Incipient Wetness Impregnation Technique Research Articles

Tri‐reforming of Methane over a Hydroxyapatite Supported Nickel Catalyst

AbstractFor the first time, a catalyst containing 5 wt. % Ni supported on a hydroxyapatite support (HAP) has been synthesized and evaluated in tri‐reforming of methane (TRM) for synthetic gas (syngas) production. Nickel nanoparticles could be easily formed on HAP surface by using the conventional incipient wetness impregnation technique. In TRM, under unfavorable reaction conditions from the thermodynamic point of view (e. g. medium reforming temperature of 700–800 °C, low steam‐to‐carbon ratio, etc.), this catalyst showed high methane conversion (up to 90 %), however, some deactivations took place. The latter could be explained by both the thermal sintering of nickel nanoparticles and the solid carbon formation. The impact of the main operational parameters has been studied. Increasing the reaction temperature, the molar ratios of oxygen‐to‐carbon and steam‐to‐carbon are favorable for the methane conversion and mostly for the stability of the catalyst. High methane conversion of ca. 90 % with a perfect catalytic stability during 300 hours‐on‐stream could be achieved at 800 °C and 1.4 bar, using a mixture containing low ratio of oxidant‐to‐carbon (molar ratio of CH4/CO2/H2O/O2/N2=1.0/0.67/0.9/0.1/0). These results offer the opportunity to further design an optimal Ni/HAP catalyst by improving metal‐support interaction and downsizing nickel nanoparticles.

Development of the Sb4O5Cl2@NbSe2 Composite: The Impact of 2H-NbSe2 Nanoparticles on Sb4O5Cl2 and Their Application for the Removal of Cr(VI)/Fe(III) and Methyl Orange from Wastewater.

A potential adsorbent, Sb4O5Cl2@NbSe2 composite, was generated from the Sb4O5Cl2 photocatalyst and 5 wt % layered 2H-NbSe2 nanoparticles for the highly effective removal of Cr(VI) and Fe(III) ions and methyl orange (MO) from aqueous solution, and a comparison was drawn against the precursors. Sb4O5Cl2 crystallites and NbSe2 nanoparticles were synthesized hydrothermally, and the composite was prepared by the incipient wetness impregnation technique. The crystal structure of Sb4O5Cl2 was determined by single-crystal X-ray diffraction (SCXRD) data. Powder X-ray diffraction (PXRD) study revealed the 2H phase of NbSe2 nanoparticles. Field emission scanning electron microscopy (FESEM) analysis confirmed the formation of the spherical-shaped NbSe2 nanoparticles from rod-shaped bulk 2H-NbSe2. Morphological changes from the hexagonal to irregular prismatic shape were found upon the formation of the Sb4O5Cl2@NbSe2 composite compared to pure Sb4O5Cl2. Negative ζ-potential values indicated that electrostatic interactions were the predominant factor for the adsorption process. Sb4O5Cl2@NbSe2 provided removal efficiencies of 99% for MO in 6 h, 96.52% for Cr(VI) within 2.5 h, and 92.43% for Fe(III) within 4 h of 10 mg/L initial concentration. The maximum adsorption capacities of the composite for MO, Fe(III), and Cr(VI) were found to be 66.56, 131.48, and 122.30 mg/g, respectively, as calculated using the Langmuir isotherm equation.

Oxidative Desulfurization of Simulated Diesel Fuel by Synthesized Tin Oxide Nano-Catalysts Support on Reduced Graphene Oxide

The modified Hummers method was applied to prepare graphene oxide (GO) from the graphite powder. Tin oxide nanoparticles with different loading (10-20 wt.%) supported on reduced graphene oxide were synthesized to evaluate the oxidative desulfurization efficiency. The catalyst was synthesized by the incipient wetness impregnation (IWI) technique. Different analysis methods like FT-IR, XRD, FESEM, AFM, and Brunauer-Emmett-Teller (BET) were utilized to characterize graphene oxide and catalysts. The XRD analysis showed that the average crystal size of graphene oxide was 6.05 nm. In addition, the FESEM results showed high metal oxide dispersions on the rGO. The EDX analysis shows the weight ratio of Sn is close to its theoretical weight. The reduction of metal oxide and (GO) has occurred in one step at temperatures of 400 °C for 2 hours. The performance of the catalysts for dibenzothiophene (DBT) removal using H2O2 as an oxidizing agent was determined under a range of different operating conditions. The results showed that the maximum desulfurization was 71.68% in the best conditions (DBT concentration = 385 ppm, time = 90 min, temperature = 60 oC, catalyst dosage = 0.04g, and amount of oxidant = 0.375 ml).

Tailoring optical and dielectric properties of TiO2 through mono- and co-doping with Ag and Sr

In this study, we applied a direct and incipient wetness impregnation technique to synthesize titanium dioxide (TiO2) doped with silver (Ag), strontium (Sr), and a combination of the two elements. The purpose was to further our understanding of doped TiO2 materials. The results of scanning electron microscopy (SEM) analysis showed that the agglomerated particles of the doped composites had smaller sizes than those of pure TiO2. The incorporation of Ag–Sr bimetallic doping led to a more pronounced reduction in the particle size. The SEM images revealed no significant morphological alterations in the TiO2, Ag/TiO2, Sr/TiO2, and Ag–Sr/TiO2 composites. We also examined the dielectric characteristics of composites within a range of temperature of 25 °C–120 °C and a range of frequency of 100 Hz to 0.3 MHz. The electrical conductivity and dielectric permittivity of TiO2 were enhanced as a result of doping. The optical characteristics of the composites indicated that the introduction of Ag, Sr, and Ag–Sr into TiO2 led to an increase in both their refractive index and Urbach energy. This led in turn to a progressive reduction in the energy band gap (Eg) from the Ag-doped samples to the Ag–Sr-doped samples, with the Sr-doped samples exhibiting an intermediate reduction in Eg. The findings of this study indicate that the introduction of Ag, Sr, and Ag–Sr into TiO2 enhanced its refractive index. Notably, the Ag–Sr/TiO2 composite exhibited the most significant increase in the refractive index of all the composites considered. This phenomenon can be attributed to the increased level of polarization and crystallinity of the compound. By contrast, the incorporation of Ag, Sr, and Ag–Sr into composite materials composed of TiO2 led to a reduction in the values of Eg, where this renders these materials suitable for various optical applications.

In situ hydro-deoxygenation onto nickel-doped HZSM-5 zeolite catalyst for upgrading pyrolytic oil.

Global energy demand has drastically increased due to urbanization and industrialization; thus, developing alternative renewable energy sources is urgently required. In the present work, upgrading the pyrolytic oil (PO) derived from fresh palm fruit was performed by the catalytic in situ hydrodeoxygenation (in situ HDO) process. Preparation of nickel-doped HZSM-5 zeolite (SiO2/Al2O3 = 40) was achieved by incipient wetness impregnation techniques using different weight percents of nickel dopant into HZSM-5. Nickel-doped HZSM-5 zeolite (Ni-HZSM-5) was further subjected to chemical reduction for 5h in the oxygen-free environment (10% H2 and 90% N2) at 550°C. The structural properties showed a potential reduction of NiO-HZSM-5 to Ni-HZSM-5, enhancing the catalytic potential. The morphological characterizations showed spherical-shaped Ni agglomerated onto HZSM-5. Acidity and oxygen contents in the pyrolytic oil were achieved by catalyst-aided HDO process at 220°C for 6h using methanol as a hydrogen donor. The catalytically upgraded pyrolytic oil (UPO) was analyzed for density, HHV, CHNO, and TGA. The best upgrading oil was distilled following ASTM D86 to separate gasoline, kerosene, and diesel. The acidity, density, HHV, and viscosity were measured before and after the upgradation processes. The results showed the potential impact of Ni with 10% doped on HZSM-5 on HDO reaction and illustrated the lowest oxygen content in upgraded pyrolytic oil products. Considerable decrease in viscosity and density level indicated that in situ HDO not only reduced oxygen content but also cracked pyrolytic oil to small molecules. The distilled product of upgrading oil was higher than pyrolytic oil by approximately 15% in volume. The viscosity, density, and HHV were under standard specifications of kerosene and diesel, except for acidity. However, the acidity was reduced by over 60% compared with raw material.

A Green Approach to Obtaining Glycerol Carbonate by Urea Glycerolysis Using Carbon-Supported Metal Oxide Catalysts.

The results of sustainable and selective synthesis of glycerol carbonate (GC) from urea and glycerol under ambient pressure using carbon-fiber-supported metal oxide catalysts are reported. Carbon fibers (CF) were prepared via a catalytic chemical vapor deposition method (CCVD) using Ni as a catalyst and liquefied petroleum gas (LPG) as a cheap carbon source. Supported metal oxide catalysts were obtained by an incipient wetness impregnation technique using Zn, Ba, Cr, and Mg nitrates. Finally, the samples were pyrolyzed and oxidized in an air flow. The obtained catalysts (10%MexOy/CFox) were tested in the reaction of urea glycerolysis at 140 °C for 6 h under atmospheric pressure, using an equimolar ratio of reagents and an inert gas flow for NH3 removal. Under the applied conditions, all of the prepared catalysts increased the glycerol conversion and glycerol carbonate yield compared to the blank test, and the best catalytic performance was shown by the CFox-supported ZnO and MgO systems. Screening of the reaction conditions was carried out by applying ZnO/CFox as a catalyst and considering the effect of reaction temperature, molar ratio of reagents, and the mode of the inert gas flow through the reactor on the catalytic process. Finally, a maximum yield of GC of about 40%, together with a selectivity to glycerol carbonate of ~100%, was obtained within 6 h of reaction at 140 °C using a glycerol-to-urea molar ratio of 1:1 while flowing Ar through the reaction mixture. Furthermore, a positive heterogeneous catalytic effect of the CFox support on the process was noticed.

Synthesis of Ruthenium-Promoted ZnO/SBA-15 Composites for Enhanced Photocatalytic Degradation of Methylene Blue Dye

Synthetic organic pigments like xanthene and azo dyes from the direct discharge of textile effluents are considered colossal global issues and attract the concern of scholars. Photocatalysis continues to be a very valuable pollution control method for industrial wastewater. Incorporations of metal oxide catalysts such as zinc oxide (ZnO) on mesoporous Santa Barbara Armophous-15 (SBA-15) support to improve catalyst thermo-mechanical stability have been comprehensively reported. However, charge separation efficiency and light absorption of ZnO/SBA-15 continue to be limiting its photocatalytic activity. Herein, we report a successful preparation of Ruthenium-induced ZnO/SBA-15 composite via conventional incipient wetness impregnation technique with the aim of boosting the photocatalytic activity of the incorporated ZnO. Physicochemical properties of the SBA-15 support, ZnO/SBA-15, and Ru-ZnO/SBA-15 composites were characterized by X-ray diffraction (XRD), N2 physisorption isotherms at 77 K, Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDS), and transmission electron microscopy (TEM). The characterization outcomes exhibited that ZnO and ruthenium species have been successfully embedded into SBA-15 support, andtheSBA-15 support maintains its structured hexagonal mesoscopic ordering in both ZnO/SBA-15 and Ru-ZnO/SBA-15 composites. The photocatalytic activity of the composite was assessed through photo-assisted mineralization of aqueous MB solution, and the process was optimized for initial dye concentration and catalyst dosage. 50 mg catalyst exhibited significant degradation efficiency of 97.96% after 120 min, surpassing the efficiencies of 77% and 81% displayed by 10 and 30 mg of the as-synthesized catalyst. The photodegradation rate was found to decrease with an increase in the initial dye concentration. The superior photocatalytic activity of Ru-ZnO/SBA-15 over the binary ZnO/SBA-15 may be attributed to the slower recombination rate of photogenerated charges on the ZnO surface with the addition of ruthenium.

Zn3Sb4O6F6 and KI-Doped Zn3Sb4O6F6: A Metal Oxyfluoride System for Photocatalytic Activity, Knoevenagel Condensation, and Bacterial Disinfection

Zn3Sb4O6F6 crystallites were synthesized by a pH-regulated hydrothermal synthetic approach, while doping on Zn3Sb4O6F6 by KI was performed by the "incipient wetness impregnation technique." The effect of KI in Zn3Sb4O6F6 is found with the changes in morphology in the doped compound, i.e., needle-shaped particles with respect to the irregular cuboid and granular shaped in the pure compound. Closer inspection of the powder diffraction pattern of doped compounds also reveals the shifting of Braggs' peaks toward a lower angle and the difference in cell parameters compared to the pure compound. Both metal oxyfluoride comprising lone pair elements and their doped compounds have been successfully applied as photocatalysts for methylene blue dye degradation. Knoevenagel condensation reactions were performed using Zn3Sb4O6F6 as the catalyst and confirmed 99% yield even at 60 °C temperature under solvent-free conditions. Both pure and KI-doped compounds were tested against several standard bacterial strains, i.e., Enterobacter sp., Escherichia coli, Staphylococcus sp., Salmonella sp., Bacillus sp., Proteous sp., Pseudomonas sp., and Klebsiella sp. by the "disk diffusion method" and their antimicrobial activities were confirmed.

Mesoporous Ce–Fe–Ni nanocomposites encapsulated in carbon-nanofibers: Synthesis, characterization and catalytic behavior in oxygen evolution reaction

Ceria-iron oxide mesoporous materials with Fe:Ce molar ratio of 5:5 and 9:1 were synthesized by hydrothermal method using CTAB as a template and subsequently modified with NiO (molar ratio Ni:Fe = 1:2) by incipient wetness impregnation technique. In order to increase the electro-capacitive properties and reduce the intrinsic impedance of the metal oxides, the samples were consecutively modified by reduction in hydrogen to obtain highly dispersed Ni–Fe alloys into ceria matrix. By exploiting the high permeability of carbon inside ferrous alloys, the metal phase has been further modified into ferrous carbides and metal alloys encapsulated within carbon nanofibers. For this purpose, a reaction, already widely studied for the production of hydrogen, was used, that is the decomposition of methanol vapors. In fact, this decomposition, in addition to producing syn-gas and methane, changes the catalysts in use through a chemical vapor deposition-carbon coating process. This fact, has been used by us to demonstrate how the newly obtained metal-carbon nanocomposites can be used for electro-catalytic purposes. The modified phases of the two molar ratios of the Fe–Ni–Ce catalysts were tested in the Oxygen Evolution Reaction (OER) in an alkaline environment (1 M KOH), showing a satisfactory and progressive increase in activity and a surprising decrease in the overpotential at 10 mA/cm2 of current density. The morphological, textural and physicochemical properties of the samples were characterized in details by XRD, N2-physisorption, TG-TPO, TEM, EDX, FTIR, XPS, Raman and Moessbauer spectroscopies.

Nickel-Decorated Mesoporous Iron–Cerium Mixed Oxides: Microstructure and Catalytic Activity in Methanol Decomposition

Nickel-decorated mesoporous cerium-iron oxide composites were synthesized by a combination of incipient wetness impregnation and template-assisted hydrothermal techniques. The effects of the Fe/Ce ratio and the calcination temperature of cerium-iron oxides on the phase composition, texture, structure, and redox properties of the composites were studied by a combination of N2 physisorption, XRD, high-resolution transmission electron microscopy, SEM, Mössbauer, Raman, XPS, ultraviolet-visible and FTIR spectroscopies, H2-temperature-programmed reduction, and total oxidation of ethyl acetate as a catalytic test. The combined physicochemical characterization and in situ FTIR investigation of methanol decomposition was used for a proper understanding of the microstructure of the Ni/FeCe oxide composites and the mechanism of the reaction occurring on them. The complex role of the FeCe support in the stabilization of highly dispersed Ni particles, the generation of surface intermediates, and the impact of the support phase transformation under the reaction medium are discussed.

Immobilization of Potassium-Based Heterogeneous Catalyst over Alumina Beads and Powder Support in the Transesterification of Waste Cooking Oil

In this work, the beads and powder potassium hydroxide (KOH) and potassium carbonate (K2CO3) supported on alumina oxide (Al2O3) were successfully prepared via incipient wetness impregnation technique. Herein, the perforated hydrophilic materials (PHM) made from low-density polyethylene (LDPE) was used as the catalyst reactor bed. The prepared catalysts were investigated using TGA, XRD, BET, SEM-EDX, TPD, FTIR while spent catalysts were analyzed using XRF and ICP-AES to study its deactivation mechanism. The catalytic performance of beads and powder KOH/Al2O3 and K2CO3/Al2O3 catalysts were evaluated via transesterification of waste cooking oil (WCO) to biodiesel. It was found that the optimum conditions for transesterification reaction were 1:12 of oil-to-methanol molar ratio and 5 wt.% of catalyst at 65 °C. As a result, the mesoporous size of beads KOH/Al2O3 and K2CO3/Al2O3 catalysts yielded 86.8% and 77.3% at 2 h’ reaction time of fatty acids methyl ester (FAME), respectively. It was revealed that the utilization of PHM for beads K2CO3/Al2O3 increase the reusability of the catalyst up to 7 cycles. Furthermore, the FAME produced was confirmed by the gas chromatography-mass spectroscopic technique. From this finding, beads KOH/Al2O3 and K2CO3/Al2O3 catalysts showed a promising performance to convert WCO to FAME or known as biodiesel.

Novel kaempferol delivery systems based on Mg-containing MCM-41 mesoporous silicas

Mesoporous silica has been widely studied as promising carriers in drug delivery systems due to their properties, which allow loading of significant amount of drugs and can solve problems related with low solubility and instability of biologically active compounds. In this study in situ (direct synthesis) and post-synthesis (incipient wetness impregnation and template ion-exchange) techniques were applied to modify MCM-41 mesoporous silica with Mg. Various characterization techniques were used to completely investigate the influence of the modification procedure on physicochemical properties of the obtained carriers. Kaempferol, a polyphenol antioxidant with many beneficial effects on human health, was loaded by incipient wetness impregnation on parent and Mg-modified MCM-41 carriers. The results from the release experiments in buffers with pH 1.2 and 6.8 show improved solubility of kaempferol from obtained formulations in comparison with pure polyphenol. Therefore, development of delivery systems on the basis of mesoporous silica carriers can improve the kaempferol bioavailability and thus to enhance the effect of the antioxidant activity of the drug.

Pt/TS-1 catalysts: Effect of the platinum loading method on the dehydrogenation of n-butane

A series of catalysts in which platinum was supported on the crystalline pure titanium silicalite (TS-1) were prepared using two different loading methods, namely, an ethylene glycol (EG) reduction method and the conventional incipient wetness impregnation (IM) technique. Various characterization techniques were used to study the effect of the loading method on the physicochemical and morphological properties of the prepared catalysts. Also the effect of the platinum-loading method on the dehydrogenation of n-butane was investigated in a fixed-bed reactor. The results show that the EG method favors the formation of a more-concentrated Pt dispersion, which results in much better catalytic activities for the selective formation of butenes and butadiene (> 97 %). This phenomenon is interpreted by carrying out density functional theory (DFT) calculations with focus on the relationship between the coverage of n-butane on Pt surface and the activation barrier for the first CH bond cleavage.

Greenhouse gas mitigation and hydrogen generation via enhanced ethylene glycol dry reforming on La-promoted Co/Al2O3 catalyst

The first investigation of La-promoted Co/Al2O3 catalysts in Ethylene Glycol-CO2 conversion (EGCC) for syngas (H2 + CO) production was conducted in this work. Co/Al2O3 catalysts modified with different La promoter loadings (1, 3, and 5%) were generated through sequential incipient wetness impregnation technique and employed for EGCC. The physicochemical attributes of the generated catalysts were examined via Brunauer-Emmett-Teller (BET), H2 temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), Raman, and temperature-programmed oxidation (TPO). 3%La-promoted catalyst owned the largest specific surface area, smallest Co crystallite size of 9.8 nm, and lowest reduction temperature among the promoted catalysts. These excellent properties resulted in the highest catalytic performance on the 3%La-promoted catalyst (i.e., C2H6O2 conversion = 77.6 %, CO2 conversion = 43.1 %, H2 yield = 75.3 %, and CO yield = 76.8 %). The significant reduction in carbon deposition of the 3%La-promoted catalyst was due to the La capability in eliminating deposited carbon via the formation of intermediate lanthanum dioxycarbonate, La2O2CO3.

Systematic experimental study for optimized hydrogen production of Ni/CeO2 prepared by incipient wetness impregnation technique

In this present work, different supports (CeO2/ZrO2) and different Ni contents based catalysts were prepared by incipient wetness impregnation method and tested in the methane steam reforming (MSR) reaction. The prepared catalysts were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD analysis confirmed the prepared Ni/CeO2 samples have a pure crystal structure. In the catalytic tests, the effects of reactivity temperature, different support, Ni loading content and the gas hourly space velocity (GHSV) on hydrogen production performance were investigated systematically. The results showed that the optimal reaction conditions for MSR by Ni/CeO2 catalyst were as follows: 10 wt % Ni/CeO2, 750oC, 1500 h−1. The stability test for 12 h at 750oC indicated that the chosen Ni/CeO2 catalyst had excellent thermal stability. (Less)

Study of Partial Oxidation of Methane by Ni/Al2O3 Catalyst: Effect of Support Oxides of Mg, Mo, Ti and Y as Promoters.

Catalysts of 10% Ni, supported on promoted alumina, were used to accomplish the partial oxidation of methane. The alumina support was doped with oxides of Mo, Mg, Ti and Y. An incipient wetness impregnation technique was used to synthesize the catalysts. The physicochemical properties of the catalysts were described by XRD, H2-TPR (temperature programmed reduction), BET, TGA, CO2-TPD (temperature-programmed desorption) and Raman. The characterization results denoted that Ni has a strong interaction with the support. The TGA investigation of spent catalysts displayed the anticoking enhancement of the promoters. The impact of the support promoters on the catalyst stability, methane conversion and H2 yield was inspected. Stability tests were done for 460 min. The H2 yields were 76 and 60% and the CH4 conversions were 67 and 92%, respectively, over Ni/Al2O3+Mg, when the reaction temperatures were 550 and 650 °C, respectively. The performance of the present work was compared to relevant findings in the literature.

N-doped carbon nanoweb-supported Ni/NiO heterostructure as hybrid catalysts for hydrogen evolution reaction in an alkaline phase

The design of the cost-effective, efficient, and durable electrocatalysts for hydrogen evolution reaction (HER) is of great importance in the field of clean and renewable energies. In this study, Ni/NiO nanocomposite supported on N-doped carbon nanoweb (Ni/NiO/NCW) hybrid materials are proposed as an efficient electrocatalyst for HER in alkaline media. A series of Ni/NiO/NCW hybrid catalysts were prepared via polymerization of polypyrrole (PPy) in the presence of a surfactant, followed by incipient wetness impregnation and heat treatment techniques. The resulting Ni/NiO/NCW hybrid catalysts exhibit an excellent electrocatalytic properties with a lower overpotential of 105.3 mV (vs RHE) at 10 mA cm−2, a smaller value of Tafel slope (55.2 mV dec−1) and almost 100% Faradaic efficiency. It also shows good stability in performance attenuation during continuous cyclic voltammetry sweeps for 1000 cycles. Its excellent electrocatalytic performance for alkaline hydrogen evolution reaction can be attributed to the synergistic effect associated with the morphological benefit of 3D N-doped carbon nanoweb and Ni/NiO heterostructure with the optimal ratio of Ni to NiO.

The Effect of Noble Metal (M: Ir, Pt, Pd) on M/Ce2O3-γ-Al2O3 Catalysts for Hydrogen Production via the Steam Reforming of Glycerol

A promising route for the energetic valorisation of the main by-product of the biodiesel industry is the steam reforming of glycerol, as it can theoretically produce seven moles of H2 for every mole of C3H8O3. In the work presented herein, CeO2–Al2O3 was used as supporting material for Ir, Pd and Pt catalysts, which were prepared using the incipient wetness impregnation technique and characterized by employing N2 adsorption–desorption, X-Ray Diffraction (XRD), Temperature Programmed Reduction (TPR), Temperature Programmed Desorption (TPD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The catalytic experiments aimed at identifying the effect of temperature on the total conversion of glycerol, on the conversion of glycerol to gaseous products, the selectivity towards the gaseous products (H2, CO2, CO, CH4) and the determination of the H2/CO and CO/CO2 molar ratios. The main liquid effluents produced during the reaction were quantified. The results revealed that the Pt/CeAl catalyst was more selective towards H2, which can be related to its increased number of Brønsted acid sites, which improved the hydrogenolysis and dehydrogenation–dehydration of condensable intermediates. The time-on-stream experiments, undertaken at low Water Glycerol Feed Ratios (WGFR), showed gradual deactivation for all catalysts. This is likely due to the dehydration reaction, which leads to the formation of unsaturated hydrocarbon species and eventually to carbon deposition. The weak metal–support interaction shown for the Ir/CeAl catalyst also led to pronounced sintering of the metallic particles.

Effects of catalyst preparation method and reaction parameters on the ultrasound assisted Photocatalytic oxidation of reactive yellow 84 dye.

In this study, the Heterogeneous Sono-photocatalytic Process was used to degrade Reactive Yellow 84 (RY 84) dye dissolved in water over iron containing TiO2 and TiO2-Ce catalysts. The catalysts were prepared by sol-gel and incipient wetness impregnation methods and characterized using XRD, SEM, Nitrogen adsorption, UV-Vis DRS and ICP-AES measurements. The TiO2 catalyst containing 1% (in weight) iron, prepared by incipient wetness impregnation technique and calcined at 300°C (1%Fe/TiO2-300°C (IW)) was found to be the most effective catalyst. Parametric study was carried out over this catalyst and COD removal of 55% and TOC removal of 38% were achieved while the decolorization efficiency reached 100% after 45min of reaction at the optimum conditions of, (25mg/L of RY 84 solution, 0.5g/L of catalyst, 5mM of H2O2, a temperature of 25°C, pH = 6 and US at a power of 40W). Decolorization of RY 84 obeyed the first order kinetics with an activation energy of 20.7kJ/mol. Sonication increased the decolorization efficiency of the heterogeneous Fenton process (UV + Catalyst+H2O2) from 92.7% to 97.5% after 30min of reaction, with the COD and TOC reductions increasing from 87% to 90% and 48% to 57% after 120min of reaction, respectively. US also decreased the toxicity of the RY 84 dye. The results obtained from this study show that, iron containing TiO2 and TiO2-Ce catalysts could be efficiently used in the hybrid process of ultrasound assisted heterogeneous photocatalytic oxidation in a wide range of experimental conditions.

Quaternary Vanado‐Molybdotungstophosphoric Acid [H5PW6Mo4V2O40] Over Natural Montmorillonite as a Heterogeneous Catalyst for the Synthesis 4H‐Pyran and Polyhydroquinoline Derivatives

AbstractSynthesis of an efficient and novel vanadium substituted molybdotungstophosphoric acid, H5PW6Mo4V2O40.14H2O (VMWP) supported on naturally occurring montmorillonite (nMont) clay by an incipient wetness impregnation technique. The support and resulting catalyst were characterized by Inductively coupled plasma atomic emission spectroscopy (ICP‐AES), Fourier transform infrared (FT‐IR), powder X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDX), Transmission electron microscopy (TEM) and thermogravimetric‐Differential thermal analysis (TG‐DTA). The study demonstrated that newly synthesized VMWP well incorporated on nMont with their good performance and activity. The catalytic application is evaluated in one‐pot multicomponent synthesis of tetrahydrobenzo[b]pyrans (4H‐Pyran) and polyhydroquinolines in excellent yield. High conversion, shorter reaction time, environmentally benign solvent simple experimental and work procedure and reusability of the catalyst are the prominent features of our synthetic route.