SnO2 MoO3 Research Articles

Mesoporous SnO2–MoO3 catalyst for diesel oxidative desulfurization: Impact of the SnO2/MoO3 ratio on catalytic efficiency

Vehicular SOx emissions have a huge detrimental impact on public health, catalytic converters, and the environment. Developing strategies to remove sulfur from diesel and thus safeguard the above is imperative. A series of SnO2–MoO3 mixed oxides and mono oxides MoO3 and SnO2 were prepared by soft template method, calcined at 450 °C and successfully tested in model diesel oxidative desulfurisation (ODS). The impact of the SnO2/MoO3 mole ratio (hereinafter denoted as Sn/Mo) on catalytic efficiency was investigated, among other catalytic parameters. The obtained samples were analyzed using X-ray diffraction (XRD), Raman spectrocscopy, scanning electron microscopy (SEM), N2-physisorption and titration method for acidic properties. The study demonstrates that mixing SnO2 and MoO3 improves acidic sites, crystallinity, and morphological properties of pure SnO2. The addition of MoO3 increased oxygen vacancies and the surface area of SnO2. High acidic site densities of 49.3, 47.4, and 46.7 mEqg−1 were observed for the catalysts with 2:1, 1:1, and 1:2 Sn/Mo mole ratio, respectively. The catalytic efficiency increased with an increase in Sn content with the highest catalytic efficiency of 99.8% for the dibenzothiophene (DBT) oxidation achieved in 30 min for Sn/Mo (2:1) catalyst compared to 92 and 70% for Sn/Mo 1:1 and 1:2 catalysts, respectively. The rate constant for the reaction was 0.057 min−1, which is eight times that of MoO3; 0.007 min−1 and three times that of SnO2; 0.017 min−1. The ODS mechanism utilizing the SnO2–MoO3 catalyst was proposed. The prepared SnO2–MoO3 catalyst demonstrated a high potential for industrial desulfurisation applications.

SnO2/SnxMo1−xO3−x solid solution nanocomposites: Demonstration of enhanced lithium storage behavior with general synergistic effects

SnO2/SnxMo1−xO3−x solid solution-based nanocomposites have been prepared via a two-step hydrothermal and following annealing processes. At a Sn/Mo molar ratio of 1:2 (the Sn/Mo = 1:2), a single-phase SnxMo1−xO3−x with ionic flake-like structure can be obtained; while, a SnO2/SnxMo1−xO3−x solid solution nanocomposite can be obtained at a Sn/Mo molar ratio of 1:1 (the Sn/Mo = 1:1), which combines with iconic sphere and flake-like structure. Then, electrochemical properties are systematically studied with pure SnO2 and pure MoO3 comparisons as anodes for LIBs. The after cycled Sn/Mo = 1:1 electrode could contain three phases of metallic Sn, MoO2 and an amorphous Sn-Mo oxides, which provide a general synergistic effect to enhance the surface charge contribution, reduce the charge transfer resistance and increase the reaction kinetics. Specifically, the Sn/Mo = 1:1 electrode exhibits a high initial coulombic efficiency of 73.5% with an excellent reversible lithium storage capacity of 735 mAh g−1 at a current density of 0.4 A g−1 after 500 cycles, and a high-rate performance with a specific capacity of 337 mAh g−1 can be obtained at current density of 4 A g−1. This work could provide some inspirations to design solid solution-based nanocomposite with a general synergistic effect to enhance the electrochemical performance for lithium storage application.

Synthesis of ternary SnO2–MoO3–C composite with nanosheet structure as high-capacity, high-rate and long-lifetime anode for lithium-ion batteries

The SnO2–MoO3–C composite anode for Li-ion batteries (LIBs) was produced via simple hydrothermal synthesis and dry ball milling. In this hybrid, nanosized-SnO2/MoO3 nanoparticles were encapsulated in plate-like graphite. MoO3 additive can protect Sn from aggregating and accelerate the reversible conversion reaction (Sn/Li2O hybrid transformation into SnO2). The SnO2–MoO3–C displays high initial coulombic efficiency of 70% (average for five cells), high reversible specific capacity of 1338.3 mAhg−1 at 0.2 A g-1 after 300 cycles, superior rate capacity of 715.08 mAhg−1 at 5 A g-1 and long-term cyclic stability, with capacity of 571.9 mAhg−1 at 2.0 A g-1 after 1000 cycles. Owing to its superior performance and simple synthesis, the SnO2–MoO3–C composite is a promising anode material for LIBs.

Synthesis of SnO2–MoO3 solid solution and its properties in the reaction of methanol dehydrogenation

X-ray diffraction analysis, synchronous-thermal analysis, and IR spectroscopy were used to confirm the possibility of obtaining a tin–molybdenum solid solution by the closed-cycle technology via joint mechanochemical activation of tin oxide (SnO2) and molybdenum oxide (h-MoO3), followed by a thermal treatment at 650°C. An analysis of the catalytic properties demonstrated that various target reaction products (methyl formate and formaldehyde) can be obtained by varying the temperature of the methanol dehydrogenation process. It was found that the selectivity toward methyl formate reaches a maximum of 99.88% at a temperature of 180°C. Raising the temperature further results in that the selectivity toward formaldehyde increases and reaches its maximum value at 260°C.

Effects of MoO3 crystalline structure of MoO3–SnO2 catalysts on selective oxidation of glycol dimethyl ether to 1,2-propandiol

Hexagonal, monoclinic and orthorhombic MoO3 crystalline phases were prepared to explore rational design requirements of the MoO3–SnO2 structure that are beneficial for the reaction of glycol dimethyl ether to 1,2-propandiol.

Effects of tetrahedral molybdenum oxide species and MoOx domains on the selective oxidation of dimethyl ether under mild conditions

A new preparation method for MoO3–SnO2 catalysts precipitated by HNO3 was developed to selectively synthesize industrially useful chemicals formaldehyde and methyl formate via oxidation of dimethyl ether.

Effects of the MoO3 structure of Mo–Sn catalysts on dimethyl ether oxidation to methyl formate under mild conditions

The effects of the Sn content on the structure of MoO3 in MoO3–SnO2 catalysts.

Selective oxidation of dimethyl ether to methyl formate over trifunctional MoO3–SnO2 catalyst under mild conditions

Dimethyl ether oxidation was conducted over MoO3–SnO2 catalysts prepared from different Sn salt precursors. Over the MoO3–SnO2 catalyst prepared from SnCl4, methyl formate selectivity reached 94.1% at 433 K without the formation of COx. The performance of the catalyst was determined by the existence form of MoO3 and the different surface bonding of Mo and O of the catalyst.

Processing and Characterization of Nanostructured Metal Oxides for Gas Sensing Applications

Nanoscience and nanotechnology involve materials and systems with at least one dimension in the range of 1-100nm that exhibit novel and size-dependent properties. This article reviews the main processing techniques used to fabricate nanomaterials, ranging from sol-gel to vapor deposition to electrospinning. Emphasis is given to metal oxide nanostructures, such as SnO2 nanoribbons and MoO3 nanowires. Their electronic properties and their gas detection behavior are presented and discussed. The high surface-to-volume ratio of metal oxide nanostructures has been exploited to develop gas sensors with higher stability, faster response, and higher sensitivity to the analytes of interest than their conventional counterparts. Commonly observed p-n type transition phenomena in nanostructured metal oxides are explained on the basis of the sensing mechanism involved in gas detection by semiconducting oxides and the size-related effects of nanomaterials in the concentration of free charge carriers. Insights are given on the future challenges in resistive gas sensing and how nanotechnology may be helpful in overcoming these burdens

The influence of molybdenum on the properties of SnO2 ceramic sensors

Abstract The properties of SnO2–MoO3 ceramic sensors for CH4 and CO detection and structural features of sensitive layers, containing different concentrations of Sn and Mo, have been studied. The sensitive layers were obtained by means of the sol–gel method—from tin hydroxide sols, stabilised with polyvinyl alcohol (PVA), with Mo6+ added. The structure of the ceramic layer corresponds to Mo6+ in SnO2 substitution solid solution (up to 25 at.% Mo) at all Mo6+ concentrations in sols. Mo5+ stabilises in SnO2 interstitial positions. At definite ratios of components and operating currents, SnO2–MoO3 sensors can selectively detect CO in CO+CH4 mixtures.

Vapor-Phase Oxidation of Ethyl Lactate to Pyruvate over Various Oxide Catalysts

Abstract Oxidation of ethyl lactate to pyruvate was carried out in vapor-phase over various oxides. MoO3 showed a higher selectivity than that of the other single oxide examined. Binary oxides containing molybdenum such as Fe2O3–MoO3 and TeO2–MoO3 showed high selectivities to pyruvate over 90% at 300 °C with high lactate conversion over 75%. The maximum activity on SnO2–MoO3 was observed at a low temperature of 250 °C.

HIGH ACTIVITY OF MoO3–SnO2 FOR HYDROCRACKING OF DIPHENYL ETHER AND DIPHENYLMETHANE

Abstract Of four newly synthesized catalysts designed for coal liquefaction, MoO3–SnO2 was superior for use with diphenyl ether and diphenylmethane with either H2 or CO + H2O. This agrees with the results of using these catalysts with a sub-bituminous coal. Carbon monoxide and H2O is superior to H2 for ether cleavage, whereas H2 is better for hydrocarbon cleavage.

The MoO3–SnO2 Catalysts. Acid-Base Properties and Catalytic Activities for 2-Butanol Decomposition and 1-Butene Isomerization

Abstract Acidic and basic properties of MoO3–SnO2 catalysts with different compositions of MoO3 were measured by adsorption of NH3, CO2, and acid-base indicators. Acidic property prevailed over basic property for all catalysts. Catalytic activities for 2-butanol dehydration and 1-butene isomerization correlated with the acidities measured under the reaction conditions.

ChemInform Abstract: IMPROVEMENT OF ACETONE YIELD IN THE OXIDATION OF PROPYLENE

AbstractDie selektive Oxidation von Propylen zu Aceton kann an SnO2‐MoO3/Bimsstein durchgeführt werde wobei Aceton optimal bei einem Gehalt von 30% Mo gebildet wird.

Improvement of Acetone Yield in the Oxidation of Propylene

Abstract The outstanding property of the SnO2–MoO3 catalyst in the oxidation of propylene to acetone was confirmed by tests of various oxide catalysts supported on pumice. The optimum composition was found to be SnO2-70/MoO3-30 mol % for the oxidation at from 170 to 260 °C. It was also found that this pumice-supported catalyst is sufficiently selective for the acetone formation even at a high temperature of 260 °C, and that it gives a high yield of acetone while keeping its high selectivity. The selectivity increases up to 90 mol % with an increase in the partial pressure of water vapor and with a decrease in the oxygen partial pressure. On the basis of such information, it can be said that a high yield of acetone can be obtained by the divided introduction of oxygen.

SURFACE COMPOSITIONS AND ACTIVITIES OF CATALYSTS STUDIED WITH X-RAY PHOTOELECTRON SPECTROSCOPY: sec-BUTANOL CONVERSIONS ON SnO2–MoO3 BINARY OXIDE CATALYSTS

Abstract The surface compositions of SnO2–MoO3 catalysts were determined using XPS and compared with the activities for sec-butanol. Surface enrichment of MoO3 occurred in the composition range of Mo/Mo+Sn < ca. 0.6, while SnO2 was enriched in the other catalysts. The activities were understood better in terms of the surface composition of the catalyst.

MEASUREMENT OF Mo+5 SPECTRA DURING METHANOL OXIDATION

Abstract Oxidation of methanol into formaldehyde on SnO2–MoO3 catalyst proceeds according to the redox mechanism of Mo+5\ightleftharpoonsMo+4.