Addition Of CeO2 Research Articles

Utilizing the superoxide dismutase activity of ceria nanoparticles to endow poly-l-lactic acid bone implants with antitumor function

Currently, numerous bone tumor patients undergo tumor recurrence after surgical resection, which seriously affects their quality of life. In this study, the ceria (CeO2) nanoparticle was added to Poly-L-Lactic Acid (PLLA) bone implants endowing the bone implant with antitumor function. The results showed that the reactive oxygen species increased in U2OS cells while it dropped in HEK293 cells as the CeO2 content increased. Meanwhile, the PLLA-8CeO2 showed a high cell inhibition rate of 53.66 % for U2OS cells and possessed a high cell viability of 76.96 ± 2.20 % for HEK293 cells, meaning that the implant could kill bone tumor cells meanwhile show good cytocompatibility for normal cells. These were mainly due to the fact that the CeO2 nanoparticles acted as a superoxide dismutase in tumor cells reducing superoxide to hydrogen peroxide, inducing an increase in reactive oxygen species levels. The excess reactive oxygen species could result in tumor cell apoptosis by disrupting mitochondrial structure, oxidizing proteins, and promoting DNA denaturation. Moreover, the compressive strength of PLLA was improved by the CeO2 addition due to its particle dispersion strengthening. Besides, the PLLA-CeO2 had a faster degradation rate compared to PLLA. Overall, the PLLA-CeO2 is a promising implant material for bone tumor treatment.

Preparation and Mechanical Properties Analysis of Rare Earth Filling Ethylene‐Allene Monomer Rubber Composite

AbstractEthylene propylene diene monomer (EPDM) rubber is used in critical sectors such as national defense, military, and aerospace. However, it has performance limitations under high temperatures, affecting its dynamic mechanical properties, creep, and stress relaxation. To overcome these limitations, rare earth cerium oxide (CeO2) was incorporated as a filler into EPDM in this study, which enhances its properties and makes it suitable for the demanding applications. It could be seen that the CeO2‐enriched EPDM has significantly improved mechanical characteristics at elevated temperatures. The Young's modulus of CeO2‐enriched EPDM increased by about 100 %, while the energy storage modulus reaches a maximum increase of around 140 % at 165 °C. The addition of CeO2 improves its damping properties, provides better creep and stress relaxation resistance, and results in greater residual strain recovery. At room temperature, the impact on the stress relaxation rate at 50 % strain is minimal for the material EPDM, and it is almost negligible for the material EPDM/CeO2.These findings demonstrate that CeO2‐enriched EPDM has enhanced performance under high‐temperature conditions. Under elevated temperature conditions, EPDM enriched with CeO2 exhibits enhanced mechanical properties, superior creep resistance, and stable stress relaxation behavior, rendering it more adept at withstanding the rigorous conditions encountered in aerospace applications.

The influence of CeO2 on the oxidation resistance of TaC/Ni composites

The in-situ TaC/Ni composites with different CeO2 content (0 wt%, 1 wt%, 2 wt%) were prepared by reactive sintering method, and their oxidation behavior in air at 1073 K was analyzed by static cyclic oxidation method to investigate the influence mechanism of CeO2 on the oxidation resistance of composites. The results show that the CeO2 particles are distributed around the TaC particles in the Ni matrix, and the oxidation behavior of composites with different CeO2 content conforms to the linear kinetic law. The oxide film is mainly composed of NiTa2O6 and a small amount of NiO. The generation reactions of Ta2O5 and NiTa2O6 induce a high expansion and compressive stress in oxide scale, leading to the formation of nonprotective oxide film with pores and cracks on the surface. As the addition of CeO2 increases from 0 wt% to 2 wt%, the thickness of oxide scale on composites obviously reduces from 505 μm to 122 μm, and the Ni and Ta oxides content decreases, leading to the reduction of pores and cracks in oxide scale. The Ce ion generated from the dissolution of CeO2 particles mainly distributes in the Ta oxides during the oxidation process, which hinders the outward diffusion of Ni and Ta ions, resulted in the improved oxidation resistance of TaC/Ni composites.

Ceria-boosted Ni/Al2O3 catalysts for enhanced H2 production via acetic acid dry reforming

Acetic acid dry reforming (ADR) is a promising route for sustainable H2 generation. However, coke inhibition during ADR is the main challenge and not resolved by using suitable promoted catalysts. In this work, Ce promotion on 10%Ni/Al2O3 catalysts with 1-5 wt%Ce was evaluated for ADR at varied temperatures of 923–998 K and stoichiometric feed in a fixed-bed rig. CeO2 addition of 1–3% enhanced metal dispersion, and surface area whilst basic CeO2 character significantly boosted the concentration and density of basic sites on catalysts. Particularly, the CO2 uptake of promoted catalysts was about 2.49–3.73 times greater than that of counterpart sample. CH3COOH and CO2 conversions were enhanced with rising Ce loading and the highest reactant conversions were observed at 3 wt%Ce. The improved adsorption of acidic CH3COOH and CO2 molecules due to increasing amount of basic sites as well as redox attributes of CeO2 promoter could be responsible for the enhancement in ADR activity and yield of H2 and CO. The mechanistic two-step pathway for coke suppression induced by CeO2 promotion was elaborated in this work. Generally, carbonaceous species formation on 3%Ce–10%Ni/Al2O3 was considerably reduced about 1.6–2.0 times. H2/CO ratio varied from 0.59 to 0.65 relying on ADR temperature over 3%Ce–10%Ni/Al2O3. These H2/CO values, two times higher than theoretical H2/CO ratio in ADR, are compatible for downstream gas-to-liquid processes to selectively yield high molecular weight olefins. Water formation rate increased from 8.67 × 10−6 to 4.71 × 10−5molH2O gcat−1 s−1 with rising temperature within 923–998 K on 3%Ce–10%Ni/Al2O3.

Study on the influence of Ni/La2O3/CeO2 composite catalysts on the characteristics and stability of biomass pyrolysis components

The impact of adding La2O3 and CeO2 separately or in combination to a Ni-Al2O3 catalyst on the volatile components of biomass pyrolysis is examined in this study. This study focuses on the effects of varying pyrolysis temperatures and catalyst usage cycles on catalytic reforming, evaluating the resulting pyrolysis yield, syngas composition, and catalyst stability. Catalyst characteristics are also analyzed. The results of this study show that the Ni-Al2O3 catalyst modified with La2O3 alone produces a 9 % reduction in tar yield and a 20 % increase in the CO + H2 fraction of the pyrolysis gas compared to the control group. When modified with CeO2 alone, the Ni-Al2O3 catalyst keeps a tar conversion efficiency above 43 % after ten consecutive usage cycles. The addition of La2O3 and CeO2 simultaneously led to a 19 % increase in hydrogen yield, with the absolute content of alcohols, ketones, and esters reaching zero at 850°C.

Cerium oxide-reinforced Fe2O3–Na2O–SiO2–B2O3 glass matrix for protection against ionizing X and gamma rays

Radiation shielding glass is an interesting material in the field of radiation shielding due to its remarkable features. In the present paper, we investigated the physical properties of radiation-shielding glass materials that consist of sodium oxide (Na2O), cerium oxide (CeO2), and iron oxide (Fe2O3) incorporated into borosilicate glasses with the formula 90SiO2-(70-x)B2O3+ 20Na2O–1Fe2O3-xCeO2 (CeFeNaBS-glasses). One of the distinguishing characteristics of this glass system is its enhanced radiation shielding capabilities. The structural studies indicated a gradual rise in glass density from 1.954 to 2.658 g/cm with further CeO2 doping. Optical studies showed that the optical band gaps went down from 3.41 eV to 3.33 eV as the amount of CeO2 in the CeFeNaBS-glass matrix rose. The decrease in optical band gap has been correlated with the rising basicity. Also, the increased basicity behavior induces more conversion of Ce3+ to Ce4+ ions by losing a 4f electron. Moreover, with further CeO2 additions, the glass color changed from light brown to dark brown. The presence of Ce4+ ions with further CeO2 additions is responsible for this color transformation. The linear and non-linear refractive indices exhibit enhanced behaviors with higher CeO2 concentrations. We used declining basicity and polarizability behaviors to describe this behavior. The incorporation of larger CeO2 concentrations enhances the ability to improve radiation shielding properties, as demonstrated by the increased values of the mass attenuation coefficient and half-value layer, especially in the energy ranges of soft tissues X-ray and hard tissues X-ray. Hence, the investigated CeFeNaBS-glasses exhibit enhanced transparency and radiation shielding capabilities, rendering them highly suitable for implementation in this domain.

Reasonably construct GDY/CeO2/Mn0.2Cd0.8S double S-scheme heterojunction for improvement photocatalytic hydrogen production

Reasonably designing and optimizing the structure of photocatalysts aims to effectively enhance light absorption, accelerate charge separation and transfer, and achieve sustainable photocatalytic hydrogen production. In this study, a simple self-assembly method was used to prepare the GDY/CeO2/Mn0.2Cd0.8S ternary system. The addition of GDY and CeO2 significantly enhances the light absorption range of Mn0.2Cd0.8S, enhancing the separation and transmission of electron hole pairs and provides more active sites for hydrogen production. Moreover, an S-scheme heterojunction was constructed between the three catalysts, maximizing their oxidation–reduction ability. In addition, the built-in electric field formed between the catalysts also provides power for electron transfer, ensuring efficient and orderly reaction. This work provides ideas for the rational construction of heterojunctions, improving charge transfer, and designing high-performance catalysts to solve energy problems.

Microstructure and performance of AlCoCrFeNiCu(CeO2)X high-entropy alloy coatings by plasma cladding

AlCoCrFeNiCu(CeO2)X (x=0 wt%, 0.3 wt%, 0.6 wt%, 0.9 wt%, and 1.2 wt%) HEA coatings were applied via plasma cladding technology to a 35CrMo steel surface in this investigation. Electron back-scattering diffraction (EBSD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to analyze the phase composition and microstructure of the coatings. A microhardness meter, a nanoindenter, a wear test machine, and an electrochemical station were used to assess the coating performance. The findings demonstrate that the phase composition of the coatings is unaffected by the addition of CeO2, with all coatings consisting of FCC and BCC phases. CeO2 was added to the coatings to refine their grain size and increase their proportion of high angle grain boundaries (HAGBs), BCC phase content, and geometrically necessary dislocation (GND) density. These improvements led to significant increases in the microhardness and wear resistance of the coatings. The 0.3 wt% CeO2 coating has the best corrosion resistance, which is caused by a number of factors including the element distribution, grain size, content of each phase, and phase distribution of the coatings. The corrosion resistance of the coating increases and then decreases nonlinearly with increasing CeO2 content.

Enhancing the catalytic performance of Cu/ZnO/Al2O3 catalyst in methanol synthesis from biomass‐derived syngas with CeO2, MnO2 and ZrO2 as promoters

AbstractThe performance of Cu/ZnO/Al2O3 (CZA) catalysts promoted by addition of CeO2, MnO2 or ZrO2 in direct methanol production from unconventional syngas was experimentally investigated. The unconventional syngas used in this study contain 25% H2, 25% CO, 20% CH4, 20% CO2 and 10% N2, representing biomass‐derived syngas cultivated from an industrial wood chips pyrolysis plant. The catalysts were synthesised using co‐precipitation technique and tested for methanol synthesis in a fixed‐bed reactor. The activity test of the catalysts showed that the addition of CeO2 or ZrO2 to the CZA catalyst improved the methanol yield, albeit with lower selectivity, whereas adding MnO2 enhanced methanol selectivity but decreased the methanol yield. ZrO2‐promoted catalyst showed the best‐improved activity and stability. The calcined and spent catalysts were characterised using X‐ray diffraction (XRD), N2 physisorption, N2O chemisorption, hydrogen temperature‐programmed reduction (H2‐TPR) and X‐ray photoelectron spectroscopy (XPS). The characterisation results indicate that the catalytic activity is dependent on Cu dispersion, Cu‐active surface area, the catalyst reducibility, Brunauer–Emmett–Teller (BET) surface area and the Cu0/Cu+ ratio. In contrast, catalyst stability was related to the proportion of Cu+ among all surface Cu species.

Densification mechanism and microstructural evolution of Si3N4 composites with CeO2 as additives during spark plasma sintering

The densification mechanism of CeO2 doped Si3N4 ceramics during spark plasma sintering (SPS) was investigated. The sintering process was observed to undergo significant densification at the intermediate stage of sintering (1435 °C–1816 °C), and the density and grain size of CeO2 doped Si3N4 ceramic were found to be greater than those of pure Si3N4 ceramic under the same sintering conditions. To determine the densification mechanism, a creep model was utilized to determine the densification mechanism which could be interpreted based on the values of the stress exponent (n) and the apparent activation energy (Q d). The results revealed that the Q d of pure Si3N4 (381.15 kJ mol−1) is higher than that of Si3N4-CeO2 powder (265.61 kJ mol−1). Moreover, the stress exponent n of Si3N4-CeO2 powder (1.12–1.33) was higher than that of pure Si3N4 powder (1.00–1.18). This can be attributed to the fact that the addition of CeO2 resulted in the formation of a liquid phase at the grain boundary which leading to a shift in the controlling mechanism from grain boundary diffusion to grain boundary sliding.

Improving wear and corrosion resistance of HVAF sprayed 316L stainless steel coating by adding TiB2 ceramic particles and CeO2

316L stainless steel is used in a wide variety of corrosion-prone locations. However, its low hardness and poor tribological properties limit its application under heavy wear conditions. In this study, 316L Fe-based composite coatings co-doped with TB2 hard phases and rare-earth CeO2 exhibited excellent wear and corrosion resistance. Firstly, 316L-TiB2 cermet powder and (316L-TiB2)/CeO2 composite powder with high sphericity and density were prepared by high energy ball milling (HEBM), spraying drying granulation (SD), plasma spheroidization (PS) process. Then, 316L coatings, 316L-TiB2 and (316L-TiB2)/CeO2 cermet coatings were deposited by high velocity air fuel (HVAF) spraying. Finally, the effects of TiB2 and CeO2 additions on the microstructure, wear and corrosion behavior of the coatings were investigated. The results showed that TiB2 hard particles and CeO2 were uniformly distributed in the HVAF sprayed 316L-TiB2 and (316L-TiB2)/CeO2 coatings. The wear resistance of the coating prepared by 316L Fe-based composite powder with TiB2 and CeO2 is significantly improved. The hardness of the (316L-TiB2)/CeO2 composite coating was increased from 269 Hv0.3 to 826 Hv0.3 for the pure 316L coating, while the volumetric wear rate was only 3.6 % of that of the pure 316L coating (110 × 10−5 down to 4 × 10−5 mm3/N). Electrochemical tests show that the corrosion resistance of the coating decreases with the addition of TiB2 alone, but it can be improved by doping CeO2. The 316L Fe-based coating prepared by adding TiB2 and CeO2 can significantly improve the wear resistance of the coating, while the corrosion resistance decreases only slightly.

Effect of CeO2 Content on Microstructure and Wear Resistance of Laser-Cladded Ni-Based Composite Coating

In order to improve the wear resistance of 45 steel, in this study, WC/Ni60 composite coatings with different CeO2 additions (0, 1, 2, and 3 wt%) were prepared on 45 steel by the laser cladding technique; the experimental analysis was carried out by means of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), a Vickers hardness tester, and a friction and wear tester. The results show that CeO2 had little effect on the phase composition of the coatings; however, with the increase in CeO2 content, the CeO2 played a key role in refining the grains of the coating, thus reducing the generation of cracks. In addition, CeO2 could effectively strengthen the internal structure of the coating and improve its microhardness and wear resistance. Particularly noteworthy is the observed reduction in both the friction coefficient and mass loss of the coating when the CeO2 addition reached 2%. This suggests an enhancement in the tribological performance of the coating at this concentration.

Experimental investigation and thermomechanical performance evaluation of supercritical water oxidation of n‐dodecane/tributyl phosphate

AbstractBACKGROUNDNuclear energy has brought immense benefits while also generating a large amount of wastewater that urgently needs to be processed. Supercritical water oxidation (SCWO) technology serves as an efficient method for wastewater treatment. In this study, a SCWO experiment was carried out with organic solvent of 30% tributyl phosphate (TBP) and 70% n‐dodecane. This study investigated the operating parameters and the effects of enhanced oxidation techniques on chemical oxygen demand (COD) removal efficiency. An organic solvent SCWO process was developed, and its energy and exergy efficiencies were assessed using Aspen Plus.RESULTSThe COD removal was about 96.18% at the experimental parameters of 500 °C, 10 min, 25 MPa, oxidation coefficient of 1.5 and material concentration of 4 wt%. COD removal increased by 3.09% with the addition of CeO2. Finally, the overall energy and exergy efficiencies of the SCWO system were found to be 58.8% and 9.1% respectively by Aspen Plus.CONCLUSIONIt was found that the reaction temperature had the greatest effect on the COD removal rate compared with other reaction parameters. The decomposition of organic solvents can be divided into two stages, fast and slow, and the addition of alkali and catalyst can effectively promote the decomposition of waste organic solvents. The experiments showed that SCWO is feasible for the treatment of n‐dodecane/TBP. © 2024 Society of Chemical Industry (SCI).

Interface structure, mechanics and corrosion resistance of nano-ceramic composite coated steels

Ceramic coating is an effective means to suppress steel corrosion, while the interface performance is far from being understood. Herein, the effects of component doping on the interface structure, multi-scale mechanical properties and corrosion resistance of alumina-based ceramic-coated steels were studied by means of density functional theory (DFT) and experimental characterizations. The DFT results show that electron transfer issues occur significantly between Fe and O atoms at the Fe/Al2O3 interface. The larger valences of Fe and O are promoted by the doping of Ti, Zr, and Ce atoms, and improve the interfacial electrostatic interaction, spacing, and energy. It screens out the well mix proportions, that is, taking titanium doped alumina as the matrix, doped with Zr or Ce. Experiments confirm that incorporation of ZrO2 or CeO2 additives effectively improve the microstructure of the ceramic-coated steel, significantly enhancing both interface bonding and corrosion resistance. In addition, the element diffusion occurs at the interface between nano-ceramic coating and steel, forming an interfacial mutual pinning structure.

Boosting sulfur tolerance in Pd/beta zeolite catalyst for toluene oxidation: the role of CeO2

This study examined the impact of CeO2 addition on the sulfur tolerance of Pd/beta zeolite catalyst in toluene catalytic oxidation. By preparing and assessing Ce-modified beta zeolite-supported Pd catalysts, it is found that the toluene complete conversion over Pd/7.5Ce-beta zeolite occurs at 190 °C, with a minimal increase of 20 °C even after sulfur poisoning. It is shown that Ce-doping markedly enhances sulfur tolerance besides catalytic activity. The underlying mechanism involves CeO2 sites capturing sulfur species, thus safeguarding active Pd species from sulfur poisoning. It can be observed that Pd0 active sites, which are crucial in the catalytic high activity, are still present in the most severely poisoned catalyst. Furthermore, Ce-modified catalyst exhibits a more stable pore structure and increased acid strength after sulfur poisoning, all of which are beneficial to improving the sulfur tolerance. Consequently, Pd/Ce-beta zeolite is a promising solution for processing sulfur-containing volatile organic compounds, offering valuable insights for developing effective and sustainable catalysts for environmental remediation.

Spectroscopic Investigations of Complex Electronic Interactions by Elemental Doping and Material Compositing of Cobalt Oxide for Enhanced Oxygen Evolution Reaction Activity

AbstractDoping and compositing are two universal design strategies used to engineer the electronic state of a material and mitigate its disadvantages. These two strategies are extensively applied to design efficient electrocatalysts for water splitting. Using cobalt oxide (CoO) as a model catalyst, it is proven that the oxygen evolution reaction (OER) performance can be progressively improved, first by Fe‐doping to form Fe‐CoO solid solution, and further by the addition of CeO2 to produce a Fe‐CoO/CeO2 composite. X‐ray absorption spectroscopy (XAS) reveals that distinct electronic interactions are induced by the processes of doping and compositing. Fe‐doping of CoO can break down the structural symmetry, changing the electronic structure of both Co and O species at the surface and decreasing the flat‐band potential (Vfb). In comparison, subsequent compositing of Fe‐CoO with CeO2 induces negligible electronic changes in the Fe‐CoO (as seen in ex situ characterizations), but significantly modifies the oxidative transformations of both Co and Fe under OER conditions. The spectroscopic investigations reveal that Fe‐doping and CeO2 compositing play different roles in modifying the electronic properties of CoO in its pristine state and during OER catalysis, in return, providing useful guidance for the design of more efficient electrocatalysts using these two strategies.

Catalysis effect of rare earth element Ce on paste boriding treatment of AISI 410 steel

Abstract Surface hardening techniques of steel are of great practical interest for applications in various industrial sectors. Boriding is one of the most economical choices. However, the chief deterrent to the widespread application of the technique is the difficulty in attaining a thick, dense boride layer. To solve this problem, a paste boriding process was performed on the surface of AISI 410 steel by introducing 6 wt.% CeO2 addition into the boriding agent. The microstructure of the boride layer is comprised of (Fe, Cr)B and (Fe, Cr)2B, which lie in the external and internal layers of the boride layer, respectively. CeO2 addition makes it possible to prepare a thick, dense boride layer on the surface of the steel substrate, thereby improving both wear and corrosion resistance of the steel. The catalysis mechanism of the rare earth element Ce can be ascribed to three aspects. First, CeO2 addition can take part in the chemical reactions involved in the boriding process to produce more active boron atoms. Second, Ce can facilitate the adsorption of active boron atoms onto the surface of the steel through preventing the formation of iron oxides on the steel’s surface. Third, Ce can diffuse into the surface of the steel and generate severe lattice distortion due to large atomic size, thereby promoting the boron diffusion. These results provide a high-quality, low-cost pathway for the surface hardening of steel in practical industrial applications.

Enhancing Hardness and Wear Resistance of MgAl2O4/Fe-Based Laser Cladding Coatings by the Addition of CeO2

Laser cladding has unique advantages in improving the wear resistance of materials or workpiece surfaces. CeO2 could play a role in promoting the flow of the molten pool and grain refinement during the laser cladding process, which is likely to further improve the wear resistance of the coating. In this work, CeO2 was introduced into the MgAl2O4/Fe-based laser cladding coating on the surface of GCr15 steel. The effects of the CeO2 content on the phase composition, microstructure, hardness, and wear resistance of the coatings were also systematically investigated. The results showed that the addition of CeO2 enhanced the continuity of the coating and reduced the size of the MgAl2O4 particles, which was associated with the addition of CeO2’s intensification of the melt pool flow. The metal grain size reduced and then increased as the CeO2 content increased, whereas the hardness and wear resistance of the MgAl2O4/Fe-based coatings increased and then decreased. Compared with the MgAl2O4/Fe-based coating without CeO2, the hardness of the MgAl2O4/Fe-based coating with 1.0 wt% CeO2 increased by 10% and the wear rate decreased by 40%, which was attributed to the metal grain refinement and particle dispersion strengthening.

Optimization of syngas production via methane bi-reforming using CeO2 promoted Cu/MnO2 catalyst

Currently, syngas plays an important role in renewable and sustainable energy production. The idea of manufacturing syngas via bi-reforming methane, which involves the combination of methane (CH4), carbon dioxide (CO2), and steam, appears very promising. As a result, the goal of this research is to improve syngas output by improving process parameters in methane bi-reforming using a 3%Ce-15%Cu/MnO2 catalyst. Optimization analysis was performed using response surface methodology (RSM). The ultrasonic impregnation (UI) method was employed to synthesize the catalysts used in this study. Following that, the catalyst was characterized using several techniques such as Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed desorption (TPD), and temperature programmed oxidation (TPO). The findings of the characterization show that the presence of CeO2 promoters has a dual effect on the size of CuO crystallites. Firstly, it reduces the size from 19.07 nm to 13.66 nm because to the dilutive effect generated by the inclusion of CeO2. Second, the presence of CeO2 promoter accelerates the transition from CuO to Cu0 metallic phase. Furthermore, the addition of CeO2 boosts the CH4 and CO2 conversion rates by 23.65% and 24.93%, respectively. As a result, the H2 yield increases significantly when compared to the unpromoted catalyst. The study investigates the influence of process parameters, specifically the reaction temperature (700–900℃), CO2 ratio (0.2–1), and gas hourly space velocity (GHSV) (16–36 L g cat−1 hr−1), on the conversion of CH4 and CO2, as well as the H2/CO ratio. The optimization study finds that the highest conversion rates for CH4 and CO2 are 78.32% and 72.45%, respectively, when the reaction temperature is 800 °C, the CO2 ratio is 0.6, and the gas hourly space velocity (GHSV) is 26 L g cat−1 hr−1. The optimum conditions result in the highest syngas ratio of 1.77. The results of the optimization are then assessed using the mean errors. The H2/CO ratio, as well as the average errors for CH4 and CO2 conversions, are discovered to be 0.15%, 0.95%, and 0%, respectively.

Microwave dielectric properties of V2O5/CeO2 doped (Mg0.95Ca0.05)TiO3‐MgO and their application to a dielectric filter

AbstractThe phase composition, microstructure, sintering characteristics, and microwave dielectric properties of nonstoichiometric MgTiO3‐CaTiO3 ceramics containing an additional 0.2 mol MgO, compositely doped with various amounts of V2O5 and CeO2 additives, were studied. The results revealed that adding an optimum amount of V2O5 and CeO2 could effectively impede second‐phase formation in Mg0.95Ca0.05TiO3‐MgO. High amounts of Mg2+ can react with MgTi2O5 to reduce the content of the secondary phase. The addition facilitated the densification of the microstructure and reduction of sintering temperature. Moreover, the dielectric performances of the material were significantly influenced by V2O5 and CeO2. Mg0.95Ca0.05TiO3‐MgO doped with 0.75 wt% CeO2 exhibited excellent frequency and temperature stabilities. In particular, when co‐doped with 0.5 wt% V2O5 and 0.75 wt% CeO2, Mg0.95Ca0.05TiO3‐MgO exhibited optimum properties after sintering at 1300°C for 2 h; a dielectric constant εr ∼ 19.92 (7 GHz),a Q×f value ∼ 65,236 GHz, and a τf value ∼ −2.03 ppm/°C. This indicates the potential of the material for microwave communication applications. Finally, a dielectric filter with a center frequency of 11.55 GHz was successfully designed and fabricated using a Mg0.95Ca0.05TiO3‐MgO sample co‐doped with 0.5 wt% V2O5 and 0.75 wt% CeO2.The filter exhibited excellent performance with a bandwidth of less than 1.5 is about 40 MHz, the loss at the center frequency point was 0.7 dB, and the 3‐dB bandwidth exceeded 200 MHz, which holds a significant practical value.