Heterogeneous Catalyst For Oxidation Research Articles

Construction of Cobalt-Containing Polyoxovanadate-Based Inorganic-Organic Hybrids as Heterogeneous Catalysts for the Selective Oxidation of Sulfides.

In order to develop efficient catalysts for the selective oxidation of sulfides, in this work, two polyoxovanadate-based inorganic-organic hybrids, [Co(H2O)3(3-bpfb)0.5(V2O6)]·(3-bpfb)0.5 (1) and [Co(H2O)2(4-bpfb)0.5(V2O6)] (2) [3-bpfb = N, N'-bis(3-pyridylformamide)-1, 4-benzenediamine, 4-bpfb = N, N'-bis(4-pyridylformamide)-1, 4-benzenediamine], were isolated under hydrothermal conditions. The structures of 1 and 2 embodied two kinds of different cobalt-containing polyoxovanadate-based inorganic chains. Compound 1 contained a one-dimensional inorganic zigzag chain created by the aggregation of {V2O6} clusters with each other, on which Co (II) ions were fixed. But it was an inorganic dimeric chain constructed from two linear {V2O6} cluster-based chains gathered by Co (II) ions in 2. The 3-bpfb and 4-bpfb ligands, as the bidentate linkers, coordinated with two Co (II) ions from adjacent chains to organize them into two-dimensional layers. The hydrogen bonds made important contributions to the formation of supramolecular structures of the two compounds. The two compounds served as heterogeneous catalysts and exhibited efficient activity for the selective oxidation of sulfide to sulfoxide and could be reused at least six times without loss of catalytic activity and stability.

Synthesis and catalytic application of nanostructured metal oxides and phosphates.

The design and development of new high-performance catalysts is one of the most important and challenging issues to achieve sustainable chemical and energy production. This Feature Article describes the synthesis of nanostructured metal oxides and phosphates mainly based on earth-abundant metals and their thermocatalytic application to selective oxidation and acid-base reactions. A simple and versatile methodology for the control of nanostructures based on crystalline complex oxides and phosphates with diverse structures and compositions is proposed as another approach to catalyst design. Herein, two unique and verstile methods for the synthesis of metal oxide and phosphate nanostructures are introduced; an amino acid-aided method for metal oxides and phosphates and a precursor crystallization method for porous manganese oxides. Nanomaterials based on perovskite oxides, manganese oxides, and metal phosphates can function as effective heterogeneous catalysts for selective aerobic oxidation, biomass conversion, direct methane conversion, one-pot synthesis, acid-base reactions, and water electrolysis. Furthermore, the structure-activity relationship is clarified based on experimental and computational approaches, and the influence of oxygen vacancy formation, concerted activation of molecules, and the redox/acid-base properties of the outermost surface are discussed. The proposed methodology for nanostructure control would be useful not only for the design and understanding of the complexity of metal oxide catalysts, but also for the development of innovative catalysts.

PdCl2-FeCl3-imidazolium ionic liquid immobilized SBA-15 for boosting heterogeneous Wacker oxidation of styrene

PdCl2-FeCl3-imidazolium ionic liquid immobilized SBA-15 (SIL-PdFe) was prepared via chloropropyltriethoxysilane grafting with the surface Si-OH and N-methyl imidazole with C-Cl bond, followed by PdCl2 and FeCl3 coordinating to imidazolium ring. The SIL-PdFe was used as a heterogeneous catalyst for solvent-free Wacker oxidation of styrene with H2O2 oxidant, exhibiting high catalytic performance with styrene conversion of 95.4% and 87.7 % selectivity (54.2% acetophenone and 33.5% benzaldehyde). The catalyst can be easily recovered and effectively reused without a significant loss in the activity and selectivity. The quenching experiments by adding tert-butanol (TBA), 1,4-benzoquinone (p-BQ) and furfural alcohol (FA) in the reaction system were conducted to identify kind of the reactive O species produced by the catalyst activating H2O2 and the reaction mechanism of the Wacker oxidation was then proposed.

Metal Incorporated Zeolites as Heterogeneous Catalysts in the Selective Partial Oxidation of Methane to Methanol: A Review

Metal Incorporated Zeolites as Heterogeneous Catalysts in the Selective Partial Oxidation of Methane to Methanol: A Review

Ceria nanocatalyst-supported oxidative organic transformations of aromatic alcohols and p-nitrotoluene

Hydrothermally derived nanocubes of CeO2(10 nm) were explored as an efficient heterogeneous catalyst in the partial oxidation of aromatic alcohols to the corresponding aldehydes and aerobic oxidation ofp-nitrotoluene top-nitrobenzoic acid. The CeO2nanocatalyst was characterized by x-ray diffraction, transmission electron microscopy (TEM), energy dispersive spectroscopy, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform infrared spectroscopy, thermal gravimetric analysis and ultraviolet-visible spectroscopy. TEM/high-resolution TEM micrographs reveal a morphology of mostly cubic nanostructures with exposed highly active {100} and {110} facets. The surface area of nanoceria was determined by BET analysis and found to be 33.8 m2g-1. To demonstrate the universality of the catalytic system, the selective oxidation of different substrates of benzylic alcohol and complete oxidation ofp-nitrotoluene was investigated under mild conditions. Absolute selectivity towards their respective aldehydes was found to be 99.50% (benzaldehyde), 90.18% (p-chlorobenzaldehyde), 99.71% (p-nitrobenzaldehyde), 98.10% (p-fluorobenzaldehyde), 94.66% (p-anisaldehyde) and 86.14% (cinnamaldehyde). Moreover, the catalytic oxidative transformation of nitrotoluene results in 100% conversion with 99.29% selectivity towards nitrobenzoic acid.

Cover Feature: Ionic liquid templated synthesis of cobalt‐substituted mesoporous aluminophosphates: A novel heterogeneous catalyst for selective oxidation of cyclohexane to cyclohexanol (ChemCatChem 8/2024)

Cover Feature: Ionic liquid templated synthesis of cobalt‐substituted mesoporous aluminophosphates: A novel heterogeneous catalyst for selective oxidation of cyclohexane to cyclohexanol (ChemCatChem 8/2024)

Catching an Oxo Vanadate Porous Acetylacetonate Covalent Adaptive Catalytic Network that Renders Mustard-Gas Simulant Harmless.

In this work, we illustrated the design and development of a metal-coordinated porous organic polymer (POP) namely VO@TPA-POP via a post-synthetic metalation strategy to incorporate oxo-vanadium sites in a pristine polymer (TPA-POP) having acetylacetonate (acac) as anchoring moiety. The as-synthesized VO@TPA-POP exhibited highly robust and porous framework, which has been utilized for thioanisole (TA) oxidation to its corresponding sulfoxide. The catalyst demonstrated notable stability and recyclability by maintaining its catalytic activity over multiple reaction cycles without any significant loss in activity. The X-ray absorption spectroscopy (XAS) and density functional theory (DFT) analysis establish the existence of V(+4) oxidation state along with the VO(O)4 active sites into the porous network and the most energetically feasible mechanistic pathway involved in the TA oxidation, respectively, indicating the role of electron density associated with vanadium center during the catalytic transformation. Thus, this work aims at the demonstration of versatility and potential of VO@TPA-POP as a porous heterogeneous catalyst for the TA oxidation followed by decontamination of sulfur mustards (HD's) to their corresponding less toxic sulfoxides in a more efficient and greener way.

Solvent Free, Selective Oxidation of Styrene Catalyzed by Cobalt Acylpyrazolone Supported onto Neutral Alumina: Synthesis and Spectral Characterization

AbstractThe present work describes the synthesis of the Cobalt acylpyrazolone complex supported over neutral alumina and its use as a heterogeneous catalyst for selective oxidation of styrene. The catalyst mentioned here was characterized by various physicochemical techniques such as FT‐IR, TGA, CV, SCXRD, PXRD and BET. This heterogeneous catalyst has successfully been used to oxidize styrene to benzaldehyde in a solvent‐free condition with good conversion (87 %) and high selectivity (90 %) using H2O2 and TBHP as oxidants. The effects of the reaction parameters (catalyst concentration, reaction duration, and temperature) have also been investigated. The existing complex was discovered to be recyclable and sustainable with no change in conversion or selectivity for benzaldehyde. FT‐IR spectra of the regenerated catalyst indicated that the catalyst was undegraded and stable after the reaction. The novel feature of the current work reported in this paper is the selective oxidation of styrene without the need for solvents under mild conditions. Single Crystal Analysis.

Streamlined synthesis of iron and cobalt loaded MCM-48: High-performance heterogeneous catalysts for selective liquid-phase oxidation of toluene to benzaldehyde

Hydrothermal synthesis of MCM-48 molecular sieves featuring the incorporation of both iron and cobalt with Si/M ratios of 20, 40 and 80 (where M represents either iron or cobalt) was performed using tetraethyl orthosilicate as the silica source and cetyltrimethylammonium bromide as a template. To gain a comprehensive understanding of the synthesized materials, these were thoroughly characterized using various techniques, including XRD, XPS, UV–Vis (DRS), FT-IR, N2 adsorption-desorption analysis, SEM with EDX, TEM, TGA and NH3-TPD analysis. XRD analysis revealed the presence of well-ordered MCM-48 structure in the metal-incorporated materials, while XPS and UV–Vis DRS confirmed the successful partial incorporation of metal ions precisely in their desired tetrahedral coordination within the framework. To assess their catalytic performance, we studied the activity and selectivity of these catalysts in liquid phase oxidation of toluene using tert-butyl hydroperoxide as the oxidant. Under optimized conditions, employing a 6% (w/w) Fe-MCM-48 (40) catalyst and maintaining a toluene to oxidant molar ratio of 1:3 at 353 K in a solvent-free environment for 8 h, the oxidation reaction resulted in the formation of benzaldehyde (88.1%) as the major product and benzyl alcohol (11.9%) as the minor product.

Hydrophobic modification of zeolite-supported platinum catalysts for complete oxidation of toluene

Zeolite-supported noble metal nanoparticles have been reported as active catalysts for complete oxidation of volatile organic compounds (VOCs) due to the combination of advantages of zeolite supports and noble metal species, where introducing more Al species (reduction of SiO2/Al2O3 ratios, SAR) and increasing hydrophobicity for zeolite supports are favorable for the complete oxidation of VOCs. Unfortunately, introduction of more Al species in the zeolite frameworks normally reduces the hydrophobicity of zeolite crystals. To overcome this problem, we rationally synthesize hydrophobic zeolites with low SAR by anchoring methyl group, exhibiting exceptionally catalytic performances in the complete oxidation of toluene at very low temperature (T90 at 144 °C) after loading Pt species (1 wt%). Characterizations of the catalysts show a vital role of hydrophobic zeolites for adsorption of more toluene and fast desorption of water. The strategy for preparation of hydrophobic zeolite-supported noble metal catalysts might offer an alternative way to develop highly efficient heterogeneous catalysts for the complete oxidation of VOCs in the future.

Ionic liquid templated synthesis of cobalt‐substituted mesoporous aluminophosphates: A novel heterogeneous catalyst for selective oxidation of cyclohexane to cyclohexanol

AbstractOrdered hexagonal mesoporous aluminophosphate and its cobalt‐substituted analogue were successfully synthesized using ionic liquid as a structure‐directing agent. The resulting materials were systematically characterized by various analytical, spectroscopic, and imaging methods, confirming the presence of divalent cobalt in the tetrahedral framework of the matrix. Further, the high surface area, pore volume, and thicker mesopore walls of these materials impart good thermal and hydrothermal stability. The mesoporous catalysts showed excellent activity towards the oxidation of cyclohexane reactions using hydrogen peroxide as an oxidant, with 98.5 % conversion and 90.4 % selectivity towards cyclohexanol.

Fe-ZSM-5 zeolite catalyst for heterogeneous Fenton oxidation of 1,4-dioxane: effect of Si/Al ratios and contributions of reactive oxygen species.

Heterogeneous Fenton oxidation using traditional catalysts with H2O2 for the degradation of 1,4-dioxane (1,4-DX) still presents challenge. In this study, we explored the potential of Fe-ZSM-5 zeolites (Fe-zeolite) with three Si/Al ratios (25, 100, 300) as heterogeneous Fenton catalysts for the removal of 1,4-DX from aqueous solution. Fe2O3 or ZSM-5 alone provided ineffective in degrading 1,4-DX when combined with H2O2. However, the efficient removal of 1,4-DX using H2O2 was observed when Fe2O3 was loaded on ZSM-5. Notably, the Brønsted acid sites of Fe-zeolite played a crucial role during the degradation of 1,4-DX. Fe-zeolites, in combination with H2O2, effectively removed 1,4-DX via a combination of adsorption and oxidation. Initially, Fe-zeolites demonstrated excellent affinity for 1,4-DX, achieving adsorption equilibrium rapidly in about 10min, followed by effective catalytic oxidative degradation. Among the Fe-ZSM-5 catalysts, Fe-ZSM-5 (25) exhibited the highest catalytic activity and degraded 1,4-DX the fastest. We identified hydroxyl radicals (·OH) and singlet oxygen (1O2) as the primary reactive oxygen species (ROS) responsible for 1,4-DX degradation, with superoxide anions (HO2·/O2·-) mainly converting into 1O2 and ·OH. The degradation primarily occurred at the Fe-zeolite interface, with the degradation rate constants proportional to the amount of Brønsted acid sites on the Fe-zeolite. Fe-zeolites were effective over a wide working pH range, with alkaline pH conditions favoring 1,4-DX degradation. Overall, our study provides valuable insights into the selection of suitable catalysts for effective removal of 1,4-DX using a heterogeneous Fenton technology.

Effective photo-catalytic degradation of Malachite Green with water stable Cu based aliphatic di-carboxylate MOFs

Four different mesoporous Cu-MOFs named as Cu(Pima), Cu(Suba), Cu(Azla) and Cu(Seba) were prepared from aliphatic di-carboxylate linkers with the dimeric Cu paddle wheels as Secondary Building Units (SBUs). These as-synthesized aliphatic Cu-MOFs were applied as fresh heterogeneous catalysts for the catalytic wet peroxide oxidation of simulated Malachite Green waste-water and characterized using PXRD, FT-IR, Fe-SEM and BET. The results exhibited a better catalytic degradation efficiency of Cu(Seba) and Cu(Azla) (>90% in 200 mins) as compared to Cu(Pima) and Cu(Suba). It was established that degradation efficiency of Cu(seba) was approximately 9.8 times better than the rest of the synthesized Cu(MOFs). It was recognized that increasing the organic linker length can evidently boost the dye degradation process. Under optimum conditions, the degradation efficiency of 98% and 97% for Cu(Seba) and Cu(Azla) were achieved respectively. A optimal condition of 1.0 mL H2O2, 50 °C temperature and 3.5 pH was obtained. A recyclability experiment of four runs was performed for Cu(Seba) and Cu(Azla) which exhibited they maintained an effective degradation efficiency of ∼80% simulated MG solution. These analytical results of the degradation efficiency for Cu(Seba) and Cu(Azla) led us on a conclusion that, as synthesized Cu-MOFs outperformed several other reported MOFs, nanoparticles, adsorbents etc., as heterogeneous catalysts in the field of dye degradation for wastewater treatment.

Synthesis of New Glycosylamine Derivatives based on Carbohydrates

Background: Glycosylamine play an important role in living organisms. Most plants store their chemical resources in the form of inactive glycosides, which are broken down and con-verted into sugar in the body of herbivores by hydrolyzing enzymes. Glycosylamine are obtained from the secondary metabolism of plants and consist of two parts. One part of it contains sugar like glucose and is inactive in most substances, and has a good effect on the solubility of the glycosyla-mine derivatives and its absorption and even its transfer from one organ to another. The therapeutic effect is related to the second part, which is called aglycan (or aglucan). Glycosylamine derivatives form a large group of valuable medicinal substances, which at the same time include some of the most dangerous and toxic substances in nature. These substances are present in many groups of flowering plants. Glycosides are made in different ways in different metabolic pathways. These materials have a complex and special chemical structure and leave special effects on the human body. Glycosylamine derivatives are called O-glycosid, N-glycosid, S-glycosid in terms of atoms coupling to anomeric carbon. Carbohydrate esterification reaction to prepare new glycosylamine derivatives is one of the most important carbohydrate reactions. The anomeric position of carbohy-drates with strong leaving groups is very important for the preparation of glycosides. Preparation of glycosylamine derivatives based on acetylated carbohydrates is the main purpose of this article. Dif-ferent carbohydrates were acetylated under mild conditions and high yields. The anomeric position was deacetylated by a magnesium oxide heterogeneous catalyst in methanol solvent. In order to pre-pare new glycosides acetylated/ deacytylated carbohydrate reacted with N-Methyl-(naphtha-2-ylmethoxy)amine. The final product was identified by various spectroscopic methods. Methods: Anhydrous sodium acetate (4 g) and α-D-glucose (28 mg, 5 g) were mixed. The mixture was transferred to a 200 ml Round-bottom flask . Acetic acid (260 mg, 25 ml) was added to the reaction mixture. The reaction mixture was heated in a boiling water bath for 2 h until complete dissolution of the glucose. Then 100 ml of ice was added. After 1 hour, White crystals formed and were washed with cold water. And then 1 mol of glucose pentaacetate per 50 ml of methanol was dissolved by a magnetic stirrer. After thatMgO (0.2gr) was added to the reaction mixture. The re-action mixture was refluxed at room temperature within 4-5 hours. After 5 hours, the solvent was removed and separated by chromatography. It is then washed with hexane and crystallized by ether-hexane. And the final step reacted with N-Methyl- (naphtha-2-ylmethoxy) amine in order to prepare new glycosylamine derivatives. Results: Magnesium oxide in methanol solvent is one of the best effective catalysts in the deacetyla-tion of the anomer position of acetylated carbohydrates. It is done under ambient temperature and in very easy conditions and makes carbohydrates susceptible to extensive chemical reactions. One of these reactions is the formation of glycosides. Various carbohydrates are acetylated by acetic anhy-dride in the presence of sodium acetate, and the anomeric position is deacetylated by a heterogeneous catalyst. In order to prepare N-glycoside, the glycosides are reacted with N-alkoxy N-methylglycosyl amine. The final products are identified by various spectroscopic methods. Conclusion: Glucose, mannose, for example, were acetylated by acetic anhydride in the presence of sodium acetate. And the anomeric position of pentaacetate glucose was selectively deacetylated with magnesium oxide in a methanol solvent. Then, the reaction for the preparation of glycosylamine de-rivatives was carried out under very mild and easy conditions. The aminoglycosides synthesized in this article are used as raw materials for the synthesis of a wide range of antibacterials.

Ru-modified Octahedral Manganese Oxide Molecular Sieve (Ru-OMS-2) as a Reusable Heterogeneous Catalyst in Selective Oxidation of Olanzapine and Other Polycyclic Compounds

Ru-modified Octahedral Manganese Oxide Molecular Sieve (Ru-OMS-2) as a Reusable Heterogeneous Catalyst in Selective Oxidation of Olanzapine and Other Polycyclic Compounds

Carbon nitride doped VxOy/SBA-15 as highly efficient catalysts for the oxidation of ethyl lactate to ethyl pyruvate

Development of high-performance heterogeneous catalysts for the selective oxidation of ethyl lactate (EL) to ethyl pyruvate (EP) is very important in the field of sustainable chemistry. In this work, a series of carbon nitride (CN) doped wVxOy/CN-SBA-15 (w = 0.5–4.8%) catalysts were prepared. The doping of CN could significantly enhance the activity of VxOy/CN-SBA-15 catalyst due to the synergistic effect of V species, CN and SBA-15. The 2.6 VxOy/CN-SBA-15 was identified as the most optimum catalyst, offering a high EL conversion (93.0%) and EP selectivity (98.7%) at 130 °C after 3 h of reaction. The O2-TPD and H2-TPR results confirmed that the redox properties of 2.6 VxOy/CN-SBA-15 are significantly improved compared with 2.7 VxOy/SBA-15, which plays an important role in the oxidation reaction. In addition, the control experiments indicated that the pyridinic-N rather than pyrrolic-N of the VxOy/CN-SBA-15 catalyst accelerated the oxidation of EL to EP.

Sustainable Production of Chemicals via Hydrotreating of CO2 and Biomass Derived Molecules Using Heterogeneous Noble Metal Oxide Catalysts

AbstractThe noble metals are widely used in heterogeneous catalysis and automobile industry. The limited natural sources and high cost of noble metals dictates improving the efficiency of modern industry. This review considers the applications of noble metal oxide as potential solutions to the sustainability issues, including biomass conversion, CO2 capture and conversion, green fuel production, etc. Noble metal oxides with their different compositions (monometallic and bimetallic) and structures exhibit a wide range of properties in heterogeneous catalysis. Although platinum metals in an oxidized form may not be the most common choice in hydroprocesses; recently, there have been studies indicating that they were highly active and selective catalysts in hydrogenation and hydrogenolysis. This review outlines the most established noble metal oxide catalysts used in hydrogenation catalysis and shed the light on the relation of noble metal oxide species to catalyst selectivity based on state‐of‐the‐art techniques. Finally, the perspectives on the application of noble metal oxide catalysts to produce value‐added chemicals are discussed.

Mesoporous silica-supported Ni–Co composite metal oxide as a heterogeneous catalyst for air oxidation of benzyl alcohols

A mesoporous silica-supported Ni–Co composite metal oxide has been synthesized and applied as an effective heterogeneous catalyst for the selective catalytic oxidation of benzyl alcohols. Various characterization methods were employed to confirm the successful synthesis of the catalysts and their nanostructure. The catalytic performances of these catalysts in the selective oxidation of substituted benzyl alcohols to aromatic aldehydes were systematically investigated using molecular oxygen from the air as the oxidant under atmospheric pressure. The NiCo@SBA-15 catalyst exhibited remarkable performance, achieving nearly 98 % conversion and almost complete selectivity at a temperature of 120 °C for 10 h, operating at 1 atm of air pressure. This catalytic performance can be attributed to the synergistic effect between Ni and Co ions, resulting in the generation of new surface-active sites in the catalyst. The catalyst also demonstrated favorable applicability and universality. Moreover, A plausible catalytic mechanism has been proposed involving the synergistic effect between bimetal species and oxygen vacancy.

Preparation of powerful exchanged Faujasite zeolite materials used as effective heterogeneous catalyst for photo-Fenton oxidation of methyl orange (MO)

Preparation of powerful exchanged Faujasite zeolite materials used as effective heterogeneous catalyst for photo-Fenton oxidation of methyl orange (MO)

Light-induced degradation of organic pollutants under high salinity conditions using titanium dioxide/ferrocene polymer nanocomposites as photocatalyst and H2O2 activator simultaneously

A schematic graph illustrating the reaction. TiO2 nanocomposites were immobilized with a ferrocene-containing polymer as the heterogeneous catalyst for photocatalytic oxidation and photo-Fenton-like reactions simultaneously to treat wastewater.