA and DTA techniques. The X-ray diffraction (XRD) pattern contains a series of peaks corresponds to the tetragonal phase structure of both TiO2 and V2O5 which are well matched with JCPDS data. The surface morphologies are revealed by SEM images. The average crystallite size is calculated by the scherrer's formula and is found to be 10nm. SEM images at different parameters are taken and revels the spherical like structures with little agglomeration. FT-IR shows the fundamental vibration modes of TiO2-V2O5. The band-gap energies are calculated from the UV Vis spectra. Raman analysis provided the qualitative information about the structure of the mixed oxide composite. The weight loss and temperature stability of the powders were analysed by TG and DTA analysis.

Synthesis and characterization of ZnO-Al2O3 oxides as energetic electro-catalytic material for glucose fuel cell

One of the thrust areas of research is to find an alternative fuel to meet the increasing demand for energy. Glucose is a good source of alternative fuel for clean energy and is easily available in abundance from both naturally occurring plants and industrial processes. Electrochemical oxidation of glucose in fuel cell requires high electro-catalytic surface of the electrode to produce the clean electrical energy with minimum energy losses in the cell. Pt and Pt based alloys exhibit high electro-catalytic properties but they are expensive. For energy synthesis at economically cheap price, non Pt based inexpensive high electro catalytic material is required. Electro synthesized ZnO-Al2O3 composite is found to exhibit high electro-catalytic properties for glucose oxidation. The Cyclic Voltammetry and Chronoamperometry curves reflect that the material is very much comparable to Pt as far as the maximum current and the steady state current delivered from the glucose oxidation are concerned. XRD image confirms the mixed oxide composite. SEM images morphology show increased 3D surface areas at higher magnification. This attributed high current delivered from electrochemical oxidation of glucose on this electrode surface.

Soot Oxidation Kinetics of Different Ceria Nanoparticle Catalysts

Catalysts for direct soot oxidation in catalyzed diesel particulate filters (CDPFs) consist typically of various mixed oxide compositions (frequently with CeO2 as the dominant component) that assist soot oxidation by enhancing the supply of oxygen from the catalyst to the soot. Apart from the composition, the material morphological characteristics may also contribute to the catalytic activity and this is the motivation for the present study. Different CeO2 nanoparticle catalysts have been obtained employing aerosol-based synthesis (ABS) and sol–gel methods. The obtained catalyst particles have been characterized with respect to their physical and morphological properties as well as with respect to their catalytic soot oxidation activity. The results have been analyzed with the aid of a multi-population kinetics model where soot is found to consist of three fractions reacting with different activation energies, namely 120, 180, and 240 kJ/mol. The occurrence of these three fractions is attributed to the formation of distinct families of surface oxygen complexes (SOCs) on the carbon surface which are subsequently gasified and hence cause soot oxidation, in agreement with accepted mechanisms of soot oxidation in the literature. The CeO2 nanoparticles oxidize catalytically all three fractions of soot, but with different “enhancement factors,” while the activation energies during catalytic oxidation remain the same. A comparison of the catalytic pre-exponentials to those of plain soot shows, in most cases, enhancements, which for some catalysts, can be up to ∼4.5, 6.5, and 2 times larger than those of plain soot, reflecting the relative capacity of the catalyst to generate more of the respective SOCs. The developed approach provides a more detailed but tractable way to describe soot oxidation (plain and catalytic), which can be readily incorporated into simulations of actual emission control systems to increase their reliability.

Determination of chemical and phase compositions of mixed oxides with the perovskite-like structure based on strontium titanates by differential dissolution method

The results of the application of stoichiographic method of differential dissolution (DD) to analyze mixed oxides with the perovskite-like structure are presented. The samples of Sr1Ti0.9Mg0.1O3 with the ABO3 stoichiometry of perovskite and samples of Sr2Ti0.9Mg0.1O4 with the A2BO4 stoichiometry of layered perovskite (where A = Sr2+; B = Ti4+, Mg2+) are prepared by a mechanochemical method and analyzed before and after catalytic tests. Conditions of the detection, identification, and quantitative determination of different phases in the compositions of the samples are described. The surface comppositions of the initial samples are determined by the DD method, and changes observed after the catalytic tests are noted. The DD results are compared with the powder XRD results.

Sn‐Beta Zeolite Catalysts with High Sn Contents Prepared from Sn–Si Mixed Oxide Composites

AbstractThe hydrothermal preparation of Sn‐beta zeolites with high Sn contents is an eminent issue in zeolite syntheses, since these zeolites are some of the most anticipated materials for industrial catalysis. In this work, first, mechanochemical treatment was utilized to obtain a Sn–Si mixed oxide composite, in which the Sn was found to be homogeneously distributed inside the silica network. The composite was further used as the reactant for the crystallization of Sn‐beta zeolite catalysts. Incorporation of Sn into the framework was achieved up to Sn/(Sn+Si)=1.6 mol %, which is the highest value reported by far using conventional hydrothermal treatment. A high catalytic performance for glucose isomerization was also confirmed. These results suggest that the utilization of a mixed oxide composite is a critical method for the preparation of stannosilicate zeolites with high Sn contents through hydrothermal treatment.