Amount Of Catalyst Research Articles

Photocatalytic Epoxy Paint Based on TiO2 for the Decontamination of Water under Visible LED and Sunlight Irradiation

AbstractSemiconductor oxides such as titanium dioxide (TiO2) have been used as photocatalysts for removing contaminants. In addition, TiO2 nanoparticles in suspension form are difficult to recover and recycle, and they are expensive. In our work, titanium dioxide has been immobilized on a commercially available, thermally stable, chemically stable, and cheap polymer. The nanocomposite is synthesized with varying percentages of TiO2, 0.25, 0.5, and 1 weight percent. The obtained nanocomposites were characterized, and the effect of the process parameter (i. e., initial concentration of MB, amount of catalyst, light wavelength, and power of light) was investigated. Also, the results show good photodegradation of MB by the TiO2‐epoxy nanocomposite. The decomposition of 10 ppm methylene blue (MB) during 200 min under 25 W visible LED irradiation can reach 95 %. This value is higher than that obtained with pristine TiO2, which does not have photocatalytic activity under LED light. The antibacterial activity of nanocomposites concerning Escherichia coli and Stephalocous aureus was studied, and an inhibition zone of 2 cm and 3.5 cm was obtained, respectively. Therefore, the TiO2‐epoxy nanocomposite was applied to a glass jar and tested after four months for the degradation of methylene blue (5 ppm) and methyl orange (8 ppm) under sunlight. The paint demonstrated good photocatalytic efficiency of 41 % and 72 % within 310 min, respectively.

Plant mediated synthesis of flower-like Cu2O microbeads from Artimisia campestris L. extract for the catalyzed synthesis of 1,4-disubstituted 1,2,3-triazole derivatives.

This study presents a novel method for synthesizing 1,4-disubstituted 1,2,3-triazole derivatives through a one-pot, multi-component addition reaction using flower-like Cu2O microbeads as a catalyst. The flower-like Cu2O microbeads were synthesized using an aqueous extract of Artimisia Campestris L. This extract demonstrated the capability to reduce and stabilize Cu2O particles during their initial formation, resulting in the formation of a porous flower-like morphology. These Cu2O microbeads exhibit distinctive features, including a cubic close-packed (ccp) crystal structure with an average crystallite size of 22.8nm, bandgap energy of 2.7eV and a particle size of 6µm. Their catalytic activity in synthesizing 1,4-disubstituted 1,2,3-triazole derivatives was investigated through systematic exploration of key parameters such as catalyst quantity (1, 5, 10, 15, 20, and 30mg/mL), solvent type (dimethylformamide/H2O, ethanol/H2O, dichloromethane/H2O, chloroform, acetone, and dimethyl sulfoxide), and catalyst reusability (four cycles). The Cu2O microbeads significantly increased the product yield from 20% to 85.3%. The green synthesis and outstanding catalytic attributes make these flower-like Cu2O microbeads promising, efficient, and recyclable catalysts for sustainable and effective chemical transformations.

Reaction of NaBH4 and NaB(OH)4 as a way to increase the yield of hydrogen in catalytic hydrolysis of sodium borohydride by water

In this work, sodium tetrahydroxoborate (NaB(OH)4) that is the main product of the hydrolysis reaction of NaBH4 with a relatively small excess of water is studied in the reaction with sodium borohydride in the presence of a catalyst and without it. It was found, that mixtures consisting of NaB(OH)4 and NaBH4 begin to melt at 70 °C with the formation of a liquid phase without destroying the close coordination environment for both types of boron atoms. When a cobalt-based catalyst is added to mixtures, significant hydrogen evolution is observed. The resulting products are hydrogen and amorphous borates with a gross composition close to [NaBO2·0.75H2O].Carrying out the catalytic hydrolysis of borohydride in the system of initial composition H2O:NaBH4:catalyst under the conditions same to that the catalytic reaction of NaBH4 and NaB(OH)4 was observed is a promising way to produce H2 since it provides a high yield of hydrogen at small amounts of catalyst and atmospheric pressure. Catalytic hydrolysis carried out in the temperature range 80–120 °C with initial molar ratios H2O:NaBH4 = 3 and 2.7, and atmospheric pressure demonstrates a hydrogen yield of 8.3 wt% and NaBH4 conversion of 96 % at only 2.3 wt% of CoCl2 as catalyst. Since the resulting final composition of borates is close to [NaBO2·0.66H2O], the potential mass yield of hydrogen in this process can reach 9.3 wt%.

Green Fabrication of ZnO Nanoparticles and ZnO/rGO Nanocomposites from Algerian Date Syrup Extract: Synthesis, Characterization, and Augmented Photocatalytic Efficiency in Methylene Blue Degradation

This innovative article provides a detailed description of the successful biosynthesis of zinc nanoparticles (ZnO-NPs) using an aqueous extract of Algerian Date Syrup, also known as molasses. A meticulous process was carried out to determine the optimal calcination temperature for ZnO-NPs, a crucial step in the preparation of these nanoparticles. The study was further extended by creating ZnO/rGOx nanocomposites through a hydrothermal method, varying the concentrations of reduced graphene oxide (rGO) at 5%, 10%, and 15%. The characteristics of the nanocomposites were thoroughly explored, encompassing chemical, optical, and morphological aspects, using sophisticated analysis techniques such as scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (UV DRS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). These analyses provided an in-depth understanding of the structure and properties of the nanocomposites. The centerpiece of this study is the evaluation of the photocatalytic degradation capacity of ZnO-NPs and ZnO/rGOx nanocomposites. These materials have demonstrated their ability to act as cost-effective and environmentally friendly photocatalysts for wastewater treatment. Experiments on methylene blue degradation under UV irradiation were conducted, yielding impressive results: a degradation efficiency of 86.6% was achieved in 140 min using 1 g/L of ZnO-NPs, and this rate reached 100% with the ZnO/rGO catalyst in the same time frame, highlighting its superiority as a photocatalyst. Furthermore, this study examined the variables affecting the photocatalysis experiment, including the solution’s pH and the amount of catalyst. The results revealed that the ZnO/rGO photocatalyst reached its optimal efficiency under neutral pH conditions and at a concentration of 1 g/L, providing crucial information for practical use of these materials. This enriched article highlights the promising potential of ZnO-NPs and ZnO/rGOx nanocomposites as efficient photocatalysts for methylene blue degradation, paving the way for significant environmental applications in wastewater treatment.

Synthesis, drug loading and release study of spherical bioactive glass regulated by two templates

In this paper, the particle size and morphology of spherical biogalsses(BGs) were regulated by changing the amount of catalyst and templating agent using the dual template method. The prepared BGs had good morphology, dispersibility, and rapid induction of hydroxyapatite generation. The cell activity was above 75 % after co-culture of BG extracts with mBMSCs cells. The surface modification of BG was carried out by γ-aminopropyl triethoxy silane (KH-550) to obtain amino functionalized BG (BG-NH2), which was then loaded doxorubicin hydrochloride (DOX) to obtain BG-DOX. The maximum loading of BG was 19.2 % and the encapsulation rate was 91.8 %. The drug release rate of BG-DOX was proportional to specific surface area, and it was capable to release DOX at high concentration for up to 10 days, which can be a good drug carrier.

Uncovering Key Factors in Graphene Aerogel-Based Electrocatalysts for Sustainable Hydrogen Production: An Unsupervised Machine Learning Approach.

The application of principal component analysis (PCA) as an unsupervised learning method has been used in uncovering correlations among diverse features of aerogel-based electrocatalysts. This analytical approach facilitates a comprehensive exploration of catalytic activity, revealing intricate relationships with various physical and electrochemical properties. The first two principal components (PCs), collectively capturing nearly 70% of the total variance, attested the reliability and efficacy of PCA in unveiling meaningful patterns. This study challenges the conventional understanding that a material's reactivity is solely dictated by the quantity of catalyst loaded. Instead, it unveils a complex perspective, highlighting that reactivity is intricately influenced by the material's overall design and structure. The PCA bi-plot uncovers correlations between pH and Tafel slope, suggesting an interdependence between these variables and providing valuable insights into the complex interactions among physical and electrochemical properties. Tafel slope stands to be positively correlated with PC1 and PC2, showing an evident positive correlation with the pH. These findings showed that the pH can have a positive correlation with the Tafel slope, however, it does not necessarily reflect a direct positive correlation with the overpotential. The impact of pH on current density (j)and Tafel slope underscores the importance of adjusting pH to lower overpotential effectively, enhancing catalytic activity. Surface area (from 30 to 533 m2 g-1) emerges as a key physical property, inclusively inverse correlation with overpotential, indicating its direct role in lowering overpotential and increasing catalytic activity. The introduction of PC3, in conjunction with PC1, enriches the analysis by revealing consistent trends despite a slightly lower variance (60%). This reinforces the robustness of PCA in delineating distinct characteristics of graphene aerogels, affirming their potential implications in diverse electrocatalytic applications. In summary, PCA proves to be a valuable tool for unraveling complex relationships within aerogel-based electrocatalysts, extending insights beyond catalytic sites to emphasize the broader spectrum of material properties. This approach enhances comprehension of dataset intricacies and holds promise for guiding the development of more effective and versatile electrocatalytic materials.

CuAAC-Based Synthesis, Copper-Catalyzed Aldehyde-Forming Hydrolytic Fission and Antiproliferative Evaluation of Novel Ferrocenoylamino-Substituted Triazole-Tethered Quinine-Chalcone Hybrids.

A series of novel triazole-tethered ferrocenoylamino-substituted cinchona-chalcone hybrids along with two representative benzoylamino-substituted reference compounds were prepared by three methods of CuAAC chemistry. In line with the limited success or complete failure of attempted conversions with low catalyst loadings, by means of DFT modeling studies, we demonstrated that a substantial part of the Cu(I) ions can be chelated and thus trapped in the aroylamino-substituted cinchona fragment and all of the accessible coordinating sites of the chalcone residues. Accordingly, increased amounts of catalysts were used to achieve acceptable yields; however, the cycloadditions with para-azidochalcones were accompanied by partial or complete aldehyde-forming hydrolytic fission of the enone C=C bond in a substituent-, solvent- and copper load-dependent manner. The experienced hydrolytic stability of the hybrids obtained by cycloadditions with ortho-azidochalcones was interpreted in terms of relative energetics, DFT reactivity indices and MO analysis of simplified models of two isomer copper-enone complexes. The novel hybrids were evaluated on HeLa, MDA-MB-231 and A2780 cell lines and showed substantial activity at low-to-submicromolar concentrations. An organometallic model carrying 3,4,5-trimethoxyphenyl residue in the enone part with a para-disubstituted benzene ring in the central skeletal region was identified as the most potent antiproliferative lead, characterized by submicromolar IC50 values measured on the three investigated cells. The biological assays also disclosed that this ferrocenoylamino-containing lead compound displays a ca. two- to five-fold more substantial antiproliferative effect than its benzoylamino-substituted counterpart.

On the effect of hafnium loading and location in mesoporous silica on the activity of catalysts in oxidation of dibenzothiophene

Oxidation of thiophenes to sulfones (easily extracted from fuel) is of crucial importance in petrochemical and automotive industry. The rational design and synthesis of stable catalysts of this process still remains one of the biggest challenges. In this work, a series of HfSBA-15 mesoporous materials with different hafnium content (3, 5 or 10 wt.%) has been prepared and studied in the liquid phase oxidation of dibenzothiophene (DBT) with H2O2. The activity of HfSBA-15 samples prepared by one-pot method was compared to that of Hf/SBA-15 synthesized by impregnation and that of HfMCF type of silica. It has been shown that hafnium loading and its location in the silica structure (framework and/or extra-framework positions) affect the efficiency of DBT oxidation. Moreover, the reaction conditions (i.e. oxidation temperature, reaction time, oxidant/sulfur ratio and catalyst amount) were optimized to achieve maximum conversion of dibenzothiophene (99 %). The location of hafnium species in SBA-15 and MCF materials was influenced by the loading of the metal and the type of silica structure (determined by the preparation method). Hafnium located in the framework of SBA-15 promoted generation of a higher number of active Lewis acid sites (LAS) and higher activity in oxidation of dibenzothiophene compared to extra-framework HfO2 species anchored in HfMCF material. It indicates that the location (framework vs extra-framework) and formation of isolated Hf4+ species are decisive for high activity of hafnium-doped mesoporous molecular sieves. This finding opens up a pathway for the development of highly efficient, stable and relatively cheap solid acid catalyst for oxidation of thiophenes to sulfones.

The analysis of classical, polynomial regression and cubic spline mathematical models in hemp biodiesel optimization: an experimental comparison

Post-pandemic inflationist pressures, climate changes and extremes, regional conflicts, and soaring food prices caused the food crisis to increase rapidly worldwide. This global problem directs producers and researchers to use oils used as feedstock in biodiesel production effectively. In this context, it is important to assay the transesterification parameters and conduct new optimization studies to increase biodiesel yield. In this study, methyl ester was produced from hemp oil by transesterification using sodium hydroxide (NaOH). Next, classical optimization study was carried out to determine the effects of catalyst amount, alcohol:oil molar ratio, reaction temperature, and reaction time variables on biodiesel yield. Secondly, the cubic spline mathematical model (CSMM) and polynomial regression mathematical model (PRMM) were applied to the first data of this optimization. Among these optimization methods, the utmost biodiesel yield registered was 96.115% at hemp seed oil (HSO):methanol molar ratio of 5.59:1, catalyst concentration of 0.531 wt%, reaction temperature of 42.5 °C, reaction time of 62.1 min, and agitation intensity of 600 rpm at PRMM. Some vital fuel properties obtained from HSO biodiesels as a result of three optimizations satisfied the EN 14214 standard. The results illustrated that the optimal yields from CSMM and PRMM are 0.765% and 1.065% higher, respectively, according to the maximum efficiency obtained from the classical optimization. The outcomes showed that CSMM and PRMM are cost-effective, easy to handle, and promising new approaches.

Reaction Kinetics and Mechanism for the Synthesis of Glycerol Carbonate from Glycerol and Urea Using ZnSO4 as a Catalyst

A series of Zn salts were used as catalysts for the reaction of glycerol and urea to produce glycerol carbonate and it was found that ZnSO4 showed the highest catalytic activity. Furthermore, the effects of reaction parameters on the glycerol conversion and glycerol carbonate yield were studied in detail. The results indicated that the glycerol conversion and glycerol carbonate yield were increased with the reaction temperature, reaction time, and catalyst amount while the optimal reaction conditions were 140 °C, 240 min, catalyst amount of 5 wt% (based on the glycerol weight), and urea-to-glycerol molar ratio of 1.1:1. During the reaction, the ZnSO4 catalyst is transformed into Zn(NH3)2SO4 at the initial stage of the reaction and then further transformed into Zn(C3H6O3). Zn(C3H6O3) and (NH4)2SO4 may be the true active species for the activation of urea and glycerol, respectively. The reaction mechanism is proposed in this article. Based on the experimental results, a reaction kinetics model considering the change in volume of the reaction system was also established, and the model parameters were obtained by fitting the experimental data. The statistical results showed that the established kinetics model is accurate.

Tailoring structural, optical, and magnetic properties of Y3+ doped CoFe2O4 nanoparticles to enhance photocatalytic activity

In recent times, there has been a significant focus on semiconductive magnetic nanomaterials due to their potential in photocatalytic applications, primarily because of their easy recoverability. In this work, CoYxFe2-xO4 nanoparticles (with varying x values: 0, 0.05, 0.10, 0.15, and 0.20) were successfully synthesized. The incorporation of Y3+ ions induced notable transformations in the structural, optical, microstructural, magnetic, and photocatalytic properties of CoFe2O4 nanoparticles. Analytical techniques such as x-ray diffraction, fourier transform infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, photoluminescence, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy were employed to investigate these effects. The investigation into the photocatalytic degradation of methylene blue (MB) under ultraviolet light irradiation was carried out. The influence of distinct elemental compositions, catalyst quantities, irradiation durations, and initial methylene blue concentrations on the decolorization process was assessed.

Facile preparation of small-sized gold nanoparticle decorated silica nanocomposites and their morphological changes in catalytic reactions

Due to the unique physicochemical properties of gold nanoparticles (AuNPs) decorated silica nanostructures (SiO2@AuNPs), they show great potential for applications in catalysis, biosensing, optical devices and medicine. It is essential to explore the catalytic effect of SiO2@AuNPs and the understanding of the essential process of catalytic reactions. We have prepared SiO2@AuNPs by loading small-sized AuNPs on surface-modified silica nanospheres. SiO2@AuNPs was used as a catalyst for the catalytic reduction of 4-nitrophenol (4-NP) in the presence of excess NaBH4, and the results showed that with the increase of the amount of catalyst from 30 to 100 μl, the corresponding rate constant K app was increased from 6.44 × 10−3 to 1.45 × 10−2 s−1, and its TOF was as high as 1.326 × 103 h−1, and the catalytic rate could still be maintained at 87% after five cycles. By analyzing the morphology and size of the SiO2 supported AuNPs before and after the catalytic reaction, it can be seen that the atoms on the surface of small-sized AuNPs supported by silica have migrated during the catalytic process, which subsequently affects the catalytic efficiency of the structure. This study proves the good catalytic effect of SiO2@AuNPs structure and lays the foundation for its wider application.

Pt Effect on H2 Kinetics Sorption in Mn Oxide-Based Polymeric Material

Recent studies have demonstrated how a material based on Mn oxide, supported by a polymeric matrix, shows an interesting H2 absorption capacity in non-drastic temperature and pressure conditions even if the reaction kinetics are particularly slow. In this study, therefore, two different percentages of Pt (5 and 10 wt%) were added to a composite sample, containing 50 wt% of Mn oxide, through a ball milling technique in order to verify the reduction in absorption kinetics of the quantity of added catalyst. The effect of the catalyst quantity on the composite matrix was investigated through morphological analyses of the SEM-EDX and TEM types, with which it was found that the distribution of Pt is more homogeneous compared to the sample containing 5%. XRD studies confirmed the simultaneous presence of the amorphous structure of the polymer and the crystalline structure of Pt, and absorption tests with the Sievert method verified a better kinetic reaction of the 10% Pt sample. In parallel, a modeling study, using the ab initio Density Functional Theory (DFT), was performed. The supercell for this study was Mn22Pt2O48. The number of H atoms gradually increased, starting from 2 (Mn22Pt2O48H2), where the initial desorption energy was 301 kJ/mol, to 211 kJ/mol for 12 H atoms (Mn22Pt2O48H12). From the experimental H2 absorption value (0.22 wt%), the number of respective H atoms was calculated (n = 5), and the corresponding desorption energy was equal to about 273 kJ/mol.

Spent Li-ion batteries derived synthesis of boron doped RGO-Bi2WO6 for photocatalytic degradation of antibiotics

The aim of the current study is to resolve two significant environmental cleanup issues. The first involves recycling the spent lithium-ion batteries (LIBs) and the second involves the degradation of the antibiotics found in water. It has been possible to synthesize reduced graphene oxide (RGO) from used LIBs that have also been doped with boron (BRGO). A nanocomposite (BWO/BR) is formed when BRGO and a visible active Bi2WO6 (BWO) are mixed together. The structural, morphological, and spectroscopic characterizations confirm the formation of BRGO, BWO, and BWO/BR nanocomposite. The antibiotics tetracycline hydrochloride (TCH) and ciprofloxacin (CIP) have been tested for photocatalytic degradation with all three of the newly made materials. It is found to decrease the bandgap of BWO (2.73 eV) to 2.22 eV upon combining with BRGO. Under visible light, BWO/BR exhibits elevated TCH degradation (93 %), which is found to increase in the presence of sunlight (95 %). In the presence of BWO/BR, the degradation of CIP was reported to be 72, 95, and 97.5 % in UV, visible, and sunlight, respectively. The effect of reaction conditions like pH, amount of catalyst and initial concentration were examined towards degradation of TCH and CIP in presence of BWO/BR. It has been discovered that pH 6 and 8 are ideal for TCH and CIP, respectively. Studies on TCH and CIP degradation in pharmaceutical effluent were also conducted; in the presence of BWO/BR and visible light, the degradation efficiencies were determined to be 69 and 72 %, respectively. All of the zone of inhibition of E. Coli, L. monocytogenes, S. typhimurium, and S. aureus were examined in presence of BWO/BR before and after exposure to visible light for 90 min, during which time a near-zero zone of inhibition was seen. There were investigations using liquid chromatography-mass spectrometry (LC-MS) to identify the intermediate products of TCH and CIP degradation.

CuWO4 Reinforced Co‐doped HAp Nanocomposite: Improved Photocatalytic Activity Towards Degradation of Eosin Y and Catalytic Activity in Crossed Aldol Condensation Reaction

AbstractPreventing the recombination of photoinduced charge carriers in different semiconductor photocatalysts is crucial but high‐performance photocatalyst is still challenging. Herein, we report the synthesis of a novel heterojunction of cobalt‐doped hydroxyapatite with CuWO4 i. e. Co‐HAp@CuWO4 nanocomposite by simple and facile ultrasonication technique. The morphological and structural features of the composite was examined using PXRD, FTIR, SEM, EDS, TEM, UV‐DRS and XPS techniques. The optical analysis showed that the band gap of Co‐HAp@CuWO4 nanocomposite is 1.59 eV which is very much lower than pure HAp. The photocatalytic efficiency of Co‐HAp@CuWO4 was assessed in the degradation of Eosin Y dye under solar light irradiation. The result of degradation capacity is 94.5 % after 70 minutes of solar irradiation and it follows pseudo first‐order kinetics. The impact of different reaction parameters such as catalyst amount, initial concentration of the dye, and solution pH was also examined. The recyclability test showed that the synthesized material was highly stable in the visible‐light driven dye degradation. Heterogeneous catalytic efficacy of the prepared nanocomposite was examined in the crossed aldol condensation reaction of benzaldehyde and acetone and the outcomes confirmed that dibenzylideneacetone (DBA) was formed in the condensation reaction in outstanding yields under optimum conditions.

Catalytic Performance Investigation of Alkali and Bifunctional Catalysts Derived from Lignocellulosic Biomasses for Biodiesel Synthesis from Waste Frying Oil.

In this study, alkali and bifunctional catalysts were synthesized for waste frying oil methyl ester (WFOME) synthesis. Coffee husk (CH) and CH blended with Eragrostis tef straw (TS) (CH-TS) lignocellulosic biomasses (LBs) were utilized during the catalysts' synthesis. The alkali catalysts were CH and CH-TS ashes, both modified by KNO3 impregnation. They are designated as C-45 and C-Mix, respectively. Zirconia (ZrO2) promoted CH ash catalysts via precipitation followed by impregnation (Bic-PP) and in situ precipitation-impregnation (Bic-Dm) were the bifunctional ones. CH and CH-TS chars were the supporting frameworks during the catalysts' composite materials (CCMs) preparation. The combustion performance of LBs and CCMs was evaluated and associated with the catalysts' physicochemical properties. Using XRD, SEM, FTIR, alkalinity, TOF, and BET surface area analysis, catalysts were characterized. The combustion performance of the LBs was in the order of TS > CH-TS > CH. Among CCMs, the highest combustion performance was for CCM-Mix (KNO3/(CH-TS char)) and the lowest was for CCM-45 (KNO3/ CH char). The C-Mix catalyst was a light green powder due to the reaction between inorganic components, whereas C-45 was dark gray due to the presence of unburned char. The CCMs for bifunctional catalysts had moderate combustion performance and yielded light gray powdered catalysts containing tetragonal ZrO2. The optimum WFOME yields were 98.08, 97, 92.69, and 93.05 wt % for C-Mix, C-45, Bic-Dm, and Bic-PP assisted WFO transesterification, respectively. The results were obtained at a reaction temperature of 65 °C, time of 1 h, and methanol to WFO molar ratio of 15:1 using catalyst amounts of 5 and 7 wt % for the alkali and bifunctional catalysts, respectively. The greatest moisture resistance was offered by the C-Mix catalyst. The best reusability was for the C-45 catalyst. Catalysts' deactivation modes include active site leaching and poisoning.

CYCLOALKYLATION OF PARA-CHLOROPHENOL WITH 1-METHYL-CYCLOALKENES IN THE PRESENCE OF A ZEOLITE-CONTAINING CATALYST

The results of alkylation reactions of para-chlorophenol with 1-methylcyclopentene and 1-methylcyclohexene in the presence of zeolite-containing catalyst Seokar-2 (TU38-101483-77) are presented in the paper. Para-chlorophenol (PCP) interacted with 1-methylcycloalkenes on a laboratory batch setup. The reaction products were separated from the catalyst by hot filtration (40-50 °C) and undergone to distillation. Methylcyclene was distilled off at atmospheric pressure, then unreacted para-chlorophenol and the target reaction product were isolated under vacuum (10 mm Hg). Optimal conditions ensuring maximum yield of 2-cycloalkyl-4-chlorophenols were determined by studying effect of temperature, reaction time, molar ratio of PCP to 1-methylcycloalkenes, and amount of catalyst on the yield and selectivity. The reaction temperature was varied from 80 to 140 °C, duration of the experiments was from 2 to 8 h, molar ratio of PCP to 1-methylcycloalkenes was from 2:1 to 1:2 mol/mol, amount of catalyst was from 5 to 15% mas. It resulted in determining of the optimal conditions for alkylation reaction of para-chlorophenol with 1-methylcyclopentene and 1-methylcyclohexene in the presence of the zeolite-containing catalyst Seokar-2: reaction temperature 110-120 °C, duration 4-6 h, molar ratio of PCP to 1-methylcycloalkenes 1:1, catalyst amount 12-15% (on the taken PCP). These conditions allow having 68.2-73.6% yield of theory for 2-cycloalkyl-4-chlorophenols for the taken PCP, and 89.3-91.8% of selectivity for the target product. The physicochemical properties, elemental composition and structure were determined by 1H NMR and IR spectroscopy after separation of the target products from alkylate by distillation.

Optimization on removal of 2,4-dichlorophenol by sodium carboxymethyl cellulose modified nanoscale Pd/Fe bimetal with response surface methodology

2,4-dichlorophenol (2,4-DCP) is a toxic and harmful organic intermediate widely used in industrial production. Recently, the utilization of nano-zero-valent iron (NZVI) for 2,4-DCP treatment has gained significant popularity, but the deactivation and agglomeration of NZVI always appear and continue to present challenges. To address these issues, sodium carboxymethyl cellulose (CMC) and noble metal catalyst Pd are used as stabilizers to improve the removal efficiency of NZVI on 2,4-DCP. The CMC-modified nanoscale Pd/Fe bimetal (CMC-Pd/Fe) particles were prepared by the liquid phase reduction method and characterized by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results showed that the addition of Pd and CMC succeeded in ameliorating the aggregation of NZVI. A five-level-four-factor central composite design (CCD) of response surface methodology (RSM) was used to optimize the removal of 2,4-DCP by CMC-Pd/Fe and explored the factors influencing the removal of 2,4-DCP, including the amount of catalyst, the initial pH of the system, the time of reaction, and the initial concentration of 2,4-DCP. A statistically significant and well-fitting quadratic regression model was successfully constructed to predict 2,4-DCP removal efficiency. The high F-value of 14.35, very low p-value (<0.0001), nonsignificant Lack of Fit, and appropriate coefficient of determination of 0.9399 demonstrate a good correlation between the experimental and predicted values of the proposed model. The analyses of variance reveal catalyst amount and reaction time have a positive effect on the removal efficiency of 2,4-DCP and the CMC-Pd/Fe catalyst amount shows the most apparent significance, with PC (percent contribution) greater than 26. Conversely, pH and 2,4-DCP concentration have a negative impact on the removal process. The optimum condition is 1.10 g/L of catalyst amount, 5.63 of pH, 2.31 h of reaction time, and 20 mg/L of initial 2,4-DCP concentration. The validation results from parallel experiments showed that the average removal efficiency of 2,4-DCP reached 96.32% under the optimal conditions.

Liquid phase selective oxidation of veratryl alcohol to veratraldehyde using pure and Mg-doped copper chromite catalysts.

Mg-doped copper chromite (CuCr2O4) nanocomposites were synthesised through conventional technique. The pure and doped CuCr2-xMgx O4 (x = 0.00-0.1, 0.2 and 0.3%) nanocomposites were characterized in terms of their morphology, crystal structure, surface area and catalytic performance. The chemical composition of CuCr2-xMgx O4 was confirmed via FT-IR. The formation of pure and doped catalysts was validated by XRD results. TEM/SEM confirmed the formation of CuCr2-xMgxO4 nanoparticles. Mg-doped samples possess a high specific surface area compared to pure CuCr2O4. Thus, the effects of temperature, solvent, time, oxidant and the amount of catalyst on the oxidation of veratryl alcohol were reported. Furthermore, detailed mechanisms of the catalytic oxidation of veratryl alcohol as well as the reusability and stability of the nanomaterial were investigated. The resulting composites were shown to be effective heterogeneous catalysts for the oxidation of veratryl alcohol.

CHITOSAN-SUPPORTED MERCURY(II) ACETATE AS A CATALYST FOR TRANSVINYLATION REACTIONS OF AZOLES

The application of homogeneous catalysts - transition metal complexes - on organic polymers is of a great interest among researchers. Heterogeneous catalysts often have a long life span and are easy to separate from the reactants and reaction products, and they can also be reused. A homogeneous catalyst on a heterogeneous support acts as if it were in solution, but simultaneously it is a separate stationary phase. In this study we tried to use chitosan as a carrier for metal ions (particularly mercury(II), knowing in advance that chitosan is a good ligand for transition metals). Interest in chitosan is associated with their unique physiological and environmental properties, such as biocompatibility, biodegradation, and chelating ability. Here, an efficient and easy method of vinylation of azoles in the presence of chitosan-supported mercury(II) acetate heterogenous catalytic system is reported. As a result, several products were synthesized in high yields. The developed procedure is easy to perform, requires less amount of catalyst, shortens reaction time, excludes the formation of side products, and provides higher selective yields of vinylated products, reduces water contamination with mercury salts. Furthermore, it is possible to recover the catalyst from the reaction mixture and recycle this catalytic system more than four times.