Catalyst For Synthesis Research Articles

Synthesis of Heterogeneous Nanocomposite Catalyst ZrO2@SBA-15 for Formic Acid Production from Hemicelluloses

Synthesis of Heterogeneous Nanocomposite Catalyst ZrO2@SBA-15 for Formic Acid Production from Hemicelluloses

Mesoporous BiCl3 immobilized silicic acid as a stabilized Lewis acid catalyst for the selective synthesis of 4-nitro-o-xylene from the nitration of o-xylene with NO2 under mild conditions

Mesoporous BiCl3 immobilized silicic acid as a stabilized Lewis acid catalyst for the selective synthesis of 4-nitro-o-xylene from the nitration of o-xylene with NO2 under mild conditions

Iron-Based Catalysts Integrated with Twinned HZSM-5 as Efficient Catalysts for Paraxylene Synthesis by CO2 Hydrogenation

Iron-Based Catalysts Integrated with Twinned HZSM-5 as Efficient Catalysts for Paraxylene Synthesis by CO₂ Hydrogenation

Synthesis of a Novel Platinum Catalyst and Its Application in the Photoactivated Hydrosilylation Reaction

Synthesis of a Novel Platinum Catalyst and Its Application in the Photoactivated Hydrosilylation Reaction

Surface oxygen vacancy regulation and active metal doping for Cu-Al based spinel catalysts synthesis toward high-efficiency reverse water-gas shift reaction

The reverse water-gas shift (RWGS) reaction is of great significance to convert CO2 to valuable feedstocks. Reasonable design and preparation of catalysts is necessary to achieve high CO2 conversion and CO selectivity. In this study, a series of Cu-Al based spinel catalysts were synthesized by coprecipitation-calcination method or A-site doped with active metal (Co, Zn, Mg, and Fe) for the RWGS reaction. The results indicated that the surface oxygen vacancies and crystal structure of CuAl2O4 can be regulated by calcination temperature. Remarkably, the CuAl-800 catalyst exhibits the highest CO2 conversion rate (62.7 %) with 100 % CO selectivity at 500 °C. Excessive calcination temperatures (> 800 °C) resulted in a well-defined spinel structure, but decreased surface oxygen vacancies and CO2 conversion rate. At calcination temperatures < 800 °C, surface oxygen vacancies increased, but the formation of CuO impurities which irreversibly converted to Cu2O during reduction, decreased catalytic activity. Compared with Zn, Mg and Fe, Co doping can significantly improved the reactivity of CuAl2O4 catalyst in RWGS reaction at 500 °C, increasing the CO2 conversion rate by 8 % while maintaining 100 % CO selectivity. The main reason is that Co doping not only effectively improves the integrity and stability of spinel structure of CuAl2O4, but also enhances its ability to dissociate and activate H species through interfacial sites of CuO-OV-CuXCo1-XAl2O4, thus further enhancing its catalytic conversion ability of CO2 to CO. These results enrich the understanding of surface chemistry of CuAl2O4 spinel and lay an important theory foundation for design of spinel-based catalysts for RWGS reaction.

Synthesis of iron loaded jackfruit peel biochar through microwave heating as a stable and active heterogenous Fenton catalyst for dye degradation

Iron-loaded biochar derived from jackfruit peels (Fe-JP) was synthesised by pyrolysis in a microwave furnace and iron was loaded onto the peels prior to pyrolysis, facilitated by sonication. The primary objective of the investigation was to examine the degradation process of methylene blue (MB) dye and Acid Red 1 (AR1) dye by the using Fe-JP biochar as a heterogeneous Fenton catalyst. The investigation encompassed an examination of the impact of different operating parameters, such as pH, catalyst dosage, and H2O2 concentration. The synthesised Fenton catalyst underwent characterization using Field Emission scanning electron microscopy (FESEM), Energy Dispersive X-ray (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques, Fourier transform infrared (FTIR) spectra analysis, Raman spectroscopy, Brunauer-Emmet-Teller (BET) analysis. At a pH of 3, using an initial MB dye concentration of 20 mg/L and initial AR1 dye concentration of 50 mg/L, an 8 mM H2O2 concentration, and a catalyst dose of 2 g/L, the maximum dye removal efficiency reached 96.5 % and 98 % respectively, while the total organic carbon (TOC) removal efficiency reached 68.5 % and 75 % respectively. The observed reaction time under the given experimental conditions was 120 min. The thermal stability of the biochar catalyst was found to be excellent based on the Thermogravimetric analysis (TGA) and Differential Scanning Calorimeter (DSC) studies. The catalysts that were developed demonstrated remarkable durability and negligible leaching of iron, hence enabling their repeated usage in subsequent cycles. The findings of the investigation suggest that the primary mechanism responsible for the degradation of the dye was the surface-based heterogeneous Fenton activity. Additionally, the effect of adsorption on the elimination of colour under varying pH conditions was examined, which had a very low influence in dye degradation (<30 %). The conducted scavenging investigations in the research have indicated the major involvement of hydroxyl radicals (OH) in the degradation process, followed by surface-bound hydroxyl radicals (OHsurface), superoxide radicals (O2−) and ultimately by singlet oxygen radicals (1O2). The study's economic analysis demonstrated that using microwave mode of heating for catalyst synthesis is both green and cost-effective. This observation suggests the possibility of practical implications in the domain of dye degradation.

Electrochemical on-surface synthesis of a strong electron-donating graphene nanoribbon catalyst

On-surface synthesis of edge-functionalized graphene nanoribbons (GNRs) has attracted much attention. However, producing such GNRs on a large scale through on-surface synthesis under ultra-high vacuum on thermally activated metal surfaces has been challenging. This is mainly due to the decomposition of functional groups at temperatures of 300 to 500 °C and limited monolayer GNR growth based on the metal catalysis. To overcome these obstacles, we developed an on-surface electrochemical technique that utilizes redox reactions of asymmetric precursors at an electric double layer where a strong electric field is confined to the liquid-solid interface. We successfully demonstrate layer-by-layer growth of strong electron-donating GNRs on electrodes at temperatures <80 °C without decomposing functional groups. We show that high-voltage facilitates previously unknown heterochiral di-cationic polymerization. Electrochemically produced GNRs exhibiting one of the strongest electron-donating properties known, enable extraordinary silicon-etching catalytic activity, exceeding those of noble metals, with superior photoconductive properties. Our technique advances the possibility of producing various edge-functional GNRs.

Sustainable Utilization of Oak Bark for MnO2 Catalyst Synthesis

Sustainable Utilization of Oak Bark for MnO2 Catalyst Synthesis

Stereoselective Synthesis of Axially Chiral Allenes and Styrenes via Chiral Phosphoric Acid Catalysis: An Overview.

Chiral allenes and styrenes are essential components in fields like medicinal chemistry, materials science, and organic synthesis. They serve a crucial role as chiral ligands and catalysts in asymmetric synthesis. Over the past decade, there has been a significant advancement in the development of practical methods utilizing organocatalytic strategies for the synthesis of chiral allenes and styrenes. It is noteworthy that despite extensive studies on the formation of allenes and styrenes, existing reviews on their construction confined to a specific organocatalysis, called chiral phosphoric acid catalysis, are less documented. This review aims to explore different conceptual approaches based on the electrophilic species involved in the reaction to produce stereoselective chiral allenes and styrenes, providing insights into recent advancements in the field. Emphasis is placed on works published since 2017, with detailed discussions on reaction mechanisms and examples from recent literature.

Synthesis of binder-free hybrid Ni-Co-Se@NiS2 nanostructures as highly active and durable electrocatalyst for hydrogen evolution reaction in alkaline media and Seawater

The Ni-Co-Se structures have been widely examined as an electrocatalyst for the hydrogen evolution reaction (HER). Despite the excellent electrical transportability, they suffer from low profusion of active electrocatalytic sites as well as poor long-term durability. Herein, we demonstrated Nickel-Disulfur doping in Ni-Co-Se as an effective method to simultaneously elevate electrocatalytic activity and stability. In this study, the preparation and optimization of the Ni-Co-Se@NiS2 core–shell structure were discussed using hydrothermal and electrodeposition processes. The electrocatalytic activity of the synthesized samples was investigated in both 1 M KOH solution and Seawater. The results of the electrochemical and microstructural investigations showed that the electrodeposition of NiS2 on Ni-Co-Se under the condition of pulsed potential with a frequency of 0.01 Hz by creating a dual micro-nanometric structure with a high edge area, needed only 73 and 81 mV of overpotentials to achieve a current density of 10 mA.cm2 in KOH and Seawater, respectively, as well as continuous stable operation over 30 h. The excellent kinetics with only 1.7 Ω.cm2 charge transfer resistance reached 300 mV overpotential, the high electrochemically active surface area (ECSA) equal to 1900 cm2, and a turnover frequency (TOF) value of 0.160 s−1 at 140 mV indicate the promising electrocatalytic HER performance of the Ni-Co-Se@NiS2 catalyst. This work introduced a novel strategy for the design and synthesis of high-level selenide-based HER catalysts.

Co/CoP@NC heterostructures as bifunctional catalysts to enhance the alkaline water splitting

The development of efficient and stable non-precious bifunctional electrocatalysts is of great significance, but it remains a great challenge. Herein, we have constructed Co/CoP@NC heterojunction catalyst loaded with Co and CoP particles on a nitrogen-doped carbon (NC) substrate using the pyrolysis-oxidation-phosphating strategy. The synergistic effect of Co and CoP particles on the NC substrate increases the active specific surface area, accelerates the charge transfer rate, and improves the intrinsic activities of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The Co/CoP@NC catalyst exhibits superior HER and OER performance. Specifically, the overpotentials required for Co/CoP@NC to reach the current density of 10 mA cm−2 are 142 and 186 mV for HER and OER, respectively. This study provides new insights into the design and synthesis of efficient and stable Co-based heterostructure catalysts.

Single atom catalyst induced by redox reaction between iron ion and aniline monomer

The effective design of a low-cost, efficient, and stable non-noble metal electrocatalyst to substitute the noble metal electrocatalyst for oxygen reduction reaction is highly significant. Even though atomically dispersed metal catalyst shows excellent catalytic activity with maximized atom efficiency, the challenge often lies in achieving uniform distribution for single-atom catalysts owing to their tendency to aggregate. In this work, we present a sequential method that involves the reduction of iron (Fe) mediated by aniline (anchored on support), followed by pyrolysis to fabricate the Fe-Nx moieties and achieve the high density of single atom active sites. The resulting Fe SA 900 catalyst exhibited a half-wave potential of 0.84 V vs. reversible hydrogen electrode (RHE) for oxygen reduction reaction and outstanding stability in alkaline condition. Using various analysis techniques and electrochemical analysis, we demonstrated that the electrocatalytic activity of the catalyst arises from Fe single atom. To validate the practical applicability of Fe-N-C catalysts, we conducted an anion exchange membrane fuel cell (AEMFC) test, which demonstrated a high performance of 212 mW cm−2 at maximum power density. This study proves that the effectiveness of a sequential strategy adopting redox reaction and following pyrolysis for precise synthesis of a single atom Fe catalyst.

One Iron for Two Iron Sites in a Metal-Organic Framework Toward Simultaneous N2-H2 Activation under Mild Conditions.

Iron-based catalysts play an important role in the ammonia industry. As one of the most abundant iron minerals, Fe3O4 containing FeII and FeIII sites is widely distributed in the earth's crust and even on exoplanets, theoretically giving it both economic and catalytic potentials in ammonia synthesis. However, in the absence of specific active co-catalyst and harsh conditions, Fe3O4 is impossible to achieve ammonia synthesis alone. Here, we designed to activate the relatively inert FeII and FeIII sites in Fe3O4 with a third FeIII site inlayed in a coordination framework (MIL-101(Fe)) to achieve the unpresented multi-site collaborative catalysis. In-depth mechanism study confirmed the roles of three different Fe sites in N2 activation, H2 activation, and product transfer, respectively. Efficient N2-H2 activation to NH3 on the Fe3O4-based catalytic system has been achieved at extremely mild conditions. Our research provides a theoretical basis and a new strategy for designing efficient non-noble metal-based ammonia synthesis catalyst with minimized energy consumption.

Bridging Dehydrogenation and Hydrogenation in Heterogeneous Catalysis: A Demonstration of a Unified Catalytic Approach.

In the pursuit of enhancing the applications of hydrogen as an energy carrier, this research delved into the utilization of a singular hybrid catalyst capable of performing both dehydrogenation and hydrogenation processes for Liquid Organic Hydrogen Carriers (LOHCs). This study presents the synthesis and characterization of a hybrid catalyst, combining an organometallic pincer complex with Pd-Ru heterostructures supported on γ-alumina. Unlike conventional transition and noble metal nanoparticles, the use of a pincer complex offers exceptional thermal stability due to its aryl backbone, which is advantageous for various endothermic dehydrogenation reactions of hydrocarbons in LOHCs. This pioneering hybrid catalyst is a novel approach, demonstrating a proof of concept. In this study, we utilized the hybrid catalyst to investigate the dehydrogenation and hydrogenation of a lower enthalpic system, specifically the cyclooctane-cyclooctene system. The dehydrogenation of cyclooctane was conducted at 443 K using tertiary butyl ethylene as a sacrificial hydrogen acceptor, while the hydrogenation of cyclooctene reaction catalyzed by Pd-Ru nanostructures occurred at 298 K and 1 atm H2. The results showed successful tandem dehydrogenation-hydrogenation reactions. However, challenges were noted in terms of catalytic activity and recyclability, providing valuable insights for further refinement and optimization.

Enhanced prednisone removal by catalytic wet air oxidation using sewage sludge derived catalyst

Sewage sludge-based catalysts have been used for the first time for the catalytic wet air oxidation (CWAO) of prednisone, a glucocorticoid pharmaceutical pollutant present in various aquatic environmental matrices. This research focuses on transforming dry sludge into carbonaceous catalysts through pyrolysis and post-treatment. Various parameters have been considered for the synthesis, finding that pyrolysis temperature and acid washing are determinant for specific surface area development. The sewage sludge derived catalysts exhibit high catalytic activity in the CWAO of prednisone (Dcat= 0.3 g·L−1, T= 100 °C, P= 15 bar). The development of porosity enhances their catalytic properties, the C-750-N catalysts demonstrated the highest activity for prednisone with 66 % TOC reduction, initial reaction rate 0.0092 mg·s−1 and 66 % CO2 selectivity. The study provides valuable insights into the synthesis, characterization, and application of sewage sludge-derived catalysts, offering a sustainable solution for wastewater treatment and pharmaceutical pollutant removal. Our present study indicates that catalysts with unique reforming properties may be potentially applicable for prednisone treatment and industrial applications.

Exploring the key role of electronic effects in Pd catalysts supported on Ni-modified N-doped porous carbon for direct synthesis of H2O2 under atmospheric pressure

Developing high-performance catalysts for direct synthesis of hydrogen peroxide (H2O2; DSHP) remains challenging. The paper proposes a strategy to optimize Pd catalysts by enriching Ni-modified N-doped porous carbon. The theoretical studies indicate that Ni modulates the electronic structure of Pd through charge transfer and strain effects, effectively reducing the adsorption energy of reaction intermediates. Furthermore, the Crystal Orbital Hamilton Population (COHP) analysis demonstrated that the energy-integrated COHP (ICOHP) of the OO bonds in O2* (* denotes the adsorbed state), OOH*, and HOOH* were positively correlated with dissociation activation energies and negatively correlated with hydrogenation activation energies. The modulation of the electronic structure of Pd by Ni reduces the hydrogenation activation energies of O2* and OOH* and increases the dissociation activation energies of O2*, OOH*, and HOOH*, thereby enhancing the selectivity and productivity of H2O2. The experimental results aligned with the theoretical predictions, showcasing that the optimized Pd-Ni7.5/NPCs catalyst exhibited remarkable H2O2 selectivity and productivity of 70.5 % and 230.31 mol kgcat-1·h-1, respectively, surpassing the performance of Pd/NPCs (47.1 % and 52.3 mol kgcat-1·h-1). This study offers profound insights into the crucial role of electron effects in DSHP using nickel-modified palladium catalysts, providing strong evidence into the design and optimization of Pd catalysts.

Unraveling the Photocatalytic Mechanism of N2 Fixation on Single Ruthenium Sites.

Photocatalytic N2 fixation offers promise for ammonia synthesis, yet traditional photocatalysts encounter challenges such as low efficiency and short carrier lifetimes. Atomically precise ligand-metal nanoclusters emerge as a solution to address these issues, but the photophysical mechanism remains elusive. Inspired by the synthesis of Au4Ru2 NCs, we investigate the mechanism behind N2 activation on Au4Ru2, focusing on photoactivity and carrier dynamics. Our results reveal that vibration of the Ru-N bond in the low-frequency domain suppresses the deactivation process leading to a long lifetime of the excited N2. By the strategy of isoelectronic substitution, we identify the single Ru sites as the active sites for N2 activation. Furthermore, these ligand-protected M4Ru2 (M = Au, Ag, Cu) NCs show robust thermal stability in explicit solvation and decent photochemical activity for N2 activation and NH3 production. These findings have significant implications for the optimization of catalysts for sustainable ammonia synthesis.

THE MECHANICALLY ACTIVATED COMPOSITES BASED ON TUNGSTEN DISULFIDE: SYNTHESIS AND PROPERTIES

In this work, the physicochemical properties of mechano-activated composites (hereinafter referred to as the mechanocomposites) obtained by mechanical activation of commercial tungsten disulfide powder in a planetary mill were studied. Mechanical activation was carried out for 2, 4 and 8 h, but this work presents the results for the last two experiments. The acceleration of the grinding media was controlled through frequency adjustment; a frequency value of 15.5 Hz, according to calculations, corresponds to an acceleration of the grinding media of 50 m/s2 or 5G. The material of the balls from which the grinding balls are made is stainless steel. Due to the relatively low acceleration values, the problem of contamination of the sample with stainless steel components does not occur as a result of surface erosion that occurs when the balls collide with each other and with the walls of the grinding bowl. Mechanical activation was carried out in an inert argon environment, since these were preliminary studies and therefore there was a need to minimize the environmental parameters taken into account. However, the oxidation process will occur during the process of discharging the sample from the grinding bowl of the planetary mill. The resulting mechanocomposites are precursors for the synthesis of monocomponent catalysts for the processing of heavy oil residue. For this purpose, it is necessary to obtain mechanocomposites containing tungsten trioxide and tungsten disulfide. The results of an experimental study of the influence, mainly, of the duration of mechanical activation on the production of tungsten mechanocomposites are presented. The resulting compounds were characterized by X-ray phase analysis (XRD), IR spectroscopy, scanning electron microscopy (SEM), thermogravimetry (TGA) and simultaneous thermal analysis (STA). For citation: Akimov Al.S., Zhirov N.A., Sudarev E.A., Akimov A.S. The mechanically activated composites based on tungsten disulfide: synthesis and properties. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 36-43. DOI: 10.6060/ivkkt.20246708.2t.

Silicomolybdic Acid Cluster as Biocompatible Catalyst for One-Pot Tandem Synthesis of Orthogonally Protected Glycosides.

The present paper describes a new and practical approach for the one-pot preparation of O-isopropylidene derivatives and also orthogonally protected S- and O-glycosides from the corresponding unprotected saccharides by employing 2 mol % of a silicomolybdic acid (SMA) cluster as a versatile and biocompatible catalyst. The present protocol is applicable to two-step one-pot tandem transformations, which include the O-isopropylidation, spiroketal functionalization, 4,6-O-arylidene acetalations, and arylidene acetylation processes under relatively mild reaction conditions. One-pot sequential transformations, low catalyst loading, rapid transformation, high to excellent reaction yields, mild reaction conditions, and a nontoxic biocompatible workup procedure are the notable advantages of devised protocol.

Modulating Cu2O/CuO on attapulgite for boosting peroxymonosulfate activation

Peroxymonosulfate (PMS) activation is an economically viable and efficient advanced oxidation process used to degrade recalcitrant organic pollutants. In this study, the copper oxide/attapulgite (CuxO/ATP) catalyst was synthesized via the hydrothermal method. The catalytic degradation efficiency was assessed using ciprofloxacin (CIP) as the model pollutant. The influence of catalyst dosage and PMS concentration on CIP degradation was examined. Additionally, the capability of the catalyst to degrade CIP under varying pH conditions, temperatures, and in the presence of diverse inorganic ions was investigated. The findings revealed that CuxO/ATP exhibited superior performance compared to pure CuxO in PMS activation for CIP degradation. Microstructural analysis indicated well-dispersed CuxO nanoflowers on the attapulgite, facilitating a synergistic effect between the two components. The presence of attapulgite enhanced the dispersion of CuxO, leading to an increase in the exposed surface area. In addition, attapulgite facilitated the adsorption of pollutants onto the CuxO interface, while CuxO, in turn, activated PMS to generate active free radicals, thereby enabling the catalytic oxidation of pollutants. Through a series of free radical quenching experiments, sulfate radicals were identified as the predominant species responsible for CIP degradation, playing a pivotal role in the system. Moreover, a plausible catalytic mechanism was discussed. Furthermore, reusability tests demonstrated the catalyst's stability and recyclability. This research not only presents a novel and robust approach for CuxO catalyst synthesis but also offers deeper insights into the mechanism underlying CuxO activation of PMS.