Superior Heterogeneous Catalyst Research Articles

Superior room-temperature efficacy of selective catalytic reduction of NOx by CO utilizing metal-modified Fe2O3 catalysts

Fe2O3-based catalysts demonstrate significant potential for the selective catalytic reduction (SCR) of nitrogen oxides (NOx) by CO. However, their effectiveness is limited at lower temperatures, impeding widespread industrial adoption. To overcome this, we optimize the Fe2O3-based catalyst component through 3 wt% cobalt (Co) loading, which improves the synergistic removal of CO and NOx pollutants. Our developed catalyst, Co-Fe2O3 on an amorphous SiO2 substrate, exhibits superior room-temperature activity in CO-SCR, achieving CO and NOx conversion ratios as well as N2 selectivity above 80 % at 25 °C, and over 93 % at 100–500 °C. The enhancement in catalyst performance is elucidated through density functional theory calculations and experimental investigations, revealing the creation of heteronuclear active sites via metal modification, and consequent improvements in redox characteristics and acidity. Our findings offer a robust pathway towards the industrial implementation of ammonia-free-SCR technology with synergistic removal of CO and NOx and provide insights for designing superior heterogeneous catalysts.

“Fe3+ modified zinc oxide nanomaterial as an efficient, multifaceted material for photocatalytic degradation of MB dye and ethanol gas sensor as part of environmental rectification”

• Fabrication of undoped ZnO and 5% Fe/ZnO by co-precipitation method. • Efficient removal of MB dyes under UV light irradiation. • Comparative study of prepared catalysts for water purification techniques. • Ethanol gas sensing application of modified ZnO material. • Humidity sensing study for the modified ZnO catalyst. In the present investigation, we report the preparation of 5% Fe 3+ doped zinc oxide (5% Fe/ZnO) nanocatalyst for organic transformations, gas sensing, and organic pollutant elimination applications via the CPT method. A broad range of analytical techniques was applied to attribute the successful modification of the nanocatalyst and to evaluate the structural and morphological properties, surface area, and chemical compositions by the x-ray diffraction, scanning electron microscopy, high resolution-transmission electron microscopy, Brunauer-Emmett-Teller, and energy dispersive spectroscopy techniques. The photocatalytic degradation of methylene blue (MB) as organic pollutant and gas sensing performance to ethanol were studied thoroughly. Due to enhanced gas sensing performance comparatively at low temperature to ethanol, it is known for ideal sensor, which has high selectivity, rapid response-recovery time, and high stability. It also showed the enhanced photocatalytic performance in the degradation of MB dye in the aqueous heterogeneous suspension. The efficiency of the semiconductor photocatalyst is found higher at the small amount of catalyst dose (0.8 g/L) and at the contact time of 100 min and pH 8.0 as operating parameters. Further, the organic transformation mechanism, enhanced gas sensing and, photodegradation mechanism were explained as the synergic effect of the ZnO and Fe doping. The results revealed that 5% Fe/ZnO nanocatalyst is promising approach to aim the goal of achieving a superior heterogeneous catalyst for the elimination of organic pollutant (MB) at optimum conditions and gas sensing performance for the detection of ethanol.

Polar bonds induced strong Pd-support electronic interaction drives remarkably enhanced oxygen reduction activity and stability

The strong metal-support interaction (SMSI) effect is attractive for improving the activity and durability of metal catalyst. Here, we uncovered that the strong polar bond in support can significantly boost the electrocatalytic oxygen reduction activity and durability of Pd nanoparticles (NPs). The mass-specific activity and surface-specific activity of optimized Pd/p-BNO at 0.90 V (vs.RHE) is almost 1.9 and 2.2 times higher than that of commercial Pt/C catalyst, respectively. By means of a joint experimental and computational study, the enhanced activity of Pd/p-BNO stems from the electron directly transfer through the strong polar OB bonds from support to Pd NPs leading to the electron-rich Pd surface. Moreover, the strong bonding effect of the caused by polarity bond effectively improves the stability of Pd/p-BNO. This progress demonstrates the vital role of polar chemical bonds in support on inducing SMSI effect, which might open up new opportunities in designing superior heterogeneous catalysts.

Molecular engineering of carbon nitride towards photocatalytic H2 evolution and dye degradation

The development of superior heterogeneous catalyst for hydrogen (H2) evolution is a significant feature and challenging for determining the energy and environmental crises. However, the dumping of numerous lethal colorants (dye) as of textile manufacturing has fascinated widespread devotion-aimed water pollution anticipation and treatment. In this regard, a photocatalytic H2 evolution by visible light using low-dimensional semiconducting materials having pollutant degradable capacity for Rhodamine B dyes (RhB) has been anticipated as a route towards environmental aspect. Here we fabricated the incorporation of organic electron-rich heterocyclic monomer 2,6-dimethylmorpholine (MP), inside electron-poor graphitic carbon nitride (g-CN) semiconductor by solid-state co-polymerization.The supremacy of copolymerization process was successfully examined via absorbent, calculated band gap, and migration of electrons on the photocatalytic performance of as-constructed CN-MP copolymer. The density functional theory (DFT) calculation provides extra support as evident for the successful integration of MP into the g-CN framework by this means-reduced band gap upon co-polymerization. The hydrogen evolution rate (HER) for g-CN was found as 115.2 μmol/h, whereas for CN-PM0.1was estimated at 641.2 μmol/h (six times higher). In particular, the pseudo-order kinetic constant of CN-MP0.1 for photodegradation of RhB was two times higher than that ofg-CN. Results show an important step toward tailor-designed and explain the vital role of the D-A system for the rational motifs of productive photocatalysts with effective pollutant degradable capability for future demand.

Synthesis of tetrazolo[1,5-a]pyrimidine-6-carbonitriles using HMTA-BAIL@MIL-101(Cr) as a superior heterogeneous catalyst

A one-pot three component reaction of benzaldehydes, 1H-tetrazole-5-amine, and 3-cyanoacetyl indole in the presence of a new hexamethylenetetramine-based ionic liquid/MIL-101(Cr) metal–organic framework as a recyclable catalyst was explored. This novel catalyst, which was fully characterized by XRD, FE-SEM, EDX, FT-IR, TGA, BET, and TEM exhibited outstanding catalytic activity for the preparation of a range of pharmaceutically important tetrazolo[1,5-a]pyrimidine-6-carbonitriles with good to excellent yields in short reaction time.

The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous Catalyst in Organic Synthesis

Mesoporous silica nanomaterials provide an extraordinary advantage for making new and superior heterogeneous catalysts because of their surface silanol groups. The functionalized mesoporous SBA-15, such as acidic, basic, BrÖnsted, lewis acid, and chiral catalysts, are used for a wide range of organic syntheses. The importance of the chiral ligands, which were immobilized on the SBA-15, was mentioned in this review to achieve chiral products as valuable target molecules. Herein, their synthesis and application in different organic transformations are reviewed from 2016 till date 2020.

Unraveling the Role of Site Isolation and Support for Semihydrogenation of Phenylacetylene.

Intermetallic compounds (IMCs) composed of transition metals and post-transition metals function as superior heterogeneous catalysts in comparison to their monometallic and bimetallic alloy counterparts. Rendering IMCs in their nanomaterial iterations further enhances their efficiency. Herein, we demonstrate the role of PdIn as well-dispersed intermetallic nanoparticles (IMNPs) for the semihydrogenation of phenylacetylene selectively to styrene at ambient conditions. Higher selectivity of PdIn was explained with the help DOS calculations. We have explored the role of a few well-known silica-based supports such as SBA-15 and MCM-41, providing insight into how they affect catalysis. As an additional support we have explored previously reported JNC-1, a mesoporous carbon material obtained via a templated strategy using SBA-15. PdIn supported on SBA-15 and JNC-1 displayed the best dispersion, while also exhibiting the most catalytic activity due to the unique nature of the porous structure.

Exploring the catalytic performance of a series of bimetallic MIL-100(Fe, Ni) MOFs

Stable mixed-metal FeIII/NiII MIL-100 MOFs have been synthesized de novo and have been explored as superior heterogeneous catalysts in acid catalyzed reactions, presenting superior performances.

Quasi-MOF: Exposing Inorganic Nodes to Guest Metal Nanoparticles for Drastically Enhanced Catalytic Activity

Summary Metal-organic frameworks (MOFs) are excellent supports for metal nanoparticles (NPs), but the interactions between metal NPs and inorganic nodes of MOFs are weak because of the presence of organic ligands. Here, we present a strategy for strengthening the metal-NP/MOF interactions through controlled deligandation of the metal/MOF composites by thermal transformation. The controlled deligandation of MOF results in the formation of a which has a transition-state structure between the porous MOF and metal oxide. The obtained metal/quasi-MOF composites not only retain a porous structure but also achieve a strong interaction between the metal NPs (i.e., Au) and the inorganic nodes (i.e., Cr–O) of the quasi-MOF, leading to dramatically enhanced catalytic performance in the low-temperature oxidation of carbon monoxide (CO). The present findings could open new avenues for the design of superior heterogeneous catalysts.

La-Metal-Organic Framework incorporating Fe3O4 nanoparticles, post-synthetically modified with Schiff base and Pd. A highly active, magnetically recoverable, recyclable catalyst for C[sbnd]C cross-couplings at low Pd loadings

Unprecedented post-synthetic modification (PSM) applied on a new La-MOF containing Fe3O4 nanoparticles (NPs), via Schiff base build-up (with pyridine-2-carboxaldehyde) and PdCl2 coordination, proved to be an advantageous strategy to produce a superior heterogeneous catalyst for Suzuki-Miyaura CC bond formation. The Fe3O4@La-MOF-Schiff base-Pd ensemble (characterized by PXRD, EDS, TEM, HAADF-STEM, VSM, TGA) showed very active, quite stable, magnetically recoverable and reusable in coupling of bromo- or iodoaryls with arylboronic acids, affording practically quantitative yields of biaryls (>99%) and high TONs and TOFs. The catalyst has been recycled up to 12 times without significant loss of the catalytic activity. A synergistic cooperativity between Pd and the oxophilic La nodes, through the organic linker, is responsible for enhancing the catalyst activity and stability.

Synthesis of MnSiO3 decorated hollow mesoporous silica spheres and its promising application in environmental remediation

In this work, the MnSiO3 decorated hollow mesoporous silica spheres (MHMSS) was facilely synthesized via an one-step thermal treatment of hollow mesoporous silica spheres (HMSS) and MnCl2⋅4H2O in a binary solvents (ethylenediamine/ethylene glycol). Intriguingly, it was found that MnSiO3 nanocrystals were formed effectively on the pore surface of HMSS without pore blocking, and the resultant MHMSS fully inherited the morphological and textural characteristics of HMSS such as spherical hollow structure with mesoporous shell, large pore size (mainly distributed around 15.5 nm), high surface area (501.5 m2 g−1), and large pore volume (1.85 cm3 g−1). More importantly, the MHMSS exhibited high catalytic activities for oxidative degradation of methylene blue (MB), basic red 5 (BR), and rhodamine B (RhB) in the presence of H2O2. Typically, 10 mL of MB (50 mg L−1) can be decolored by 80% in 1 min and nearly 93% in 10 min. Moreover, the MHMSS also showed excellent adsorption properties in term of capacity and kinetics on removal of Pb2+. The Pb2+ adsorption could reach equilibrium within 100 min, and the maximum adsorption amount was up to 279.4 mg g−1 at 313.15 K, significantly higher than those found for many other adsorbents. The present results suggest that the MHMSS hybrid material can not only be used as a superior heterogeneous catalyst for degradation of organic contaminants, but also act as a highly efficient adsorbent for adsorptive removal of heavy metal ions, which may provide insight into the design and development of high-efficiency nanomaterials and nanotechnologies for environmental remediation.

Graphene oxide grafted with iridium complex as a superior heterogeneous catalyst for chemical fixation of carbon dioxide to dimethylformamide

A novel graphene oxide (GO)-immobilized heteroleptic iridium complex was synthesized and demonstrated as a first heterogenized homogeneous catalyst for the production of dimethylformamide (DMF) from carbon dioxide, hydrogen, and dimethylamine. The synthesized hybrid catalyst showed comparable activity as homogeneous heteroleptic iridium complex with additional benefits such as facile recovery and recycling of the catalyst. After completion of the reaction, the heterogeneous catalyst was easily recovered by filtration, and reused for subsequent recycling processes without any significant change in the catalytic efficiency.

Magnetic Co3O4/reduced graphene oxide nanocomposite as a superior heterogeneous catalyst for one-pot oxidative esterification of aldehydes to methyl esters

Magnetic Co3O4/reduced graphene oxide nanocomposite as a superior heterogeneous catalyst for one-pot oxidative esterification of aldehydes to methyl esters.

Microspheres with Au@SiO2 core and mesoporous aluminosilica shell as superior heterogeneous catalysts for the aerobic epoxidation of cis-cyclooctene.

A novel microspherical composite with an Au@SiO2 core and mesoporous aluminosilica shell is synthesized and used as the heterogeneous catalyst in the aerobic epoxidation of cis-cyclooctene, exhibiting great catalytic activity and stability.

Different Crystallographic One-dimensional MnO2 Nanomaterials and Their Superior Performance in Catalytic Phenol Degradation

Three one-dimensional MnO2 nanoparticles with different crystallographic phases, α-, β-, and γ-MnO2, were synthesized, characterized, and tested in heterogeneous activation of Oxone for phenol degradation in aqueous solution. The α-, β-, and γ-MnO2 nanostructured materials presented in morphologies of nanowires, nanorods, and nanofibers, respectively. They showed varying activities in activation of Oxone to generate sulfate radicals for phenol degradation depending on surface area and crystalline structure. α-MnO2 nanowires exhibited the highest activity and could degrade phenol in 60 min at phenol concentrations ranging in 25-100 mg/L. It was found that phenol degradation on α-MnO2 followed first order kinetics with an activation energy of 21.9 kJ/mol. The operational parameters, such as MnO2 and Oxone loading, phenol concentration and temperature, were found to influence phenol degradation efficiency. It was also found that α-MnO2 exhibited high stability in recycled tests without losing activity, demonstrating itself to be a superior heterogeneous catalyst to the toxic Co3O4 and Co(2+).

Fe–clay as effective heterogeneous Fenton catalyst for the decolorization of Reactive Blue 4

Decolorization of anthraquinone dye Reactive Blue 4 (RB4) in an aqueous solution was investigated by using Fe–ball clay (Fe–BC) as heterogeneous catalyst. The best reacting conditions were found to be 0.80 wt.% of iron ions loading on ball clay (BC) when the dosage of catalyst is 5.0 g L −1 with initial pH of 3.0, [H 2O 2] 0 of 8 mM, [RB4] 0 of 50 mg L −1 at temperature 30 °C. Under these conditions, 99% decolorization efficiency of RB4 was achieved within 140 min reaction time. The results indicated that Fe–BC has proven to be a superior heterogeneous catalyst for decolorization of RB4 in an aqueous solution.

Ruthenium(0) Nanoclusters Stabilized by a Nanozeolite Framework: Isolable, Reusable, and Green Catalyst for the Hydrogenation of Neat Aromatics under Mild Conditions with the Unprecedented Catalytic Activity and Lifetime

The hydrogenation of aromatics is a ubiquitous chemical transformation used in both the petrochemical and specialty industry and is important for the generation of clean diesel fuels. Reported herein is the discovery of a superior heterogeneous catalyst, superior in terms of catalytic activity, selectivity, and lifetime in the hydrogenation of aromatics in the solvent-free system under mild conditions (at 25 degrees C and 42 +/- 1 psig initial H(2) pressure). Ruthenium(0) nanoclusters stabilized by a nanozeolite framework as a new catalytic material is reproducibly prepared from the borohydride reduction of a colloidal solution of ruthenium(III)-exchanged nanozeolites at room temperature and characterized by using ICP-OES, XRD, XPS, DLS, TEM, HRTEM, TEM/EDX, mid-IR, far-IR, and Raman spectroscopy. The resultant ruthenium(0) nanoclusters hydrogenate neat benzene to cyclohexane with 100% conversion under mild conditions (at 25 degrees C and 42 +/- 1 psig initial H(2) pressure) with record catalytic activity (initial TOF = 5430 h(-1)) and lifetime (TTO = 177 200). They provide exceptional catalytic activity not only in the hydrogenation of neat benzene but also in the solvent-free hydrogenation of methyl substituted aromatics such as toluene, o-xylene, and mesitylene under otherwise identical conditions. Moreover, they are an isolable, bottleable, and reusable catalyst in the hydrogenation of neat aromatics. When the isolated ruthenium(0) nanoclusters are reused, they retain 92% of their initial catalytic activity even for the third run in the hydrogenation of neat benzene under the same conditions as those of the first run. The work reported here also includes (i) far-infrared spectroscopic investigation of nanozeolite, ruthenium(III)-exchanged-nanozeolite, and ruthenium(0) nanoclusters stabilized by a nanozeolite framework, indicating that the host framework remains intact after the formation of a nanozeolite framework stabilized ruthenium(0) nanoclusters; (ii) the poisoning experiments performed by using tricyclohexylphosphine (P(C(6)H(11))(3)) and 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane PC(6)H(11)O(3) to examine whether the ruthenium(0) nanoclusters are encapsulated in the cages or supported on the external surface of nanozeolite; (iii) a summary section detailing the main findings for the "green chemistry"; and (iv) a review of the extensive literature of benzene hydrogenation, which is also tabulated as part of the Supporting Information .

Potassium Fluoride/Basic Alumina as Far Superior Heterogeneous Catalyst for the Chemoselective Conjugate Addition of Nitroalkanes to Electron‐Poor Alkenes Having Two Electron‐Withdrawing Groups in α‐ and β‐Positions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Potassium Fluoride/Basic Alumina as Far Superior Heterogeneous Catalyst for the Chemoselective Conjugate Addition of Nitroalkanes to Electron‐Poor Alkenes Having Two Electron‐Withdrawing Groups in α‐ and β‐Positions

AbstractThe chemoselective, conjugate addition of nitroalkanes to electron‐poor alkenes, with two electron‐withdrawing groups in the α‐ and β‐positions, can be easily performed at room temperature under solventless conditions using potassium fluoride/basic alumina as heterogeneous catalyst.

ChemInform Abstract: Nitroaldol (Henry) Reaction Catalyzed by Amberlyst A‐21 as a Far Superior Heterogeneous Catalyst.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.