Addition Of Catalyst Research Articles

Development of a tributyl phosphate-based hydrophobic deep eutectic solvent for liquid-liquid microextraction of total parabens in beverages

Deep eutectic solvents (DESs) are new alternative solvents used in sample preparation for dissolution, extraction and preconcentration of analytes. In this work,a tributyl phosphate (TBP)-based hydrophobic deep eutectic solvent was applied in the liquid–liquid microextraction (LLME) of total parabens in beverages.The sample preparation procedure consisted of two main steps: the phase transfer catalyst-assisted alkaline hydrolysis of parabens and the LLME of parabens’ hydrolysate p-hydroxybenzoic acid (PHBA). The hydrolysis procedure was improved efficiently by the addition of phase transfer catalyst and the extractant became greener as the natural lauric acid (LauA) was used as the component of the DES. It was verified that the DES composed of TBP and LauA (3:1, mol/mol) was the most effective option for PHBA extraction. Response surface methodology (RSM) based on Box-Behnken design (BBD) was adopted to optimize the predominant experimental conditions. The proposed method provided satisfactory linearity (R2 ≥ 0.9991), detection limits (0.02 μmol/L), precisions (RSDs ≤ 4.5%), recoveries (85.2% to 104.6%) and negligible matrix effects, which offered a promising way for screening total parabens in various beverage samples.

Multicomponent Dearomative Difluoroalkylation of Isoquinolines with Difluorinated Silyl Enol Ethers: Divergent Synthesis of gem-Difluorinated Heterocycles.

A multicomponent dearomative difluoroalkylation of isoquinolines has been developed with difluorinated silyl enol ethers serving as poor nucleophiles without an additional transition-metal or organic catalyst. The sequential oxidative rearomatization under different alkaline conditions provides a controllable formal C-H difluoroalkylation and difluoromethylation method for isoquinolines without peroxide or metal oxidant. A series of isoquinolines including a pharmaceutical, phenanthridine, quinolines, and difluorinated silyl enol ethers were suitable substrates to construct gem-difluorinated heterocycles. The inexpensive starting materials, mild reaction conditions, and simple operation also show practical and environmentally benign advantages.

Financial Services Digitainability: Financial Inclusion and Efficiency in EU Countries

Digitalization of financial services is one of the biggest challenges of the last decade, both in the EU and globally. The rapid development of digital technologies undoubtedly creates a favourable environment for significant progress in the financial sector, moreover, the Global Financial Crisis (GFC) and the pandemic have served as additional catalysts. However, several aspects on the way to financial services digitainability are still insufficiently explored. Considering the latest trends in the financial sector and advances in digital transformation, this study aims to identify the key drivers for the implementation of digital financial services and initiatives that managers should pursue to effectively transform business processes. The methodological base of the research consists of an extensive analysis of current publications in such areas as digital transformation, sustainable development, digital financial services, etc. The article investigates two aspects of financial sustainability: financial inclusion and operational efficiency of financial institutions, based on Eurostat data on financial services provided in the EU during 2011 - 2021, the Digital Economy and Society Index variables, and European Central Bank data on operational expenses. Correlation and regression analysis methods are used to study the relationships between variables under investigation, as well as statistical tests to acquire necessary evidence for statistical inferences about the proposed hypotheses. The results of the study provide the possibility to judge current trends in the use of digital financial services in the EU countries, determine the main drivers of sustainable digital financial services, as well as to observe the benefits of digital transformation in the financial sector.

Evaluation of the viscoelastic behavior, thermal transitions, and self‐healing efficiency of microcapsules‐based composites with and without a catalyst using dynamic mechanical analysis technique

AbstractThis comprehensive study investigates the viscoelastic behavior, thermal transitions, and self‐healing efficiency of microcapsule‐based composites with and without a catalyst. The composites consist of urea‐formaldehyde/dicyclopentadiene microcapsules embedded in an epoxy matrix, with the addition of Grubbs' catalyst. Our research examines the impact of repetitive dynamic mechanical analysis (DMA) testing and the presence of Grubbs' catalyst on the composites' self‐healing efficiency and dynamic mechanical properties. Using laser microscopy, optical microscopy, Fourier‐transform infrared spectroscopy, and thermogravimetric analysis, we employ various characterization techniques to enhance our understanding of the composite behavior. The findings emphasize the importance of evaluating self‐healing efficiency through DMA, which is a reliable, expeditious, and non‐destructive method. The results show that incorporating Grubbs' catalyst significantly enhances the self‐healing performance of the composites, effectively mitigating the degradation of mechanical properties due to aging. Furthermore, the inclusion of catalyst particles improves stiffness, rigidity, and energy dissipation characteristics, facilitating the self‐healing process. However, careful consideration is necessary to balance mechanical properties and the glass transition temperature when designing self‐healing composites. This study demonstrates a promising self‐healing efficiency of approximately 73% and 44% in the second and third DMA tests, respectively, for composites containing microcapsules and Grubbs' catalyst.

Radical Covalent Catalysis: Recent Advances and Future Developments

AbstractRadical covalent catalysis, namely radical catalysis via a radical catalyst addition and elimination process, has emerged in the past few decades. This review is aimed to summarize the recent advances of radical covalent catalysis by highlighting some outstanding challenges and confirming potential areas of improvement, which may offer inspiration for future studies.

Effect of the catalyst type on pyrolysis products distribution of polymer blends simulating plastics contained in waste electric and electronic equipment

The valorization of the plastic part from waste electric and electronic equipment (WEEE) is of significant importance for the upcycling of this waste stream with pyrolysis proposed as an appropriate, environmentally friendly, thermo-chemical recycling technique. The subject of this study is to investigate the distribution of the products obtained after the addition of certain catalysts in the pyrolysis of polymer blends with a composition similar to that of plastics in WEEE. Specifically, blends of acrylonitrile-butadiene-styrene (ABS), high impact polystyrene (HIPS), polycarbonate (PC), polypropylene (PP) and poly(vinyl chloride) (PVC) were examined in experiments taking place in a lab scale pyrolyser coupled with gas chromatography/mass spectrometry (Py-GC/MS) for the on-line recording of the products obtained. Six different catalysts (CaO, γ-Al2O3, Fe2O3, ZSM-5, Silicalite, Al-MCM41) were used and the optimum pyrolysis temperatures were selected for each system based on evolved gas analysis. The results from catalytic cracking were compared and evaluated in terms of the number of compounds produced, the ratio between aromatic and aliphatic products, and the intensity of the peaks. It was found that the best choice for the decomposition of ABS is Fe2O3 and for HIPS the Al-MCM41. γ-Al2O3 affects PC degradation and CaO exhibits specific selectivity to this polymer. Pyrolysis of blends results in the production of a mixture of hydrocarbons together with other aliphatic and aromatic compounds. Polymer blends including chlorinated compounds such as PVC start degrading at relatively low temperatures, slightly over 200 °C. Degradation occurs in two steps with peaks around 300 and 465 °C, respectively. The first is attributed to the removal of halogenated compounds and the second to the scission of the main carbon chain. PVC degradation produces chlorine radicals that affect the degradation mechanism. The presence of the catalysts did not significantly change the temperatures of degradation. However, they do change the type of the products obtained. Pyrolysis of the styrenic polymers, i.e. ABS or HIPS resulted in mainly aromatic compounds with one, two or even three aromatic rings, whereas PC results in several phenols. CaO is proposed as the best choice for catalytic cracking of Blend A, whereas Silicalite should be considered for Blend B since it leads in the production of more aromatic compounds compared to conventional pyrolysis.

In-depth analysis of the effect of catalysts on plasma technologies for treatment of various wastes

Energy security and waste management are gaining global attention. The modern world is producing a large amount of liquid and solid waste as a result of the increasing population and industrialization. A circular economy encourages the conversion of waste to energy and other value-added products. Waste processing requires a sustainable route for a healthy society and clean environment. One of the emerging solutions for waste treatment is plasma technology. It converts waste into syngas, oil, and char/slag depending on the thermal/non-thermal processes. Most of all the types of carbonaceous wastes can be treated by plasma processes. The addition of a catalyst to the plasma process is a developing field as plasma processes are energy intensive. This paper covers the detailed concept of plasma and catalysis. It comprises various types of plasma (non-thermal and thermal) and catalysts (zeolites, oxides, and salts) which have been used for waste treatment. Catalyst addition improves gas yield and hydrogen selectivity at moderate temperatures. Depending on the properties of the catalyst and type of plasma, comprehensive points are listed for the selection of the right catalyst for a plasma process. This review offers an in-depth analysis of the research in the field of waste-to-energy using plasma-catalytic processes.

Cobalt Vanadate (Co3V2O8) Hollow Microspheres as a Polysulfide Adsorption and Conversion Catalyst for Li–S Batteries

A lithium–sulfur battery (Li–S) is considered as one of the most suitable emerging energy storage technologies for electric vehicles (EVs) due to its higher specific capacity, energy density, and low cost. However, the dissolution of lithium polysulfides (LiPS) in an electrolyte causes a huge shuttle effect, which results in poor cycle life and rate performance. Herein, Co3V2O8 (CVO) hollow microspheres have been prepared by the solvothermal method and used as catalyst additives to the sulfur electrode (cathode host). It was found that CVO acts as a bifunctional additive, the vanadium and oxygen sites immobilize the LiPS through V–S and Li–O interactions, while the cobalt site facilitates the rapid conversion of long-chain LiPS into short ones (Li2S2/Li2S). Furthermore, the hollow microspheres act as a sulfur reservoir and can confine (encapsulate) more LiPS during the electrochemical conversion process, thus inhibiting the shuttle effect. In this work, the chemical adsorption and polysulfide conversion ability of CVO is corroborated by XPS and cyclic voltammetry studies, respectively. Even at a higher sulfur loading of 5.4 mg cm–2, CVO containing the Li–S cell (denoted as S@CVO/CNT Vs Li) demonstrates an initial discharge capacity of 694 mAh g–1 at 0.5 C, and after 200 cycles, the observed capacity is 566 mAh g–1, which amounts to 81% capacity retention. Similarly, the cell delivers an excellent rate capability of up to 5 C rate. At the 1 C rate, the cell shows an initial discharge capacity of 904 mAh g–1 (S-loading of 3 mg cm–2) and 692 mAh g–1 after 300 cycles with 77% capacity retention.

Toward versatile biobased epoxy vitrimers by introducing aromatic N-heterocycles with stiff and flexible segments

Recyclable materials with simultaneous multifunctionality and high performance, especially polymers synthesized from biobased monomers, have recently attracted a great deal of interest. However, current traditional vitrimers exhibit trade-offs between high performance and reprocessing. To circumvent this inherent contradiction, we report the first attempt to introduce an aromatic N-heterocycles (the fixed ‘stiff’ segments) derived from biomass functionalized with ester groups (the dynamic ‘flexible’ segments) into a thermoset system. The resulting resins exhibited high flexural strength (151 MPa) and toughnesses, a high glass transition temperature (205 ℃), intrinsic flame retardancy (UL-94 V-0) and acid/base resistance. In addition, the ester groups and aromatic N-heterocycles enabled dissolution of the network in ethylene glycol without additional catalyst. Importantly, the degradation solution could be directly reused into high-value photothermal conversion coatings and adhesives with 100% recyclability just by evaporating the ethylene glycol at elevated temperatures. Additionally, the conjugated aromatic N-heterocycles enhanced the adhesive properties and photothermal conversion of the system. The ease with which biobased materials bearing N-heterocycles and ester groups can be synthesized, recycled, and reused without losing value provides a new direction for closed-loop, high-performance and versatile polymer life cycles.

Co-pyrolysis of medical protective clothing and oil palm wastes for biofuel: Experimental, techno-economic, and environmental analyses.

The ongoing global pandemic of COVID-19 has devastatingly influenced the environment, society, and economy around the world. Numerous medical resources are used to inhibit the infectious transmission of the virus, resulting in massive medical waste. This study proposes a sustainable and environment-friendly method to convert hazardous medical waste into valuable fuel products through pyrolysis. Medical protective clothing (MPC), a typical medical waste from COVID-19, was utilized for co-pyrolysis with oil palm wastes (OPWs). The utilization of MPC improved the bio-oil properties in OPWs pyrolysis. The addition of catalysts further ameliorated the bio-oil quality. HZSM-5 was more effective in producing hydrocarbons in bio-oil, and the relevant reaction pathway was proposed. Meanwhile, a project was simulated to co-produce bio-oil and electricity from the co-pyrolysis of OPWs and MPC from application perspectives. The techno-economic analysis indicated that the project was economically feasible, and the payback period was 6.30-8.75 years. Moreover, it was also environmentally benign as its global warming potential varied from -211.13 to -90.76kg CO2-eq/t. Therefore, converting MPC and OPWs into biofuel and electricity through co-pyrolysis is a green, economic, and sustainable method that can decrease waste, produce valuable fuel products, and achieve remarkable economic and environmental benefits.

Self-catalysed hydrogenation of heavy oil and coal mixtures

Abstract Coal liquefaction and heavy oil processing have become the urgent need for national energy strategic technology reserves in China. However, the inactivation of solid catalysts in these processes is an inevitable problem. Therefore, a self-catalysed method was proposed. The properties of raw oil could be changed by adding a modifier, as it has the function of self-catalysis, and the additional catalyst is no longer needed. The effect of 200 ppm modifier on the hydrogenation of heavy oil and 500 ppm on the hydrogenation of coal and oil were investigated. The results showed that modifiers could be miscible with heavy oil at 50~100 °C and could change the properties of oil. When the temperature exceeded 250 °C, the sulfur element in the heavy oil combined with the metal element brought in by the modifier to form a particle with the size of 2–8 nm, which could interact with the hydrogen molecule to activate the hydrogen molecule. Activated hydrogen atoms further formed the complexes with nickel, vanadium, calcium, iron, and other elements in heavy oil to achieve the purpose of purifying and lightening the oil phase. Therefore, the self-catalysed method could be widely used in oil refining and would greatly promote the development of the oil refining and catalysis industry.

Advances in Catalytic Decomposition of N2O by Noble Metal Catalysts

Nitrous oxide (N2O) is an environmental pollutant that has a significant greenhouse effect and contributes to the depletion of the ozone layer. To address the issues caused by N2O, direct catalytic decomposition of N2O to N2 and O2 has been demonstrated as one of the most efficient methods for its removal. Various metals, particularly noble metals, including Rh, Ru, Pd, Pt, Au, and Ir, have been widely used and investigated as catalysts to facilitate this transformation. Therefore, this review aims to provide an overview of the advances in noble metal-based catalysts studied in recent years. The comprehensive discussion includes the influence of multiple factors, such as catalyst supports, preparation methods, additives, and impurity gases (such as O2, H2O, SO2, NO, and CO2) on the performance of versatile catalysts. Furthermore, this review offers insights into the future trends of catalyst systems for the direct catalytic decomposition of N2O.

Tin(II)‐Based Metal–Organic Frameworks Enabling Efficient, Selective Reduction of CO2 to Formate under Visible Light

AbstractCertain metal complexes are known as high‐performance CO2 reduction photocatalysts driven by visible light. However, most of them rely on rare, precious metals as principal components, and integrating the functions of light absorption and catalysis into a single molecular unit based on abundant metals remains a challenge. Metal‐organic frameworks (MOFs), which can be regarded as intermediate compounds between molecules and inorganic solids, are potential platforms for the construction of a simple photocatalytic system composed only of Earth‐abundant nontoxic elements. In this work, we report that a tin‐based MOF enables the conversion of CO2 into formic acid with a record high apparent quantum yield (9.8 % at 400 nm) and >99 % selectivity without the need for any additional photosensitizer or catalyst. This work highlights a new MOF with strong potential for photocatalytic CO2 reduction driven by solar energy.

Tin(II)-Based Metal-Organic Frameworks Enabling Efficient, Selective Reduction of CO2 to Formate under Visible Light.

Certain metal complexes are known as high-performance CO2 reduction photocatalysts driven by visible light. However, most of them rely on rare, precious metals as principal components, and integrating the functions of light absorption and catalysis into a single molecular unit based on abundant metals remains a challenge. Metal-organic frameworks (MOFs), which can be regarded as intermediate compounds between molecules and inorganic solids, are potential platforms for the construction of a simple photocatalytic system composed only of Earth-abundant nontoxic elements. In this work, we report that a tin-based MOF enables the conversion of CO2 into formic acid with a record high apparent quantum yield (9.8 % at 400 nm) and >99 % selectivity without the need for any additional photosensitizer or catalyst. This work highlights a new MOF with strong potential for photocatalytic CO2 reduction driven by solar energy.

Catalytic pyrolysis of corn stalk for the production of aromatics: The effects of wet torrefaction and Zn/Ni-HZSM-5 on pyrolysis behavior

The pyrolysis of corn stalk (CS) was carried out to investigate the effect of wet torrefaction (WT) pre-treatment and Zn/Ni-HZSM-5 on the production of bio-oil characteristics. The synergy between WT and the loaded metal catalyst was also analyzed. The oxygen content of the CS was reduced from 50.5% to 40.8% with WT, and hemicellulose was almost removed. WT pretreatment also significantly reduced the oxygenated compounds of bio-oil and increased the selectivity of phenols, aromatics, and anhydro-sugars. The addition of catalyst improved the deoxygenation, oligomerization, and aromatization during pyrolysis. The loading of Zn and Ni could optimize the pyrolysis reaction path and increased the relative content of monocyclic aromatics (MAHs) from 3.58% to 9.67% and 6.44% during the pyrolysis of CS-WT, respectively, and bimetallic catalyst further enhanced the relative content of MAHs to 11.1%. The relative content of aromatics below C9 was higher than other groups (14.8%). Thus, the WT pretreatment of raw materials and synergistic effect of catalysts can jointly optimize the biomass pyrolysis reaction.

Development of a Raman-Based Test for Rapid Thiol Scavenger Detection in Oil and Gas Applications

A rapid and efficient Raman-based method to identify potential thiol scavengers for oil and gas applications is described. The procedure was validated using the nucleophilic addition of ethanethiol (EtSH) to several commercial hydrogen sulfide (H2S) scavengers under sonication conditions at room temperature. A success metric was defined by the appearance of a strong C–S–C band in the Raman spectrum of the reaction mixture associated with the formation of a new thioether functionality. The simplicity of the method facilitates the sampling of a wide variety of substrates as well as the introduction of multiple variations to the original test protocol, such as the use of different solvents, sources of energy, the addition of catalysts, and temperature changes.

Ultrasonic‐Assisted One‐Pot Batch Simultaneous Synthesis of Two Different Types of Heterocyclic Derivatives and DFT Study

AbstractA green method called “one‐pot batch synthesis” has been developed for the simultaneous synthesis of two different types of heterocyclic derivatives, oxazolo [3, 2‐c] pyrimidines and hydroxyl ethyl dihydropyrimidones. The reaction was conducted under ultrasonic irradiation in green bio‐based solvent lactic acid without any additional catalysts and additives. From β‐hydroxyethyl urea, acetoacetyl esters/amines and aromatic aldehydes, fifteen oxazolopyrimidine and eleven hydroxyl ethyl dihydropyrimidones were synthesized using the method for the first time. The generation mechanism of two different kinds of products under ultrasonic irradiation from the same reaction conditions was explained by Density Functional Theory. All products were obtained in high yields and characterized by IR, NMR, ESI MS, and X‐ray diffraction.

A novel luminol-coordinated silver(I) organic gel with self-enhanced chemiluminescence applied for uric acid detection

A novel silver(I)-based metal–organic gel (AgMOG) consisting of luminol as the ligand was synthesized by a facile strategy, which was found to exhibit self-enhancing chemiluminescence (CL) property. Based on this, a new AgMOG-K2S2O8 CL system without additional catalyst was established. According to the results of CL spectra, electron spin resonance (ESR) spectra as well as the influence of radical scavengers to AgMOG-K2S2O8 system, the possible CL mechanism of this system was discussed. In this CL system, AgMOG exhibited the dual properties of catalysis and luminescence. On the one hand, AgMOG can catalyze K2S2O8 to produce SO4•−. The generated SO4•− can be converted to hydroxyl radical (OH•) under alkaline condition, and further converted to other radical oxygen species (ROS, such as 1O2 and O2•−). Furthermore, the reaction between the K2S2O8 and H2O can form H2O2, which also can be catalyzed by AgMOG to produce ROS. On the other hand, the AgMOG can be oxidized by ROS to emit strong CL signal. Then, based on the quenching effect of uric acid (UA) to this CL system, a method for UA detection was established with a good linearity over the range from 0.08 to 10 µmol·L−1. In this work, a new CL luminant with catalytic property was synthesized by a simple method, and a self-enhancing AgMOG-K2S2O8 CL system was developed for the first time, providing a novel direction for the application of MOG in the CL field.

Hydrothermal liquefaction of starch using homogeneous and heterogeneous co-catalysts

We examined the hydrothermal liquefaction (HTL) of potato starch with K2HPO4, which dissolves in hot, compressed water, along with metal-containing co-catalysts, which present a separate solid phase in the reaction system. Co-catalytic HTL with K2HPO4 and either Mo2C or Co-Mo/γ-Al2O3 produced more biocrude than did HTL with no catalyst or either catalyst alone. The synergistic effect of co-catalysis was greatest when the masses of K2HPO4 and Co-Mo/γ-Al2O3 were equal. At this condition, HTL with the two catalysts produced a biocrude that contained more than 90% of the chemical energy originally in the biomass feedstock. This biocrude also had a larger portion (61 wt%) of desirable lighter components (volatilized below 343 ℃) than did the biocrudes from HTL with either catalyst individually at the same conditions (38 and 41 wt%). With the addition of catalysts, there was less aliphatic content in the biocrude, and more ethers and aromatics appeared. The use of K2HPO4 and Co-Mo/γ-Al2O3 together for HTL led to greater fractions of alcohols, aldehydes/ketones, hydrocarbons, and phenolic compounds in the biocrude. In addition, less of the organic carbon in the feedstock migrated to the aqueous products. We identify catalysis of different HTL pathways to account for the experimental observations.

Evaluation of Heterogeneous Catalytic Ozonation Process for the Removal of Micropollutants from Water/Wastewater: Application of a Novel Pilot-Scale Continuous Flow System

The present study evaluates the removal of micropollutants from water/wastewater contaminated sources through the application of a heterogeneous catalytic ozonation process, using a pilot-scale continuous operation unit, composed of a membrane module for the diffusion and effective dilution of ozone into the liquid phase to be treated and a plug flow reactor/continuous stirred tank reactor (PFR/CSTR) contact reactor system in series, where the catalyst is recirculated in dispersion mode. The solid materials tested as catalysts are natural and calcined zeolite, Bayoxide and alumina, whereas the examined micropollutants, used in this case as probe compounds, are p-chlorobenzoic acid (p-CBA), atrazine, benzotriazole and carbamazepine. A high-performance liquid chromatography system was used to determine the removal of micropollutants. In the case of p-CBA, an ozone-resistant compound, the addition of catalyst was found to significantly enhance its degradation rate, leading to >99% removal under the optimum defined conditions, i.e., in terms of catalyst concentration, pH, temperature, and process time. On the other hand, in the case of atrazine, a different ozone-resistant compound, the introduction of examined catalysts in the ozonation process was found to reduce the degradation of micropollutant, when compared with the application of single ozonation, indicating the importance of specific affinity between the pollutant and the solid material used as catalyst. Benzotriazole, a moderately ozone-reactive compound was degraded by more than 95% under all experimental conditions and catalysts tested in the pilot unit, while carbamazepine, a highly ozone-reactive compound, was completely removed even during the first stage of treatment process (i.e., at the membrane contactor). When increasing the pH value (in the range 6–8) and the contact time, the performance of catalytic ozonation process also improved.