Papers by Keyword: Heterogeneous Catalysis

Abstract: In order to produce biodiesel from waste palm oil (WPO), a calcium oxide (CaO) catalyst was developed using waste powder chalk and tested as a transesterification catalyst for the biofuel process. Generating CaO catalyst required a calcination method that was carried out at 900 °C for 3 h. Further investigation was conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The transesterification procedure was carried out applying response surface methodology (RSM) based on box-Behnken design (BBD). The BBD experimental design was employed, and the 3 process parameters investigated were catalyst concentration (3-5 wt.%), methanol/oil mole ratio (12-18), and reaction time (60-120 min). Experiments conducted under the optimal conditions predicted yielded over 97%, which was in excellent agreement with the expected value (a relatively small margin of error). This study demonstrates that WPO and waste chalk as low-cost feedstock are excellent sources of raw material for biodiesel production, and that a sustainable generation of biodiesel can be accomplished by optimizing process variables.

Abstract: After treating industrial wastewater efficiently and adequately to avoid harm from it being reused and disposed of in the past, the majority of countries in the world have moved to integrated planning and sound management to reuse it. The efficiency of water treatment and reuse depends on a set of environmental standards and controls that are connected to the nature of this water and the eventual purpose of treating and reusing it in order to prevent the environmental repercussions of an integrated method. A framework that assures environmental protection must be employed for this treatment and reuse. The emphasis is on developing reusable resources in order to transition from a linear to a circular economy. Finding the primary pathway for heterogeneous and homogeneous catalysis to pollutant degradation, optimizing the layout for integrating Fenton processes into large-scale treatment plants, particularly its coupling with biological treatment, and analyzing or enhancing heterogeneous catalyst lifetime are all important. are some of the main challenges mentioned in this research. This study intends to analyze the efficacy of the Fenton process in treating water in an effective and economical way compared to other conventional techniques.

Abstract: In the current study, exceptional and reasonable heterogeneous ZnO/PVP nanocatalysts were synthesized via the chemical reduction method followed by ultra-sonication for methyl orange degradation in the aqueous medium. The synthesized nanocatalysts were confirmed using different characterization techniques such as Energy Dispersive X-ray, Scanning Electron Microscope, X-ray diffraction analysis, Zeta Potential, Dynamic light Scattering, UV-Visible spectroscopy, and Fourier Transform Infrared Spectroscopy. To validate the competency of the nanocatalysts as the photocatalyst, the synthesized ZnO/PVP nanocatalysts were applied to the degradation of methyl orange dye. Lastly, the fabricated catalyst demonstrated splendid catalytic efficiency; within 90 seconds, more than 98% degradation of methyl orange dye was perceived using 150 μg nanocatalysts dose in the aqueous medium. The fabricated ZnO/PVP nanocatalysts illustrate many benefits above traditional routes for degrading the toxic and hazardous dye, like a short time, high percentile of degradation, the least amount of nanocatalysts, and admirable reusability. On the above facts, it is recommended that these viable and effective nanocatalysts can be applied successfully on the commercial level for degradation hazard pollutants.

Abstract: Use of quicklime as a sole catalyst for transesterification is limited by poor chemical stability and post-reaction recovery. This study investigates the effect of dry milling time on the transesterification catalytic performance (activity and recovery) of mechanically alloyed MgO, Al₂O₃ and eggshell derived quicklime. Raw chicken eggshells were calcined at 900 °C. The resulting flaking eggshell ash was directly mixed and comminuted with MgO and Al₂O₃ in ball milling (BM) machine for 15, 30, 60, 90, 120 and 150 minutes. Each of the catalyst samples was analyzed for surface morphology and particle size distribution, and then utilized for biodiesel production. Analyses of catalyst samples showed that mean particle size reduced, while powder agglomeration advanced with milling time. Optimum catalytic performance was achieved with the composite alloyed for 120 minutes (Z120) and that resulted in fatty acid methyl ester (FAME) yield of 88.4% and catalyst recovery of 98.3%. Sample Z120 was further characterized by TEM, EDX, XRD and BET. Calcination of the composite catalyst enhanced its activity. Dry high energy BM of oxides can be utilized effectively for synthesis of composite catalysts.

Abstract: Сatalytically active hybrid polymer-oxide material, based on molybdenum oxide compounds with iron group (Fe, Ni, Co) metals and polyvinyl-pyrrolidone, is obtained by method of transient electrolysis. Surface morphology and elemental composition of the obtained hybrid polymer-oxide material are examined with an electron microscopy and X-ray micro-fluorescent microanalysis; its phase composition and its chemical bonds structure formation between metal oxide compounds and polymer macromolecules are determined by X-ray phase analysis and IR spectroscopy. High catalytic activity of the obtained hybrid polymer-oxide material in the model reaction of hydrogen peroxide decomposition by the gaso-metric method is shown, which allows us to conclude that it is possible to use the obtained hybrid polymer-oxide materials as catalysts for wastewater treatment to purify it from organic and inorganic impurities.

Abstract: In this work was investigated the catalytic potential of a new heterogeneous catalyst of stoichiometry Ca_0.5K_0.5TiCu_0.25O₃ , with double perovskite structure, in the preparation of biodiesel via ethylic route. The catalyst was synthesized by the Polyol Modified method and characterized by X-ray diffraction, scanning electron microscopy, infrared spectroscopy and gas chromatography coupled to mass spectrometry. The investigation of the catalytic activity was carried out from transesterification reaction of commercial soybean oil with ethyl alcohol. Single-phase and crystalline powders related to the CaTiO₃ phase were obtained with an average crystallite size at around 17.25 nm. The new catalyst showed high efficiency for the production of biodiesel via heterogeneous catalysis with a yield at around 97%, with reaction time of 8 hours at 78°C and 15% of catalyst mass in relation to the soybean oil mass.

Abstract: Hydrous hydrazine is a promising hydrogen carrier material because of its high content of hydrogen (8.0 wt.%) and easy recharging as a liquid. Amorphous Ni_8.1Co_1.0Pt_0.9/Ce₂O₃ nanoparticles with low precious-metal content were synthesized by a facile co-reduction method at room temperature under ambient atmosphere. The increased degree of amorphization was attributed to the introduction of Ce₂O₃. The resultant Ni_8.1Co_1.0Pt_0.9/Ce₂O₃ nanocomposite was employed as an efficient nanocatalyst towards the decomposition of hydrous hydrazine to H₂, and exhibited excellent catalytic activity and 100% H₂ selectivity. Turnover frequency (TOF) value catalyzed by amorphous Ni_8.1Co_1.0Pt_0.9/Ce₂O₃ is 93.75 h^-1, which is much higher than Ni_8.1Co_1.0Pt_0.9 (4.39 h^-1) at 298 K. The development of the improved catalytic performance and low-cost catalyst with amorphous structure is believed to strongly promote the practical application of hydrous hydrazine as a hydrogen storage material.

Abstract: Catalysis is one of the hottest research topics in chemistry. In recent years, metal complexes attracted great interest as catalysts towards various types of organic reactions. However, these catalysts, in most cases, suffer from the deficits during their recovery, recycling and the difficulty in separation of catalysts from the products. Therefore, the design and synthesis of recoverable and recyclable catalyst is very important aspect in catalysis. The aim of this review article is to highlight the speedy growth in the synthesis and catalytic applications of magnetic nanoparticles (Fe₃O₄, MNPs) supported N-heterocyclic carbene (NHC) and amine based metal complexes in various organic reactions. Furthermore, these catalysts can be easily separated from the reaction media with the external magnet and reused various times without a substantial loss of catalytic activity.

Abstract: The market for 1,3-propanediol (1,3-PDO) is growing rapidly due to its expanding uses in the polymer material industry. Catalytic hydrogenolysis of glycerol is a promising new way to produce 1,3-PDO sustainably. This paper reviews the recent advances in studies on heterogeneous catalysts for the selective hydrogenolysis of glycerol to 1,3-PDO. The main employed metal catalysts include platinum, copper, rhodium and iridium. With the intent to give a rationally guide to the development of new catalysts in future research, the catalysts performances are summarized and discussed with reaction mechanisms.

Abstract: Metal-Organic Framework Materials MIL‑101(Cr) ([Cr₃X(H₂O)₂O(bdc)₃]∙n(H₂O), where X⁻ = F⁻ or OH⁻, n ≈ 25 and H₂bdc stands for 1,4-benzene-dicarboxylic acid] and MOF‑5(Zn) [Zn₄O(bdc)₃] were prepared by hydrothermal or solvothermal methods as well as Microwave‑Assisted Synthesis (MWAS), for which the detailed synthetic parameters were optimized. The crystal structures were confirmed by powder X-ray diffraction and the materials were further characterized by FT‑IR absorption spectroscopy. MIL‑101(Cr) and MOF‑5(Zn) showed weak catalytic activity in the oxidation of terpene, thiophene and cis-cyclooctene. Reasonable catalytic activity was observed for MOF-5(Zn) in the epoxidation of cis-cyclooctene and a 100 % of selectivity was observed for the epoxide. The structural stability of the materials was tested under the employed catalytic medium for oxidation reactions. MOF-5(Zn) revealed a remarkable structural stability at high temperature and also in the presence of high oxidant amounts.