Search Results (935)

The rational design of supported Lewis acid catalysts is frequently impeded by an incomplete understanding of how the support’s synthetic history governs its intrinsic acidity and catalytic efficacy. Herein, we elucidate the structure–property–performance relationship linking the aging dynamics of a boehmite precursor to the activity of the resultant chlorinated alumina (Al₂O₃–Cl) catalyst in n-butane isomerization. Using n-butane as the probe feedstock, we investigated how alumina supports with distinct physicochemical properties regulate the performance of Al₂O₃–Cl catalysts for n-butane isomerization. By systematically adjusting the aging parameters (stirring rate, temperature, and time), we reveal that the structural evolution of the alumina support transitions from initial particle aggregation to Ostwald ripening and surface reconstruction. A decisive structure–performance correlation is identified: precursor synthesis conditions govern both the population and accessibility of specific surface hydroxyls (notably Type II terminal OH groups), which act as anchoring sites for the generation of active Lewis acid centers upon chlorination. Optimal aging parameters (300 rpm, 90 °C, 6 h) promote the formation of a hierarchical pore architecture with a maximized density of accessible hydroxyls, thereby affording enhanced Lewis acidity and superior isomerization activity. This work provides a fundamental framework for tailoring solid acid catalysts by precisely engineering the precursor architecture. Full article

Synthetic dyes frequently persist through conventional wastewater treatment, motivating the use of advanced oxidation processes capable of breaking down these stable molecules. Metal-doped carbon dots (CDs) offer a tuneable platform for catalytic dye degradation in water, although their performance varies strongly with operating conditions. The aim of this work was to determine how temperature, H₂O₂ dosage, and pH influence the catalytic behaviour of Fe-, Cu-, Zn-, and Mg-doped CDs during the degradation of methylene blue (MB) and rhodamine B (RB), optimised using a Taguchi L27 orthogonal array design. Temperature and oxidant loading were the dominant factors: higher temperatures accelerated reactions through Arrhenius-type kinetics, while increasing H₂O₂ availability improved removal until excessive levels began to suppress •OH generation. Across all condition sets, apparent rate constants spanned 7.0 × 10⁻⁴–2.65 × 10⁻² min⁻¹, with t₅₀ values of 26–217 min and t₉₀ extending from ~86 min to >700 min; final decolourisation ranged from ~17% to nearly 100%. pH played a secondary role, mainly affecting dye speciation and surface adsorption. Dopant identity shifted the optimum operating region for each catalyst: Fe- and Cu-CDs achieved complete or near-complete removal of both dyes at pH 7 and 50 °C with relatively low H₂O₂ dosage (0.5–1.0 mL); Zn-CDs reached equivalent performance at pH 7 and 25 °C but required higher oxidant loading (1.5 mL of H₂O₂), reflecting their photo-induced rather than thermally driven activation mechanism; Mg-CDs performed comparably under the same conditions as Fe- and Cu-CDs. The resulting condition–catalyst map highlights the operating regimes that maximise efficiency while minimising chemical input, providing a practical framework for selecting carbon-dot-based catalysts for water treatment applications. Full article

In this study, we prepare N–doped biochar loaded with β-CD, using cotton stalks as a carbon source, and evaluate its removal efficiency for tetracycline (TC) and methylene blue (MB) from aqueous solutions. This composite uniquely integrates molten salt activation, nitrogen doping, and β-CD grafting, resulting in an exceptionally high specific surface area of 1943 m²/g and abundant active sites. The findings reveal that β-CD-NKBC-1.5 (5 g of N–doped biochar loaded with 1.5 g of β-CD) demonstrates remarkable capabilities for both TC and MB removal across an extensive pH spectrum, reaching peak adsorption levels of 1269.8 and 969.4 mg/g at 308.15 K, respectively—outperforming most previously reported biochar-based adsorbents. The adsorption process is well described by the pseudo-second-order and Langmuir models, indicating that monolayer chemisorption is the dominant mechanism. β-CD-NKBC-1.5 exhibits preferential adsorption for TC and MB and maintains high adsorption efficiency even with coexisting ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, and SO₄²⁻) at concentrations up to 500 mg/L. The adsorption mechanism involves Lewis acid–base interactions, hydrogen bonding, π–π stacking, and pore filling. Full article

Ammonia decomposition represents a promising route for carbon-free hydrogen production, provided that efficient and cost-effective catalysts are developed. In this study, lanthanum-based mixed oxide catalysts (LaNi, LaCo, and LaCe) were synthesized via a controlled co-precipitation method and systematically evaluated for catalytic ammonia decomposition under atmospheric pressure in the temperature range of 350–500 °C. Comprehensive characterization combining N₂ physisorption, XRD, SEM–EDX, TGA–DTG, XPS, and FTIR-pyridine adsorption revealed pronounced structure–property relationships. LaNi exhibited the highest surface area (31.11 m²·g⁻¹), well-developed mesoporosity, and a balanced Lewis/Brønsted acidity (C_L/C_B ≈ 0.82), leading to superior catalytic performance with NH₃ conversion reaching ~48% at 500 °C (GHSV = 50 h⁻¹). LaCo showed intermediate activity (~30% conversion), while LaCe displayed limited performance (<13%), most likely due to its dense morphology and low surface accessibility. Increasing gas hourly space velocity resulted in decreased ammonia conversion for all catalysts, highlighting the critical role of residence time. These findings demonstrate that the catalytic efficiency of lanthanum-based systems is governed by the synergistic interplay between surface area, mesoporous architecture, and acidity distribution, with LaNi emerging as the most promising catalyst among the investigated materials. Full article

Carbon dioxide (CO₂) capture is a cornerstone of global carbon neutrality, yet the high energy penalty associated with solvent regeneration—particularly for monoethanolamine (MEA) systems—remains a major barrier to its sustainable deployment. This study presents a sustainable and high-performance catalytic solution using micro-sized iron oxyhydroxide (β-FeOOH). Characterized by a high specific surface area ($287 m²/g) and a synergistic distribution of abundant Lewis and Brønsted acid sites, the β-FeOOH catalyst significantly enhances CO₂ desorption kinetics. Experimental results demonstrate that the incorporation of β-FeOOH into a 30 wt% MEA solution increases the CO₂ desorption rate by 10.9% while simultaneously lowering the regeneration temperature from the conventional 120 °C to 85 °C. Such a reduction in thermal requirements offers a pathway to utilize low-grade industrial waste heat, drastically improving the process’s energy efficiency. Furthermore, the catalyst exhibited remarkable cyclic stability over ten consecutive cycles, maintaining its structural integrity and catalytic activity. These findings highlight β-FeOOH as an eco-friendly, cost-effective, and robust catalyst that aligns with the principles of green chemical engineering, offering a scalable strategy to enhance the sustainability of carbon capture operations. Full article

This study aims to systematically investigate the influence of substituent effects on the strength of Lewis acid–base interactions in frustrated Lewis pairs (FLPs). Specifically, -C₆F₅ groups of the classical Lewis acid B(C₆F₅)₃ are sequentially replaced with -C₆Cl₅, -C₆Br₅, and -C₆I₅ groups, and the Lewis acids are paired with the Lewis base 1,3-disubstituted imidazol-2-ylidene (ItBu) to form FLPs. Further energy decomposition analysis (sobEDA), orbital analysis, and molecular fragment density difference (MFDD) analysis reveal the nature of the substituent effect on the interaction energy (∆Eint) of the FLPs. The research findings indicate that the ∆Eint of B(C₆F₅)3-ItBu, B(C₆F₅)_x(C₆Y₅)_3−x-ItBu (x = 0, 1, 2; Y = Cl, Br, I) originates mainly from the interaction between the outermost halogen atom of the Lewis acid and the central carbon (C) atom of the Lewis base, rather than from the interaction between the central atoms boron (B) and carbon (C). This mechanism ultimately leads to a ∆Eint for B(C₆F₅)₂(C₆Y₅)-ItBu (Y = Cl, Br, I) that is comparable to that of B(C₆F₅)₃-ItBu. This indicates that modified B(C₆F₅)₂(C₆Y₅) (Y = Cl, Br, I) exhibits greater potential for the construction of novel FLPs. Full article

Titanosilicates are Lewis acid catalysts widely applied in liquid-phase olefin epoxidation; however, in the presence of water, their performance is often limited by structural instability, active-site deactivation, and competing side reactions. This review critically examines hydrophobization strategies—based on controlled reduction in silanol groups or incorporation of organic functionalities—and discusses the experimental approaches used to evaluate surface hydrophobicity, including water adsorption measurements, infrared spectroscopy of silanols, contact angle analysis, and complementary spectroscopic methods. Although direct quantitative comparison among studies is hindered by differences in reaction systems and the lack of standardized catalytic metrics, consistent trends emerge. Lower silanol densities are generally associated with improved preservation of isolated tetrahedral Ti (IV) sites, higher H₂O₂ utilization efficiency, and reduced secondary epoxide ring-opening, leading to enhanced activity and selectivity under comparable conditions. These improvements are attributed to decreased local water activity, suppression of non-productive oxidant decomposition, and stabilization of Ti-peroxo intermediates responsible for direct epoxidation. Incorporation of organic groups produces a similar beneficial effect when introduced in moderate amounts, increasing surface hydrophobicity without significantly perturbing Ti coordination. However, beyond an optimal loading, catalytic performance declines due to pore blockage, diffusion limitations, and partial masking of active sites, revealing a threshold behavior. Fluoride also plays a dual role: when used during synthesis, it influences the insertion and distribution of framework Ti, whereas as a post-treatment, it primarily regulates silanol density and surface polarity while preserving active sites. Finally, hydrophobicity cannot be considered independently, as its impact depends on the solvent, oxidant, olefin nature, and active-site location, which collectively govern activity, selectivity, and catalyst stability. Full article

Polysilicon is widely used in the photovoltaic and semiconductor industries. The presence of trace phosphorus impurities in the trichlorosilane feedstock can severely degrade the quality of polysilicon products. To address the urgent need for complete phosphorus removal of trichlorosilane, in this work, on the basis of the reducing ability of PCl₃ and the stronger Lewis base properties of its oxidation product, POCl₃, we developed an efficient material, xMo/Al₂O₃[y], using Al₂O₃ as the support and Mo species as active substances through a simple and straightforward method. Under the optimized preparation conditions of 7.8% Mo loading and a calcination temperature of 450 °C, the adsorbent exhibited optimal performance in an organic system simulating a trichlorosilane system with a P adsorption capacity of 53.52 mg g⁻¹, achieving near-complete elimination of phosphorus impurities. A series of characterization analyses suggested the following primary removal mechanism: initial oxidation of PCl₃ to POCl₃ by Mo⁶⁺ species, followed by its complexation with Mo sites via Lewis acid-base interactions. Furthermore, surface morphology damage during the removal process and the accumulation of reaction products on the spent adsorbent are the main factors contributing to its deactivation. This work presents an effective strategy for the deep dephosphorization of trichlorosilane. Full article

The demand for high-energy-density and fast-charging solid-state lithium metal batteries (SSLMBs) often subjects practical devices to internal thermal loads, making high-temperature operation a common operational condition rather than an isolated scenario. To address the interfacial degradation and dendrite growth accelerated by such thermomechanical stresses, we developed a composite gel electrolyte (CGE) by incorporating an optimal concentration of active Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) into a fluoropolymer network. The abundant Lewis acidic sites on the LLZTO surfaces promote competitive solvation decoupling by interacting with anions, thereby modulating the primary solvation sheath of Li⁺. This localized modulation lowers the lithium-ion migration activation energy to 0.248 eV and facilitates a dual-interfacial passivation mechanism. Specifically, a rigid, inorganic-rich solid electrolyte interphase (SEI) forms to suppress morphological instability at the lithium anode, while an organic-dominated cathode electrolyte interphase (CEI) enhances the oxidative stability up to 4.3 V. As a result, symmetric cells demonstrate stable electrodeposition for over 450 h at 80 °C and 0.5 mA cm⁻². Furthermore, NCM811/Li full cells utilizing this CGEs exhibit significantly improved thermal resilience and cycling stability. Full article

The rapid growth of polyethylene terephthalate (PET) waste and the limitations of conventional recycling methods for mixed waste streams emphasize the need for chemical recycling routes that deliver high-value monomers in a sustainable, resource-efficient manner. This work explores N-heterocyclic carbenes (NHCs) as organocatalysts for the glycolysis of PET with ethylene glycol to bis(hydroxyethyl)terephthalate (BHET), aiming for milder conditions and higher activity. A systematic catalyst screening links steric and electronic properties (percent buried volume, Tolman electronic parameter) of the NHCs to performance in the glycolysis process, resulting in a catalyst system with high PET conversion (up to 97%) and BHET yield (up to 65%). Mechanistic investigations (experimental and computational) support an anionic activation pathway for glycolysis. To lower the reaction temperature, selective cosolvent systems were explored, albeit with some loss of catalytic activity. Cooperative catalysis combining NHCs with Lewis acids enhances activity, leading to a high conversion (up to 90%) while maintaining lower temperatures than state-of-the-art glycolysis methods. The process was successfully transferred to post-consumer waste streams to validate the practicality. Full article

This comprehensive review provides a consolidated and practically oriented overview of the Friedel–Crafts reaction in pharmaceutical synthesis, bringing together data from 93 peer-reviewed studies published between 1962 and 2025. Through a structured and comparative analysis of the literature retrieved from the Scopus and PubMed databases, this work integrates scattered information into a single, accessible resource, designed to guide researchers in drug discovery and development. The findings identify alkylation and acylation as the dominant Friedel–Crafts transformations, often enabling the synthesis of pharmacologically relevant scaffolds depending on substrate structure and the efficiency and selectivity of the catalytic system. These include compounds with anticancer, anti-inflammatory, and antimicrobial potential. Trends in catalyst and solvent selection highlight both the persistent reliance on classical Lewis acids in chlorinated media and a gradual interest in more sustainable alternatives, although their adoption remains system-dependent. By consolidating 63 years of research into a unified reference, this review underscores the versatility and enduring relevance of Friedel–Crafts methodologies in medicinal chemistry but also offers a data-driven foundation for their optimized and more sustainable application in future pharmaceutical development. Full article

Biodiesel is a promising, renewable, and environmentally friendly alternative fuel. Numerous studies have focused on improving the biodiesel production process from various feedstocks using different activation methods and catalysts. However, the reaction times typically range from tens of minutes to hours. This study presents, for one of the first systematic studies exploring time, the potential of using millimeter-wave electromagnetic radiation generated by a gyrotron as an activation method for biodiesel production reactions. Esterification was carried out using free fatty acids and fatty waste, specifically brown grease (BG), in the presence of the Lewis acid catalyst AlCl₃. Complete conversion of oleic acid was achieved after only 0.4 s of exposure to millimeter waves. When BG was used as the feedstock, a biodiesel yield of 73–76% was obtained within only 3.0 s. Gyrotron-based electromagnetic activation was benchmarked against conventional thermal and sonication-assisted methods, demonstrating high effectiveness. This study presents an efficient and novel process that reduces reaction times while utilizing fatty waste as a feedstock, aligning with the principles of green chemistry, the circular economy, and sustainable development. Full article

Cellulose has received significant attention, given its high demand for the transition to sustainable fuels and renewable energy, addressing the environmental challenges of fossil fuels. Fast pyrolysis is a process that can transform cellulose into bio-oil. Although the bio-oils produced contain considerable amounts of oxygen and water, they are highly corrosive and highly viscous, which limits their utility as biofuels. Pyrolysis bio-oils require upgrading to remove oxygen and corrosive components, thereby enhancing their stability for use as biofuels and their environmental sustainability. This study investigates the catalytic pyrolysis of cellulose without a catalyst and with Ga/HZSM-5 catalysts with various gallium loadings (0.3, 3 and 9 wt%) and bulk Ga₂O₃ catalysts using pyrolysis/gas chromatography–mass spectrometry (Py/GC-MS). The catalytic influence of different gallium loadings on HZSM-5 in cellulose pyrolysis reactions is discussed using a range of characterisation techniques, including ICP, XRD, N₂ porosimetry, DRIFTS, and TPRS. The main production of oxygenated compounds (furan, sugar, ketone and phenol) and hydrocarbon products, including total aromatic and monocyclic and polycyclic aromatics, as well as benzene, toluene, xylene (BTX) and naphthalene compounds, using a family of Ga-doped HZSM-5 catalysts for cellulose pyrolysis is investigated for making sustainable cellulose-derived fuel. Ga(3)/HZSM-5 formed the highest amount of aromatics, displaying that aromatic yield depends on the Brønsted-to-Lewis acid balance (2.3 ratio) and total acidity (1.03 mmol·g⁻¹), rather than on gallium loading alone. Full article

The increasing energy demand and global dependence on conventional fuels have resulted in severe greenhouse gas (GHG) emissions, necessitating the development of sustainable bioenergy alternatives. Algal is recognized as a promising feedstock for the production of fourth-generation biofuels. This study optimizes catalytic pyrolysis of Arthrospira platensis for bio-oil production via a dual-bed catalyst system of iron-impregnated dolomite (Fe/DM) and a copper-impregnated spent fluid catalytic cracking catalyst (Cu/sFCC). A face-central composite design (FCCD) and response surface methodology (RSM) were used for the delineation of optimal conditions, ensuring that all experimental tests remained within feasible operating conditions of 500–600 °C, a reaction time of 45–75 min, a N₂ flow rate of 50–200 mL/min, and a catalyst loading of 5–20 wt%. The bio-oil yield was maximized at 39.73 ± 2.86 wt% at 500 °C for 45 min, a N₂ flow of 50 mL/min, and 5 wt% catalyst loading to feedstock with a 0.4:0.6 mass ratio of Fe/DM: Cu/sFCC. The dual-catalysts combined Brønsted and Lewis acid sites enhanced the catalytic activity, which promotes the cleavage of carbon–carbon and carbon–hydrogen bonds, including the mechanism of catalytic pathways such as dehydration, decarboxylation, oligomerization, aromatization, and further cracking reactions, and was successful in converting high-molecular-weight molecules into lighter hydrocarbons and significantly improving product selectivity, demonstrating a highly effective pathway for producing high-quality sustainable biofuel. Full article

Protein phosphorylation and dephosphorylation reactions of intracellular molecules catalyzed by enzymes such as kinases and phosphatases are essential reactions in a lot of cellular functions such as intracellular signal transduction in living systems. The design and synthesis of artificial enzyme mimics are important research topics in bioorganic and bioinorganic chemistry. In this paper, we report on the construction of artificial phosphatases via the supramolecular self-assembly of compounds such as an amphiphilic bis(Zn²⁺-cyclen) (cyclen = 1,4,7,10-tetraazacyclododecane) complex, barbital derivatives modified with benzocrown ethers and boronophenyl groups, and a copper(II) ion in a two-phase solvent system. We have developed a hypothesis whereby a mono(4-nitrophenyl)phosphate (MNP) substrate coordinates to the Cu₂(µ-OH)₂ core in supramolecular complexes and is activated either by Lewis acidic units such as alkali metal (Li⁺, Na⁺ and K⁺)-benzocrown ether complexes or by boronophenyl moieties. The findings suggest that supramolecular phosphatase functionalized with a benzo-12-crown-4-Li⁺ complex shows a higher level of activity in the MNP hydrolysis of a two-phase solvent system compared with that of our previous supramolecular phosphatases in terms of hydrolysis activity and catalytic turnover. Full article