Design Of Catalysts Research Articles

Rational Design of Diatomic Active Sites for Elucidating Oxygen Evolution Reaction Performance Trends

AbstractDiatomic catalysts, especially those with heteronuclear active sites, have recently attracted significant attention for their advantages over single‐atom catalysts in reactions with relatively high energy barrier, e.g. oxygen evolution reaction. Rational design and synthesis of heteronuclear diatomic catalysts are of immense significance but have so far been plagued by the lack of a definitive correlation between structure and catalytic properties. Here, we report macrocyclic precursor constrained strategy to fabricate series of transition metal (MT, Ni, Co, Fe, Mn, or Cu)‐noble (MN, Ir or Ru) centers in carbon material. One notable performance trend is observed in the order of Cu−MN<Mn−MN<Fe−MN<MN<Co−MN<Ni−MN. Meanwhile, the pathway has been not altered, still following the traditional adsorption reaction mechanism. The effect of the MT atoms on the performances could possibly originate from the distinct adsorption/desorption behaviors of key intermediates (i.e. *OH, *O and/or *OOH), strongly implying that ΔG*OOH–ΔG*OH could be used as the performance descriptor. We believe that our work provides useful strategy for synthesis of diatomic active sites with sole coordination configuration and varied composition, and in‐depth insight to their catalytic mechanism, which could be used for further optimization of diatomic catalysts towards oxygen electrocatalysis.

Machine learning assisted screening of nitrogen-doped graphene-based dual-atom hydrogen evolution electrocatalysts

Nitrogen doped graphene-based dual-atom catalysts (NG-DACs) usually exhibit high reactivity for hydrogen evolution reaction (HER). The experimental design of efficient DACs-based HER catalysts, however, is time-consuming and expensive. In this work, a density functional theory combined with machine learning (DFT-ML) strategy is adopted towards the rapid screening of NG-DACs HER catalyst. The adsorption energies of HER intermediates on NG-DACs obtained by DFT calculations and their elemental features were used for the ML database construction. The prediction performance of three ML algorithms was evaluated, and gradient boosted regression (GBR) is found exhibit the best prediction accuracy. Using the HER energetics on Pt (111) as reference, quick screening of the NG-DACs with high HER activity was achieved, resulting to twenty-four potential catalysts. Further selection and validation of the ML-screened catalysts were performed by the hydrogen adsorption Gibbs free energy analysis. Accordingly, four promising NG-DACs HER catalysts were predicted using the proposed DFT-ML based catalyst prediction framework. The DFT-ML strategy offers an promising approach for the screening of new HER electrocatalysts.

Dynamic control and quantification of active sites on ceria for CO activation and hydrogenation

Ceria (CeO2) is a widely used oxide catalyst, yet the nature of its active sites remains elusive. This study combines model and powder catalyst studies to elucidate the structure-activity relationships in ceria-catalyzed CO activation and hydrogenation. Well-defined ceria clusters are synthesized on planar CeO2(111) and exhibit dynamic and tunable ranges of Ce coordination numbers, which enhance their interaction with CO. Reduced ceria clusters (e.g., Ce3O3) bind CO strongly and facilitate its dissociation, while near-stoichiometric clusters (e.g., Ce3O7) adsorb CO weakly and promote oxidation via carbonate formation. Unlike planar ceria surfaces, supported ceria clusters exhibit dynamic properties and enhanced catalytic activity, that mimic those of powder ceria catalysts. Insight from model studies provide a method to quantify active sites on powder ceria and guide further optimization of ceria catalysts for syngas conversion. This work marks a leap toward model-guided catalyst design and highlights the importance of site-specific catalysis.

Reductive Coupling of N-Heteroarenes and 1,2-Dicarbonyls for Direct Access to γ-Amino Acids, Esters, and Ketones Using a Heterogeneous Single-Atom Iridium Catalyst.

Despite their significant importance, the challenges in direct and diverse synthesis of N-heterocyclic γ-amino acids/esters/ketones hamper exploration of their applications. Herein, by developing a multifunctional heterogeneous iridium single-atom catalyst composed of silica-confined iridium species and a boron-doped ZrO2 support (Ir-SAs@B-ZrO2/SiO2), we describe its utility in establishing a new reductive coupling reaction of N-heteroarenes and 1,2-dicarbonyls for selective and diverse construction of the as-described compounds in a straightforward manner. The striking features, including good substrate and functionality tolerance, high step and atom economy, exceptional catalyst reusability, and diversified product post-transformations, highlight the practicality of the developed chemistry. Mechanistic studies reveal that the synergy between the active Ir sites and acidic support favors a chemoselective reduction of the more inert N-heteroarenes and affords requisite enamine intermediates. In this work, the concept on precise transformation of reductive intermediates will open a door to further develop useful tandem reactions by rational catalyst design.

Pairing Oxygen Reduction and Water Oxidation for Dual‐Pathway H2O2 Production

AbstractHydrogen peroxide (H2O2) is a crucial chemical applied in various industry sectors. However, the current industrial anthraquinone process for H2O2 synthesis is carbon‐intensive. With sunlight and renewable electricity as energy inputs, photocatalysis and electrocatalysis have great potential for green H2O2 production from oxygen (O2) and water (H2O). Herein, we review the advances in pairing two‐electron O2 reduction and two‐electron H2O oxidation reactions for dual‐pathway H2O2 synthesis. The basic principles, paired redox reactions, and catalytic device configurations are introduced initially. Aligning with the energy input, the latest photocatalysts, electrocatalysts, and photo‐electrocatalysts for dual‐pathway H2O2 production are discussed afterward. Finally, we outlook the research opportunities in the future. This minireview aims to provide insights and guidelines for the broad community who are interested in catalyst design and innovative technology for on‐site H2O2 synthesis.

Enhancing Ozone Decomposition in Humid Environments through Carbon Doping to Disrupt the Hydrogen Bond Network in Mullite YMn2O5.

The strong adsorption of water molecules at the active site of the catalyst presents significant challenges in ozone decomposition, particularly at room temperature and in humid environments. To address this issue, we doped carbon atoms into the Mn-mullite YMn2O5 catalyst to replace oxygen, resulting in efficient and stable ozone decomposition under highly humid conditions. Utilizing DFT calculations, our study demonstrated that carbon doping disrupts hydrogen bond networks on the catalyst surface, thereby reducing water adsorption. Furthermore, carbon doping regulated the electronic structure of active sites, fundamentally reversing the adsorption strength of water and ozone molecules, which avoids the decline in catalytic activity caused by competitive water adsorption. Experimentally, under room temperature and relative humidity (RH) 50%, the carbon-doped YMn2O5 catalyst maintained 100% conversion in decomposing 100 ppm of ozone for at least 24 h, surpassing the most reported catalysts against water poisoning. Furthermore, the utilization of a carbon-doped mullite-loaded air cleaner demonstrated promising application in degrading ozone. The approach of enhancing catalyst water resistance through carbon doping, which disrupts hydrogen bonds, provided valuable insights into the design of stable and efficient room-temperature ozonolysis catalysts.

Pd(NHC)(μ-Cl)Cl]2: The Highly Reactive Air- and Moisture-Stable, Well-Defined Pd(II)-N-Heterocyclic Carbene (NHC) Complexes for Cross-Coupling Reactions.

ConspectusPalladium-catalyzed cross-coupling reactions owing to their high specificity and superb chemoselectivity represent a powerful tool for the rapid construction of C-C and C-X bonds across various areas of chemical research, including pharmaceutical development, polymer and agrochemical industries, bioactive natural products, and advanced functional materials, rendering them indispensable for modern synthetic chemists. The major driving force for the advances in this critical field is the design of increasingly more reactive and more selective ligands and precatalysts that aim not only to address challenging cross-coupling processes but also to achieve optimal reactivity, selectivity, and functional group compatibility under mild, user-friendly, operationally simple, and broadly applicable conditions. In this context, Pd(II)-N-heterocyclic carbene complexes (NHC = N-heterocyclic carbene) have garnered prevalent attention among practitioners of organic synthesis due to their unique electronic and steric characteristics that are unmatched among other ligands. In particular, the superior σ-donating ability of NHC ligands in conjunction with conformational flexibility as well as the ease of steric and electronic modification and high stability to air and moisture enable highly effective fundamental elementary steps in catalytic cycles and facile formation of well-defined complexes.The key factor in the design of well-defined, air- and moisture-stable Pd(II) precatalysts involves the incorporation of supporting ligands, which are essential for ensuring the stability of Pd(II)-NHC complexes and facile activation of Pd(II)-NHC precatalysts to catalytically active monoligated Pd(0)-NHC species under the reaction conditions. Notably, [Pd(NHC)(μ-Cl)Cl]2 chloro dimers, which can be readily synthesized via a one-pot, atom-economic process, are the most reactive Pd(II)-NHC complexes synthesized to date. These well-defined, air- and moisture-stable dimers readily dissociate to monomers and are activated to Pd(0)-NHC catalysts under both mild and strong base conditions, showcasing enhanced reactivity and selectivity among their Pd(II)-NHC counterparts. This balance between high, operationally simple stability, which is characteristic of Pd(II) complexes together with the ease of activation to the strongly nucleophilic Pd(0)-NHC catalysts, renders [Pd(NHC)(μ-Cl)Cl]2 the most reactive Pd(II)-NHC precatalysts developed to date for a broad range of general cross-coupling processes, including C-X, C-O, C-N, and C-S activation and enabling the direct late-stage functionalization of complex compounds decorated with a wide range of sensitive functional groups.In this Account, we outline [Pd(NHC)(μ-Cl)Cl]2 as a highly reactive Pd(II)-NHC precatalyst that should be routinely used as the first choice Pd complexes for a wide range of challenging cross-coupling reactions. The advancements in this field over the past 20 years emphasize the critical role of catalyst design to achieve optimal reactivity. Consequently, [Pd(NHC)(μ-Cl)Cl]2 chloro dimers should be recommended as the go-to complexes in the powerful toolbox of Pd-catalyzed cross-coupling reactions. These now commercially available Pd(II)-NHC complexes see widespread use across the synthetic chemistry community and enable the accelerated application of challenging cross-couplings in the synthesis of new molecules.

Prediction of holey graphyne-supported single atom catalyst for nitrogen reduction reaction by interpretable machine learning and first-principles calculations

The electrocatalytic nitrogen reduction reaction (NRR) with efficient and selective electrocatalysts has emerged as a promising alternative for sustainable ammonia synthesis. In this study, we designed a novel class of single-atom catalysts (SACs), denoted as TM@HGY, by embedding 3d, 4d, and 5d transition metals into synthesized holey graphyne (HGY), and investigated their potential for NRR using a combined approach of density functional theory (DFT) calculations and machine learning. Through stability assessments and a three-step screening strategy, Sc@HGY, V@HGY, and Mo@HGY were identified as promising NRR electrocatalysts. Notably, V@HGY exhibited an exceptionally low limiting potential of −0.16 V, which is superior to all the known NRR SACs supported by graphyne-family members. Machine learning (ML) analysis revealed that the Mendeleev number (Nm), group (G), and d-orbital radius (Rd) of the absorbed metal atom are the primary contributors to the structural stability and catalytic activity of these SACs, and clear strategies for optimizing catalyst design were further suggested based on their intrinsic relationships. This work reveals the significant potential of TM@HGY in NRR, providing powerful guidance for designing high-performance SACs in the field of sustainable ammonia synthesis.

Progressive Fabrication of a Pt‐Based High‐Entropy‐Alloy Catalyst toward Highly Efficient Propane Dehydrogenation

High‐entropy alloys (HEAs) have emerged as burgeoning heterogeneous catalysts due to their vast material space, unique structure, and superior stability. However, the dominant trial‐and‐error approaches hamper the exploration of efficient catalysts, necessitating the development of rational design strategies. Here, we report a progressive approach to the design and fabrication of HEA catalysts guided by alloying effects toward propane dehydrogenation. Cu, Sn, Au, and Pd are selected and demonstrated to induce dilution, encapsulation, surface enrichment, and inhomogeneity effects on Pt. The fabricated HEA, PtCuSnAuPd/SiO2, exhibits excellent activity, selectivity, and stability. The propylene formation rates reach 256 and 390 molC3H6 gPt−1 h−1 at 550 and 600 °C, respectively. Systematic characterizations reveal that the random elemental mixing, structural stability, and high Pt exposure promote the exposure of abundant stable isolated Pt sites. This work comprehensively explores the rational design and fabrication of HEA catalysts from a unique perspective, offering opportunities for developing advanced catalysts.

Progressive Fabrication of a Pt-Based High-Entropy-Alloy Catalyst toward Highly Efficient Propane Dehydrogenation.

High-entropy alloys (HEAs) have emerged as burgeoning heterogeneous catalysts due to their vast material space, unique structure, and superior stability. However, the dominant trial-and-error approaches hamper the exploration of efficient catalysts, necessitating the development of rational design strategies. Here, we report a progressive approach to the design and fabrication of HEA catalysts guided by alloying effects toward propane dehydrogenation. Cu, Sn, Au, and Pd are selected and demonstrated to induce dilution, encapsulation, surface enrichment, and inhomogeneity effects on Pt. The fabricated HEA, PtCuSnAuPd/SiO2, exhibits excellent activity, selectivity, and stability. The propylene formation rates reach 256 and 390 molC3H6 gPt-1 h-1 at 550 and 600 °C, respectively. Systematic characterizations reveal that the random elemental mixing, structural stability, and high Pt exposure promote the exposure of abundant stable isolated Pt sites. This work comprehensively explores the rational design and fabrication of HEA catalysts from a unique perspective, offering opportunities for developing advanced catalysts.

Dry Reforming of Methane on Low‐Loading Rh Catalysts

Dry reforming of methane (DRM) is a promising catalytic process for converting greenhouse gases (CH4 and CO2) into syngas (CO and H2). This study investigates DRM under moderate conditions (550 °C) using supported ultra‐low loading (0.05 wt%) metal (M) catalysts (M = Rh, Ru, Pt, Pd, Ir, Au, and Ni). The reaction was carried out for 6 h with a flow rate of 30 mL/min for both CH4 and CO2, using 0.10 g of catalyst. Among these catalysts, 0.05 wt% Rh/Al2O3 exhibited the highest DRM activity. The effect of catalyst supports revealed that Al2O3 is the most effective support for 0.05 wt% Rh. The DRM activity of Rh species supported on Al2O3 and SiO2 was compared, and the Rh species on Al2O3 outperformed those on SiO2, indicating Al2O3 enhances the DRM activity of Rh. When comparing the DRM activity of Rh nanoparticles and Rh single atoms, it was suggested that Rh nanoparticles might exhibit superior performance for DRM. Coke deposited on 0.05 wt% Rh/Al2O3 is removed by CO2, maintaining stable catalytic activity. These findings provide valuable insights into the design of catalysts that minimize the use of noble metals in DRM reactions.

Heterogeneously Catalyzed Reductive Depolymerization of Lignin to Value-Added Chemicals.

Lignin is an abundant renewable source of aromatics, but its complex heterogeneous structure poses challenges for its depolymerization and valorization. Heterogeneously catalyzed reductive depolymerization (HCRD) has emerged as a promising approach, utilizing heterogeneous catalysts to facilitate selective bond cleavage in lignin and hydrogen transfer to stabilize the products under mild conditions. This review provides a comprehensive understanding of the hydrogen transfer mechanisms in HCRD, involving different hydrogen sources, including molecular hydrogen, alcohols, formic acid, etc., and the native hydrogen donor groups in lignin. The interaction between hydrogen sources and catalyst design is explored, emphasizing how catalyst characteristics must align with specific hydrogen transfer pathways to optimize efficiency and selectivity. Precious metal-based and non-precious metal-based catalysts are examined, highlighting advances that enhance hydrogen activation and transfer. Comparative analyses of hydrogen sources reveal distinct advantages and limitations. The significance of HCRD in lignin valorization and the development of integrated biorefineries is underscored, emphasizing its potential to contribute to a sustainable bioeconomy through improved process integration and economic viability.

Electron transfer mediated activation of periodate by contaminants to generate 1O2 by charge-confined single-atom catalyst.

The electron transfer process (ETP) is able to avoid the redox cycling of catalysts by capturing electrons from contaminants directly. However, the ETP usually leads to the formation of oligomers and the reduction of oxidants to anions. Herein, the charge-confined Fe single-atom catalyst (Fe/SCN) with Fe-N3S1 configuration was designed to achieve ETP-mediated contaminant activation of the oxidant by limiting the number of electrons gained by the oxidant to generate 1O2. The Fe/SCN-activate periodate (PI) system shows excellent contaminant degradation performance due to the combination of ETP and 1O2. Experiments and DFT calculations show that the Fe/SCN-PI* complex with strong oxidizing ability triggers the ETP, while the charge-confined effect allows the single-electronic activation of PI to generate 1O2. In the Fe/SCN + PI system, the 100% selectivity dechlorination of ETP and the ring-opening of 1O2 avoid the generation of oligomers and realize the transformation of large-molecule contaminants into small-molecule biodegradable products. Furthermore, the Fe/SCN + PI system shows excellent anti-interference ability and application potential. This work pioneers the generation of active species using ETP's electron to activate oxidants, which provides a perspective on the design of single-atom catalysts via the charge-confined effect.

Fueling the future of clean energy with self‐supported layered double hydroxides‐based electrocatalysts: A step toward sustainability

AbstractAmid the ongoing transition toward renewable fuels, the self‐supported layered double hydroxides (LDHs) are envisioned as propitious electrocatalysts for reinvigorating the electrocatalysis realm, thereby facilitating environmental remediation and bolstering sustainable global energy security. Exploiting appealing attributes such as unique lamellar structure, abundant active sites, tunable intercalation spacing and compositional flexibility, LDHs boast remarkable activity, selectivity and stability across diverse energy‐related applications. By virtue of addressing the technological and time prominence of excavating their renaissance, this review first encompasses the facile state‐of‐the‐art synthetic approaches alongside intriguing modification strategies, toward deciphering the authentic structure–performance correlations for advancing more robust and precise catalyst design. Aside from this, heterostructure engineering employing diversified ranges of coupling materials is highlighted, to construct ground‐breaking binder‐free LDHs‐based heterostructures endowing with unprecedented activity and stability. Subsequently, the milestone gained from experimental research and theoretical modeling of this frontier in multifarious electrocatalytic applications, including HER, OER, UOR, AOR, seawater splitting and other fundamental conversion reactions is rigorously unveiled. As a final note, a brief conclusion is presented with an outline of future prospects. Essentially, this review aspires to offer enlightenment and incite wise inspiration for the future evolution of innovative and resilient next‐generation catalysts.image

Photothermal Induced Dual-Interface: Accelerating Sustainable Hydrogen Evolution from Formic Acid.

Formic acid (FA), a liquid hydrogen storage carrier, can release hydrogen via photothermal catalysis, providing a clean and sustainable solution toward a carbon-neutral energy cycle. Despite recent advances in the design of efficient catalysts, the development of advanced systems with high H2 yield, stability, and durability remains challenging due to the inefficient photothermal conversion and mass transfer in the traditional liquid-solid bulk system, as well as the trade-off between hydrogen storage density and dehydrogenation rate. Here, we address these challenges by creating a photothermal-induced dual-interface characterized by high spectral absorption and low heat loss, a facile supply of FA, and vaporization of FA to minimize the energy barrier of the reaction. As a result, a record hydrogen evolution rate (200.9 mmol g-1 h-1) is achieved in a high concentration (26 M) of FA, which is about 15 times higher than the liquid-solid bulk system. In addition, it can be operated continuously for more than 192 h without additive addition and energy consumption, providing a strategy for accelerating interfacial mass transfer to improve catalytic activity, and also presents a reference for sustainable hydrogen production.

Design of a New Catalyst, Manganese(III) Complex, for the Oxidative Degradation of Azo Dye Molecules in Water Using Hydrogen Peroxide

In the current work, chloro(meso-tetrakis(phenyl)porphyrin) manganese(III) [Mn(TPP)Cl] was synthesized following two steps: the preparation of meso-tetraphenylporphyrin (H⁠2TPP) and the insertion of manganese into the free porphyrin H2TPP. The compounds were characterized using SEM, FT-IR, UV, TGA/DTA, and XRD analyses. Manganese(III) meso-porphyrins exhibited hyper-type electronic spectra with a half-vacant metal orbital with symmetry, such as [dπ:dxz and dyz]. The thermal behavior of [Mn(TPP)(Cl)] changed (three-step degradation process) compared to the initial H2TPP (one-step degradation process), confirming the insertion of manganese into the core of the free porphyrin H2TPP. Furthermore, [Mn(TPP)Cl] was used to degrade calmagite (an azo dye) using H2O2 as an oxidant. The effects of dye concentration, reaction time, H2O2 dose, and temperature were investigated. The azo dye solution was completely degraded in the presence of [Mn(TPP)(Cl)]/H2O2 at pH = 6, temperature = 20 °C, C0 = 30 mg/L, and H2O2 = 40 mL/L. The computed low activation energy (Ea = 10.55 Kj/mol) demonstrated the efficiency of the proposed catalytic system for the azo dye degradation. Overall, based on the synthesis process and the excellent catalytic results, the prepared [Mn(TPP)Cl] could be used as an effective catalyst for the treatment of calmagite-contaminated effluents.

Exploring Pt-Cu synergistic effects on porous SiO2 support with different Pt loadings for low-temperature oxidation of CO and C3H6

To address the high cost of noble metals, this study aims to optimize Pt loading and the synergistic effect of Cu on porous SiO2 support for low-temperature oxidation of CO and C3H6. A simulated test bench system was used to evaluate the performance of PtxCu1/SiO2 (where x= 0.3, 0.5, 0.7, and 1 wt%), Cu1/SiO2 and Ptx/SiO2 (where x= 0.5 and 1 wt%) catalysts with varying Pt loadings. Comprehensive characterization, including BET, XRD, SEM, TEM, and XPS was conducted to assess particle size, structure, and surface morphology. The effects of Pt incorporation on reduction and oxidation properties were further examined using H2-TPR and CO-TPD techniques. Results demonstrated a significant enhancement in catalytic activity with the addition of Cu confirming a synergistic interaction between Pt and Cu. This synergy was particularly pronounced in lower Pt loadings, where PtxCu1/SiO2 composites outperformed Ptx/SiO2 in catalytic activity. Pt addition reduced the particle size, which resulted in the creation of PtCu alloy, with 1 and 0.7 % wt Pt loading exhibiting comparable effects in CO conversion and 0.7 % Pt loading exhibiting better activity at higher temperatures in C3H6 oxidation indicating that catalytic activity was maintained even with a reduced Pt loading. Additionally, minimal difference in activity for C3H6 oxidation was observed among PtxCu1/SiO2 catalysts with 0.7, 0.5, and 0.3 wt% Pt loadings as indicated by T50 and T80 values. Reducing Pt loading from 0.7 wt% had minimal impact on catalytic efficiency for C3H6 oxidation with catalysts maintaining high activity. 0.7 wt% Pt loadings provide sufficient active sites for effective CO and HC oxidation. The enhanced catalytic activity and stability of bimetallic catalysts over monometallic Cu/SiO2 and Pt/SiO2 result from the simultaneous presence of active sites created by the synergetic effect of PtCu alloy formation with optimal ratio and well-optimized surface. These findings demonstrate the potential to optimize Pt usage without compromising catalytic performance, offering a cost-effective approach to catalyst design.

Machine learning-assisted screening of efficient ionic liquids for catalyzing CO2 cycloaddition reaction

The catalysis of CO2 cycloaddition reactions by ionic liquids holds significant promise in addressing environmental and chemical synthesis challenges. However, the design of effective ionic liquid catalysts is hindered by the sheer diversity of cation-anion combinations, leading to challenges in targeted catalyst development. This study addresses these issues by utilizing experimental data collected from literature on reactions involving epoxy compounds as substrates, conducted without solvents or co-catalysts, to establish a database for machine learning (ML). Simple descriptors derived from the ion pair structures of ionic liquids are employed as inputs for five ML classification algorithms to predict the yield of CO2 cycloaddition reactions. Subsequently, the highly accurate ML models are applied to forecast the catalytic performance of 1344 ionic liquids under ambient conditions. This approach identifies 13 cation structures and 8 anion structures that exhibit superior catalytic properties. Further refinement through density functional theory (DFT) calculations selects ion pair structures capable of catalyzing CO2 cycloaddition reactions at ambient temperature and pressure, demonstrating the efficacy of this method in guiding the design and development of ionic liquid catalysts for CO2 conversion reactions involving epoxy compounds.

Modulating structure of Ce-UiO-66 by introducing fluorinated terephthalic acid for enhanced removal efficiency of antibiotics: Insights into degradation kinetics and pathways

In this work, the 2-fluoroterephthalic acid with asymmetric structure and high electronegative F species was introduced in the assembly of Ce-UiO-66 catalysts to increase the defect density and enlarge pore structure for enhancement in removal efficiency of sulfamethoxazole. Owing to the strong coordination ability from high electronegative F species of 2-fluoroterephthalic acid with Ce-oxo nodes, the designed CUF exhibited improved interfacial properties (accelerated electron transfer rate, available active sites and enhanced interaction with PMS), which was favorable for the exploration and accessibility of active sites with sulfamethoxazole and PMS to decrease the adsorption barrier and accelerate PMS activation. As a result, the CUF catalysts exhibited higher adsorption capacity (173.4 mg/g) than that of CUH (117.8 mg/g), the enhanced degradation efficiency of sulfamethoxazole with a rate constant higher than 2.3 times CUH, good elimination (>95 %) of methylene blue, tetracycline and ibuprofen. In addition, the CUF/PMS system possessed satisfactory stability in wide solution pH, recycling and real water and good potential application in continuous wastewater treatment based on the designed dynamic catalytic reactor. This work provided deep insight into the design of catalysts with high adsorption performance and degradation efficiency based on the structure–activity relationship.

Kinetics of continuously catalyzed peroxymonosulfate in a fixed-bed reactor

Most studies have been conducted in batch reactors. Therefore, understanding the catalytic reaction kinetics and mass transfer in continuous catalytic reactors is essential for the design of heterogeneous catalysts and optimisation of catalytic degradation processes in heterogeneous systems. In this research, granular catalysts (Co-600/AlSi-0.25/AP) is used to investigate the kinetic constants and mass transfer resistance for the continuous catalytic decomposition of peroxymonosulfate (PMS) and degradation of p-nitrophenol (PNP) in a fixed bed reactor. The flow rate is 5 mL/min and reaction temperature is 30 °C, intrinsic kinetic constants of PMS decomposition and PNP degradation are 48 and 195 kg−1·min−1·L, respectively, which are 20–30 times of the apparent kinetic constants of PMS decomposition and PNP degradation in fixed bed reactors, respectively. The decomposition rates of PMS and PNP are controlled by mass transfer, and the reaction takes place in the diffusion-controlled regime. The mass transfer kinetic model based on the plug-flow model shows a good agreement between the calculated data and the experimental data. Which indicate that PMS decomposition and pollutant degradation in a fixed-bed reactor can be predicted by mass transfer kinetic modelling, guide the design of catalysts and the optimisation of heterogeneous catalytic reaction system in a fixed-bed reactor.