Single Step Sol Gel Research Articles

Ag nanoparticle dispersed TiO2 thin films by single step sol gel process: Evaluation of the physical properties and photocatalytic degradation

The photocatalyst must be low cost, high performing, and recyclable for efficient water treatment applications. Herein, we deposited TiO2 and Ag-dispersed TiO2 thin films via sol-gel spin coating and post-deposit annealing at 400 °C for 50 min. The physical properties of TiO2 and Ag: TiO2 thin films were analyzed by X-ray, Raman analysis, Atomic Force Microscope, Scanning Electron Microscopy, Electron Dispersive Spectroscopy, Transmission Electron Microscopy, and UV–visible transmittance spectroscopy. The structural evaluation established that the films were of anatase phase without any peaks related to metallic Ag or Ag oxides. The scanning transmission electron microscopy images demonstrated the presence of Ag nanoparticles with a diameter of ∼8 nm distributed on the film surface. The cross-sectional images from the high-angle annular dark-field scanning transmission electron microscopy confirmed the presence of Ag nanoparticles along the thickness of the Ag: TiO2 thin films. The optical bandgap of the Ag: TiO2 samples red shifted from 3.35 eV to 3.00 eV when the doping concentration reached 8 wt%. Photocatalysis showed by all samples were analyzed following the degradation of methylene blue (MB) with UV-light illumination. The Ag: TiO2 thin films demonstrated a substantial improvement in photocatalytic efficiency. The 4 wt% Ag doped TiO2 sample degraded 98% of MB in 180 min, a degradation efficiency 60% higher than the undoped samples.

Optimizing the synthesis of Ag/γ‐Al2O3 for selective reduction of NOx with C3H6: Experiments and modelling

AbstractAg/γ‐Al2O3 is an effective catalyst for the selective reduction of NOx (SCR) using propylene as a reducing agent. The catalyst performance is greatly influenced by the synthesis procedure. Various methods for synthesis of Ag/γ‐Al2O3 are analyzed, and their performance is examined via packed bed reactor experiments in this work. An optimal one‐pot synthesis method, single‐step sol–gel (SSG) synthesis, is explored systematically. The SSG‐synthesized catalyst shows better performance than those prepared via wet impregnation. The influence of synthesis conditions, specifically pH, on the textural and morphological properties of the SSG‐synthesized Ag/γ‐Al2O3, and therefore the activity for hydrocarbon‐based SCR in a packed‐bed reactor, are analyzed using experiments and simulations. The optimized catalyst demonstrates excellent performance (90% NOx conversion) for NOx reduction under nominal operating conditions with a wide activity temperature window (300–600°C). The catalyst shows good time‐on‐stream performance and is effective at higher inlet oxygen concentrations and space velocities. A global kinetic model, which uses synthesis‐pH‐dependent parameters, is proposed, and its ability to predict the activities of these catalysts is validated.

Composition of Organically Modified Silica for the Superhydrophobic Surface with Low Sliding Angle

Extremely water-repellent surfaces with low sliding angle (SA) have been obtained with a facile single-step sol-gel strategy via co-condensation of tetraethoxysilane (TEOS) and hexadecyltrimethoxysilane (HDTMS) in basic media with an efficient self-cleaning property. We investigated the effect of the molar ratio of HDTMS and TEOS on the properties of the modified silica-coated poly(ethylene terephthalate) (PET) film. A high water contact angle (WCA) of 165° and a low SA of 1.35° were obtained at a molar ratio of 0.125. The dual roughness pattern for the low SA was developed by a one-step coating of the modified silica with a molar ratio of 0.125. The evolution of the surface to the dual roughness pattern by nonequilibrium dynamics depended on the size and shape factor of modified silica. The primitive size and the shape factor of the organosilica with a molar ratio of 0.125 were 70 nm and 0.65, respectively. We also presented a new method to determine the superficial surface friction (ζ) of the superhydrophobic surface. The ζ was a physical parameter that characterized the slip and rolling behavior of water droplets on the superhydrophobic surface along with the equilibrium property WCA and the static frictional property SA.

Antibacterial effect of 3D printed mesoporous bioactive glass scaffolds doped with metallic silver nanoparticles

The development of new biomaterials for bone tissue regeneration with high bioactivity abilities and antibacterial properties is being intensively investigated. We have synthesized nanocomposites formed by mesoporous bioactive glasses (MBGs) in the ternary SiO2, CaO and P2O5 system doped with metallic silver nanoparticles (AgNPs) that were homogenously embedded in the MBG matrices. Ag/MBG nanocomposites have been directly synthesized and silver species were spontaneously reduced to metallic AgNPs by high temperatures (700 °C) obtained of last MBG synthesis step. Three-dimensional silver-containing mesoporous bioactive glass scaffolds were fabricated showing uniformly interconnected ultrapores, macropores and mesopores. The manufacture method consisted of a combination of a single-step sol–gel route in the mesostructure directing agent (P123) presence and a biomacromolecular polymer such as (hydroxypropyl)methyl cellulose (HPMC) as the macrostructure template, followed by rapid prototyping (RP) technique. Biological properties of Ag/MBG nanocomposites were evaluated by MC3T3-E1 preosteoblastic cells culture tests and bacterial (E. coli and S. aureus) assays. The results showed that the MC3T3-E1 cells morphology was not affected while preosteoblastic proliferation decreased when the presence of silver increased. Antimicrobial assays indicated that bacterial growth inhibition and biofilm destruction were directly proportional to the increased presence of AgNPs in the MBG matrices. Furthermore, in vitro co-culture of MC3T3-E1 cells and S. aureus bacteria confirmed that AgNPs presence was necessary for antibacterial activity, and AgNPs slightly affected cell proliferation parameters. Therefore, 3D printed scaffolds with hierarchical pore structure and high antimicrobial capacity have potential applications in bone tissue regeneration. Statement of significanceThis study combines three key scientific aspects for bone tissue engineering: (i) materials with high bioactivity to repair and regenerate bone tissue that (ii) contain antibacterial agents to reduce the infection risk (iii) in the form of three-dimensional scaffolds with hierarchical porosity. Innovative methodology is described here: sol-gel method, which is employed to obtain mesoporous bioactive glass matrices doped with metallic silver nanoparticles where different polymer templates facilitate the different size scales presence, and rapid prototyping technique that provides ultra-large macroporosity according to computer-aided design. The dual scaffolds obtained are biocompatible and deliver active doses of silver capable of combating bone infections, which represent one of the most serious complications associated to surgical treatments of bone diseases and fractures.

Optical and morphological characterization of ZnO nano-sized powder synthesized using single step sol-gel technique

ZnO is a wide band gap semiconductor and is very attractive because of its fundamental and technological importance. It is extensively used in research due to its properties viz. excellent chemical & thermal stability, large exciton binding energy, anti-corrosion and heat resistance. It is a promising material for optoelectronic devices in both UV and Visible regions. In the present investigation, ZnO nano powder was synthesized by single step Sol-gel technique using zinc acetate dihydrate as a precursor and ethanol as a medium. The synthesized ZnO nano powder was characterized using UV–Vis, FTIR, XRD, RAMAN, Photoluminescence (PL), Nano-particle size analyzer, SEM and EDX techniques. UV–Vis spectra gives intense peak at 372 nm wavelength showing the presence of absorption band due to ZnO nano powder. The chemical bonding among Zn and O can be clearly observed from FTIR spectrum. XRD spectra displays sharp peaks which indicates the crystalline nature of ZnO. It also shows homogeneity and size consistency of prepared nanoparticles. The crystallite size of ZnO nano powder were calculated using Scherrer's formula. The morphology and elemental analysis have been studied via SEM and EDX techniques. All the characterization results have been correlated with each other.

ZnO: SnO2 nanocomposite efficacy for gas sensing and microbial applications

The unique characteristics of 2-dimensional hetero structure offers efficient gas sensing with high selectivity to identify gases from the interference gases which is quite difficult. In the present work, ZnO: SnO2Nano composite clusters (NCC) is prepared. A resistive metal oxide volatile organic compound (VOC) gas sensor is fabricated with nullifying the effect of humidity by increasing temperature optimally. A single-step SOL-GEL (SG) synthesis is used to prepare ZnO: SnO2 NCC with maximum Zn/Sn molar concentration ratio of 3. The morphological studies through Scanning Electron Microscopy (SEM), electrical properties due to oxygen vacancies and energy band variations of Nanocomposite are measured. The enhancement of gas sensor sensitivity due to highly mesoporous nature of the composite is observed. From the findings, the abundant mesopores in the range of 2 nm-14 nm and specific surface area of 54.2 m2 g−1 with the average crystal size of 14.236 nm, and polar surface area of the composite 25.9651Åis achieved. When compared to bare ZnO and SnO2 gas sensors, the present gas sensor offers the higher selectivity with enhanced performance due to the mesoporous structure. Fast repeatability rate of 2200 sec at 350C to ethanol is attained and the overall selectivity of the sensor increased twice as 2.085. The NCC compound is tested firstly with micro organisms such as B. subtilis (B. S), Bacillus cereus (B. C), B. coagulans (B. C), Pseudonymous auriginosa (P. A) are considered for antimicrobial activity. From the findings, zinc stannate compound showed good efficacy towards B. cereus Gram positive and P.A gram-negative. A bacterial growth is arrested highly with B. cereus.

Nanocomposite of (α-Mn3O4/MnO)@rGO as a high performance electrode material for supercapacitors

It is demonstrated for the first time, strongly coupled reduced graphene oxide with α-Mn3O4/MnO nanocomposite acts as an electrode material for supercapacitors. The material has displayed an optimum specific energy of 21 and 10.8 Wh/kg, and a power density of 206 and 3979 W/kg at the constant current values of 1 and 20 mA respectively. Furthermore, capacity retention of ~92.7 % was observed after 3000 cycles at a scan rate of 100 mV/s. This material was synthesized via a single step sol-gel route and subsequently calcined at 700 °C in an inert atmosphere (N2). The obtained (α-Mn3O4/MnO)@rGO nanomaterial was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscope (HR-TEM), scanning tunneling electron microscope-energy dispersive x-ray spectroscopy (STEM–EDS) to investigate the phase and structural morphology. Furthermore, electrochemical studies such as cyclic voltammetry (CV), Galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy for the nanocomposite were performed with three electrode systems in an aqueous electrolyte of 1 M KOH.

A statistical modeling-optimization approach for efficiency photocatalytic degradation of textile azo dye using cerium-doped mesoporous ZnO: A central composite design in response surface methodology

This paper investigates a new modeling approach of central composite design (CCD) in Response Surface methodology (RSM) for the optimization of methyl orange (MO) photodegradation based to the prepared materials under UV–vis irradiation. Mesoporous zinc oxide (ZnO) have been synthesized at different cerium (Ce) contents (2, 5 and 7wt%) through a single step sol gel method. Subsequently, cerium nanoparticles (CeNPs) have been impregnated on mesoporous ZnO. The physico-chemical characteristics of each catalyst are described through several approaches. The photocatalytic activity of the prepared catalysts shows that CeNPs enhance the photocatalytic performance of ZnO at 2wt% Ce content. MO photodergadation processes of the optimal catalyst can be mathematically described as a function of pH-solution, catalyst dosage and MO concentration being modeled by a CCD-RSM.Based on a statistical modeling (quadratic regression) and an optimization process (ANOVA analysis), the optimum conditions were achieved for pH of solution of 5.58, MO concentration of 20.72mgL−1and catalyst dosage of 0.63gL−1 which allowed reaching 100% of photodegradation. Overall, the value of the adjusted coefficient of determination (R2=0.9901) indicates that the considered model was quite suitable and that the selected CCD-RSM was successful in optimizing the photodegradation conditions of MO.

Superior Ce–Nb–Ti oxide catalysts for selective catalytic reduction of NO with NH3

A series of Ce–Nb–Ti oxide catalysts synthesized by a single step sol-gel (SG) method were evaluated and characterized for selective catalytic reduction (SCR) of NO with ammonia. The experimental results showed that the doping of Nb could enhance the catalytic activity of CeO2/TiO2 significantly. Ce20Nb20Ti exhibited the best NH3–SCR activity and great resistance to high gas hourly space velocity (GHSV), H2O, and SO2. Its superior SCR performance could be ascribed to the better dispersion of Ce, more chemisorbed oxygen species and Ce3+/Ce4+ redox pairs on the catalyst surface, increased redox ability and surface acidity, and strong interaction among Ce, Nb, and Ti species after the introduction of Nb2O5. In situ DRIFT results revealed that the doping of Nb was conducive to the adsorption of NOx and NH3 species, and enhanced the reaction of pre-adsorbed NH3 species with NOx species and that of adsorbed NOx species with NH3 species.

Synthesis and Characterizations of Fe3O4 Added with Al2O3 Nanoparticles via Sol-Gel Technique

A single step sol-gel has been established as a new route for synthesizing AkCb-added Fe3O4 nanoparticles. In this work, the effects of Al2O3 composition towards the micro structure and magnetic properties of AkCb-added Fe3O4 samples were investigated. A series of Fe and Al nitrate mixture solutions were prepared by varying the Al nitrate composition from 2.0 wt. % to 10.0 wt. %. A dropwise of propylene oxide has dimed out the clear red mixture solution with a significant release of heat before turned into a gel. The gel was dried at 90 °C for 48 h in a ventilated oven which then pulverized into a powder by using mortar grinder. The powder was calcinated at 900 °C for 1 h in a normal furnace atmosphere. The XRD results revealed that the existence of polycrystalline Fe3O4 were completed at calcination temperature 900 °C. The SEM images of the Fe3O4 with 10.0 wt.% of Al2O3 samples showed a distinct nanoparticles micro structure due to the increased of Fe3O4 nucleation initiated by Al2O3 nanoparticles. The Vickers microhardness of the Al2O3 added Fe3O4 samples were significantly increased as the Al2O3 content was increased up to 10.0 wt.% attributed from good distribution of Al2O3 nanoparticles in the sample. Subsequently, the magnetic properties of Fe3O4 investigated by alternating gradient magnetometer, AGM was insignificantly reduced by the addition of Al2O3 nanoparticles. This work indicated that the sol-gel reaction is an effective method to achieve uniform distribution and high purity of AkCb-added Fe3O4 nanoparticles with optimum microhardness and ferromagnetic performances.

A new technique for the synthesis of lanthanum substituted nickel cobaltite nanocomposites for the photo catalytic degradation of organic dyes in wastewater

Developing cost-effective and more efficient nanocatalysts for the treatment of organic pollutants from process industry is always challenging for the researchers working in the field of chemistry, chemical, energy and environment engineering. In this work, a cost-effective and more efficient nanocatalysts, i.e., Nickel Cobaltite nanocomposites and its Lanthanum (La) doped derivatives with controlled surface morphology has been synthesized at 393.15 K through single step sol–gel method. The surface morphology, chemical composition, and crystal structure of the synthesized nanocomposites were analysed by scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), and X-rays diffraction (XRD), respectively. The rough surface and well-crystallized metallic nanocomposites confirm the successful synthesis of nanocatalysts. The molar ratio of Lanthanum to Cobalt (Lax:Coy) showed a significant influence on the surface morphology and catalytic activity (Kapp = 0.15–0.47 min−1) of the products. Synthesized nanocomposites showed high catalytic activity for the reduction of methylene blue under solar irradiation. Photocatalytic results for the reduction of methylene blue show that the catalytic activity of synthesized nanocatalysts increases with the increase in the doping concentration of Lanthanum.

Single step sol-gel synthesized Mn2O3-TiO2 decorated graphene for the rapid and selective ultra sensitive electrochemical sensing of dopamine

Single step sol-gel synthesized TiO2 and Mn2O3 decorating the pristine graphene (Gr) and graphene oxide (GO), by traditional physical mixing, for selective dopamine (DA) sensing in the presence of its potential interferences in PBS buffer (pH 5). Resulted binary and ternary composites were characterized by XRD, FTIR, UV-DRS, Raman, FE-SEM and TEM techniques. The ternary (TiO2-Mn2O3-Gr (TMGr)) composite showed higher electrochemical activities compared to the binary (TiO2-Gr (TGr), Mn2O3-Gr (MGr) and TiO2-Mn2O3 (TM)) composite in the presence of K3[Fe(CN)6]/K4[Fe(CN)6] redox probe. The same was observed for dopamine (DA) sensing at pH 5. Due to the presence of intrinsic (hydroxyl, acid and epoxide) functional groups with lesser sp2 hybridized carbon network, the GO-metal oxide composites showed poor electrochemical activity than the Gr-metal oxide composite. Concentration studies by differential pulse voltammetry (DPV) revealed a wide linear range from 0.02 to 100 nM with the lowest detection limit 0.026 nM. The ternary composite was validated for DA sensing by injecting commercial dopamine into the blood serum and urine samples and observed ≥98% signal recovery. The developed sensor showed good stability and reproducibility.

Enhanced Photocatalytic Efficiency of a Least Active Ag-TiO2 by Amine Adsorption.

An Ag–TiO2 photocatalyst with 3.5 atom % silver content, synthesized by a single step sol–gel method, possessed silver nanoparticles (AgNPs; 1–5 nm) on the TiO2 surface, but owing to the nonplasmonic nature of AgNPs and the wide band gap of TiO2, this material exhibited poor activity in a photocatalytic degradation reaction. However, this least active Ag–TiO2 catalyst showed a sudden increase in activity during a photocatalytic amine self-coupling reaction showing the highest activity, which was interpreted as amine (reactant) adsorption-driven activity enhancement. We found that amine adsorption occurred over AgNPs converting into plasmonic AgNPs as well as on the TiO2 surface reducing the band gap and therefore facilitated the visible light excitation and the electron-transfer process efficiently, resulting into overall enhancement in the photocatalytic activity. Thus, a very efficient, stable, and visible light active photocatalyst (amine-adsorbed Ag–TiO2) was developed by simply adsorbing an amine in the least active Ag–TiO2 photocatalyst.

Structural, Optical, Thermal and Photocatalytic Dye Degradation Properties of BiFeO3–WO3 Nanocomposites

In the present work, nanocomposites of BiFeO3–WO3 (BFO–WO3) have been successfully synthesized for the first time by a single step sol–gel method. The main objective lies in enhancing the photocatalytic activity of BiFeO3 by modifying it with a WO3 matrix. Powder x-ray diffraction studies on BFO–WO3 confirm the presence of the monoclinic character of WO3 along with rhombohedral BFO. In addition, elemental mapping using energy dispersive x-ray analysis ascertains the existence of tungsten ions in the BFO matrix. Field emission scanning electron microscopy analysis on pure and nanocomposites depicts the distinct morphologies of the nanoparticles upon modification of BFO with WO3. From the UV–Vis–NIR spectrum, it has been noticed that there is a reduction in the band gap energy from 1.8 eV (BFO) to 1.5 eV (BFO–WO3) suggesting the increase in the absorption of a visible portion of light upon loading of WO3 in BFO. Thermogravimetric analysis/differential thermal analysis trace of BFO–WO3 nanocomposites shows that there is a suppression of the multiferroic character of BiFeO3, when it is modified with WO3. However, the photodegradation of methylene blue using BFO–WO3 nanoparticles found to have been enhanced to 91%. The increase in dye removal property may be due to the fact that the higher surface area of nanocomposites due to the incorporation of WO3 particles. The other significant results have been discussed in detail.

Synergistic effect of oxygen vacancies and highly dispersed Pd nanoparticles over Pd-loaded TiO2 prepared by a single-step sol–gel process for deoxygenation of triglycerides

Renewable diesel has gained attention in recent years due to its superior fuel properties compared to the conventional biodiesel. The uses of Pd supported TiO2 (Pd/TiO2) and Pd supported activated carbon (Pd/C) catalysts for the deoxygenation of triglycerides to renewable diesel were investigated. Two different types of titania supports, i.e. mesoporous titania synthesized by a surfactant-assisted templating sol–gel method (SG-TiO2) and commercial P25-TiO2 (P25-TiO2), were used to investigate the effect of TiO2 crystal structure on the catalytic activity. The prepared catalysts were characterized by N2 adsorption-desorption isotherms, X-ray diffraction (XRD), H2 chemisorption, H2 temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The liquid products obtained from the deoxygenation of triglycerides in beef fat over the prepared catalysts at 325 °C, 500 psig, and H2/triglyceride molar ratio of 30 were in the diesel fuel specification range (C15-18). The main liquid products were n-heptadecane (n-C17) and n-pentadecane (n-C15), resulting from the decarboxylation or decarbonylation pathways. It was found that the Pd/P25-TiO2 catalyst exhibited a higher catalytic performance compared to the Pd/C catalyst. The formation of defects (oxygen vacancies and Ti3+) on TiO2, Pd dispersion and inducement of SMSI effect play an important role in the catalytic activity and the diesel yield on Pd/SG-TiO2 catalysts. Furthermore, the Pd incorporation methods, i.e. incipient wetness impregnation (IWI), photochemical deposition (PCD) and single-step sol–gel (SSSG), were also investigated. The Pd/TiO2 prepared by SSSG method exhibited the highest conversion of beef fat and selectivity to the diesel fuel (C15-18) which could be due to its well-dispersed Pd nanoparticles with relatively small size, high defects on TiO2 support and strong SMSI behavior.

Effect of Ca Doping on the Selective Catalytic Reduction of NO with NH3 Over Ce–Ti Oxide Catalyst

A series of Ca doped Ce–Ti oxides prepared by a single step sol–gel method were investigated for the selective catalytic reduction of NO with NH3. The results show that Ca doping had both positive and negative effects on the activities of Ce–Ti oxide. Ca0.1CT possessed the best catalytic activity and widest temperature window. Further investigations on BET, XRD, XPS, H2-TPR and NH3-TPD demonstrated that the good SCR performance of Ca0.1CT could be attributed to the increase in the amount of Ce3+ and surface adsorbed oxygen as well as the enhancement of Bronsted acidity and redox ability. In addition, the good dispersion of active Ce species, the alleviation of support sintering, and the interaction among Ce, Ti and Ca species were also responsible for its enhanced activity.

Graphene oxide encapsulated in alginate beads for enhanced sorption of uranium from different aquatic environments

Single step sol gel method was used for synthesising new generation hybrid material (Cal-Alg-GO beads) by impregnating graphene oxide (GO) in calcium alginate (Cal-Alg). The optimum composition of the hybrid material was 8% loading of graphene oxide into 4% Ca-alginate matrix. Although alginate itself have tendency for uranium uptake from aquatic medium, impregnation of GO enhanced it several times. Uptake studies were carried out in batch mode and the Cal-Alg-GO beads were found to be highly efficient for uranium decontamination (>90%) in the pH range of 4–5. Beads were successfully tested for uptake of uranium from groundwater/river water/lake water. Sorption isotherm was seen to follow Langmuir model (R2 = 0.98) and the uptake capacity evaluated was 29.4 mg g−1. Mechanism of sorption was proposed based on the zeta potential values of the GO and presence of various species of uranium at different pH. High sorption of uranium was attributed to the interaction of oxygen containing functional groups of GO with positively charged species of uranium while the negatively charged functional groups of alginate further enhanced the sorption.

A novel CeO2-MoO3-WO3/TiO2 catalyst for selective catalytic reduction of NO with NH3

A novel CeO2-MoO3-WO3/TiO2 (CMWT) catalyst was prepared by a single step sol-gel (SG) method. It exhibited 93.8%–98.9% of NO conversion at 275–450°C and high tolerance to 10% H2O and 1000ppm SO2 at a gas hourly space velocity (GHSV) of 90,000h−1. Superior SCR activity of CMWT catalyst could be attributed to the presence of more Ce3+ and chemisorbed oxygen, higher redox ability, stronger adsorption capacity of NH3 species and the strong interaction among ceria, molybdenum, tungsten and titania.

Remarkable activity and stability of Ni catalyst supported on CeO2-Al2O3 via CeAlO3 perovskite towards glycerol steam reforming for hydrogen production

The effects of CeO2-Al2O3 mixed oxide preparation methods on the physical and chemical properties of CeO2-Al2O3, and the catalytic performance toward glycerol steam reforming (GSR) over the CeO2-Al2O3-supported Ni catalysts were investigated. Three CeO2-Al2O3 supports were prepared by a single-step sol-gel (SS) of ceria and alumina precursors, followed by the impregnations of ceria precursors on both a xerogel Al2O3 (IS) and a commercial Al2O3 (IC). The characterization techniques used were N2 adsorption-desorption, H2-chemisorption, XRD, H2-TPR, NH3-TPD, XANES, XPS and TGA. The sol-gel derived supports generate not only a well-developed mesoporous structure, but also the incorporation of the Ce species into the Al2O3 structure forming CeAlO3 perovskite. This formation suppresses the interaction between Ni and Al2O3, thereby increasing the number of active and Brønsted acid sites to improve the bifunctional metal-acid properties of Ni/CeO2-Al2O3 in the hydrogenolysis and dehydrogenation-dehydration of condensable intermediates that produce more H2. The formation of CeAlO3 is remarkably promoted by the single-step sol-gel preparation method, and the catalyst supported on the SS-derived oxide exhibits excellent activity and strong resistances to coke formation, phase transformation, and nickel sintering.

Preparation and Characterization of CeO2-MoO3/TiO2 Catalysts for Selective Catalytic Reduction of NO with NH3

ABSTRACTCeO2-MoO3/TiO2 catalysts were prepared by three methods: a single step sol-gel (SG), impregnation (IM) and coprecipitation (CP) method. These catalysts were investigated for selective catalytic reduction (SCR) of NO with NH3. The results indicate that the catalyst prepared by the SG method possessed the widest temperature window (about 250–475°C), best SCR activity below 450°C and resistance against 10% H2O and 1000 ppm SO2 at a gas hourly space velocity (GHSV) of 90,000 h–1. According to the results of BET, XRD, XPS, H2-TPR and TEM, it is found that larger BET surface area, more highly dispersed active species of Ce and Mo, presence of more Ce3+ and chemisorbed oxygen, synergistic effect among ceria, molybdenum and titania, and better redox ability can contribute to the better deNOx performance of the CeO2-MoO3/TiO2 catalyst prepared by the SG method, compared with those by the IM and CP methods.