Here in, FeZnK/ZrO2 catalysts were synthesized by using citric acid (CA) chelation method. These catalysts were pretreated under H-2(g) or CO(g) or CO/H-2(g) for 2 h at 350 degrees C and subsequently tested in CO2-FT reaction at 300 degrees C and 2.0 MPa. The resultant fresh or spent samples were characterized by using BET-SA, XRD, TPD, TPR, XPS, HR-TEM, SEM-mapping-EDX and Mossbauer techniques. Improved textural properties (SA/pore width) and uniformly dispersed iron particles were obtained in FeZnK/ZrO2 catalysts through CA chelating method as established by BET-SA and SEM-mapping results respectively. The carbidization under CO/H2(g) produced Fe7C3 phase due to the ease reduction of dispersed iron oxides in CA catalyst as evidenced by XRD, HR-TEM and Mossbauer results. On the other hand, CA catalyst carbidized under CO(g) exhibited Fe7C3/Fe phases suggests inadequate carbidiztion of reduced iron species in agreement with H-2-TPD results. Among the CO/H-2 gas pretreatment ratio (0.45, 0.93 and 1.25), Fe7C3 with optimum particle size of 30.0 nm was achieved at CO/H-2(g) = 0.93. Two fold increase in the -C2-C4= olefins yield (7.29 mmol gcat catalyst (3.24 mmol gcat(-1) h(-1)) was observed for CA catalyst. It was associated with stable Fe7C3 phase existed in a greater extent on the surface (Fe-C = 0.21 atom.%) in close vicinity to K (0.25 atm.%) and resulted in dissociative activation of adsorbed CO2/H-2(g). In the present study, citric acid chelating method followed by CO/H-2 gas pretreatment at 350 degrees C for only 2 h generated stable Fe7C3/ZrO2 unlike, literature reports (5-10 h pretreatment) and has the potential for further developments in CO2-FT process.

Increased demand for ethylene has motivated direct ethane dehydrogenation over Pt-based catalysts. PtSn/γ-Al2O3 and PtSnZnCa/γ-Al2O3 catalysts were investigated with the aim of understanding the effect of the pretreatment environment on the state of dispersed Pt for ethane dehydrogenation. The catalysts were prepared by the impregnation method and pretreated in different environments like static air (SA), flowing air (FA), and nitrogen (N2) atmospheres. A comprehensive characterization of the catalysts was performed using Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), Temperature-Programmed Reduction (TPR), NH3 Temperature-Programmed Desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), and Transmission Electron Microscopy (TEM) techniques. The results reveal that the PtSn on Al2O3 catalyst pretreated in the static air environment (PtSn-SA) exhibits 21% ethylene yield with 95% selectivity at 625 °C. XPS analysis found more platinum and tin on the catalyst surface after static air treatment. The overall acidity of the catalysts decreased after thermal treatment in static air. Elemental mapping demonstrated that Pt agglomeration was pronounced in catalysts calcined under flowing air and nitrogen. These factors are responsible for the enhanced activity of the PtSn-SA catalyst compared to the other catalysts. The addition of Zn and Ca to the PtSn catalysts increases the yield of the catalyst calcined in static air (PtSnZnCa-SA). The PtSnZnCa-SA catalyst showed the highest ethylene yield of 27% with 99% selectivity and highly stable activity at 625 °C for 10 h.

The La based perovskite type LaMO3 (M = Ni, Co) oxides were prepared by combustion synthesis method using citric acid as organic fuel. These catalyst precursors tested for ammonia decomposition. The LaNiO3 and LaCoO3 catalysts showed good activity for NH3 decomposition. The LaNiO3 catalyst displayed greater activity than LaCoO3. This due to high surface area and easily reducibility of Ni species. A 50% of La was substituted by Ce in both LaNiO3 and LaCoO3 catalysts. A remarkable effect on catalytic performance was observed with the partial substitution of La by Ce in perovskite catalyst especially at lower temperatures. The La0.5Ce0.5NiO3 catalyst exhibited highest activity among all prepared samples. The achieved superior activity is due to boost in surface area, reducibility and suitable basicity. The SEM elemental mapping of La0.5Ce0.5NiO3 catalyst concluded that metal oxide constituents dispersed homogeneously. The La0.5Ce0.5NiO3 catalyst showed excellent stable catalytic performance during 50 h time on study at 550 °C.

Mesoporous tantalum-zirconium oxide (TZ) solid acid catalysts were synthesized by sol-gel method and employed in the biodiesel production from higher water (2.0 and 4.0 wt%) and palmitic acid (20.0 wt%) added soybean oil (SBO) or yellow grease feedstocks. Characterization of TZ catalysts were done by using BET-surface area, XRD, Raman spectroscopy, XPS and NH3-TPD techniques. Only 35.0% methyl palmitate and 14.0% SBO fatty acid methyl ester (FAME) yield was obtained on bare ZrO2 at 180 degrees C. Addition of tantalum to ZrO2 significantly improved the yield of methyl palmitate (95.0%) and SBO FAME (88.6%) at 180 degrees C. The greater ester yield on TZ catalysts was associated with improved acidity due to the presence of Ta-O-Ta, Ta--O and Zr-O-Ta species which readily interacted with methanol and triglycerides. Further, 20.0 mol.% tantalum loaded zirconium oxide catalyst (20TZ) exhibited consistent biodiesel yield upto two recycles of feed containing 2.0 wt% of added water and 20 wt% PA in SBO. It is noteworthy that, 80.0% yellow grease FAME formation was observed on 20TZ catalyst at 180 degrees C. The results emphasize, TZ solid acid catalysts are highly efficient compared to polyoxometalates and or sulphated zirconium oxide solid acid catalysts for biodiesel production from higher water and free fatty acid containing feedstocks.

This study is aimed at investigating the impact of catalyst preparation’s approach (either sequential and/or simultaneous wet impregnation) to a mesoporous series of Pt/A, Sn/A, PtSn/A, SnPt/A, (PtSn)/A, (PtSn)Zn/A, and (PtSnZn)/A catalysts for direct ethane dehydrogenation. The (PtSn)/A and (PtSnZn)/A had shown both higher initial specific activity (s-1) and reaction rate constant Kd (h-1) (13063.86 (s-1) and 12489.69 (s-1) and 0.09 (h-1) and 0.06 (h-1)), respectively. The catalyst preparation approach had direct impact to the availability and dispersion of mesoporous particles of either active metal and/or promoter that influences either to hinder the C-C cleavage and/or to promote C-H bond cleavage in the dehydrogenation of ethane to ethene. The active metal component was present in the form of Pt, Pt+2, Al+3, Sn+4, and Zn+2 states. The enhanced catalytic activity is attributed to the Pt4Sn and PtZn formed phases in addition to highly dispersed mesoporous Pt particles. Based on the obtained results, the catalysts prepared by using simultaneous wet impregnation had shown higher catalytic activity and catalyst stability as to that of sequential wet impregnation.

Herein, we report high-performance Pd and Ca-promoted Pd nanoparticles (NPs) (similar to 2-6 nm) over mesoporous CeO2 with dual functionality of converting CO2 to methanol and its dehydration to di-methyl ether (DME) in a single catalyst bed prepared by a single-pot sol-gel chelating (SGC) method. Moreover, Ca promotion (0.5wt. %, optimized value) greatly improved the catalytic performance (X-CO2 : 30.5 %, S-DME: 70.5 % and space time yield (STYDME): 5276 mmol/kgcat.hr at 325 degrees C and 20 Bar) by increasing Pd-0 content over CeO2 and tuned the redox properties of CeO2 as well as basicity/acidity of tested samples as evidenced by the characterization results. In situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) provided insights of the formation of DME and CH4 with visible respective IR bands along with the identification of various transient surface species emerged over the catalyst surface at actual reaction conditions which led us to propose a reaction mechanism following a formate route to methanol and its subsequent dehydration to dimethyl ether. (C) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

This study is aimed to understand the role of alkaline earth elements (AEE) to the catalytic performance of PtSnM1/γ-Al2O3catalystfor the direct propane dehydrogenation (where M1 = Mg, Ca, Sr, Ba). All the catalysts were prepared by using wet impregnation.The overall catalytic performance of all the catalysts was studied at different reaction temperatures, feed composition ratios and GHSV. The best operating reaction conditions were575and#186;C, feed composition ratio of C3H8:H2:N2 = 1.0:0.5:5.5 and GHSV of 3800h-1. An optimal addition of “Ca” to PtSn//γ-Al2O3 catalyst, enhanced the catalytic activity of PtSnM1/γ-Al2O3 catalyst in comparison to other studied AEE. This catalyst had shown the highest propane conversion (~ 55.8 %) with 95.7 % propylene selectivity and least coke formation (7.11 mg.g-1h-1). In general, the increased catalytic activity of PtSnM1/γ-Al2O3 is attributed to the reduced coking extent during the reaction. In addition, the enhanced thermal stability of the PtSnCa/γ-Al2O3catalystis because of the protective layer betweenγ-Al2O3 and active metal, which allows the formation of active species such as PtSn, PtCa2 and Pt2Al phases?

This study is aimed to investigate the electro-catalytic activity of Au supported on both CeO2 and activated carbon (AC) to convert CO2 to mixture of C1-C4 hydrocarbons in the presence of ionic liquid (IL) 1-butyl-3-methylimidazolium methylsulfonate. The studied catalyst samples were prepared by using simultaneous wet impregnation method. The sample containing 0.6 % Au showed higher electro-catalytic activity than the sample contained 0.3 % Au. Both, the average Au particles size and the transformation of layered non-uniformed semi-oval structure to flaked tiny circular like-structure were mainly responsible for the higher catalytic activity of 0.6Au-CeO2-AC sample. In addition, the overall electro-catalytic activity depends upon the applied reaction voltage. Overall, the presence of IL, the surface morphology, and average Au particles size had played a key role in the electro-catalytic conversion of CO2 to hydrocarbons.

The aim of this work is to understand the influence of second metals (M = Ce or Pd or Nb) on Mo2C active phase reduction into metallic molybdenum and on surface MoOx species of M-Mo2C/HZSM-5 catalysts studied for methane dehydroaromatization at 700 °C with GHSV 1800 mL. gcat−1. h−1. The fresh and spent catalysts were characterized by using ATR-FTIR, HRTEM/STEM, BET surface area, XRD, TPO, NH3-TPD-mass, XPS and H2-TPR techniques. Essentially, the highest benzene yield of 8.4% on Pd–Mo2C/HZSM-5 catalyst for 10 h of continuous operation was associated with limited Mo2C active phase reduction into metallic molybdenum at Pd–Mo proximity via Pd2+ to Pd0 step and promoted coke burning through reduced carbon deposits formation. Further, the surface reduction of CeO2 to Ce2O3 decreased the methane conversion due to sluggish MoOx species transformation to Mo2C active phase. On the other side, Nb2O5 primarily reduced into NbO2/NbO resulted in surface MoOx species and external surface Mo2C particles eventually produced superior coke via CH4 decomposition on Nb–Mo2C/HZSM-5 catalyst. The decreasing order of benzene yield after 10 h of reaction at 700 °C as follows: Pd–Mo2C/HZSM-5 (8.4%) > Mo2C/HZSM-5 (7.4%) > Nb–Mo2C/HZSM-5 (5.8%) > Ce–Mo2C/HZSM-5 (5.2%).

Excellent CO2 hydrogenation activity results were obtained on Cu-Zn-Al-K (CZA-K) catalyst with 10% of CO2 conversion and 98% of methanol selectivity at 220 degrees C. The CZA-K catalyst was precipitated by using 4 M K2CO3/KOH solution. For comparison purpose, CZA-Na and CZA catalysts were synthesized by using 4 M solutions of Na2CO3/NaOH and (NH4)(2)CO3/NH4OH respectively. Characterization of these catalysts was done by using BET-poresize, XRD, FTIR-DRIFTs, high pressure-TPR, CO2-TPD-mass, XPS and HAADF-STEM-EDX techniques. Among the catalysts studied maximum methanol space time yield of 14.4 mmol.g(cat)(-).h(-) was obtained on CZA-K at 240 degrees C with 2400 h(-) GHSV of CO2/H-2 mole ratio equals to 1:4. Greater methanol yield was associated with superior surface Cu+/Cu-0 content in CZA-K was obtained through K2CO3/ KOH precipitation. Further, FTIR-DRIFTs spectra suggests the interaction of CO(2 )with the potassium existed in the CZA framework (0.65% K, EDX) led to the formation of K-O-(CO)-O surface species. To some extent, CO2 dissociation to CO and subsequent CH4 formation was limited by this species in presence of H-2. At 240 degrees C, steady catalytic activity was observed for 100 h of continuous operation on CZA-K. It was associated with fewer carbon deposits formation and segregated active metals in CZA-K catalyst. The decreasing order of CO2 hydrogenation activity at 240 degrees C with 3.0 MPa feed-gas pressure as follows: CZA-K (14% CO2 conversion and 96% methanol selectivity) > CZA-Na (11% and 94%) > CZA (9% and 92%). (C) 2020 The Authors. Published by Elsevier B.V. on behalf of King Saud University.

High surface area tungsten nitride catalysts synthesized from ammonium meta-tungstate and employed as catalysts for ecofriendly H-2 production from NH3. A series of tungsten nitride catalysts synthesized by using CiA (citric acid) as chelating agent with different molar ratio of W and CiA. The synthesized materials characterized using BET-surface area, X-ray diffraction, X-ray photoelectron spectroscopy and SEM techniques. The BET value of as-synthesized tungsten nitride was raised from 25 to 80 m(2) g(-1). The influence of amount of CiA in preparation on the catalysts surface area was investigated. The catalyst performance measured within the desired range of temperature 300-600 degrees C. A pure phase of tungsten nitride was formed by this preparation method. The catalyst with the ratio of CiA/W = 3 exhibited the best catalytic performance. The increased activity of WN-31 catalyst was mainly due to increased surface area, decreased particle size and high surface concentration. The WN-31 catalyst showed stable performance during time on study for 25 h. These bulk tungsten-based materials are easy to synthesize and highly stable material in the reaction atmosphere. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Here in, for the first time we are reporting molybdenum carbide reduction into metallic molybdenum during methane aromatization on HZSM-5 (Si/Al ratio = 23, 30, 50 and 80) at methane space velocity of 1800 mL.gcat−.h−. Benzene yield was influenced by the surface metallic molybdenum through the non-aromatic carbon deposits formation via linear hydrocarbons degradation on HZSM-5 with fewer acidity (Si/Al ratio = 30, 50 and 80). Our XPS analysis results demonstrated improved surface metallic molybdenum in spent Mo2C/HZSM-5 = 80 (0.71 atom. %) and 50 (0.54 atom. %) samples over Mo2C/HZSM-5 = 30 (0.33 atom. %) and 23 (0.20 atom. %) samples. Furthermore, HR-TEM and FFT analysis images clearly established fine distribution of distorted spherical shaped Mo2C particles with 6–14 nm size in spent Mo2C/HZSM-5 = 23. On the other hand, Mo2C particle size was increased upto 22 nm in Mo2C/HZSM-5 = 80. The ease reduction of Mo2C into metallic molybdenum and aggregation of Mo2C particles in spent higher Si to Al ratio (50 and 80) samples was associated with weak interactions between Mo2C and the HZSM-5 with fewer acidity. At 700 °C, the order of benzene yield as follows: Mo2C/HZSM-5 = 80 (2.2%) < Mo2C/HZSM-5 = 50 (3.25%) < Mo2C/HZSM-5 = 30 (5.2%) < Mo2C/HZSM-5 = 23 (8.0%).

PdZn-based catalysts have evolved as a very effective catalytic material for CO2 hydrogenation to methanol. ZrO2-supported PdZn and Ca-PdZn catalysts, synthesized by the simple impregnation method, exhibited excellent catalytic activity with impressive selectivity to methanol when tested for direct CO2 hydrogenation reaction. These catalysts were able to achieve up to 97-100 % methanol selectivity with significant CO2 conversion (single-pass of more than 10% in the case of Ca-doped PdZn/ZrO2) under reaction conditions of 20-30 bar, 2400 mL/g-h, H-2/CO2 = 3:1, 220-270 degrees C. Addition of calcium to PdZn/ZrO2 catalyst had a positive impact on overall catalytic performance and catalyst lifetime. Ca-doped PdZn/ZrO2 catalyst also showed high stability for at least 100 h (on stream) implying the catalyst was very stable and resistant to sintering. The catalysts were characterized using BET, CO-chemisorption, CO2-TPD, XRD, XPS, SEM-EDS and TPR. Whereas, in-situ DRIFT study identified surface reaction transient intermediates, formates and methoxy species, and therefore, a reaction mechanism of formate pathway is proposed based on the DRIFT analysis.

The influence of Pd loading was studied for the gas phase catalytic hydrodechlorination of 1,2,4-trichlorobenzene over Pd supported on Mg-Al mixed oxide support with Mg:Al ratio 2:1. The Mg-Al support was prepared from hydrotalcite precursor. A series of catalysts was prepared with different loadings of Pd (1–6 wt%) on Mg-Al mixed oxide support. The performance of catalytic material was evaluated at different temperatures ranging from 425–575K. The fresh and used catalysts were characterized with different analytical techniques such as BET surface area, X-ray diffraction studies, Temperature programmed reduction, X-ray photoelectron spectroscopy and CO-chemisorption studies. H2-Temperature programmed desorption studies was also performed to understand the metal-support interaction and suitable active sites. The 4wt% of Pd on Mg-Al mixed oxide catalyst showed the highest conversion and selectivity among all catalysts and maintained steady activity with 10 h of time-on-stream studies. The main reasons for high activity are suitable metal-support interactions, Pd particle size, high surface area, and high surface Pd atomic concentration. The influence of Pd loading was studied for gas phase catalytic hydrodechlorination of 1,2,4-trichlorobenzene over Pd supported on Mg-Al mixed oxide support with Mg:Al ratio 2:1. The different Pd-loadings in catalyst was studied for hydrodechlorination. The 4wt% of Pd on Mg-Al mixed oxide catalyst showed the highest performance among all the catalysts.

Mg-Fe Layered Double Hydroxide (LDH) with M2+: M3+ 3:1 stoichiometric ratio was synthesized and employed as catalyst precursor for COx-free hydrogen production from ammonia. The resulting catalyst showed good catalytic activity. A series of Mg/Co-Fe layered double hydroxides were synthesized by replacing Me2+ with Co2+ without disturbing M2+:M3+ ratio. The influence of nature and extent of Co(II) substitution on structure, morphology and surface properties were studied. A systematic study was carried out using these materials as catalyst precursors for ammonia decomposition. BET, XRD, TPR, XPS, CO2-TPD and TEM techniques were used to characterize the synthesized catalysts. These Fe-based catalysts are highly active, highly stable and not promoting any stable surface nitridation during the ammonia decomposition reaction. Among all catalysts, the Mg3Co3Fe2 catalyst showed the highest activity i.e. 100% conversion at 6,000 h(-1) and 60% at 50,000 h(-1) space velocities at 550 degrees C. The registered superior catalytic activity was result of the formed specific catalyst's properties like high surface area, high surface Co and Fe atomic concentration and suitable basicity. These Fe-based materials are, cost-effective, easily synthesize and highly stable, thus attractive for large-scale operation. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Different mole ratio Al-B catalysts (Al-10B to Al-35B) were synthesized by using sol-gel (SG) method. Ethyl benzene (EB) dehydrogenation in the presence of oxygen and water steam was carried out on these catalysts at 450–500 °C with EB contact time of 0.54 gcat.s.cm–3. Acidity of Al-B catalysts was estimated by using NH3-TPD-mass spectral analysis studies. SEM-mapping images revealed fine distribution of boron up to 15% of its loading in alumina (Al-15B), whereas, boron aggregation was observed in higher boron content (Al-25B and Al-35B) catalysts. Essentially, acid sites of very weak strength (Tmax ≤ 125 °C) were observed for Al and Al-10B catalysts and resulted in low EB conversion and styrene yield. On the other hand, acid sites of weak strength (Tmax ≤ 180 °C) were observed for Al-25B and Al-35B catalysts and resulted in high EB conversion. However, greater styrene yield (43.2%) with reasonable EB conversion (46%) was obtained on acid sites of weak moderate strength in Al-15B catalyst. Further, Al-15B catalyst was synthesized by using co-precipitation (COP) and impregnation (IMP) methods. Acid sites related to NOx formation during the NH3-TPD-mass analysis on IMP and COP catalyst essentially improved the EB conversion to 66% and 63% respectively at 500 °C. However, these acid sites were diminished in Al-B SG catalyst and resulted in 50% of EB conversion at 500 °C. At 50% of EB conversion level, styrene selectivity of 73%, 82.5% and 84% were observed on Al-B IMP, Al-B COP and Al-SG catalysts, respectively. Hence, different method of preparation of Al-B catalyst generated acid sites of different strength and density and thereby influenced the styrene formation.

We report the compositional optimization of Pd:Zn/CeO2 catalysts prepared via sol-gel chelatization for the hydrogenation of CO2 under mild reaction conditions. The formation of a PdZn alloy, which is the main active phase for this reaction, was maximized for the catalyst with a Pd to Zn ratio close to 1. For this catalyst, a maximum conversion of 14%, close to thermodynamic equilibrium, and high selectivity to methanol (95%) were achieved at 220 degrees C, 20 bar, 2400 h(-1) GHSV and H-2:CO2 stoichiometric ratio of 3:1. The formation of PdZn alloys was achieved by reducing the catalyst precursor at 550 degrees C under hydrogen flow and confirmed by XRD. XPS study confirmed the presence of Pd, being maximum for the optimized catalyst composition. At lower temperature, i.e. 180 degrees C, 1.0PdZn catalyst showed 100% selectivity to methanol with 8% CO2 conversion. RWGS reaction is responsible for the production of CO and its selectivity increases with temperature. In situ DRIFTS suggests that CO2 is activated as adsorbed CO3- species over CeO2. Surface micro-kinetics demonstrates that methanol can be formed either via formaldehyde or formic acid surface intermediates.

Silver catalysts supported on ceria-zirconia (CZ) mechanically mixed oxide were synthesized by wet impregnation and chelating methods. Nominal loadings of 5 wt.% of Ag was deposited on the CZ support. These catalysts were tested for the CO2 hydrogenation reaction to methanol with feed gas composition of CO2–H2 = 3:1 at 250 °C, 20 bar total pressure and GHSV of 1800 h−1. The calcined and reduced catalysts were characterized using XRD, BET, TPR, SEM-EDS, XPS and FTIR-DRIFTs techniques. Finely deposited silver crystallites sized in the range of 20–50 nm were observed through SEM and HR-TEM analysis. TPR and XRD studies demonstrated the presence of Ag2O and metallic silver (Ag0) on CZ support. About 10% of CO formation was observed on chelating catalyst (5Ag/CZ CHE). However, only, 5% CO was observed on impregnated (5Ag/CZ IMP) catalyst. The greater CO formation was associated with ease reduction of Ag2O to metallic silver in 5Ag/CZ CHE catalyst. Further, 70% of methanol selectivity was observed on 5Ag/CZ IMP due to the presence of Ag2O on CZ. FTIR-DRIFTs results revealed the methanol formation via formate intermediates and CO formation via RWGS reaction on the studied catalysts.

This work focuses on a novel synthesis route, using citric acid as a chelating agent, for the formation of gamma-Mo2N and Co3Mo3N bulk catalyst and their application for NH3 decomposition reaction for hydrogen production having its application for onboard generation of hydrogen for fuel cell in transportation vehicles. Successful formation of the pure bulk phase of Co3Mo3N was confirmed by using XRD, XPS, HRTEM techniques. The prepared Co3Mo3N catalyst showed high surface area 15.23 m(2)/g and high catalytic activity compared to bulk gamma-Mo2N for this decomposition reaction, having 97% conversion of NH3 at 550 degrees C at 6000 h(-1). (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Oxides of chromium (Cr), molybdenum (Mo), or tungsten (W) were supported on mixed oxides of cerium and zirconium (CeO2-ZrO2) by an incipient wetness impregnation process, and used to investigate their activities for partial oxidation of methanol. High Resolusion Transmission Electron Microscope (HR-TEM) revealed that nanoparticles of Cr2O3, MoO3 or WO3 were formed on the CeO2-ZrO2 support. The particle sizes of Cr2O3, MoO3 and WO3 were 2-4, 3-6 and 4-5 nm, respectively. As a result of partial oxidation of methanol at 275 – 450 °C, formaldehyde (CH2O) was obtained as the major product over all these catalysts. Cr2O3 supported on CeO2-ZrO2 produced both CO and CO2 along with H2 production, while MoO3 and WO3 on CeO2-ZrO2 support generated only CO as a by-product. It was found that MoO3 supported on CeO2-ZrO2 showed the highest methanol conversion and CH2O yield among these three catalysts.