Addition Of MoO3 Research Articles

Role of MoO3 /ZnO substitutions on radiation shielding and mechanical characteristics of lead silicate glasses

In the composition range of x= 0-5 mol%, glasses in the system 60SiO2-35Pb3O4-(5 − 𝑥𝑥) ZnO-xMoO3 have been investigated. An amorphous network structure characterizes the glasses. The density values for the LZSM glasses scaled between 5.91 g/cm³ for Mo0 and 6.249 g/cm³ for Mo5. The ultrasonic technique indicates that the shear and longitudinal speeds (VT & VL) increase linearly as the amount of MoO3 substituted for ZnO in the fabricated glasses increases. The elastic moduli were calculated and found to be increased with an increase in both ultrasonic velocities and density of the glass, which suggests a correlation between these parameters in the fabricated glasses. The radiation attenuation capacity with the addition of MoO3 increased systematically, which indicates the role of MoO3 in modifying the glass composition and enhances its ability to attenuate against harmful radiation. Mo5 establishes excellent protective resources compared to other substances, so Mo5 develops a favorable selection for building radiation absorption blocks. Such blocks show an acute character in protecting both nature and a person's health versus the dangerous impacts of radiation exposure.

Gamma Radiation Shielding and Interaction Properties of MoO3-Doped Cadmium Zinc Lithium-Borate Glasses

This study, theoretically examined the impact of MoO3 addition on gamma radiation shielding properties of cadmium zinc lithium-borate (BCZLMx) glasses to find the optimal quantity of molybdenum oxide (MoO3) needed for a stable glass matrix with excellent gamma shielding capabilities. Gamma radiation transmission parameters that include Mass attenuation coefficient, Mass energy absorption coefficient, Equivalent atomic number, Effective electron density, Dose rate, Exposure buildup factors and Energy absorption buildup factor were evaluated using FLUKA and XCOM computer programs. Results showed that 60B2O3-20CdO-10ZnO-8Li2O-2MoO3 (BCZLM5) was the most stable and efficient glass sample for X-rays and gamma radiation shielding across all photon energy ranges. Hence, BCZLM5 should be deployed for X-rays and gamma radiation shielding to provide maximum protection and exceptional safety for workers in hospital X-ray rooms and nuclear installations against ionizing radiation.

Synergic process of molybdenum recovery and ceramic preparation for clean and efficient utilization of industrial leaching residues

Ammonia-leaching residues of roasted molybdenite concentrates are intractable wastes and are mostly stockpiled in factories. Common treatments suffer from low Mo recovery and secondary pollution. This study has developed a synergistic process involving a single-step roasting with the addition of Al2O3 and MoO3 to recover Mo and simultaneously prepare porous refractories from the residues containing 5.6% Mo. The Mo separation efficiency, ceramic properties, and thermal behaviors—including chemical reactions, melting transformations, ceramic structure evolutions, and Mo species migrations—were comprehensively investigated. It was found that the addition of Al2O3 facilitated CaMoO4 decomposition to release volatile MoO3, thus promoting Mo recovery. The mullite started to form at about 900 °C, grew into whiskers, and further into interconnected clusters, under the catalytic effect of liquid MoO3 and the sintering effect of glassy melt. Liquid MoO3 was scattered on the outer surface of whisker clusters, achieving a high separation efficiency of over 98% after roasting at 1300 °C for 150 min. Meanwhile, a ceramic with a high porosity of 64.2% and a high compressive strength of 21.2 MPa was obtained, exhibiting promise for serving as a high-temperature insulation refractory. Overall, this study presents a novel approach for both the profound recovery of Mo and the value-added utilization of gangue minerals derived from CaMoO4-bearing wastes.

High thermal stability molybdenum-Boosted lithium tellurite glass for radiation shielding

A novel glass system was developed using the melt-quenching technique. The primary aim was to investigate molybdenum-rich compositions (MoO3 > Li2O), with the general formula (69–2x) TeO2–(31+x)–MoO3–xLi2O (where x = 0, 5, 10, and 15 mol%). The physical, structural, thermal, mechanical and radiation shielding properties were evaluated. The synthesized glasses were characterized through their densities, molar volumes, and oxygen packing density, which revealed that the density and molar volume decreased as the amount of Li2O and MoO3 increased in the glass structure, while the oxygen packing density increased as a function of both Li2O and MoO3. Raman spectroscopy was used to analyze the glass structure, which showed a superimposed reduction of all Te units due to the formation of Te–O–Mo and a coordination change from MoO4 to MoO6. The interplay between Li2O and MoO3 has a direct effect on the thermal stability of the glass and reveals that glasses with higher MoO3 content and lower Li2O content exhibit enhanced thermal stability. The mass attenuation coefficient for the synthesized systems varied from 37.07 to 32.38 cm2 g−1 at 0.015 MeV. The fast neutrons removal cross-section exhibits a range from 0.090 to 0.096 cm−1 across all samples, while the thermal neutrons cross section values lie within the interval of 1.22–8.16 cm−1. The glass sample with the highest concentration of TeO2 showed superior values of mass attenuation, and fast neutrons removal cross-section, along with the lowest values of half value layer and mean free path. Nevertheless, the addition of MoO3 and Li2O improved thermal stability and led to adequate radiation protection levels. The results indicate the significant potential of MoO3-rich tellurite materials for shielding against gamma-ray and neutron radiation.

The role of MoO3 on the physical, elasto-mechanical and nuclear shielding efficiency of barium-boro-bismuthate glass system: Comparative investigation

Investigations were conducted on the effect of molybdenum addition on the physical, elasto-mechanical and nuclear shielding characteristics of five different glasses, designated S1 through S5, with varying amounts of MoO3. The mechanical parameters of the examined glasses, including their Young (Y), bulk (B), shear (S) and longitudinal (L) moduli, microhardness (H), and poisons ratio, were calculated utilizing the Makishima-Mackenzie technique. The physical and mechanical characteristics of the examined glasses are improved by the addition of MoO3. The Y, B, S, and L moduli rose with increasing MoO3 concentrations from 34.6680 to 35.9989 GPa, 14.13578–14.664 GPa, 21.10714–22.60943 GPa, and 31.70897–33.59673 GPa, respectively. The H values of the glass network also dropped from 0.016431 to 0.016885 GPa. Moreover, as the concentration of MoO3 rose, the Poisson ratio value changed from 0.427021 to 0.429533. The MCNP5 code and WinXCOM program were used to compute various shielding parameters for X/gamma-rays in the energy range between 0.015 and 15 MeV. A good agreement was found between the estimated values using both MCNP5 code and WINXCOM program. The S5 glass sample exhibited the greatest gamma-ray attenuation characteristics among the examined glasses. When compared to other radiation shielding materials including recently studied glasses and polymers as well as other typical gamma ray shielding materials, the current glass composition offers complete (100 %) x-ray protection and effective efficacy for gamma-ray shielding at energies up to 15 MeV. Calculations were made of the studied glasses' macroscopic removal cross sections (∑R), which were then compared to those of commonly used neutron shielding materials. S1 sample performed the best ∑R value while S5 displays a value (0.10516 cm−1) that is comparable to those of graphite, concrete, basalt magnetite, and a few other recently studied glasses and alloys. The heavy ions (proton and alpha particle) attenuation parameters have been evaluated in energy range between 0.01 and 15 MeV. Regarding the studied glasses, the S5 sample was shown to have the best proton and alpha shielding properties. These results imply that the glass samples under study make good nuclear shielding materials for a range of applications.

Fabrication of high-permeance SiC filters reinforced with in situ-grown mullite whiskers for gas/solid filtration

The pursuit of cost-efficiency, superior strength, and excellent gas permeance has driven the development of silicon carbide (SiC) membranes or filters for gas/solid filtration. In this study, SiC filters with high gas permeance reinforced with in situ-grown mullite whiskers were successfully prepared through reaction bonding. Low-cost kaolin and bauxite were used as sintering aids and raw materials for mullite whisker formation, and MoO3 was used as an additive to promote mullite whisker growth. The effects of different sintering temperatures and the addition of kaolin, bauxite, and MoO3 on filter performance were systematically investigated. When the sintering aid and MoO3 content additions were 6 and 1.5 wt%, respectively, and the sintering temperature was 1450 °C, the resulting ceramic filter exhibited a porosity of 45.5 %, a bending strength of 17.9 MPa, and an average pore size of 47.7 µm. Moreover, the filter exhibited a high Darcy’s permeability coefficient of 2.42 × 10−11 m2, satisfactory chemical stability, and thermal shock resistance. The addition of MoO3 facilitated the consumption of the molten phases and increased the anisotropic growth rate of the mullite whiskers, which contributed to the fabrication of the high-permeance filters. Finally, the ceramic filters demonstrated good performance for the filtration of dusty gases loaded with fly ash particles with a mean size of 15.3 µm at room temperature and 300 °C, and the removal rate reached > 99.9 %. The pressure drop was a little lower than that of our commercially available SiC filters. The SiC filters showed good prospects in the field of gas/solid filtration.

The glass-forming region and 2.7 μm emission properties of Er3+-doped TeO2–MoO3–Nb2O5 tellurite glass

In this paper, the glass forming region of TeO2–MoO3–Nb2O5(TMN) tellurite glass and the luminescence properties of Er3+ doped TMN glass at 2.7 μm were studied. The effects of MoO3 on the thermal and optical properties of the glass were analyzed. The formation region of TMN glass was predicted by thermodynamic method and verified by experiment. It can be found that the glass-forming ability, thermal and optical properties of TMN glass change significantly with the change of MoO3 content. The addition of MoO3 significantly improves the anti-crystallization stability, fluorescence lifetime and quantum efficiency of tellurite glass. The calculation results show that the quantum efficiency of 80TeO2–15MoO3–5Nb2O5–1Er2O3 glass sample is 16 %. These results indicate that TMN glass has a broad application prospect in mid-infrared laser materials.

The effects of MoO3 addition on microwave dielectric properties of Bi6B10O24 ceramics for ULTCC applications

The effects of MoO3 addition on microwave dielectric properties of Bi6B10O24 ceramics for ULTCC applications

Effect of MoO3/WO3 modulation on high-temperature wettability and crystallization behavior of glass and its application in solar cell

The role of glass in the metallization contact of crystalline silicon solar cells is crucial. Numerous studies have been conducted to investigate the reaction between the main components in glass and SiNx antireflection layer during sintering. Additionally, the low content component in glass plays an indispensable role in etching and wetting silicon base. The present study investigated the impact of ionic radius on glass properties through manipulation of the elemental composition of transition metals Mo and W. The results indicated a significant decrease in the characteristic temperature point of glass and an increase in wettability after the addition of MoO3 and WO3. Furthermore, the thermal expansion of glass was observed to increase with higher WO3 content. Screen printing for the preparation of silver electrodes revealed that glass-silver pastes had optimal printing properties. When the quality ratio of MoO3 and WO3 was 7:3, it effectively enhanced the precipitation of Bi2WO6 and Pb7.90Mo0.10O12.15 crystals in the glass, leaded to a reduction in the band gap of the glass. This resulted in an increased imprint of silver crystals within the glass layer, with more nano-silver crystals were deposited near the pyramid. Consequently, an optimal metallization contact was established between the silver grid and emitter. The average aspect ratio of silver grid improved from 0.415 for AG-1 to 0.469 for AG-3, which enhanced the photoelectric conversion efficiency of crystalline silicon solar cells.

Effect of lattice disorder on charge transfer in lead molybdate crystals

*e-mail: tbochkova@meta.uaElectrical properties of PbMoO4 crystals, grown from the stoichiometric charge and non-stoichiometric charge with an excess of MoO3, are studied and compared in this work. The crystals are grown by Czochralski method in the direction at an angle of 30° to [100] axis in (001) plane. The single crystals are free from gas bubbles, cracks and have a weak yellowish color. It is found that the addition ofMoO3 excess (0.5 mol.%) to the stoichiometric charge notably increases the crystal lattice disorder. It is assumed that the appearance of lead ion vacancies plays the main role in the structural disordering. An increase of conductivity in DC and AC field, changes of current-voltage characteristics and AC-conductivity spectra are interpreted based on the model of hopping conductivity in disordered systems.

Elucidating the influences of MoO3 in Na2O- ZnO - B2O3 - SiO2: Fabrication, optical, and γ-ray protection properties for the novel high-density glasses

The melt-quenching method was employed to synthesize glasses with varying compositions within the xMoO3-(30−x) Na2O- 5ZnO - 43.5B2O3 - 21.5SiO2 system, where (0 ≤x≤ 10) mol%. The densities increased from 2.93 to 3.67 g/cm3, while their molar volumes decreased from 22.48 to 20.18 cm3/mol. Based on the measurements, the optical band gap of the base glass was 3.53 eV. At its highest MoO3 content, this value decreased to 2.34 eV. The Urbach energy values for NaMo0, NaMo2, NaMo4, NaMo6, and NaMo10 glasses were 0.258, 0.323, 0.348, 0.37, and 0.435 eV, respectively. With an increase in molybdenum level, it was observed that the refractive index values also increased. These structural, optical, and radiation shielding behaviors were attributed to the structural modifications resulting from substituting Na2O with MoO3, leading to improved radiation shielding efficiency with the addition of MoO3. The Fast Neutron Removal Cross Section (FNRCS) (∑R) for the NaMo0, NaMo2, NaMo4, NaMo6, and NaMo10 glasses were 0.116 cm−1, 0.12 cm−1, 0.127 cm−1, 0.131 cm−1, and 0.135 cm−1, respectively. From the current work, we may conclude that NaMo glasses can serve as efficient shields in nuclear radiation environments. In general, it can be deduced that adding Na2O-ZnO-B2O3-SiO2 glasses improves their optical characteristics and enhances their capacity to absorb neutrons and photons for use in nuclear medicine applications.

Grain‐growth Inhibitor with Three‐section‐sintering for Highly Dispersed Single‐crystal NCM90 Cubes

AbstractSingle crystallization of LiNixCoyMn1‐x‐yO2(NCM) is currently an effective strategy to improve the cycling life of NCM cathode, owing to the reduced surface area and enhanced mechanical strength, but the application of single crystal NCM(SC‐NCM) is being hindered by severe particle agglomeration and poor C‐rate performance. Here, a strategy of three‐section‐sintering(TSS) with the presence of grain‐growth inhibitor was proposed, in which, the TSS includes three sections of phase‐formation, grain‐growth and phase‐preservation. While, the addition of MoO3 inhibits the grain growth and restrains the particle agglomeration. With the help of TSS and 1 mol % of MoO3, highly dispersed surface Mo‐doped SC‐NCM(MSC‐NCM) cubes are obtained with the average diameter of 1.3 μm. Benefiting from the surface Mo‐doping and the reduced surface energy, the Li+‐migration preferred (1 0 4) crystalline facet is exposed as the dominant plane in MSC‐NCM cubes, because of which, C‐rate performance is significantly improved compared with the regular SC‐NCM. Furthermore, this preparation strategy is compatible well with the current industrial production line, providing an easy way for the large‐scale production of SC‐NCM.

Grain-growth Inhibitor with Three-section-sintering for Highly Dispersed Single-crystal NCM90 Cubes.

Single crystallization of LiNix Coy Mn1-x-y O2 (NCM) is currently an effective strategy to improve the cycling life of NCM cathode, owing to the reduced surface area and enhanced mechanical strength, but the application of single crystal NCM(SC-NCM) is being hindered by severe particle agglomeration and poor C-rate performance. Here, a strategy of three-section-sintering(TSS) with the presence of grain-growth inhibitor was proposed, in which, the TSS includes three sections of phase-formation, grain-growth and phase-preservation. While, the addition of MoO3 inhibits the grain growth and restrains the particle agglomeration. With the help of TSS and 1 mol % of MoO3 , highly dispersed surface Mo-doped SC-NCM(MSC-NCM) cubes are obtained with the average diameter of 1.3 μm. Benefiting from the surface Mo-doping and the reduced surface energy, the Li+ -migration preferred (1 0 4) crystalline facet is exposed as the dominant plane in MSC-NCM cubes, because of which, C-rate performance is significantly improved compared with the regular SC-NCM. Furthermore, this preparation strategy is compatible well with the current industrial production line, providing an easy way for the large-scale production of SC-NCM.

Li2O–V2O5–MoO3–Fe2O3 amorphous cathode material for lithium-ion batteries based on coordinated multi-electron effect and stable network structure

The amorphous cathode materials Li2O–V2O5–MoO3 and Li2O–V2O5–MoO3–Fe2O3 were produced via melt quenching. By analyzing the structure, elemental valence, and electrochemical characteristics of Li2O–V2O5–MoO3 at different ratios, the effects of MoO3 addition on vanadium-based amorphous cathode materials were explored. 20Li2O–60V2O5–20MoO3 has a high initial capacity (268.0 mAh/g for the first reversible discharge at a current density of 50 mA/g), which is based on the properties that MoO3 supplies additional oxidation reductions and has [MoO6] structural units to widen the diffusion channels for lithium ions in the network structure. Unfortunately, the network of the structural elements [MoO6] and [VO4] is unstable, which causes the material to have poor cycle stability and exhibit an unsatisfactory current response. The network structure stability of Li2O–V2O5–MoO3–Fe2O3 is increased by adding Fe2O3 to provide [FeO4], which strengthens the link between each structural unit. Vanadium oxidation reductions are promoted, and iron oxidation reductions replace the role of molybdenum in the charge/discharge. The discharge product transforms from LiVMoO5 to Li2FeV3O8 with increased de-embedding Li efficiency. The 20Li2O–60V2O5–10MoO3–10Fe2O3 achieves an initial reversible specific capacity of 255.2 mAh/g at 50 mA/g, 139.7 mAh/g additional specific capacity after 100 cycles, and 110.5 mAh/g specific capacity at a high current density of 400 mA/g. The test findings show that 20Li2O–60V2O5–10MoO3–10Fe2O3 efficiently increases high-current responsiveness and cycle stability while retaining a high capacity. In this study, we propose a compositional design strategy, which is based on the coordinated multi-electronic effect of multiple transition metal elements and the design of a stable disordered network structure, to incorporate MoO3 and Fe2O3 into vanadium-based amorphous to create a novel cathode material. This work offers a fresh perspective on investigating innovative lithium-ion battery cathode materials.

Development of mid-infrared glass lens based on TeO2-ZnO-La2O3 glass system

Investigation on thermal, mechanical and optical properties is of utmost importance in designing optical glass for the development of mid-infrared camera module. In this study, two tellurite glass systems, namely the ternary TeO2 −ZnO−La2O3 (TZL) system modified with various concentrations of ZnO and the quaternary TeO2 −ZnO−La2O3 −MoO3 (TZL-Mo) system incorporated with various concentrations of MoO3, were fabricated using the melt-quenching method for mid-infrared optical glass lens. The effects of ZnO and MoO3 contents on characteristic properties of the glasses were investigated. The thermal stabilities were found to be > 117 °C in both the glass systems. The coefficients of thermal expansion decreased from 14.26 to 12.6 and 13.91–13.08 (×10−6/K) with increasing the ZnO and MoO3 contents in the TZL and TZL-Mo glass systems, respectively. Notably, the thermal stability and coefficient of thermal expansion were improved considerably with the addition of MoO3 to the ternary TeO2 −ZnO−La2O3 (TZL) tellurite glass composition. The Knoop hardness values increased from 339 to 384 and 326–371 kgf/mm2 with increasing the contents of ZnO and MoO3, respectively. The glass composition of 60TeO2 − 30ZnO− 7La2O3 − 3MoO3 was selected to produce molded glass lens using the glass molding process because of its attractive thermal and optical characteristics. The average transmittance of the glass in the range of 3–5 µm was found to be 91% after the anti-reflection coating process. Finally, the TZL-Mo3 aspherical lens was developed with diameter of 22 mm for mid-IR camera module.

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.

Structural studies of molybdo-phosphate glasses doped with Zn2+ and Cl- ions

Molybdo – Phosphate glasses with a chemical formula xMoO3-15ZnO-2 PbCl2-(83-x) NaPO3 doped with Zn2+ and Cl- ions has been synthesized by microwave route. The vitreous system is studied for the structural evolution using Infra-Red Spectra. The modulated DSC of the investigated samples shows strong composition dependent trends. Glass transition temperatures (Tg) extracted from DSC lies between 593 K and 647 K and it increases with MoO3 content. Addition of MoO3 replaces weaker linkages like P-O-P by stronger Mo-O-P and Mo-O-Mo linkages. The variation of Tg can be understood in terms of the structural groupings, cross- link density and bond strength of the glass network forming units. To verify the variation to the presence of Na2O creates several structural units. Density of the glass samples increases with the concentration of MoO3. Tg, density and molar volume of the glass samples were also observed. Analysis of the Structural investigations have been carried out using Infra-Red Spectra to study the network modification that reveals the structure of molybdo-phosphate glass network made of corner shared tetrahedral [POO3/2]0 and octahedral [MoO4/2]- units.

Comparison of tribological performances of plasma sprayed YSZ, YSZ/Ag, YSZ/MoO3 and YSZ/Ag/MoO3 coatings from 25 to 800 °C

YSZ, YSZ/Ag, YSZ/MoO3 and YSZ/Ag/MoO3 coatings were prepared on Inconel 718 alloys substrates by the atmospheric plasma spraying process. Their microstructures, mechanical and tribological properties were compared. The results show that the presence of soft Ag and dual addition of Ag and MoO3 exhibit enhanced impact resistance of YSZ coating, nevertheless the inclusion of MoO3 conversely deteriorates this property of YSZ coating. As referenced with YSZ coating, all composite coatings exhibit improved tribological properties from 25 to 800 °C. The presence of Ag in YSZ matrix provides effective function on reducing friction and wear at ambient temperatures, surprisingly YSZ/MoO3 composite coating demonstrate worse wear due to its poor mechanical strength. In contrast, the dual dopants of Ag and MoO3 are in favor of outstanding tribological performance. Characterization of the worn surface of YSZ/Ag coating reveals the enriched Ag island exists being responsible for its better frictional performance at ambient temperature. A distinct tribo-layer covers on the wear surface of YSZ/Ag/MoO3 coating at 800 °C, primarily consisting of Ag2MoO4, which ultimately contributes to reduced friction and improved wear resistance. The formation of Ag2MoO4 and its working mechanism are proposed for the tribological characteristics of YSZ/Ag/MoO3 coating over 500 °C.

Effect of MoO3 addition on fly ash based porous and high-strength mullite ceramics: In situ whisker growth and self-enhancement mechanism

In this paper, using only high alumina fly ash as raw material and MoO3 as additive agent, the high-strength porous mullite ceramics were achieved by in situ mullite whisker growth via a calcination method. The influence of MoO3 addition on pore structure and mechanical properties of as-prepared mullite ceramics was investigated. The mechanism of MoO3 promoting the formation of mullite whiskers and improving the strength of matrix was elucidated. The porous mullite ceramic reached its best performance with a high porosity of 49.4% and an improved compressive strength of 13.03 MPa with 10 wt% MoO3 addition calcinated at 1300 °C. Specifically, MoO3 facilitated the mullite whisks growth mainly by reducing melting point of amorphous SiO2/quartz and changing crystal structure of Al2O3. The larger aspect ratio of mullite grain at 1300 °C was easier to form an interlocking structure, which enhanced the strength of mullite ceramic while maintaining high porosity.

Redox MoO3/CaMnO3 catalysts for chemical-looping oxidative dehydrogenation of propane: A greener approach of propylene production

A redox catalyst with MoO3 loaded on CaMnO3 perovskite was evaluated for chemical-looping oxidative dehydrogenation (ODH) of propane to produce propylene. This approach requires less energy for the production per unit of propylene with minimum CO2 emission, which is highly desirable from an environmental perspective. H2-TPR indicates that the incorporation of MoO3 minimizes the release of surface oxygen, which is favorable for high propylene selectivity. XRD reveals the presence of active sites, while scanning SEM-EDX show uniform dispersion of deposited MoO3 on CaMnO3. XPS analysis demonstrates that MoO3 addition promotes the formation of lattice oxygen which improves the propylene selectivity. The highest propylene yield of 30.6% with a propylene selectivity of 59% was achieved at 550 ℃ with 10% MoO3/CaMnO3. The catalysts also show stable activity in successive redox cycles. The addition of MoO3 enhances propylene yield and selectivity, due to free lattice oxygen, as revealed by XPS and H2-TPR.