Catalyst For Reaction Research Articles

Organocatalyzed Stereoselective Glycosylation: An Overview of the Last Decade

Abstract: Even though there has been an important evolution in the synthesis of oligosaccharides, the efficient and stereoselective study of glycosidic bonds through non-toxic, moderate, and inexpensive techniques is one of the most challenging fields in organic synthesis. Glycosyl reactions play a fundamental role in biological material and structure-activity relationships, having numerous medicinal chemistry applications. For this, interesting strategies have evolved over the years to control the stereoselectivity of glycosidic bonds, including the manipulation of different reaction elements, mainly promoters or catalysts, but also involving the nature of donors and solvents. This review looks at glycosylation methodologies in the last decade resulting in the specific formation of alpha or beta glycosidic bonds.

Mn-modulated Co–N–C oxygen electrocatalysts for robust and temperature-adaptative zinc-air batteries

Flexible zinc-air batteries (FZABs) are featured with safety and high theoretical capacity and become one of the ideal energy supply devices for flexible electronics. However, the lack of cost-effective electrocatalysts remains a major obstacle to their commercialization. Herein, we synthesized a porous dodecahedral nitrogen-doped carbon (NC) material with Co and Mn bimetallic co-embedding (CoxMn1−x@NC) as a highly efficient oxygen reduction reaction (ORR) catalyst for ZABs. The incorporation of Mn effectively modulates the electronic structure of Co sites, which may lead to optimized energetics with oxygen-containing intermediates thereby significantly enhancing catalytic performance. Notably, the optimized Co4Mn1@NC catalyst exhibits superior E1/2 (0.86 V) and jL (limiting current density, 5.96 mA cm−2) compared to Pt/C and other recent reports. Moreover, aqueous ZAB using Co4Mn1@NC as a cathodic catalyst demonstrates a high peak power density of 163.9 mW cm−2 and maintains stable charging and discharging for over 650 h. Furthermore, FZAB based on Co4Mn1@NC can steadily operate within the temperature range of −10 to 40 °C, demonstrating the potential for practical applications in complex climatic conditions.

Upcycling of Cr-Containing Sulfate Waste into Efficient FeCrO3/Fe2O3 Catalysts for CO2 Hydrogenation Reaction.

Upcycling Cr-containing sulfate waste into catalysts for CO2 hydrogenation reaction benefits both pollution mitigation and economic sustainability. In this study, FeCrO3/Fe2O3 catalysts were successfully prepared by a simple hydrothermal method using Cr-containing sodium sulfate (Cr-SS) as a Cr source for efficient conversion and stable treatment of Cr. The removal rate of Cr in Cr-SS can reach 99.9% at the optimized hydrothermal conditions. When the synthesized catalysts were activated and used for the CO2 hydrogenation reaction, a 50% increase in CO2 conversion was achieved compared with the catalyst prepared by impregnation with a comparable amount of Cr. According to the extraction and risk assessment code (RAC) of the Reference Office of the European Community Bureau (BCR), the synthesized FeCrO3/Fe2O3 is risk-free. This work not only realizes the detoxification of the Cr-SS but transfers Cr into stable FeCrO3 for application in a catalytic field, which provides a strategy for the harmless disposal and resource utilization of Cr-containing hazardous waste.

A bio-waste-mediated novel fabrication of ZnCr2O4 nanoparticles: a heterogeneous catalyst in Biginelli reaction

A bio-waste-mediated novel fabrication of ZnCr2O4 nanoparticles: a heterogeneous catalyst in Biginelli reaction

High-temperature treatment promotes N2O decomposition over Fe-impregnated Al-rich SSZ-13 zeolites

Fe/SSZ-13 catalysts were prepared via the impregnation method and calcined at different temperatures. The catalytic activity of Fe/SSZ-13 catalysts in the N2O catalytic decomposition reaction was greatly influenced by the calcination temperature. As the calcination temperature rose to 800 °C, the catalytic efficiency of N2O decomposition performance gradually improved. Nevertheless, if the temperature of calcination exceeded 800 °C, the efficiency diminished as a result of the disintegration of the molecular sieve framework. Various characterization methods were used to investigate the impact of calcination temperature on iron species. The results showed that the high-temperature treatment could promote the dispersion and reduction of Fe2O3 particles on the catalyst surface, which led to the generation of more active species (such as Fe3O4 and FeO) and provided more oxygen vacancies which favored the N-O breakage, thus improving the N2O decomposition activity.

Precise control of platinum coordination environment on fullerene-derived catalysts for oxygen reduction reaction

The interaction between catalysts and supports is recognized as a crucial factor influencing catalytic activity and stability. However, the carbon materials, which have been widely employed as the support at present, encounter challenges including intricate composition and the difficulty of precise control. In this study, the fullerene-derived carbon materials serve as support to electrocatalysts with low platinum. Fullerene-based materials, as the only carbon material with a well-defined molecular structure, have a controllable active site structure, which can provide a reaction model for studying metal-support interactions. Four kinds of fullerene-derived catalysts such as Pt/fullerene, Pt/nitrogen-doped fullerene, Pt/sulfur-doped fullerene, and Pt/phosphorus-doped fullerene, were synthesized. Once the coordination environment of the Pt particles was controlled, thus their catalytic performance was modulated. Despite a platinum loading of only 4.2%, Pt/N-fullerene demonstrates superior oxygen reduction activity and stability compared to commercial Pt/C (20%). Density functional theory calculations show that the introduction of heteroatoms can change the surface charge distribution of fullerenes, in which N-fullerene has a more negative electrostatic potential and can effectively anchor Pt. This research establishes a foundation for understanding the catalysts-support interaction and further precise control of the coordination environment of Pt. This provides new insights for designing efficient ORR catalysts.

One-step synthesis of hydroxyl-functionalized ionic hyper-cross-linked polymers with high surface areas for efficient CO2 capture and fixation

Ionic liquid-based functional materials have attracted significant attention for their distinctive structure in the field of CO2 capture and conversion. In this work, a series of hydroxyl-functionalized ionic hyper-cross-linked polymers are prepared through a one-step Friedel-Crafts reaction involving hypoxanthine (HX) and benzimidazole (BI) as the monomers, along with various halohydrocarbon crosslinking agents. These polymers demonstrate a high specific surface area (558–1480 m2·g−1), well-developed microporous structure, and unique ion sites, enabling them to exhibit remarkable and reversible CO2 adsorption properties. Particularly noteworthy is their CO2 adsorption capacity, which surpasses that of similar ionic polymers documented in the literature, reaching 157.5 mg·g−1 at 273 K and 1 bar. Additionally, these polymers function as recyclable catalysts in the cycloaddition reaction of CO2 and epoxides, enabling the conversion of CO2 into cyclic carbonates with yields of up to 99 % even without a co-catalyst. Mechanism investigation reveals that the introduction of hydroxyl groups in the polymer is the key to improving catalytic activity through a synergistic catalytic effect. This research provides a novel concept for designing ionic functional materials with capabilities in both CO2 adsorption and catalytic activity.

Vacancy-Enhanced Sb-N4 Sites for the Oxygen Reduction Reaction and Zn-Air Battery.

With the advantages of a Fenton-inactive characteristic and unique p electrons that can hybridize with O2 molecules, p-block metal-based single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) have tremendous potential. Nevertheless, their undesirable intrinsic activity caused by the closed d10 electronic configuration remains a major challenge. Herein, an Sb-based SAC featuring carbon vacancy-enhanced Sb-N4 active centers, corroborated by the results of high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure, has been developed for an incredibly effective ORR. The obtained SbSA-N-C demonstrates a positive half-wave potential of 0.905 V and excellent structural stability in alkaline environments. Density functional theory calculations reveal that the carbon vacancies weaken the adsorption between Sb atoms and the OH* intermediate, thus promoting the ORR performance. Practically, the SbSA-N-C-based Zn-air batteries achieve impressive outcomes, such as a high power density of 181 mW cm-2, showing great potential in real-world applications.

Cobalt catalysts for COx-free hydrogen production: Effect of catalyst type on ammonia decomposition in gliding discharge plasma reactor

Hydrogen is considered the cleanest, most environmentally friendly fuel and energy carrier required for the gradual decarbonisation of many industrial sectors. Using ammonia as a Cox-free source of hydrogen is the most reasonable and most applicable method. This paper studies the properties and activity of cobalt catalysts in the ammonia decomposition reaction using a plasma-catalytic system. The effect of catalyst type (supported versus bulk) was evaluated. The catalysts were examined using XRD, STEM-EDX, and sorption techniques (N2 physisorption, TGA-TPR, H2-TPD, CO2-TPD) to reveal the influence of physicochemical properties of these two types of catalysts on the efficiency of NH3 decomposition in the plasma-catalytic process using a gliding discharge plasma. The results disclose that the supported-type catalyst (Ba-Co/CeO2) decomposed NH3 more effectively than the bulk-type catalyst (Co/Ce/Ba). At discharge power of 300 W and flow rate of 180 dm3 h–1 of NH3:N2 mixture (50/50 vol%), the ammonia conversion over the Ba-Co/CeO2 catalyst was 70%, whereas over the Co/Ce/Ba catalyst it was only 21%. The favourable performance of the supported-type catalyst was attributed to a more thermally stable surface area compared with the bulk-type catalyst. Smaller and more stable cobalt nanoparticles (NPs) with numerous weak hydrogen adsorption sites were also seen. Meanwhile, the strong basic sites were generated, improving the electron-donating ability of the surface active sites. High ammonia conversion and relatively low-energy consumption of the plasma-catalytic ammonia decomposition over Ba-Co/CeO2 make it suitable for practical hydrogen production applications, such as fuel cells and hydrogen storage.

Construction of iron-modulated VN/V3O4/Co5·47N nanoparticles with rich heterogeneous interfaces for efficient oxygen evolution reaction

With the increasing need of clean energy demand, the development of efficient and green electrocatalysts for water electrolysis plays an irreplaceable role in the realization of large-scale production of hydrogen. Herein, an original iron modulated heterogeneous VN/V3O4/Co5·47N nanoparticles (FVOCN) is successfully synthesized using hydrothermal technique and in situ pyrolysis protocol. Through a series of characterization, it is found that the addition of iron in VN/V3O4/Co5·47N (VOCN) can significantly regulate the electronic structure and make it have better electrochemical oxygen evolution activity in 1 M KOH solution as opposed to the VOCN. The catalyst is obtained at the sintering temperature of 600 °C has the best performance, which only requires a lower overpotential of 270 mV to attain the current density of 10 mA cm−2 and superior to commercial IrO2. The method of introducing iron into vanadium-based, cobalt-based nitrides and vanadium-based oxides can broaden the research content of new electrochemical oxygen evolution reaction (OER) catalysts and provide a reference idea for the development of energy industry.

Synthesis of HNTs-Ca/Zn catalyst for biodiesel production from acidulated palm oil: Optimized by GA-BP

The development of heterogeneous base catalyst with acid resistance has become a major topic in the current research on the biodiesel production process. Halloysite nanotubes (HNTs) is supported with bimetallic of calcium and zinc for modification and labeled as HNTs-Ca/Zn to show both the acid and base characteristics. Further, this supported catalyst is used to produce biodiesel from the acidulated palm oil through catalyzing transesterification in one-step in this study. The HNTs-Ca/Zn catalyst, synthesized by the impregnation method, is characterized by TG-DTG, XRD, XPS, TEM, SEM-EDX, nitrogen adsorption-desorption, CO2/NH3-TPD, FTIR and Raman. The capability of the HNTs-Ca/Zn catalyst in catalyzing transesterification is investigated, where the maximum yield of 95.22% is achieved with the molar ratio of Zn to Ca of 1.5. The advantage of HNTs-Ca/Zn1.5 catalyst is prominent when the transesterification source oil is acidulated, where the biodiesel yield of 92.66% is obtained even at the acid value of 26.02 mg KOH g−1. Besides, reusability of the catalyst is acceptable, where the yield of 77.91% is maintained after the fourth reused cycle. Further, the Genetic Algorithm-Back Propagation (GA-BP) neural network is used to train and predict the transesterification parameters of the reaction temperature, catalyst amount and methanol to oil molar ratio. The prediction of the biodiesel yield is reasonable. At the predicted reaction parameters of 158 °C, catalyst amount of 7.1 wt.% and methanol to oil molar ratio of 15.5, the predicted biodiesel yield is 98.71%, where the experimental verification value is 98.60%. Therefore, the HNTs-Ca/Zn catalyst is considered to demonstrate exceptional catalytic performance and recyclability, offering the potential for biodiesel production.

Polyacrylonitrile‐based porous polymer spheres and their conversion to N‐doped carbon materials for adsorption and electrocatalysis

AbstractBecause of their tunable porosity and specific surface area, porous materials are of high interest for the purification of wastewater by adsorption as well as in electrocatalysis, where, in particular, developing metal‐free carbon‐based catalysts for the oxygen reduction reaction (ORR) is researched. The carbon spheres presented here can meet these two requirements simultaneously. Porous polyacrylonitrile (PAN) spheres were firstly prepared by droplet shaping cum nonsolvent induced phase separation. Then, they were converted to nitrogen‐doped carbon spheres by two‐step carbonization via preoxidation and pyrolysis. During the pyrolysis step, carbon dioxide was used to reopen the pores of the materials that had been blocked after the preoxidation step. By this way, specific surface area values of carbon spheres of more than 1000 m2/g could be obtained. Best performing carbon materials (C#3) showed high adsorption capacity (e.g., 296 mg/g for methyl orange at solute equilibrium concentration of 24 mg/L in water). The XPS analysis revealed that only quaternary (N‐Q) and pyridinic (N‐6) nitrogen sites were found in these carbon spheres. The best ORR performance was found also for C#3 carbon spheres, with a potential of 0.81 V versus reversible hydrogen electrode (RHE) at −1 mA/cm2 and electron transfer number of 3.5 at 0.6–0.8 V versus RHE, as determined by rotating disk or rotating ring disk electrode tests. In conclusion, all results confirm that these PAN‐derived carbon spheres are potentially valuable materials for both wastewater treatment by adsorption and electrocatalytic oxygen reduction.

Synergistic effect of Zr and K promoters on iron-based catalysts in CO hydrogenation reaction

There is a growing demand for decreasing fossil fuel usage. That being said, we should move toward renewable and sustainable energy sources. Iron-based catalysts are usually employed in this route. In this work, an incipient impregnation process was used for preparing four γ-Al2O3 supported iron-based catalysts with different weight percents including 20Fe/5Cu/γ-Al2O3, 20Fe/5Cu/2K/γ-Al2O3, 20Fe/5Cu/3Zr/γ-Al2O3 and 20Fe/5Cu/1.5Zr/1K/γ-Al2O3 under the pressure of 20 atm, the temperature of 285 °C, H2 to CO ratio of one, and a gas hourly space velocity of 2 NL/ (h. gCat). BET, FE-SEM, XRD, H2-TPR, ICP, and TEM techniques were used to determine the characteristics of the catalysts, while gas chromatography results were used to determine CO conversion and product selectivity. Due to the synergistic effect of the two promoters, the doubly-promoted catalyst exhibited a C5+ selectivity of 64.2 %, surpassing both the Fe/Cu/γ-Al2O3 catalyst and the singly-promoted catalysts. This result highlights the enhanced performance of the doubly-promoted catalyst. Compared to the other catalysts prepared, the doubly-promoted catalyst demonstrated a higher carbon monoxide (CO) conversion rate of 67.7 % and yield of 43.5 %. Moreover, The results demonstrate the significant impact of Zr and K promoters of the synthesized Fe-based catalysts on hydrocarbon product distribution.

Molecular Fe─N4 Moieties Coupled with Atomic Co─N4 Sites Toward Improved Oxygen Reduction Performance

AbstractResearch on high‐efficiency and cost‐efficient catalysts for oxygen reduction reaction (ORR) is still a vital but challenging issue for commercializing metal–air batteries. Herein, a single‐molecule/atom hybrid catalyst is developed to boost the ORR, in which iron phthalocyanine molecules containing molecular Fe─N4 moieties couple with atomic Co─N4 sites on the surface of polyhedral carbon. Density functional theory calculations reveal that face‐to‐face laminated construction of Fe─N4 and Co─N4 in the hybrid catalyst can effectively modulate the electronic structure of active iron atoms and reduce the energy barrier of the rate‐determining step for ORR. As a result, this hybrid catalyst demonstrates excellent ORR performance, featuring a half‐wave potential of 0.904 V, a peak power density of 238.3 mW cm−2 for zinc–air battery, and outstanding electrocatalytic stability. This work offers a distinctive and robust molecular/atomic engineering approach to creating efficient electrocatalysts, advancing the fields of metal–air batteries.

Chloromethylation of Lignin as a Route to Functional Material with Catalytic Properties in Cross-Coupling and Click Reactions.

Invited for this issue's cover are researchers from Tallinn University of Technology (TalTech). The image depicts the lignin chemical evolution route from raw biomass through a greener chloromethylation procedure developed by the research team. It showcases the transformation into lignin-supported metal nanoparticles, serving as a catalyst for various chemical reactions in both batch and continuous flow conditions. The Research Article itself is available at 10.1002/cssc.202301588.

One-dimensional biomass-based carbon nanotubes loaded with MoS2 as catalysts for the electrocatalytic nitrogen reduction reaction

In recent years, electrochemical conversion of nitrogen to ammonia at low temperature and atmospheric pressure has become a hot research topic because of its advantages of low carbon emission, low energy consumption and high energy transfer rate. The development of catalysts with high catalytic activity and flexibility are an important topic in the current nitrogen reduction reaction. In this paper, CNT@MoS2 composite catalysts were prepared by catalytic pyrolysis of biomass to prepare one-dimensional carbon nanotubes and then combined with MoS2 by a hydro thermal method. It was found that 120 CNT@MoS2 had better NRR activity and selectivity, NH3 yield rate of 21.2 μg h−1 mg−1 was achieved at −0.44 V vs. The Faraday efficiency can reach 5.4%. The catalytic performance is more than 3 times higher than CNT. The mechanism of MoS2-catalyzed NRR was further investigated by DFT theoretical calculations. The results of the theoretical calculations are in good agreement with the experimental results, providing a reasonable explanation for the high reduction performance of the catalyst. This study offered a promising avenue for exploring and rationalizing the design of electrocatalytic materials for NRR.

Facile synthesis of pyrite FeS2 on carbon spheres for high-efficiency Fenton-like reaction

Designing iron-based catalysts for Fenton-like reactions with peroxymonosulfate (PMS) as oxidants have attracted growing attentions. Herein, pyrite FeS2 supported on carbon spheres (FeS2@C) is synthesized by a facile low-temperature method. The FeS2@C/PMS system can degrade carbamazepine (CBZ) effectively in a wide pH range. Sulfate radicals (SO4·-), hydroxyl radicals (·OH), superoxide radical (O2·-), and singlet oxygen (1O2) are the responsible reactive oxygen species (ROSs) for CBZ degradation. Moreover, in the simulated fixed-bed reactor, the FeS2@C/PMS system can maintain a high CBZ removal ratio of >95% for than 8 h, exhibiting its excellent stability. The outstanding performance of FeS2@C/PMS system is attributed to the presence of carbon spheres and lattice S2−, which together promote the Fe(III)/Fe(II) redox cycle. The FeS2@C is a promising catalyst due to its facile synthesis, low cost, high efficiency, and excellent stability to activate PMS for organics degradation.

Constructing dendritic arrays composed of copper nanowires loaded with polyaniline for efficient nitrate electroreduction to ammonia

The use of electrochemical method to remove nitrate and reduce it to ammonia under mild conditions has attracted widespread attention. In this study, a dendritic structured electrode composed of polyaniline (PANI) modified copper nanowires was designed and synthesized on copper foam (CF) as the electrocatalytic nitrate (NO3-) reduction reaction (NO3-RR) catalyst. The PANI can not only accelerate the migration of electron, but also provide abundant active sites. The optimized sample exhibited an attractive electrocatalytic ability for NO3- reduction to NH3 with conversion rate, faradaic efficiency, and selectivity of 95.1%, 96.1%, and 98.38%, respectively, at −0.89 V vs reversible hydrogen electrode (RHE). This work provides an efficient and convenient solution for solving nitrate pollution and achieving nitrogen cycling.

DESCRIPTION OF BIODIESEL PRODUCTION FROM WASTE OIL RAW MATERIALS BY SOLID ACID CATALYSIS IN THE SIMULATOR PROGRAM

Increasing biodiesel production to reduce usage of its fossil based alternative is important for meeting consumption demand in more environmentally friendly way. The problem is utilization of edible resources for that purpose as it leads shortage in supply (increase in cost), instead usage of non-edible resources consisting sufficient amount of the free fatty acid content could be considered. This study focused on analysis of the inexpensive high FFAs raw materials to manufacture biodiesel with SO4-2/TiO2-SiO2 comprised solid acid catalyst. In addition to being readily recyclable, the solid acid catalyst has the ability to catalyze both esterification and transesterification at the same time. After analysis of the various parameters, ideal ones were found to be two hundred degree Celsius temperature, 9 to 1 methanol/oil ratio at 3 weight percent concentration of the catalyst for reaction. The outputs showed that the catalyst was quite effective in converting the cheap source to the biodiesel and manufacturing ten thousand tonnes seems viable. Keywords: biodiesel, solid acid, esterification, transesterification, waste oil feedstock.

Enzymolytic lignin derived Fe–N codoped porous carbon materials as catalysts for oxygen reduction reactions

Numerous active sites and hierarchical pore structures are important for improving catalytic performance for the oxygen reduction reaction (ORR). In this work, a series of iron-nitrogen-doped porous carbon materials (Fe–N–C) with ORR catalytic activity were prepared by a one-step pyrolysis method using enzymolytic lignin as the raw material, soy protein isolate and iron chloride as dopants. The results showed that the samples with the best performance have abundant Fe-Nx active sites and mesoporous structures. At the same time, the electrocatalytic results indicate that the half-wave potential of catalyst was 0.84 V, which reached 96.55% of commercial Pt/C catalysts (E1/2 = 0.86 V), it still preserves an initial current density of 92%, after 10,000 s of circulation, which is much better than Pt/C (86%). Due to the low cost, high activity and stable ORR property, the prepared non-precious metal electrocatalyst will play an important role in the applications of fuel cells.