Search results for: cobalt-copper catalytic systems

Authors: Srinivas Nerella

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A series of new heterodentate N, O-donor ligands derived from condensing 3-amino Coumarins with hydroxy benzaldehydes and acetophenones were used to afford new mononuclear Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) coordination compounds. All the complexes were characterized by IR, 1H-NMR, 13C-NMR, Mass, ESR, Electronic spectra, Conductance, Magnetic and Thermal studies. The ligands show hexa coordination in Mn(II), Co(II), Ni(II), and Pd(II) complexes resulting octahedral geometries, while the ligands in Zn(II) and Cu(II) complexes show tetra coordination resulting tetrahedral and square planar geometries respectively. These mononuclear complexes were investigated as catalysts in the hydrothiolation of aromatic and aliphatic alkynes with thiols. These metal complexes were acted as versatile catalysts and gave good yields.

Keywords: schiff bases, divalent metal complexes of schiff bases, Catalytic activity, hydrothiolation

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Authors: Abolfazl Bezaatpour, Sahar Khatami

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Fe3O4 nanoparticles were prepared by the co-precipitation method and silica was then coated on the magnetic nanoparticles followed by modification with (3-aminopropyl) trimethoxysilane. Then, dioxomolybdenum(VI) Schiff base complex of N,N′-bis(5-chloromethyl-salicylidine)-1,2-phenylenediamine) was immobilized on the surface of magnetic nanoparticles as a heterogeneous catalyst. The catalyst was identified by scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), X-ray diffraction, IR spectroscopy, diffuse reflectance spectra and atomic absorption spectroscopy techniques. The catalyst shows excellent catalytic activity in epoxidation of olefins using tert-butylhydroperoxide in 1,2-dichloroethane. In this report, the supported complex exhibited 100% selectivity for epoxidation with 100% conversion for cyclooctene. Nanocatalyst can be easily recovered by a magnetic field and reused for subsequent reactions for at least 5 times with less deterioration in catalytic activity.

Keywords: dioxomolybdenum (VI), epoxidation, nanocatalysis, nanoparticles, Schiff base

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Authors: Akmuhammet Karayev, Hassam Mazhar, Mamdouh Al Harthi

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Polyethylene terephthalate (PET) recycling stands as a pivotal solution in combating plastic pollution and fostering a circular economy. This study addresses the catalytic glycolysis of PET, a key step in its recycling process, using synthesized catalysts. Our focus lies in elucidating the catalytic mechanism, optimizing reaction kinetics, and enhancing reactor design for efficient PET conversion. We synthesized anionic clays tailored for PET glycolysis and comprehensively characterized them using XRD, FT-IR, BET, DSC, and TGA techniques, confirming their suitability as catalysts. Through systematic parametric studies, we optimized reaction conditions to achieve complete PET conversion to bis hydroxy ethylene terephthalate (BHET) with over 75% yield within 2 hours at 200°C, employing a minimal catalyst concentration of 0.5%. These results underscore the catalysts' exceptional efficiency and sustainability, positioning them as frontrunners in catalyzing PET recycling processes. Furthermore, we demonstrated the recyclability of the obtained BHETs by repolymerizing them back to PET without the need for a catalyst. Heating the BHETs in a distillation unit facilitated their conversion back to PET, highlighting the closed-loop potential of our recycling approach. Our work embodies a significant leap in catalytic glycolysis kinetics, driven by sustainable catalysts, offering rapid and high-impact PET conversion while minimizing environmental footprint. This breakthrough not only sets new benchmarks for efficiency in PET recycling but also exemplifies the pivotal role of catalysis and reaction engineering in advancing sustainable materials management.

Keywords: polymer recycling, catalysis, circular economy, glycolysis

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Authors: R. H. Hwang, J. H. Park, K. B. Yi

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Nitrous oxide (N2O) is now distinguished as an environmental pollutant. N2O is one of the representative greenhouse gases and N2O is produced by both natural and anthropogenic sources. So, it is very important to reduce N2O. N2O abatement processes are various processes such as HC-SCR, NH3-SCR and decomposition process. Among them, decomposition process is advantageous because it does not use a reducing agent. N2O decomposition is a reaction in which N2O is decomposed into N2 and O2. There are noble metals, transition metal ion-exchanged zeolites, pure and mixed oxides for N2O decomposition catalyst. Among the various catalysts, cobalt-based catalysts derived from hydrotalcites gathered much attention because spinel catalysts having large surface areas and high thermal stabilities. In this study, the effect of promoter and K addition on the activity was compared and analyzed. Co3O4 catalysts for N2O decomposition were prepared by co- precipitation method. Ce and Zr were added during the preparation of the catalyst as promoter with the molar ratio (Ce or Zr) / Co = 0.05. In addition, 1 wt% K2CO3 was doped to the prepared catalyst with impregnation method to investigate the effect of K on the catalyst performance. Characterizations of catalysts were carried out with SEM, BET, XRD, XPS and H2-TPR. The catalytic activity tests were carried out at a GHSV of 45,000 h-1 and a temperature range of 250 ~ 375 ℃. The Co3O4 catalysts showed a spinel crystal phase, and the addition of the promoter increased the specific surface area and reduced the particle and crystal size. It was exhibited that the doping of K improves the catalytic activity by increasing the concentration of Co2+ in the catalyst which is an active site for catalytic reaction. As a result, the K-doped catalyst showed higher activity than the promoter added. Also, it was found through experiments that Co2+ concentration and reduction temperature greatly affect the reactivity.

Keywords: Co₃O4, K-doped, N₂O decomposition, promoter

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Authors: Indranil Chakraborty, Kalyan Mandal

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Herein, we synthesize MnFe₂O₄ nano−hollow spheres (NHSs) of average diameter 100 nm through a facile template free solvothermal process and carry out a time dependent morphological study to investigate their process of core excavation. Further, a surface engineering of as−synthesized MnFe₂O₄ NHSs has been executed with organic disodium tartrate dihydrate ligand and interestingly, the surface modified MnFe₂O₄ NHSs are found to capable of emerging multicolor fluorescence starting from blue, green to red. The magnetic measurements through vibrating sample magnetometer demonstrate that room temperature superparamagnetic nature of MnFe₂O₄ NHSs remains unaltered after surface modification. Moreover, functionalized MnFe₂O₄ NHSs are found to exhibit excellent reusable photocatalytic efficiency in the degradation of cationic dye, methylene blue with rate constant of 2.64×10−2 min.

Keywords: nano hollow sphere, tartrate modification, multiple fluorescence, catalytic property

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Authors: Ali Zaker, Zhi Chen

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Due to the concerns about the depletion of fossil fuel sources and the deteriorating environment, the attempt to investigate the production of renewable energy will play a crucial role as a potential to alleviate the dependency on mineral fuels. In this respect, biofuels are measured as a vital nominee for national energy security and energy sustainability. Sewage sludge (SS), as an alternative source of renewable energy with a complex composition, is a major waste generated during wastewater treatment. Stricter legislation is continuously refining the requirements for the level of removal of various pollutants in treated water, causing continuous growth of sludge production, which has become a global challenge. In general, there are two main procedures for dealing with SS: incineration and landfill. However, there are a variety of limitations in these options (e.g., production of greenhouse gases and restrictive environmental regulations) in regard to negative social and economic impacts. Pyrolysis is a feasible and cost-effective technology that can simultaneously tackle boundaries concerning the current disposal routes while retrieving bioenergy. Pyrolysis of SS has drawn vigorous interest in research due to the ability of high mass yield of pyrolytic liquid production. Nonetheless, the presence of high molecular weight hydrocarbons and oxygenated- and nitrogenated compounds poses a considerable challenge. In this context, catalytic pyrolysis is another attainable route in order to upgrade the bio-oil quality. Among different catalysts (i.e., zeolites) studied for sewage sludge pyrolysis, activated chars are eco-friendly and low-cost alternatives. The beneficial features comprise comparatively large surface area, long-term stability, and enriched surface functional groups. In light of these premises, this research attempts to investigate the catalytic pyrolysis of sewage sludge with a high-performance sludge-based activated char in contrast to HZSM5 from a theoretical and experimental point of view.

Keywords: catalytic pyrolysis, sewage sludge, char, HZSM5, bio-oil.

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Authors: Aliyu Adamu, Fahrul Huyop, Roswanira Abdul Wahab, Mohd Shahir Shamsir

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Halogenated organic compounds occur in huge amount in biosphere. This is attributable to the diverse use of halogen-based compounds in the synthesis of various industrially important products. Halogenated compound is toxic and may persist in the environment, thereby causing serious health and environmental pollution problems. L-2-haloacid dehalogenases (EC 3.8.1.2) catalyse the specific cleavage of carbon-halogen bond in L-isomers of halogenated compounds, which consequently reverse the effects of environmental halogen-associated pollution. To enhance the efficiency and utility of these enzymes, this study investigates the catalytic amino acid residues and the molecular functional mechanism of DehL, by classical molecular dynamic simulations, MM-PBSA and ab initio fragments molecular orbital (FMO) calculations. The results of the study will serve as the basis for the molecular engineering of the enzyme.

Keywords: DehL, Functional mechanism, Catalytic residues, L-2-haloacid dehalogenase

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Authors: Z. Jamalzadeh, A. Niaei, H. Erfannia, S. G. Hosseini, A. S. Razmgir

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Due to developing the industries, the emission of pollutants such as NOx, SOx, and CO2 are rapidly increased. Generally, NOx is attributed to the mono nitrogen oxides of NO and NO2 that is one of the most important atmospheric contaminants. Hence, controlling the emission of nitrogen oxides is urgent environmentally. Selective Catalytic Reduction of NOx is one of the most common techniques for NOx removal in which Zeolites have wide application due to their high performance. In zeolitic processes, the catalytic reaction occurs mostly in the pores. Therefore, investigation the adsorption phenomena of the molecules in order to gain an insight and understand the catalytic cycle is of important. Hence, in current study, molecular simulations is applied for studying the adsorption phenomena in nanocatalysts applied for SCR of NOx process. The effect of cation addition to the support in the catalysts’ behavior through adsorption step was explored by Mont Carlo (MC). Simulation time of 1 Ns accompanying 1 fs time step, COMPASS27 Force Field and the cut off radios of 12.5 Ȧ was applied for performed runs. It was observed that the adsorption capacity increases in the presence of cations. The sorption isotherms demonstrated the behavior of type I isotherm categories and sorption capacity diminished with increase in temperature whereas an increase was observed at high pressures. Besides, NO sorption showed higher sorption capacity than NH3 in H–ZSM5. In this respect, the Energy distributions signified that the molecules could adsorb in just one sorption site at the catalyst and the sorption energy of NO was stronger than the NH3 in H-ZSM5. Furthermore, the isosteric heat of sorption data showed nearly same values for the molecules; however, it indicated stronger interactions of NO molecules with H-ZSM5 Zeolite compared to the isosteric heat of NH3 which was low in value.

Keywords: Monte Carlo simulation, adsorption, NOx, ZSM5

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Authors: Yves Mann Elate Lea Mbassi, Marie Solange Evehe Bebandoue, Wilfred Fon Mbacham

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Improving the catalytic performance of enzymes has been a long-standing theme of analytical biochemistry research. Induction of peroxidase activity by metals is a common reaction in higher plants. We thought that this increase in peroxidase activity may be due, on the one hand, to the stimulation of the gene expression of these enzymes but also to a modification of their chemical reactivity following the binding of some metal ions on their active site. We tested the effect of some metal salts (MgCl₂, MnCl₂, ZnCl₂, CaCl₂ and CuSO₄) on the activity and thermostability of peroxidase A6, a thermostable peroxidase that we discovered and purified in a previous study. The chromogenic substrate used was 3,3′,5,5′-tetramethylbenzidine. Of all the metals tested for their effect on A6, only magnesium and copper had a significant effect on the activity of the enzyme at room temperature. The Mann-Whitney test shows a slight inhibitory effect of activity by the magnesium salt (P = 0.043), while the activity of the enzyme is 5 times higher in the presence of the copper salt (P = 0.002). Moreover, the thermostability of peroxidase A6 is increased when calcium and copper salts are present. The activity in the presence of CaCl₂ is 8 times higher than the residual activity of the enzyme alone after incubation at 80°C for 10 min and 35 times higher in the presence of CuSO4 under the same conditions. In addition, manganese and zinc salts slightly reduce the thermostability of the enzyme. The activity and structural stability of peroxidase A6 can clearly be activated by Cu₂+, which therefore enhance the oxidation of 3,3′,5,5′-tetramethylbenzidine, which was used in this study as a chromogenic substrate. Ca₂+ likely has a more stabilizing function for the catalytic site.

Keywords: peroxidase activity, copper ions, calcium ions, thermostability

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Authors: Neslihan Beyazit, Sahin Bayraktar, Cahit Demetgul

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Transition metal ions have an important role in biochemistry and biomimetic systems and may provide the basis of models for active sites of biological targets. The presence of copper(II), iron(II) and zinc(II) is crucial in many biological processes. Tetradentate N2O2 donor Schiff base ligands are well known to form stable transition metal complexes and these complexes have also applications in clinical and analytical fields. In this study, we present salient structural features and the details of cathecholase activity of Fe(II) complex of a new Schiff Base ligand. A new asymmetrical N2O2 donor Schiff base ligand and its Fe(II) complex were synthesized by condensation of 4-nitro-1,2 phenylenediamine with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one and by using an appropriate Fe(II) salt, respectively. Schiff base ligand and its metal complex were characterized by using FT-IR, 1H NMR, 13C NMR, UV-Vis, elemental analysis and magnetic susceptibility. In order to determine the kinetics parameters of catechol oxidase-like activity of Schiff base Fe(II) complex, the oxidation of the 3,5-di-tert-butylcatechol (3,5-DTBC) was measured at 25°C by monitoring the increase of the absorption band at 390-400 nm of the product 3,5-di-tert-butylcatequinone (3,5-DTBQ). The compatibility of catalytic reaction with Michaelis-Menten kinetics also investigated by the method of initial rates by monitoring the growth of the 390–400 nm band of 3,5-DTBQ as a function of time. Kinetic studies showed that Fe(II) complex of the new N2O2 donor Schiff base ligand was capable of acting as a model compound for simulating the catecholase properties of type-3 copper proteins.

Keywords: catecholase activity, Michaelis-Menten kinetics, Schiff base, transition metals

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Authors: Jamshid Hussain, Kuen Song Lin

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Over one thousand tons of pig hair biowaste (PHB) are produced yearly in Taiwan. The improper disposal of PHB can have a negative impact on the environment, consequently contributing to the spread of diseases. The treatment of PHB has become a major environmental and economic challenge. Innovative treatments must be developed because of the heavy metal and sulfur content of PHB. Like most organic materials, PHB is composed of many organic volatiles that contain large amounts of hydrogen. Hydrogen gas can be effectively produced by the catalytic gasification of PHB using a laboratory-scale fixed-bed gasifier, employing 15 wt% NiO/Al₂O₃ catalyst at 753–913 K. The derived kinetic parameters were obtained and refined using simulation calculations. FE–SEM microphotograph showed that NiO/Al₂O₃ catalyst particles are Spherical or irregularly shaped with diameters of 10–20 nm. HR–TEM represented that the fresh Ni particles were evenly dispersed and uniform in the microstructure of Al₂O₃ support. The sizes of the NiO nanoparticles were vital in determining catalyst activity. As displayed in the pre-edge XANES spectra of the NiO/Al₂O₃ catalysts, it exhibited a non-intensive absorbance nature for the 1s to 3d transition, which is prohibited by the selection rule for an ideal octahedral symmetry. Similarly, the populace of Ni(II) and Ni(0) onto Al₂O₃ supports are proportional to the strength of the 1s to 4pxy transition, respectively. The weak shoulder at 8329–8334 eV and a strong character at 8345–8353 eV were ascribed to the 1s to 4pxy shift, which suggested the presence of NiO types onto Al₂O₃ support in PHB catalytic gasification. As determined by the XANES analyses, Ni(II)→Ni(0) reduction was mostly observed. The oxidation of PHB onto the NiO/Al₂O₃ surface may have resulted in Ni(0) and the formation of tar during the gasification process. The EXAFS spectra revealed that the Ni atoms with Ni–Ni/Ni–O bonds were found. The Ni–O bonding proved that the produced syngas were unable to reduce NiO to Ni(0) completely. The weakness of the Ni–Ni bonds may have been caused by the highly dispersed Ni in the Al₂O₃ support. The central Ni atoms have Ni–O (2.01 Å) and Ni–Ni (2.34 Å) bond distances in the fresh NiO/Al₂O₃ catalyst. The PHB was converted into hydrogen-rich syngas (CO + H₂, >89.8% dry basis). When PHB (250 kg h−1) was catalytically gasified at 753–913 K, syngas was produced at approximately 5.45 × 105 kcal h−1 of heat recovery with 76.5%–83.5% cold gas efficiency. The simulation of the pilot-scale PHB catalytic gasification demonstrated that the system could provide hydrogen (purity > 99.99%) and generate electricity for an internal combustion engine of 100 kW and a proton exchange membrane fuel cell (PEMFC) of 175 kW. A projected payback for a PHB catalytic gasification plant with a capacity of 10- or 20-TPD (ton per day) was around 3.2 or 2.5 years, respectively.

Keywords: pig hair biowaste, catalytic gasification, hydrogen production, PEMFC, resource recovery

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Authors: Huanru Wang, Jianzhun Jiang

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At present, the preparation of the catalyst by carbon carrier is one of the improvement directions of the C₂ pre-hydrogenation catalyst. Carbon materials can be prepared from coal direct liquefaction residues, coconut shells, biomass, etc., and the pore structure of carbon carrier materials can be adjusted through the preparation process; at high temperatures, the carbon carrier itself also shows certain catalytic activity. Therefore, this paper mainly selected typical activated carbon and coconut shell carbon as carbon carrier materials, studied their microstructure and surface properties, prepared a series of carbon-based catalysts loaded with Pd, and investigated the effects of the content of promoter Ag and the concentration of reductant on the structure and performance of the catalyst and its catalytic performance for the pre hydrogenation of C₂. In this paper, the carbon supports from two sources and the catalysts prepared by them were characterized in detail. The results showed that the morphology and structure of different supports and the performance of the catalysts prepared were also obviously different. The catalyst supported on coconut shell carbon has a small specific surface area and large pore diameter. The catalyst supported on activated carbon has a large specific surface area and rich pore structure. The active carbon support is mainly a mixture of amorphous graphite and microcrystalline graphite. For the catalyst prepared with coconut shell carbon as the carrier, the sample is very uneven, and its specific surface area and pore volume are irregular. Compared with coconut shell carbon, activated carbon is more suitable as the carrier of the C₂ hydrogenation catalyst. The conversion of acetylene, methyl acetylene, and butadiene decreased, and the ethylene selectivity increased after Ag was added to the supported Pd catalyst. When the amount of promoter Ag is 0.01-0.015%, the catalyst has relatively good catalytic performance. Ag and Pd form an alloying effect, thus reducing the effective demand for Ag. The Pd Ag ratio is the key factor affecting the catalytic performance. When the addition amount of Ag is 0.01-0.015%, the dispersion of Pd on the carbon support surface can be significantly improved, and the size of active particles can be reduced. The Pd Ag ratio is the main factor in improving the selectivity of the catalyst. When the additional amount of sodium formate is 1%, the catalyst prepared has both high acetylene conversion and high ethylene selectivity.

Keywords: C₂ hydrogenation, activated carbon, Ag promoter, Pd catalysts

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Authors: S. Ghosh, L. Ramos, A. N. Kouamé, A.-L. Teillout, H. Remita

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Catalytic materials have attracted continuous attention due to their promising applications in a variety of energy and environmental applications including clean energy, energy conversion and storage, purification and separation, degradation of pollutants and electrochemical reactions etc. With the advanced synthetic technologies, polymer nanostructures and nanocomposites can be directly synthesized through soft template mediated approach using swollen hexagonal mesophases and modulate the size, morphology, and structure of polymer nanostructures. As an alternative to conventional catalytic materials, one-dimensional PDPB polymer nanostructures shows high photocatalytic activity under visible light for the degradation of pollutants. These photocatalysts are very stable with cycling. Transmission electron microscopy (TEM), and AFM-IR characterizations reveal that the morphology and structure of the polymer nanostructures do not change after photocatalysis. These stable and cheap polymer nanofibers and metal polymer nanocomposites are easy to process and can be reused without appreciable loss of activity. The polymer nanocomposites formed via one pot chemical redox reaction with 3.4 nm Pd nanoparticles on poly(diphenylbutadiyne) (PDPB) nanofibers (30 nm). The reduction of Pd (II) ions is accompanied by oxidative polymerization leading to composites materials. Hybrid Pd/PDPB nanocomposites used as electrode materials for the electrocatalytic oxidation of ethanol without using support of proton exchange Nafion membrane. Hence, these conducting polymer nanofibers and nanocomposites offer the perspective of developing a new generation of efficient photocatalysts for environmental protection and in electrocatalysis for fuel cell applications.

Keywords: conducting polymer, swollen hexagonal mesophases, solar photocatalysis, electrocatalysis, water depollution

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Authors: Mahsa Faramarzi Asli, Mina Sarabi

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The important issues that are addressed in most advanced industrial countries in recent decades, discussion of minimizing heat losses through the buildings. And the most influential parameters in the calculation of building energy consumption, is heat exchange, which takes place between the interior and outer space. One of the solutions to reduce heat loss is using materials with low thermal conductivity. The purpose of this article, is the effect of using some frontages with nano-concrete photo catalytic precast materials for reducing energy consumption in buildings. For this purpose, estimating the energy dissipation through the facade built with nano-concrete photo catalytic precast materials on a sample building in Tabriz city by BCS 19 software ( topic 19 simulation) is done and the results demonstrate reduce heat loss through the facade nano- concrete.

Keywords: nano materials, optimize energy consumption, themal, stability

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Authors: Jian Huang, Weixin Qian, Hongfang Ma, Haitao Zhang, Weiyong Ying

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Cobalt catalysts were supported on extruded silica carrier and different-type (SiO₂, γ-Al₂O₃) commercial supports with different shapes and sizes to produce heavy hydrocarbons for Fischer-Tropsch synthesis. The catalysts were characterized by N₂ physisorption and H₂-TPR. The catalytic performance of the catalysts was tested in a fixed bed reactor. The results of Fischer-Tropsch synthesis performance showed that the cobalt catalyst supported on spherical silica supports displayed a higher activity and a higher selectivity to C₅⁺ products, due to the fact that the active components were only distributed in the surface layer of spherical carrier, and the influence of gas diffusion restriction on catalytic performance was weakened. Therefore, it can be concluded that the eggshell cobalt catalyst was superior to precious metals modified catalysts in the synthesis of heavy hydrocarbons.

Keywords: fischer-tropsch synthesis, cobalt catalyst, support shape, heavy hydrocarbons

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Authors: D. Shehu, Z. Alias

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Glutathione S-transferases (GSTs) are family of enzymes that function in the detoxification of variety of electrophilic substrates. In the present work, we report a novel zeta-like GST (designated as KKSG9) from the biphenyl/polychlorobiphenyl degrading organism Acidovorax sp. KKS102. KKSG9 possessed low sequence similarity but similar biochemical properties to zeta class GSTs. The gene for KKSG9 was cloned, purified and biochemically characterized. Functional analysis showed that the enzyme exhibits wider substrate specificity compared to most zeta class GSTs by reacting with 1-chloro-2,4-dinitrobenzene (CDNB), p-nitrobenzyl chloride (NBC), ethacrynic acid (EA), hydrogen peroxide, and cumene hydroperoxide (CuOOH). The enzyme also displayed dehalogenation function against dichloroacetate (a common substrate for zeta class GSTs) in addition to permethrin, and dieldrin. The functional role of Tyr12 was also investigated by site-directed mutagenesis. The mutant (Y12C) displayed low catalytic activity and dehalogenation function against all the substrates when compared with the wild type. Kinetic analysis using NBC and GSH as substrates showed that the mutant (Y12C) displayed a higher affinity for NBC when compared with the wild type, however, no significant change in GSH affinity was observed. These findings suggest that the presence of tyrosine residue in the motif might represent an evolutionary trend toward improving the catalytic activity of the enzyme. The enzyme as well could be useful in the bioremediation of various types of organochlorine pollutants.

Keywords: Acidovorax sp. KKS102, bioremediation, glutathione s-transferase, site-directed mutagenesis, zeta

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Authors: Kamran Dastafkan, Chuan Zhao

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Improving surface chemistry is a promising approach in addition to the rational alteration in the catalyst composition to advance water electrolysis. Here, we demonstrate an evident enhancement of oxygen evolution on an iron-nickel vanadate catalyst synthesized by a facile successive ionic adsorption and reaction method. The vanadate-modified catalyst demonstrates a highly efficient oxygen evolution in 1 M KOH by requiring low overpotentials of 274 and 310 mV for delivering large current densities of 100 and 400 mA cm⁻², respectively where vigorous gas bubble evolution occurs. Vanadate modification augments the OER activity from three aspects. (i) Both the electrochemical surface area (47.1 cm²) and intrinsic activity (318 mV to deliver 10 mA cm⁻² per unit ECSA) of the catalytic sites are improved. (ii) The amorphous and roughened nanoparticle-comprised catalyst film exhibits a high surface wettability and a low-gas bubble-adhesion, which is beneficial for the accelerated mass transport and gas bubble dissipation at large current densities. The gas bubble dissipation behavior is studied by operando dynamic specific resistance measurements where a significant change in the variation of the interfacial resistance during the OER is detected for the vanadate-modified catalyst. (iii) The introduced vanadate poly-oxo-anions with high charge density have electronic interplay with Fe and Ni catalytic centers. Raman study reveals the structural evolution of β-NiOOH and γ-FeOOH phases during the OER through the vanadate-active site synergistic interactions. Achievement of a high catalytic turnover of 0.12 s⁻¹ put the developed FeNi vanadate among the best recent catalysts for water oxidation.

Keywords: gas bubble dissipation, iron-nickel vanadate, low-gas bubble-adhesion catalyst, oxygen evolution reaction

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Authors: Corazon Virtudazo-Ligaray, Mark Daniel G. de Luna, Meng-Wei Wan, Ming-Chun Lu

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A series of ternary compound catalyst with nanocomposites of ceria, tungsten trioxide and titania (CeO2-WOx-TiO2) with different WOx mole fraction (10, 20, 30, 40) have been synthesized by sol-gel method. These nanocomposite catalysts were used for oxidative extractive desulfurization of model fuel oil, which were composed of dibenzothiophene (DBT) dissolved in toluene. The 30% hydrogen peroxide, H2O2 was used as oxidant and acetonitrile as extractant. These catalysts were characterized by SEM-EDS to determine the morphology. Catalytic oxidation results show that the catalysts have high selectivity in refractory fuel oil with organo sulfur contents. The oxidative removal of DBT increases as the HPW content increases. The nanocomposites CeO2-WOx-TiO2 also shows high selectivity for DBT oxidation in the DBT–toluene acetonitrile system. The catalytic oxidative desulfurization ratio of model fuel reached to 100% with nanocomposites CeO2-WOx-TiO2 (35-30-35) mol percent catalyst nanocomposition under 333 K in 30 minutes.

Keywords: ceria, oxidative desulfurization, titania, phosphotungstic acid

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Authors: Anaam H. Al-ShaikhAli, Mansour A. Al-Herz

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The research leverages the proven HS-FCC technology to directly crack crude oils into petrochemical building blocks. Crude oils were subjected to an optimized hydro-processing process where metal contaminants and sulfur were reduced to an acceptable level for feeding the crudes into the HS-FCC technology. The hydro-processing is achieved through a fixed-bed reactor which is composed of 3 layers of catalysts. The crude oil is passed through a dementalization catalyst followed by a desulfurization catalyst and finally a de-aromatization catalyst. The hydroprocessing was conducted at an optimized liquid hourly space velocity (LHSV), temperature, and pressure for an optimal reduction of metals and sulfur from the crudes. The hydro-processed crudes were then fed into a micro activity testing (MAT) unit to simulate the HS-FCC technology. The catalytic cracking of crude oils was conducted over tailored catalyst formulations under an optimized catalyst/oil ratio and cracking temperature for optimal production of total light olefins.

Keywords: petrochemical, catalytic cracking, catalyst synthesis, HS-FCC technology

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Authors: Roman J. Jedrzejczyk, Damian K. Chlebda, Anna Dziedzicka, Rafal Wazny, Agnieszka Domka, Maciej Sitarz, Przemyslaw J. Jodlowski

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The aim of this study was to obtain antimicrobial material based on thin zirconium dioxide coatings on structured reactors doped with metal nanoparticles using the sonochemical sol-gel method. As a result, dense, uniform zirconium dioxide films were obtained on the kanthal sheets which can be used as support materials in antimicrobial converters with sophisticated shapes. The material was characterised by physicochemical methods, such as AFM, SEM, EDX, XRF, XRD, XPS and in situ Raman and DRIFT spectroscopy. In terms of antimicrobial activity, the material was tested by ATP/AMP method using model microbes isolated from the real systems. The results show that the material can be potentially used in the market as a good candidate for active package and as active bulkheads of climatic systems. The mechanical tests showed that the developed method is an efficient way to obtain durable converters with high antimicrobial activity against fungi and bacteria.

Keywords: antimicrobial properties, kanthal steel, nanocomposite, zirconium oxide

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Authors: Riad Benelmir, Muhammad Shoaib Ahmed Khan

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The socio-economic importance of the olive oil production is significant in the Mediterranean region, both in terms of wealth and tradition. However, the extraction of olive oil generates huge quantities of wastes that may have a great impact on land and water environment because of their high phytotoxicity. Especially olive mill wastewater (OMWW) is one of the major environmental pollutants in olive oil industry. This work projects to design a smart and sustainable integrated thermochemical catalytic processes of residues from olive mills by hydrothermal carbonization (HTC) of olive mill wastewater (OMWW) and fast pyrolysis of olive mill wastewater sludge (OMWS). The byproducts resulting from OMWW-HTC treatment are a solid phase enriched in carbon, called biochar and a liquid phase (residual water with less dissolved organic and phenolic compounds). HTC biochar can be tested as a fuel in combustion systems and will also be utilized in high-value applications, such as soil bio-fertilizer and as catalyst or/and catalyst support. The HTC residual water is characterized, treated and used in soil irrigation since the organic and the toxic compounds will be reduced under the permitted limits. This project’s concept includes also the conversion of OMWS to a green diesel through a catalytic pyrolysis process. The green diesel is then used as biofuel in an internal combustion engine (IC-Engine) for automotive application to be used for clean transportation. In this work, a theoretical study is considered for the use of heat from the pyrolysis non-condensable gases in a sorption-refrigeration machine for pyrolysis gases cooling and condensation of bio-oil vapors.

Keywords: biomass, olive oil extraction, adsorption cooling, pyrolisis

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Authors: Mohamed A. Adam Abakar, Abdullah M. Asiri, Sher Bahadar Khan

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In this paper, nickel oxide-zinc oxide (NiO-ZnO) catalyst was embedded in an alginate polymer (Na alg/NiO-ZnO), a nanocomposite that was used as a nano-catalyst for catalytic conversion of deleterious contaminants such as organic dyes (Acridine Orange “ArO”, Methylene Blue “MB”, Methyl Orange “MO”) and 4-Nitrophenol “4-NP” as well. FESEM, EDS, FTIR and XRD techniques were used to identify the shape and structure of the nano-catalyst (Na alg/NiO-ZnO). UV spectrophotometry is used to collect the results and it showed greater and faster reduction rate for MB (illustrated in figures 2, 3, 4 and 5). Data recorded and processed, drawing and analysis of graphs achieved by using Origin 2018. Reduction percentage of MB was assessed to be 95.25 % in just 13 minutes. Furthermore, the catalytic property of Na alg/NiO-ZnO in the reduction of organic dyes was investigated using various catalyst amounts, dye types, reaction times and reducing agent dosages at room temperature (rt). NaBH4-assisted reduction of organic dyes was studied using alg/NiO-ZnO as a potential catalyst.

Keywords: Alginate, metal oxides, nanocomposites-based, catalysts, reduction, photocatalytic degradation, water treatment

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Authors: M. Belhadj Lachachi, Tayeb Benabdallah, M. Hadj Youcef, Jason M. Lynama

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The application of inorganic chemistry to catalysis and environmental chemistry is a rapidly developing field, and novel catalytic metal complexes are now having an impact on the industrial development practice. Advances in organometallic chemistry are crucial for improving the design of compounds to reduce toxic side effects and understand their mechanisms of action. The reaction of platinum(II) organometallic complexes with bidentate Schiff bases derived from 2-Hydroxynaphtalydeneaniline have been carried out. It concerns N,N’-naphtalidene para-nitroaniline (1-a), the, the N,N’-naphtalidene para-ethoxyaniline (1-b), the N,N’-naphtalideneaniline (1-c), the N,N’-naphtalidene para-chloroaniline (1-d) and the N,N’-naphtalidene para-methoxyaniline (1-e). The ligands were fully characterized by I.R., elemental analysis, 1H-NMR, 13C-NMR, ESI Mass Spectrometry and X-Ray Diffraction. The resulting metal complexes were obtained as a cationic species, through a simple substitution reaction, leading to two geometric isomers [1, 2], and characterized by IR, 1H-NMR, 13C-NMR, LIFDI Mass Spectrometry and supported by Elemental Analysis and X-Ray diffraction. Furthermore, a bimetallic platinum complex was prepared from the same ligands and dichloro(1,5-cyclooctadiene)platinum and characterized by X-Ray diffraction [3]The catalytic properties of the prepared platinum complexes in the hydrogenative and dehydrogenative silylation of styrene were investigated, and reaction kinetics conversion to products was determined by 1H-NMR and confirmed by GC-MS. This presentation will detail a comparison of the catalytic activity of five platinum organometallic complexes bearing different Schiff base ligands in the hydrosilylation of styrene, varying the experimental conditions of temperature, nature of the complex and the loading of the catalyst.

Keywords: catalysis, hydrosilylation, organometallic, schiff base

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Authors: Z. Jamalzadeh, A. Niaei, H. Erfannia

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Due to developing industries, the emission of pollutants such as NOx, SOx, and CO2 are rapidly increased. Generally, NOx is attributed to the mono nitrogen oxides of NO and NO2 that is one of the most important atmospheric contaminants. Hence, controlling the emission of nitrogen oxides is environmentally urgent. Selective catalytic reduction of NOx is one of the most common techniques for NOx removal in which zeolites have wide application due to their high performance. In zeolitic processes, the catalytic reaction occurs mostly in the pores. Therefore, investigation of the adsorption phenomena of the molecules in order to gain an insight and understand the catalytic cycle is of important. Hence, in current study, benefiting from molecular simulations, the adsorption phenomena in the nanocatalysts of SCR of NOx process was investigated in order to get a good insight of the catalysts’ behavior. The effect of cation addition to the support in the catalysts’ behavior through adsorption step was explored by Mont Carlo (MC) using Materials Studio Package. Simulation time of 1 Ns accompanying 1 fs time step, COMPASS27 Force Field and the cut off radios of 12.5 Ȧ was applied for performed runs. It was observed that the adsorption capacity increases in the presence of cations. The sorption isotherms demonstrated the behavior of type I isotherm categories and sorption capacity diminished with increase in temperature whereas an increase was observed at high pressures. Besides, NO sorption showed higher sorption capacity than NH3 in H–ZSM5. In this respect, the energy distributions signified that the molecules could adsorb in just one sorption site at the catalyst and the sorption energy of NO was stronger than the NH3 in H-ZSM5. Furthermore, the isosteric heat of sorption data showed nearly same values for the molecules; however, it indicated stronger interactions of NO molecules with H-ZSM5 zeolite compared to the isosteric heat of NH3 which was low in value.

Keywords: Monte Carlo simulation, adsorption, NOx, ZSM5

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Authors: Yuri A. Kalvachev, Totka D. Todorova

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Zeolite mordenite has been investigated as a transition metal support for the preparation of efficient catalysts in the oxidation of volatile organic compounds (VOCs). The highly crystalline mordenite samples were treated with hydrofluoric acid and ammonium fluoride to get hierarchical material with secondary porosity. The obtained supports by this method have a high active surface area, good diffusion properties and prevent the extraction of metal components during catalytic reactions. The active metal phases platinum and copper were loaded by impregnation on both mordenite materials (parent and acid treated counterparts). Monometalic Pt and Cu, and bimetallic Pt/Cu catalysts were obtained. The metal phases were fine dispersed as nanoparticles on the functional porous materials. The catalysts synthesized in this way were investigated in the reaction of complete oxidation of propane and benzene. Platinum, copper and platinum/copper were loaded and there catalytic activity was investigated and compared. All samples are characterized by X-ray diffraction analysis, nitrogen adsorption, scanning electron microscopy (SEM), X-ray photoelectron measurements (XPS) and temperature programed reduction (TPR). The catalytic activity of the samples obtained is investigated in the reaction of complete oxidation of propane and benzene by using of Gas Chromatography (GC). The oxidation of three organic molecules was investigated—methane, propane and benzene. The activity of metal loaded mordenite catalysts for methane oxidation is almost the same for parent and treated mordenite as a support. For bigger molecules as propane and benzene, the activity of catalysts based on treated mordenite is higher than those based on parent zeolite.

Keywords: metal loaded catalysts, mordenite, VOCs oxidation, zeolites

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Authors: Bayan Alqasem, Israa Othman, Mohammad Abu Haija, Fawzi Banat

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The large-scale production of wastewater containing highly toxic pollutants made it necessary to find efficient water treatment technologies. Phenolic compounds, which are known to be persistent and hazardous, are highly presented in wastewater. In this study, different ferrite catalysts CrFe₂O₄, CuFe₂O₄, MgFe₂O₄, MnFe₂O₄, NiFe₂O₄, and ZnFe₂O₄ were employed to study the catalytic degradation of phenol aqueous solutions. The catalysts were prepared via sol-gel and co-precipitation methods. All of the prepared catalysts were characterized using infrared spectroscopy (IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The ferrites catalytic activities were tested towards phenol degradation using high-performance liquid chromatography (HPLC). The photocatalytic properties of the ferrites were also investigated. The experimental results suggested that CuFe₂O₄ is an effective catalyst for the removal of phenol from wastewater. Additionally, different CuFe₂O₄composites were also prepared either by varying the metal ratios or incorporating chemically reduced graphene oxide in the ferrite cluster.

Keywords: phenol degradation, ferrite catalysts, ferrite composites, photocatalysis

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Authors: Renzhi Qi, Zhaoping Zhong

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Under the dual pressure of the global energy crisis and environmental pollution, avoiding the consumption of non-renewable fossil fuels based on carbon as the energy carrier and developing and utilizing non-carbon energy carriers are the basic requirements for the future new energy economy. Electrocatalyst for water splitting plays an important role in building sustainable and environmentally friendly energy conversion. The oxygen evolution reaction (OER) is essentially limited by the slow kinetics of multi-step proton-electron transfer, which limits the efficiency and cost of water splitting. In this work, CeO₂@NiCo-NRGO/NF hybrid materials were prepared using nickel foam (NF) and nitrogen-doped reduced graphene oxide (NRGO) as conductive substrates by multi-step hydrothermal method and were used as highly efficient catalysts for OER. The well-connected nanosheet array forms a three-dimensional (3D) network on the substrate, providing a large electrochemical surface area with abundant catalytic active sites. The doping of CeO₂ in NiCo-NRGO/NF electrocatalysts promotes the dispersion of substances and its synergistic effect in promoting the activation of reactants, which is crucial for improving its catalytic performance against OER. The results indicate that CeO₂@NiCo-NRGO/NF only requires a lower overpotential of 250 mV to drive the current density of 10 mA cm-2 for an OER reaction of 1 M KOH, and exhibits excellent stability at this current density for more than 10 hours. The double layer capacitance (Cdl) values show that CeO₂@NiCo-NRGO/NF significantly affects the interfacial conductivity and electrochemically active surface area. The hybrid structure could promote the catalytic performance of oxygen evolution reaction, such as low initial potential, high electrical activity, and excellent long-term durability. The strategy for improving the catalytic activity of NiCo-LDH can be used to develop a variety of other electrocatalysts for water splitting.

Keywords: CeO₂, reduced graphene oxide, NiCo-layered double hydroxide, oxygen evolution reaction

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Authors: Khaled Alshammari

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A facile approach to synthesizing highly active and stable Au/NiO catalysts for the hydrogenation of nitro-aromatics is reported. Preformed gold nanoparticles have been immobilized onto NiO using a colloidal method. In this article, the reduction of 4-nitrophenol with NaBH4 has been used as a model reaction to investigate the catalytic activity of synthesized Au/NiO catalysts. In addition, we report a systematic study of the reduction kinetics and the influence of specific reaction parameters such as (i) temperature, (ii) stirring rate, (iii) sodium borohydride concentration and (iv) substrate/metal molar ratio. The reaction has been performed at a substrate/metal molar ratio of 7.4, a ratio significantly higher than previously reported. The reusability of the catalyst has been examined, with little to no decrease in activity observed over 5 catalytic cycles. Systematic variation of Au loading reveals the successful synthesis of low-cost and efficient Au/NiO catalysts at very low Au content and using high substrate/metal molar ratios.

Keywords: nonochemistry, catalyst, nanoparticles supported, characterization of materials, colloidal nanoparticles

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Authors: M. Masar, P. Janota, J. Sedlak, M. Machovsky, I. Kuritka

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Zinc oxide (ZnO) nano crystals assembled porous architecture was prepared by thermal decomposition of zinc oxalate precursor at various temperatures ranging from 400-900°C. The effect of calcining temperature on structure and morphology was examined by scanning electron microscopy (SEM), X-ray diffractometry, thermogravimetry, and BET adsorption analysis. The porous nano crystalline ZnO morphology was developed due to the release of volatile precursor products, while the overall shape of ZnO micro crystals was retained as a legacy of the precursor. The average crystallite size increased with increasing temperature of calcination from approximately 21 nm to 79 nm, while the specific surface area decreased from 30 to 1.7 m2g-1. The photo catalytic performance of prepared ZnO powders was evaluated by degradation of methyl violet 2B, a model compound. The significantly highest photo catalytic activity was achieved with powder calcined at 500°C. This may be attributed to the sufficiently well-developed crystalline arrangement, while the specific surface area is still high enough.

Keywords: ZnO, porous structure, photodegradation, methyl violet

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Authors: V. Srinivasan, S. M. Sriram Nandan

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Today in the modern world the most important problem faced by the mankind is increasing the pollution in a very high rate. It affects the ecosystem of the environment and also aids to increase the greenhouse effect. The exhaust gases from the automobile is the major cause of a pollution. Automobiles have increased to a large number which has increased the pollution of our world to an alarming rate. There are two methods of controlling the pollution namely, pre-pollution control method and post-pollution control method. This paper is based on controlling the emission by post-pollution control method. The ratio of surface area of nanoparticles to the volume of the nanoparticles is inversely proportional to the radius of the nanoparticles. So decreasing the radius, this ratio is leading resulting in an increased rate of reaction and thus the concentration of the pollution is decreased. To achieve this objective, use of cobalt-graphene element is proposed. The proposed method is mainly to decrease the cost of platinum as it is expensive. This has a longer life than the platinum-based catalysts.

Keywords: automobile emissions, catalytic converter, cobalt-graphene, replacement of platinum

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