Search Results (126)

The activation of peracetic acid (PAA) to generate highly reactive species has emerged as a promising advanced oxidation process (AOP) for the degradation of refractory organic pollutants. This review systematically summarizes the recent advancements in PAA-based AOPs, encompassing various activation strategies, underlying reaction mechanisms, and applications across different environmental matrices. The activation methods are critically discussed, including direct energy activation, homogeneous catalysis, and heterogeneous catalysis. The generation process of diverse reactive species, like hydroxyl radicals (HO·), organic radicals (CH₃C(O)O·, CH₃C(O)OO·), and singlet oxygen (¹O₂), was introduced, and their oxidation selectivity and anti-interference ability were compared. Furthermore, the practical applications of PAA-based AOPs in treating wastewater, groundwater, and contaminated soil/sediments are reviewed. Finally, this review outlines critical challenges, including potential toxic byproduct formation, catalyst stability, and economic feasibility, and proposes future research directions to facilitate the transition of PAA-based AOPs from laboratory-scale research to full-scale implementation. This review provides insights for developing efficient, selective, and sustainable oxidation technologies, thereby contributing to the mitigation of emerging contaminant threats and the advancement of environmental remediation practices. Full article

This study researches the underexplored potential of the palladium-catalyzed Hayashi–Miyaura reaction in asymmetric synthesis, focusing on the preparation of novel derivatives of 2,2-diaryl-1-nitroethanes. These compounds are of interest as potential building blocks in medicinal and materials chemistry, yet they remain largely unexamined in enantioselective transformations. The study specifically targets three challenging substrates: 1,3-dimethoxy-5-(2-nitro-1-(o-tolyl)ethyl)benzene, 2-(2-nitro-1-phenylethyl)phenol, and 4-(2-nitro-1-phenylethyl)phenol. These molecules were selected to probe the reaction’s tolerance toward ortho-substitution and free hydroxyl groups—features known to complicate catalytic processes. Full article

Diphenylmethane, recently recognized as a candidate for liquid organic hydrogen carrier systems, is traditionally produced by alkylation of benzene with benzyl chloride using homogeneous catalysts. In the current context, the need for a transition toward processes that reduce environmental impact and move toward sustainability has become increasingly evident. In this work, the benzylation of benzene by benzyl chloride using metal–organic frameworks (MOFs) as catalysts is proposed, as alternative materials that combine the advantages of homogeneous and heterogeneous catalysis. Reaction experiments were carried out in an isothermal batch reactor with commercial Basolite C300 and Basolite F300 MOFs, based on Cu and Fe as active species, respectively. The results demonstrate catalytic activity using both proposed catalysts under the studied conditions, with the results of the Fe-based MOF being more favorable, given the greater standard reduction potential of Fe. Compared with their corresponding metal chlorides, the proposed MOFs improve the alkylation activity. Based on a two-step reaction mechanism, a pseudo first-order kinetic model has been developed for the reaction with MOFs as catalysts. The kinetic parameters were obtained by fitting the model to the experimental data, demonstrating good agreement and validating the proposed mechanistic pathway. Full article

The conversion of CO₂ into valuable chemicals such as formic acid offers a promising approach to reducing CO₂ emissions. This study presents a techno-economic assessment of two continuous catalytic processes for formic acid production via carbon dioxide (CO₂) hydrogenation. The processes differ in the type of nitrogenous base used, operating under either homogeneous or heterogeneous catalytic conditions. Process simulations and techno-economic evaluations were performed in SuperPro Designer^TM for a medium-scale facility with an annual CO₂ processing capacity of around 14 kMT. The homogeneous catalysis pathway demonstrated superior plant performance, producing 13.03 kMT of formic acid per year at 99.78% purity. In contrast, the heterogeneous pathway required higher capital investment and exhibited lower overall efficiency. The techno-economic analysis confirmed the economic viability of the homogeneous process, with a production cost of $1.18/kg and favorable investment indicators, whereas the heterogeneous route proved economically unattractive under the evaluated assumptions. Sensitivity analysis identified the selling price of formic acid as the most critical profitability parameter, with the homogeneous process remaining robust across varying conditions. Overall, homogeneous catalytic CO₂ hydrogenation demonstrates a technically efficient and economically promising process for the chemical transformation of CO₂, contributing to carbon management. Full article

Developing a robust Fenton-like catalyst through a feasible method is a significant challenge and is crucial for sustainability in wastewater treatment. Herein, we report a novel dual-phase H₂O₂ activation for ^•OH generation via both heterogeneous surface-mediated reactions and homogeneous radical propagation pathways. Mechanistic investigations revealed that the surface Fe²⁺/Fe³⁺ redox cycle was the primary driver of catalysis at pH 5. Notably, the catalyst produced fewer secondary pollutants than Fenton reactions and was effective in treating pollutants with high concentrations. The oxidative performance of the PAS-ISe was comparable to that of commercial FeSO₄·7H₂O in terms of chemical oxygen demand (COD) removal efficiency and reaction kinetics. Besides, the utility of the catalyst was 2-75-fold greater than that of state-of-the-art Fenton or photo-Fenton-like catalysts. A detailed techno-economic analysis confirmed the feasibility of this strategy and significant cost advantages over existing heterogeneous catalyst synthesis methods. This study concurrently proposes a low-cost approach to valorizing hazardous sludge and effectively treating industrial wastewater, which may support circular economic principles. Full article

Catalysis plays a pivotal role in green chemistry practices, particularly in reducing waste generated during chemical synthesis. Decatungstate (DT) emerges as a potent photocatalyst for Type I oxidations, exhibiting remarkable resilience to oxygen quenching, a characteristic that sets it apart from other excited triplet state photocatalysts. While homogeneous DT catalysis demonstrates effectiveness, its solubility poses challenges for its separation and recycling. To address these limitations, we focus on the development and comparison of heterogeneous DT photocatalysts, aiming to optimize their yield, recovery, and reusability. We synthesized tetrabutylammonium decatungstate (TBADT)-supported catalysts using silica, alumina, titanium dioxide, and glass wool and characterized them using diffuse reflectance measurements. Subsequently, we evaluated their photocatalytic performance by monitoring the oxidation of 1-phenylethanol and cyclohexanol under UVA irradiation. Our findings reveal that TBADT@silica emerges as the most effective catalyst, achieving approximately 20% conversion of cyclohexanol and 50% conversion of 1-phenylethanol with good reusability. Interestingly, we observed that 3-aminopropyl-triethoxysilane (APTES) treatment, intended to enhance DT anchoring, unexpectedly quenches the ³DT* triplet state, reducing catalytic activity. This unexpected finding underscores the importance of careful consideration in designing robust and recyclable heterogeneous decatungstate catalysts. Our research contributes significantly to the advancement of heterogeneous photocatalysis, paving the way for future applications in flow photochemistry. Further, we share a Python code (Google 3.12.11) to correct spectra obtained in Cary spectrometers. Full article

Cocktail-type catalysis represents a significant shift in the understanding of catalytic processes, recognizing that multiple interconverting species—such as metal complexes, clusters, and nanoparticles—can coexist and cooperate within a single reaction environment. Originating from mechanistic studies on palladium-catalyzed systems, this concept challenges the classical division between homogeneous and heterogeneous catalysis. Instead, it introduces a dynamic framework where catalysts adapt and evolve under reaction conditions, often enhancing efficiency, selectivity, and durability. Using advanced spectroscopic, microscopic, and computational techniques, researchers have visualized the formation and transformation of catalytic species in real time. The cocktail-type approach has since been extended to platinum, nickel, copper, and other transition metals, revealing a general principle in catalysis. This approach not only resolves long-standing mechanistic inconsistencies, but also opens new directions for catalyst design, green chemistry, and sustainable industrial applications. Embracing the complexity of catalytic systems may redefine future strategies in both fundamental research and applied catalysis. Full article

Hydroformylation is one of the most widely applied homogeneous catalytic processes in the chemical industry, constituting the predominant manufacturing platform for aldehyde synthesis at commercial scales. Nevertheless, hydroformylation shares with traditional homogeneous catalysis the inherent limitation of difficult catalyst recovery and recycling. Developing heterogeneous catalysts for such reactions is thus critically needed. Herein, a stable nitrogen-rich covalent triazine framework (CTF) was synthesized via a mild Friedel–Crafts alkylation method and employed as a support for Rh single-atom catalysts (Rh/CTF-TPA). In the hydroformylation of 1-decene, the Rh/CTF-TPA catalyst exhibits an exceptional reaction efficiency (TOF > 1900 h⁻¹), outperforming the homogeneous Rh(CO)₂(acac). Experimental and characterization results revealed that the CTF support enhances catalytic performance through two key mechanisms: (1) strong enrichment of reactants within its special structure, and (2) efficient dispersion of Rh single-atom sites stabilized by abundant nitrogen coordination. This work demonstrates a rational design strategy for heterogeneous hydroformylation catalysts by leveraging nitrogen-rich porous frameworks to synergistically optimize metal anchoring and reactant enrichment, offering a promising alternative to conventional homogeneous systems. Full article

Copper complexes have attracted significant interest for catalyzing oxidative dehydrogenative carboxylation of alkanes to form esters. Here, we report a heterogeneous catalyst, in which copper complexes are immobilized on coal-bearing kaolin for the synthesis of allylic esters via C(sp³)-H bond activation through cross-dehydrogenation coupling reactions between cyclic alkanes and aromatic carboxylic acids. Systematic optimization of reaction conditions—including catalyst loading, copper content, oxidant, temperature, and reaction time—resulted in a high yield of 71% of allylic ester, comparable to homogeneous transition metal catalysts. The catalyst is easily recoverable via centrifugation and retains its activity over five consecutive reuse cycles. This system demonstrates broad substrate compatibility with various aromatic carboxylic acids and cyclic alkanes. Beyond offering an efficient and reusable catalytic route for allylic ester synthesis, this work highlights the potential of coal-bearing kaolin as a sustainable support material for transition metal catalysis and provides an environmentally benign method for activating inert C(sp³)–H bonds. Full article

Aqueous biphasic catalysis has gained recognition as a sustainable and efficient method that combines the advantages of both homogeneous and heterogeneous catalytic systems. This approach enables the separation and recycling of catalysts, leading to reduced environmental impact and lower operational costs. A key component of this method is the use of transition metal catalysts, which are crucial for facilitating various reactions when paired with different types of ligands, primarily hydrophiles. This combination is essential for achieving high success rates in recyclable catalytic systems. The reaction conditions, including temperature, pressure, and pH, significantly influence catalytic performance. However, challenges such as limited substrate solubility and catalyst leaching persist, underscoring the need for further research into advanced ligand design, catalyst immobilization techniques, and scalable process integration. This review systematically examines recent experiments in the aqueous biphasic catalysis of olefins, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework. From an initial pool of 597 articles, 104 were found to be relevant and focused specifically on aqueous biphasic catalysis. The study investigates key reactions, the factors that influence these biphasic reactions, and the catalytic systems that facilitate them. By highlighting both progress and ongoing challenges, this work underscores the potential of aqueous biphasic catalysis to bridge the gap between green chemistry principles and industrial applications. Full article

In the current environmental scenario, the proposal of alternatives for petroleum-based products has considerably increased, with the aim of looking for bioproducts with interesting properties such as biodegradability, sustainability and efficiency, among others. In this sense, the role of biolubricants is promising, offering a wide range of possibilities through different methods and operating conditions. Specifically, double transesterification could be a suitable process in a biorefinery context. The aim of this work was to produce a biolubricant through double transesterification with methanol and neopentyl glycol (NPG) under different reaction conditions by using homogeneous catalysis (sodium methoxide). Different catalyst concentrations, among other changes in reaction conditions (temperature ranging between 100 and 140 °C and NPG/FAME ratios between 0.5 and 2), were used, obtaining high conversion values (96%) and a final product with a high viscosity (20.7 cSt), which allows for its use as engine oil (SAE 5W). In conclusion, biodiesel and biolubricant production was feasible through homogeneous catalysis, proving the feasibility of this process at the laboratory scale. Further studies, including the use of different heterogeneous catalysts, as well as the implementation of this process at a semi-industrial scale, are recommended. Full article

Solketal, a widely used glycerol-derived solvent, can be efficiently synthesized through heterogeneous catalysis, thus avoiding the significant product losses typically encountered with aqueous work-up in homogeneous catalysis. This study explores the catalytic synthesis of solketal using solid acid catalysts derived from recovered carbon blacks (rCBs), which are obtained through the pyrolysis of end-of-life tires. This was further converted into solid acid catalysts through the introduction of acidic functional groups using concentrated H₂SO₄ or 4-benzenediazonium sulfonate (BDS) as sulfonating agents. Additionally, post-pyrolytic rCB treated with glucose and subsequently sulfonated with sulfuric acid was also prepared. Comprehensive characterization of the initial and modified rCBs was performed using techniques such as elemental analysis, powder X-ray diffraction, thermogravimetric analysis, a back titration method, and both scanning and transmission electron microscopy, along with X-ray photoelectron spectroscopy. The catalytic performance of these samples was evaluated through the batch mode glycerol acetalization to produce solketal. The modified rCBs exhibited substantial catalytic activity, achieving high glycerol conversions (approximately 90%) and high solketal selectivity (around 95%) within 30 min at 40 °C. This notable activity was attributed to the presence of -SO₃H groups on the surface of the functionalized rCBs. Reusability tests indicated that only rCBs modified with glucose demonstrated acceptable catalytic stability in subsequent acetalization cycles. The findings underscore the potential of utilizing end-of-life tires to produce effective acid catalysts for glycerol valorization processes. Full article

The Special Issue “Exclusive Papers of the Editorial Board Members and Topical Advisory Panel Members of Catalysts in Section “Catalytic Materials” contains 14 peer-reviewed research articles and 1 review paper (Contributions 1–15), which broadly focus on the field of homogeneous and heterogeneous catalysis, with an emphasis on synthesis, physico-chemical characterizations, and applications in several environmental protection reactions, such as CO₂ valorization, NOx SCR, removal of VOCs, photocatalysis [...] Full article

Industrial scale-up of hydrothermal supercritical water gasification process requires catalytic integration to reduce the high operational temperatures and pressures to enhance controlled chemical reaction pathways, product yields, and overall process economics. There is greater literature disparity in consensus on what is the best catalyst and reactor design for hydrothermal gasification. This arises from the limited research on catalysis in continuous flow hydrothermal systems and rudimentary lab-scale experimentation on simple biomasses. This review summarizes the literature status of catalytic hydrothermal processing, especially for continuous gasification and in situ catalyst handling. The rationale for using low and high temperatures during catalytic hydrothermal processing is highlighted. The role of homogeneous and heterogeneous catalysts in hydrothermal gasification is presented. In addition, the rationale behind certain designs and component selection for catalytic investigations in continuous hydrothermal conversion is highlighted. Furthermore, the effect of different classes of catalysts on the reactor and reactions are elaborated. Overall, design and infrastructural challenges such as plugging, corrosion, agglomeration of the catalysts, catalyst metal leaching, and practical assessment of catalyst integration towards enhancement of process economics still present open questions. Therefore, strategies for catalytic configuration in continuous hydrothermal process must be evaluated on a system-by-system basis depending on the feedstock and experimental goals. Full article

The design of metal–organic frameworks (MOFs) allows the definition of properties for their final application in small-scale heterogeneous catalysis. Incorporating various catalytic centers within a single structure can produce a synergistic effect, which is particularly intriguing for cross-coupling reactions. The URJC-1 material exhibits catalytic duality: the metal centers act as Lewis acid centers, while the nitrogen atoms of the organic ligand must behave as basic centers. The impact of reaction temperature, catalyst concentration, and basic agent concentration was evaluated. Several copper-based catalysts, including homogeneous and heterogeneous MOF catalysts with and without the presence of nitrogen atoms in the organic ligand, were assessed for their catalytic effect under optimal conditions. Among the catalysts tested, URJC-1 exhibited the highest catalytic activity, achieving complete conversion of 4-nitrobenzaldehyde with only 3% mol copper concentration in one hour. Furthermore, URJC-1 maintained its crystalline structure even after five reaction cycles, demonstrating remarkable stability in the reaction medium. The study also examined the impact of various substituents of the substrate alcohol on the reaction using URJC-1. The results showed that the reaction had high activity when activating substituents were present and for most cyclic alcohols rather than linear ones. Full article