γ-Al2O3 Catalyst Research Articles

Performance comparison of WO3/SiO2 to ZSM-5 and γ-Al2O3 in the catalytic dehydration of methanol

The performance of ZSM-5, γ-Al2O3 and WO3/SiO2 catalysts for the dehydration of methanol was studied in a fixed bed reactor over a temperature range of 150 to 450 °C and at atmospheric pressure. A parallel reaction scheme for dehydration of methanol to dimethyl ether and methane was proposed for the WO3/SiO2 catalyst, and kinetic parameters for the two reactions were identified. The WO3/SiO2 catalyst was less active than both ZSM-5 and γ-Al2O3 for dehydration. At temperatures above 400 °C, experimental data indicated that WO3/SiO2 could be producing heavier hydrocarbons than the other catalysts. The gas product for γ-Al2O3 and WO3/SiO2 also contained ethylene and methane whereas the gas product for ZSM-5 contained propane and propylene. At higher temperatures ZSM-5 produced gasoline range hydrocarbons but a similar product was absent from all experiments conducted using the WO3/SiO2 and γ-Al2O3 catalysts. It has been shown that WO3/SiO2 can function as a methanol dehydration catalyst for the synthesis of dimethyl ether.

Effective Cu/Re promoted Ni-supported γ-Al2O3 catalyst for upgrading algae bio-crude oil produced by hydrothermal liquefaction

Catalytic hydrotreating of algae bio-crude oil from hydrothermal liquefaction (HTL) of Nannochloropsis sp. was performed. Different Ni-based catalysts, including Ni/γ-Al2O3, Ni-Cu/γ-Al2O3, Ni-Re/γ-Al2O3, and Ni-Cu-Re/γ-Al2O3, (10%Ni, 5%Cu, 2.5%Re) were used in upgrading of the bio-crude oil. Most catalytic systems could effectively eliminate S and decrease the N and O contents, and enhance more than 20% improvement in the higher heating value (HHV) of the bio-oil (34 to 41–45 MJ/kg). Introducing only Cu could enhance the CO hydrogenation resulting in higher aromatic and alcohol compounds. While the addition of Re is effective for hydrodeoxygenation, it lowers denitrogenation due to amination reaction. Ni-Cu-Re/γ-Al2O3 ternary alloy offered the best results on the overall performance, achieving the highest upgraded bio-oil yield of 58 wt% and the highest energy recovery in the upgrading process (ERupgrade) of 64.6%. As ER in HTL process (ERHTL) was ca. 71.8%, the overall ER (ERoverall) from algae biomass to upgraded bio-oil of 46.4% can be achieved for Ni-Cu-Re/γ-Al2O3 catalyst. Carbon efficiency approx. 47.7% can be attained as the carbon in the algae biomass feedstock was retained in the upgraded bio-oil. In addition, reaction pathways for the formation of different hydrotreated products catalyzed by mono-, bi-, and tri- metallic Ni-Cu-Re have been proposed.

Boosting hydrodesulfurization activity of CoMo/Al2O3 catalyst via selective graphitization of alumina surface

The positive effect of alumina surface graphitization by CVD with ethylene on the activity of CoMo catalysts in hydrodesulfurization has been demonstrated. X-ray diffraction, Raman spectroscopy, High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and nitrogen physisorption showed that alumina surface graphitization does not significantly change the morphology and textural characteristics of the support. However, it has a significant impact on the morphology of supported sulfide component resulting in the formation of particles with a shorter slab length (2.9 vs 3.3 nm) and higher stacking number (2.4 vs 2.1) as compared to the sample based on γ-Al2O3. The results of CoMoS/γ-Al2O3 and CoMoS/[email protected]γ-Al2O3 catalysts testing in hydrotreating reactions demonstrated a similar activity in hydrodenitrogenation of quinoline and 1.7 times higher activity of CoMoS/[email protected]γ-Al2O3 in hydrodesulfurization of dibenzothiophene. Higher hydrodesulfurization activity of CoMoS/[email protected]γ-Al2O3 sample is attributed to improved dispersion of the supported sulfide component and enhanced promotion of MoS2 by cobalt. Thus, the simple CVD approach presented here allows selective modification of the surface of commercially available alumina supports with a layer of graphite-like carbon and can be used to improve the activity of conventional hydrotreating catalysts.

NO x storage and reduction assisted by non-thermal plasma over Co/Pt/Ba/γ-Al2O3 catalyst using CH4 as reductant

NO x storage and reduction (NSR) technology has been regarded as one of the most promising strategies for the removal of nitric oxides (NO x ) from lean-burn engines, and the potential of the plasma catalysis method for NO x reduction has been confirmed in the past few decades. This work reports the NSR of nitric oxide (NO) by combining non-thermal plasma (NTP) and Co/Pt/Ba/γ-Al2O3 (Co/PBA) catalyst using methane as a reductant. The experimental results reveal that the NO x conversion of NSR assisted by NTP is notably enhanced compared to the catalytic efficiency obtained from NSR in the range of 150 °C–350 °C, and NO x conversion of the 8% Co/PBA catalyst reaches 96.8% at 350 °C. Oxygen (O2) has a significant effect on the removal of NO x , and the NO x conversion increases firstly and then decreases when the O2 concentration ranges from 2% to 10%. Water vapor reduces the NO x storage capacity of Co/PBA catalysts on account of the competition for adsorption sites on the surface of Co/PBA catalysts. There is a negative correlation between sulfur dioxide (SO2) and NO x conversion in the NTP system, and the 8% Co/PBA catalyst exhibits higher NO x conversion compared to other catalysts, which shows that Co has a certain SO2 resistance.

Highly Active and Selective PtSnM1/γ-Al2O3 Catalyst for Direct Propane Dehydrogenation

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?

Highly Active and Selective PtSnM1/γ-Al2O3 Catalyst for Direct Propane Dehydrogenation

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?

Promoted adsorption of methyl mercaptan by γ-Al2O3 catalyst loaded with Cu/Mn

This paper describes the effect of loaded metal(including Fe, Cu, Mn, and Co) on catalytic performance of γ-Al2O3 catalysts for the removal of CH3SH. The catalysts are synthesized by the method of impregnation, and used in room temperature to absorb CH3SH. The experiment investigated the effect of components, loading and calcination temperature for the catalytic activity. The results showed that metal-modified γ-Al2O3 can enhance removal effect of CH3SH. CH3SH removal capacity of various metal-reforming catalysts decline as follows: Cu–Mn/γ-Al2O3> Cu–Co/γ-Al2O3≈ Cu/γ-Al2O3> Cu–Fe/γ-Al2O3> Co/γ-Al2O3> Mn/γ-Al2O3> Fe/γ-Al2O3. Among these samples the γ-Al2O3 catalyst loaded with 15% Cu and 5% Mn has the best removal rate and stability, which could reach a 100% removal rate of CH3SH in about 85 min. The catalysts were characterized by XRD, N2-adsorption/desorption techniques, CO2-TPD and FT-IR. It indicated that CuO was the mainly active ingredient on γ-Al2O3 carrier. Meanwhile, as the second elements, MnOx was in favor of diffusion of CuO on the carrier and improved activity of catalyst.

Elucidating the origin of selective dehydrogenation of propane on γ-alumina under H2S treatment and co-feed

A bulk γ-Al2O3 catalyst shows high selectivity for propane dehydrogenation upon pretreatment and co-feeding with H2S. The reaction kinetics, deactivation rates, and active sites for propane dehydrogenation on this catalyst were characterized using fixed bed conversion studies, NH3-TPD, O2-TPO, XPS, and density functional theory (DFT). Specifically, we observe that the selectivity to propylene was 94% at ca. 16% propane conversion at 560 °C for a C3H8:H2:H2S ratio of 1.1:1:0.1 on γ-Al2O3. Our results indicate that H2S can irreversibly modify the active sites of γ-Al2O3, postulated to be defect sites on the 110 facet comprised of a tri-coordinated Al atom, such that the modified site was more active and selective towards propylene and less inhibited by co-fed H2S. Along with XPS and O2-TPO, the dehydrogenation-regeneration experiments suggest the formation of sulfurous coke and strong adsorption of reaction products result in a less active catalyst. This study shows the potential of alumina/metal-sulfide as an earth-abundant and relatively benign class of catalysts for alkane activation, especially in the context of sour natural gas upgrading.

Enhanced catalytic activity of ultrasmall NiMoW trimetallic nanocatalyst for hydrodesulfurization of fuels

As the need of the hour, it is imperative to develop highly active HDS catalyst capable of desulfurizing refractory organic sulfur compounds (DBT; 4, 6 DMDBT etc.). In comparison to well established bimetallic catalysts (e.g. NiMo/NiW), trimetallic catalysts exhibit synergistic effect between active metal species which promotes both direct desulfurization (DDS) and hydrogenation pathway (HYD) and hence display higher catalytic activity. The synergistic effect is determined by the catalytically active amorphous phase formed due to partial substitution of Mo by W during synthesis of trimetallic nanocatalysts. This can be achieved by synthesizing the catalyst as ultrasmall size nanocatalysts. To this end, in the present study we report NiMoW trimetallic nanocatalysts preparation procedure using colloidal synthesis technique. For the sake of better comparison, Ni/(Ni + Mo + W) molar ratio for all the investigated catalysts (bimetallic and trimetallic) was kept the same (~0.28 ± 0.03). For the hydrodesulfurization of dibenzothiophene (DBT), because of improved synergistic effect, trimetallic NiMoW/γ-Al2O3 showed ~ 36% higher conversion in comparison to NiMo/ γ-Al2O3 and ~ 21% higher DBT conversion in comparison to NiW/ γ-Al2O3 catalyst. The catalytic activity of synthesized nanocatalysts was compared with catalyst prepared using well established metal impregnation method. Improved catalytic activity in case of synthesized NiMoW nanoclusters is attributed to the controlled partial substitution of Mo by W during the colloidal synthesis which enhances the synergistic effect.

Preparation and Catalytic Activity of Co-Mo/γ-Al2O3 Catalyst for Hydro-desulfurization Reaction

In this study, a bimetallic CoMo spicy supported on γ-Al2O3 heterogeneous catalyst was successfully prepared by an incipient wetness impregnation for Hydrodesulphurization (HDS) reaction of An-Najaf oil refinery heavy naphtha. The structural characteristics of the prepared 5Co-15Mo/γ-Al2O3 catalyst were evaluated by Scanning Electron Microscopy (SEM) and X-Ray Powder Diffraction (XRD) spectroscopies. The surface area, pore volume and pore size were determined by a Brunauer–Emmett–Teller (BET) method. The catalytic activity in the removal of sulphur compound from a heavy naphtha through the HDS at four different reaction temperatures (523, 548, 573, 598 °K) and four different liquid hourly space velocities (3, 4, 5, and 6 hr-1) under a constant ratio of 150 mL H2/1 mL naphtha and a hydrogen gas pressure of 1.5 MPa, has revealed that the prepared catalyst was efficient to remove 82 % of sulphur at 598 °K temperature and 3 hr-1 time. The enhanced selectivity of the CoMo/γ-Al2O3 catalyst through a hydro-treating reaction ascribes to the bimetallic-support interaction and the dispersion of MoS2 particles that leaded to a large edge-to-corner ratio of CoMoS slabs.

Hydrogen production via surrogate biomass gasification using 5% Ni and low loading of lanthanum co-impregnated on fluidizable γ-alumina catalysts

Abstract Nickel on alumina support offers opportunity for gasification of biomass for hydrogen production. In a recent contribution from our research team, (González Castañeda, D. G., et al. 2019) showed that cerium or lanthanum co-impregnation at 2 wt% with nickel may have a favorable effect for biomass catalytic gasification. However, and given an observed influence of lanthanum on the formation of small Ni crystallite sizes, five Ni/γ-Al2O3 based fluidizable La promoted catalysts were studied. Nickel-alumina catalysts promotion was effected varying La in the 0.5 and 1.0 wt% range. Once impregnation precursors loaded, they were reduced at 480 °C via an activation step. Catalysts were characterized using BET, XRD, AA, TPR, TPD, H2-chemisorption, TEM-EDX and FTIR. Catalyst performance was established in a fluidized CREC Riser Simulator, using: a) glucose as surrogate biomass, b) 600 °C, c) steam/biomass (S/B) ratio of 1, d) catalyst /biomass (C/B) ratio of 3.2 and e) 20 s reaction time. Data obtained was analyzed using an ANOVA statistical data analysis package with the 5 wt% Ni and 0.5–1 wt% La and Ce on γ-Al2O3 catalysts, prepared using a pH of 1 of impregnating solution were the best yielding 0.53–0.56 hydrogen molar fractions. These catalysts also gave a 39% reduced coke, and this while compared with the coke formed on the 2% Ce – 5 wt%Ni/γ-Al2O3 (González Castañeda, D. G., et al. 2019). This promising performance was assigned to the dominant NH3-TPD medium acidity, the high catalyst specific surface (∼140 m2/g), and the good 9% metal dispersion with 9–10 nm nickel crystallites.

Heterogeneous oxidation mechanism of SO2 on γ-Al2O3 (110) catalyst by H2O2: A first-principle study

Here, we present a simulation research of the heterogeneous oxidation mechanism of SO2 on Al2O3 (mineral oxides) surface by H2O2, density functional theory (DFT) calculations was used to investigate the adsorption mechanism of SO2 and H2O2 on the perfect and Odefect γ-Al2O3 (110) surfaces. The results show that SO2 molecularly adsorbed on the prefect and Odefect surfaces, while H2O2 was adsorbed in the molecule form on the perfect surface. In particular, H2O2 dissociation only occurred on the Odefect γ-Al2O3 (110) surface. The oxygen defects not only enhanced the adsorption intensities of H2O2 and SO2, but also promoted the H2O2 decomposition (H2O2→OH + OH). Analysis of partial density of states, differential charge density and Mulliken population indicated that H2O2 decomposition followed the Haber-Weiss mechanism (formation of surface OH), and SO2 was oxidized by the OH radicals to form HOSO2 molecule when SO2 and H2O2 co-adsorbed on Odefect γ-Al2O3 (110) surface. Moreover, the lower energy barrier of H2O2 decomposition (32.69 kJ/mol) and SO2 oxidation (78.21 kJ/mol) demonstrated that SO2 to be oxidized easily by the H2O2 on the Odefect γ-Al2O3 (110) surfaces. These results can well explain the formation mechanism of OH radicals and the oxidation mechanism of SO2 by H2O2 on the mineral dust at the molecular level, which is of great significance for understanding the role of H2O2 in the heterogeneous oxidation of SO2 on the mineral dust and the formation mechanism of sulfate aerosols in the atmosphere.

Catalytic Technologies for Solving Environmental Problems in the Production of Fuels and Motor Transport in Kazakhstan

This research is devoted to solving an environmental problem, cleaning of the Kazakhstan air basin, through treatment of auto-transport toxic exhaust by improving the hydrocarbon composition of motor fuels and neutralizing exhaust gas toxic components. The catalytic hydrodearomatization of gasoline fractions (from the reforming stage) of the Atyrau and Pavlodar Refineries and the neutralization of exhaust gas toxic components from an internal combustion engine (ICE) were studied. Two hydrotreated gasoline fractions were tested during ICE operation. The research shows that 100% benzene conversion is observed over Rh-Pt(9:1)/γ-Al2O3 catalysts; that is, benzene is completely removed from both fractions, and the aromatics content decreases from 56.24–58.12% to 21.29–21.89%, within the values of the Euro-5,6 standard. Catalytic treatment of fuels reduces fuel consumption of the ICE engine by 2–3% compared to the initial gasoline fractions, the CO content in the exhaust gases decreases by 6.6–16.2%, and the hydrocarbon content decreases by 7.8–24.7%. In order to neutralize the ICE exhaust gas toxic components, the catalyst 10% Co + 0.5% Pt/Al2O3 was used, with which the CO conversion reaches 100% and the hydrocarbon conversion 94.2% and 91.5% for both gasoline fractions. The catalysts were characterized by electron microscopy (EM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), thermoprogrammed desorption (TPD) and thermoprogrammed reduction (TPR) methods. It was shown by the TPD and EM methods that at the addition of Pt to the Rh-catalyst, the formation of mixed bimetallic Rh-Pt-agglomerates occurs, and hydrogen appears in the TPD spectrum, adsorbed in the form of a new single peak uncharacteristic for the Rh-catalyst. This leads to high activity and selectivity in the hydrogenation of benzene and aromatic compounds in the gasoline fractions. The XRD and TPR results show the formation of CoAl2O4 spinels, on which inactive oxygen is formed for the oxidation of CO and hydrocarbons. Modification of the catalyst by Pt and Mg prevents spinel formation, thereby increasing the activity of the catalysts.

Fischer-Tropsch Synthesis on Fe-Co-Pt/γ-Al2O3 catalyst: A mass transfer, kinetic and mechanistic study

Mass transfer limitations and kinetics studies were performed for Fischer-Tropsch Synthesis over spherical 10wt% Fe-10wt% Co-0.5wt% Pt/79.5wt% γ-Al2O3 catalyst in a fixed bed reactor. The external mass transfer limitation was checked by studying the effect of gas hourly space velocity (GHSV) and feed flow rate (at constant GHSV) on CO conversion. Theoretical and practical methods were applied to assess the effect of catalyst pellet size on the internal mass transfer limitation. The results indicated there is external diffusion limitation for GHSV lower than 4,200 h−1. Both the theoretical and practical methods showed that the reaction is free of internal diffusion limitation with average particle sizes of 0.21 and 0.42 mm due to Thiele modulus smaller than 0.4, denoting that the rate of reaction is kinetically controlled. The kinetics results demonstrated the combined enol and carbide mechanism-based model was able to provide a good fit for the experimental data.

Effect of Cobalt Oxide Content on the Activity of NiO-Co2O3/γ-Al2O3 Catalyst in the Reaction of Dry Reforming of Methane to Synthesis Gas

The effect of cobalt oxide content on the activity of NiO-Co2O3/γ-Al2O3 catalyst was investigated in process of dry reforming of methane (DRM) to synthesis gas. It was found that among the studied catalysts the highest activity is shown by the NiO-Co2O3/ γ-Al2O3, where methane conversion is 89%. It was determined by the scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) there are oxides of Ni and Co in the form of nanosized particles on active NiO-Co2O3/γ-Al2O3 catalyst and Co-Ni alloys, formed after the reaction of DRM, the size of 17‒23 nm. Thermogravimetric Analysis (TGA)/ Differential Thermal Analysis (DTA)/ Differential Scanning Calorimetry (DSC) of catalyst showed that the highest weight loss (2.7%) is observed at a degree from 30 to 260 °C after DRM. After heating above 300 °C there is a slight increase in weight, accompanied by an exothermic effect on the DSC curve due to the gas adsorption used to purge the unit. The data indicate the absence of coke formation on NiO-Co2O3/γ-Al2O3 surface. According to TPR-H2 there are peaks at relatively low temperatures of Т1mах = 205 °C and Т2mах = 497 °C on thermally programmed reduction (TPR) TPR-Н2 spectrum of NiO-Со2О3/γ-Al2O3, which are associated with the formation of easily reducible cobalt and nickel oxides, indicating the presence of active and mobile oxygen in the catalyst. These results confirm that the activity of NiO-Co2O3/γ-Al2O3 is due to the formation of nanophases, the presence of active oxygen, and the absence of coke on the catalyst surface.

Renewable Butene Production through Dehydration Reactions over Nano-HZSM-5/γ-Al2O3 Hybrid Catalysts

The development of new, improved zeolitic materials is of prime importance to progress heterogeneous catalysis and adsorption technologies. The zeolite HZSM-5 and metal oxide γ-Al2O3 are key materials for processing bio-alcohols, but both have some limitations, i.e., HZSM-5 has a high activity but low catalytic stability, and vice versa for γ-Al2O3. To combine their advantages and suppress their disadvantages, this study reports the synthesis, characterization, and catalytic results of a hybrid nano-HZSM-5/γ-Al2O3 catalyst for the dehydration of n-butanol to butenes. The hybrid catalyst is prepared by the in-situ hydrothermal synthesis of nano-HZSM-5 onto γ-Al2O3. This catalyst combines mesoporosity, related to the γ-Al2O3 support, and microporosity due to the nano-HZSM-5 crystals dispersed on the γ-Al2O3. HZSM-5 and γ-Al2O3 being in one hybrid catalyst leads to a different acid strength distribution and outperforms both single materials as it shows increased activity (compared to γ-Al2O3) and a high selectivity to olefins, even at low conversion and a higher stability (compared to HZSM-5). The hybrid catalyst also outperforms a physical mixture of nano-HZSM-5 and γ-Al2O3, indicating a truly synergistic effect in the hybrid catalyst.

Production of Hydrogen-Rich Gas by Oxidative Steam Reforming of Dimethoxymethane over CuO-CeO2/γ-Al2O3 Catalyst

The catalytic properties of CuO-CeO2 supported on alumina for the oxidative steam reforming (OSR) of dimethoxymethane (DMM) to hydrogen-rich gas in a tubular fixed bed reactor were studied. The CuO-CeO2/γ-Al2O3 catalyst provided complete DMM conversion and hydrogen productivity > 10 L h−1 gcat−1 at 280 °C, GHSV (gas hourly space velocity) = 15,000 h−1 and DMM:O2:H2O:N2 = 10:2.5:40:47.5 vol.%. Comparative studies showed that DMM OSR exceeded DMM steam reforming (SR) and DMM partial oxidation (PO) in terms of hydrogen productivity. Thus, the outcomes of lab-scale catalytic experiments show high promise of DMM oxidative steam reforming to produce hydrogen-rich gas for fuel cell feeding.

A novel α-Fe2O3/AlOOH(γ-Al2O3) nanocatalyst for efficient biodiesel production from waste oil: Kinetic and thermal studies

Abstract Different α-Fe2O3 loading (4–12 wt%) doped nanowires AlOOH/γ-Al2O3 catalysts are synthesized using a deposition hydrothermal technique and thoroughly characterized using XRD, SAED-TEM, FTIR, UV–Vis, N2 sorptiometry and XPS measurements. The 12 wt% α-Fe2O3/AlOOH(γ-Al2O3) catalyst presented the highest fatty acid methyl ester (FAME) Yield that comprised of 100% for virgin oil and 94.3% for the waste one, all performed under mild optimized conditions (60 °C, methanol to oil molar ratio = 6:1, 3 wt% catalyst, reaction rate 600 rpm and within 3 h reaction time). It also shows high recyclability without significant loss in activity because of the superior large surface area (323.3 m2/g), high number of acid sites (0.45 mmol g−1), deep pore volume (0.322 ml/g) and to the exposed active site planes (110) and (214) of α-Fe2O3. The kinetic constant (k = 0.016–0.02 min−1) and the activation energy (Ea = 57.4 kJ mol−1) of the reaction together with ΔH ‡ (59.4 kJ mol−1), ΔG ‡ (+95.9 kJ mol−1) and ΔS ‡ (- 0.108 kJ mol−1) values elaborate that the reaction is endothermic, non-spontaneous and obey an associative path. The fuel properties derived from cottonseed oil exhibited high quality biodiesel comparable to the international (ASTM) standards.

Synthesis and Thermal Stability of Palladium Nanoparticles Supported on γ-Αl2O3

Background: Deposition of palladium nanoparticles from colloidal solution on various supports produces palladium catalysts with a predetermined size and concentration of the palladium nanoparticles, which allows to study the nanoparticle size effects and support influence on palladium catalytic properties. Objective: The goal of the present work was the development of a preparation method of systems supported on γ-Al2O3 palladium nanoparticles with a controlled size and determination of their thermal stability in oxidizing and reducing atmospheres. Methods: We demonstrated the preparation of Pd/γ-Al2O3 composite by precipitation of the size-controlled palladium nanoparticles with a narrow size distribution from colloidal solution. The composites were characterized by X-ray diffraction (XRD), and transmission electron microscope (TEM) methods. Result: The size and size distribution of the nanoparticles supported on γ-Al2O3 were found to be increasing upon precipitation due to strong Pd/γ-Al2O3 interaction. A significant enlargement of the supported nanoparticles occured at 300°C. The aggregation of the nanoparticles was observed at temperatures above 500°C resulting in an increase in their size. Conclusion: Our findings are not only applicable for the preparation of a model Pd supported on the γ-Al2O3 catalyst but could be applicable to the designing of the Pd-containing catalyst for important industrial high-temperature processes.

Catalytic methanation over nanoparticle heterostructure of Ru/Fe/Ce/γ-Al2O3 catalyst: Performance and characterisation

Abstract A novel trimetal-oxides (Ru/Fe/Ce) supported on γ-Al2O3 catalyst was synthesised by simple impregnation method and the activity was investigated at atmospheric pressure. The results showed that Ru/Fe/Ce (5:10:85)/γ-Al2O3 catalyst calcined at 1000 °C for 5 h was effective and gave a 97.20% of CO2 conversion at 275 °C with 93.5% of CH4 formation. The catalyst possesses medium-strength basic sites with the best reduction temperature of