Catalyst For Reduction Research Articles

Gold Nanoparticle Catalyzed Solvent Switchable Selective Partial Reduction of Nitrobenzene to N‐Phenylhydroxylamine and Azoxybenzene

Impregnation of phosphine‐decorated polymer immobilized ionic liquid with the tetrachloroaurate anion results in reduction of the gold(III) to gold(I) with concomitant oxidation of the phosphine to its oxide. In situ reduction of the resulting precursor, AuCl@O=PPh2‐PEG‐PIILS, generated the corresponding O=PPh2‐PEGPIIL‐stabilised AuNPs, AuNP@O=PPh2‐PEGPIILS, which is a highly active and selective catalyst for the solvent dependent partial reduction of nitrobenzene to N‐phenylhydroxylamine in water and azoxybenzene in ethanol. The initial TOFs are comparable to those obtained with gold nanoparticles generated by reduction of tetrachloroaurate‐impregnated phosphine oxide decorated polymer immobilized ionic liquid AuCl4@O=PPh2‐PEGPIILS i.e. the activity and selectivity profiles do not depend on whether the AuNPs are generated from Au(III) or in situ generated Au(I). In stark contrast, gold nanoparticles prepared by NaBH4 reduction of AuCl@PPh2‐PEGPIILS based on gold(I) confined in phosphine modified polymer immobilized ionic liquid gave markedly lower initial TOFs. The use of dimethylamine borane as the hydrogen donor resulted in a substantial enhancement in activity for reductions conducted in water compared with NaBH4 and the initial TOF of 20,400 mole nitrobenzene converted mol Au‑1h‑1 obtained with AuNPs generated in situ from AuCl4@O=PPh2‐PEGPIILS is among the highest to be reported for the metal nanoparticle catalyzed selective reduction of nitrobenzene to N‑phenylhydroxylamine.

Tuning Strategies of Indium‐Based Catalysts for Electrocatalytic Carbon Dioxide Reduction

In electrocatalytic carbon dioxide reduction (CO2RR), indium (In)‐based catalysts with low toxicity and environmental benefits are renowned for their specific high selectivity for formic acid and intrinsic inertia for the competing hydrogen evolution reaction. However, recent studies have reported various products over In‐based catalysts showing comparable or even higher selectivity for carbon monoxide (CO) than for formic acid (HCOOH), puzzling the reaction pathway for CO2 reduction. This article presents a comprehensive review of recent studies on electrocatalytic CO2RR over In‐based catalysts highlighting the formation pathway of specific products. First, the mechanism of electrocatalytic CO2RR with the multiple reaction pathways is concluded considering the relationship between reaction intermediates and selectivity. Furthermore, the regulation strategies for multiple product formation are summarized, including crystalline phase engineering, alloying, nanostructuring, and structural modulation of In single atom, where the effect of key intermediates (*COOH, *OOCH, and *OCHO) on product generation is systematically discussed to achieve high selectivity. Finally, the intrinsic regulation mechanisms of these strategies are analyzed and the challenges and opportunities for the development of next‐generation In‐based catalysts are proposed.

Co-In Bimetallic Hydroxide Nanosheet Arrays With Coexisting Hydroxyl and Metal Vacancies Anchored on Rod-Like MOF Template for Enhanced Photocatalytic CO2 Reduction.

Layered double hydroxides (LDHs) can serves as catalysts for CO2 photocatalytic reduction (CO2PR). However, the conventionally synthesized LDHs undergo undesired aggregation, which results in an insufficient number of active sites and limits the desirable electron transfer required for CO2PR. The metal-organic framework (MOF) template-grown LDHs demonstrate excellent promise for exploiting the strengths of both MOFs and LDHs. Herein, the in situ growth of MIL-68(In)-NH2 MOF-templated Co-In bimetallic catalyst (CoIn-LDH/MOF) having an ultrathin nanosheet morphology on the preserved rod-like MOF template is demonstrated. Compared to the conventionally grown bimetallic LDH (CoIn-LDH), CoIn-LDH/MOF not only exposes more active sites but also possesses hydroxyl vacancies (VOH) and Co vacancies (VCo). Thus, CoIn-LDH/MOF performs a higher CO generation rate of 2320µmol g-1 h-1 during CO2PR, demonstrating improved activity and selectivity than those in CoIn-LDH. Experiments coupled with calculations reveal that the CoIn-LDH/MOF-driven CO2PR follows the *COOH pathway. The lower energy barriers for the formation of *COOH and CO(g) can be attributed to the coexistence of VOH and VCo in CoIn-LDH/MOF, effectively promoting charge transfer and enhancing CO2PR performance. This study provides a new strategy to obtain high-performant LDH-based catalysts with improved morphology.

Deactivation Mechanism of Spent TiO2-Based Selective Catalytic Reduction (SCR) Catalysts and State-of-the-Art Recycling Technologies.

Nitrogen oxides (NOx) make up a group of gases that are mainly formed during the combustion of fossil fuels at high temperatures. NOx contributes to environmental degradation by forming acid rain and enhancing global warming. Exposure to air with a high concentration of NOx can aggravate respiratory diseases, particularly asthma. The elimination of NOx in practical applications mainly proceeds through selective catalytic reduction (SCR) of NOx with NH3 to harmless N2 and H2O. One practical issue of the SCR process is the deactivation of TiO2-based SCR catalysts. In addition, growing numbers of spent SCR catalysts present a serious waste-management challenge for recyclers at end of life. It is therefore crucial to disclose the deactivation mechanism of the spent TiO2-based NH3-SCR catalysts and propose effective recycling technologies for waste valorization. Here we outline the catalyst deactivation pathways for TiO2-based SCR catalysts and critically review methods of improving the direct sustainability of spent catalysts, in areas such as direct regeneration and recovery of spent catalysts. Through this review, the challenges, solutions, and future strategies for handling spent SCR catalysts are clarified for future studies of application on an industrial scale.

Magnetically retrievable carbon-wrapped CNT/Ni nanospheres as efficient catalysts for nitroaromatic reduction.

We present a facile strategy for synthesizing magnetically retrievable carbon-wrapped CNT/Ni nanospheres (C-wrapped CNT/Ni) that enhance the catalytic performance of metals for environmental pollutant reduction. Structural and compositional analyses using X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDS), and field emission scanning electron microscopy (FESEM) confirmed the phase purity, morphology, and structure of the C-wrapped CNT/Ni. XRD, Raman, and EDS data validate the formation of the nanospheres, while FESEM images reveal uniform Ni nanospheres wrapped with a carbon layer through interconnected, evenly dispersed CNTs. Initially, Ni nanoparticles were anchored onto multiwalled carbon nanotubes to form magnetic CNT/Ni nanospheres, which were then coated with a carbon layer to prevent aggregation, improve Ni particle stability, and introduce additional surface functionalities. The catalytic efficacy of C-wrapped CNT/Ni was assessed through the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The reaction rate constant (k app = 0.6167 min-1) with C-wrapped CNT/Ni is approximately six times higher than that with bare Ni nanospheres (k app = 0.1056 min-1). This enhanced catalytic activity is attributed to the synergistic effect between the spherical Ni core and the wrapped carbon layer, mediated by the interconnected CNT, which promotes efficient hydride formation. Additionally, C-wrapped CNT/Ni demonstrates exceptional reusability in the 4-NP reduction process. The integration of these features within a single framework suggests its significant potential for diverse engineering and environmental applications.

Enhanced electrochemical oxygen reduction reaction on “C–O–Si” bonds in Si-doped graphene-like carbon

The use of heteroatom-doped carbon materials as non-precious metal catalysts for oxygen reduction reactions has attracted much attention from researchers. This paper presents the synthesis of two-dimensional Si-doped graphene-like materials (Si-GLC) featuring “C–O–Si” bonds through an in-situ doping method. Since the electronegativity of the Si (1.90) is much smaller than that of C (2.55) and O (3.44), the formation of the “C–O–Si” bond causes Si to lose a large number of electrons and become positively charged. This increases the adsorption of electronegative oxygen, thereby improving the activity of oxygen reduction reactions. The adsorption energy of oxygen molecules on Si-GLC was calculated to be −3.57 eV using density functional theory, much lower than on GLC (−2.18 eV). This suggests that Si doping enhances the adsorption of oxygen molecules by graphene-like materials, which is crucial for improving the performance of oxygen reduction reaction. Si-GLC displayed a half-wave potential of 0.80 V (vs. RHE) and a diffusion-limited current density of 5.81 mA cm−2 in 0.1 M KOH solution, demonstrating excellent catalytic activity for oxygen reduction reaction. It also exhibits good stability and tolerance to methanol crossover effect. In-situ doping creates “C–O–Si” bonds, modulating charge density and providing a strategy for high-performance oxygen reduction catalysts.

Confined growth of ultrasmall monodisperse gold nanoparticles in amino functionalized cellulose beads as effective catalysts for 4-nitrophenol reduction.

This study aims to prepare a monodisperse catalyst with a space-confined strategy, employing cellulose beads (CBs) as a carrier. Amino functionalized cellulose beads (ACBs) were prepared by grafting polyethyleneimine into the space of CBs via glutaraldehyde cross-linking. The in-situ reduction method was successfully employed to confine monodisperse ultrasmall gold nanoparticles (AuNPs) within the amino functionalized cellulose beads (AuNPs@ACBs) matrix. The AuCl4- ions were first immobilized on the amino substance (such as -NH3+/-NH2+, CN and CN) by chelation and electrostatic interaction. Then the Au(III) was reduced to Au(0) by electron transfer. The presence of amino groups in ACBs controls the size and dispersion of AuNPs. AuNPs@ACBs was used as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), it reveals excellent catalytic activity, which can be ascribed to the smaller particle size of AuNPs (TOF = 7.86 min-1). The spherical structure of AuNPs@ACBs permits straightforward recovery from the aqueous solution after the reaction is completed, thus improving the reusability and catalytic stability. The catalytic efficiency of AuNPs@ACBs can still reach 64.7 % after 10 cycles. After more than 3000 min, the column continues to run without detecting 4-NP in the eluent, which is still working.

Improving SO2 Tolerance and Low-Temperature Denitrification Performance in NH3-SCR Catalysis: A Comprehensive Study on Nb and Mn Modified CeO2 Catalysts

In pursuit of improving the performance of MnCe-based catalysts in NH3-assisted selective catalytic reduction (NH3-SCR) of NOx technology, particularly their SO2 resistance and low-temperature activity, a series of NbMnCeOx catalysts were synthesized. Results reveal that the Nb0.1Mn2Ce5Ox catalyst provides the most excellent SO2 resistance and SCR catalytic activity. Incorporating Nb into the MnCeOx structure enriches the formation of additional chemisorbed oxygen species and surface acidity, promoting NO2 production while effectively preventing the over-oxidation of NH3 to produce N2O. The incorporation of Nb and Mn into CeO2 improves the content of Brønsted- and Lewis-acid sites, facilitating the NH3 capture and NH4+ generation, thus enabling the NH3-SCR process via both Eley-Rideal (E-R, Mechanism S1) and Langmuir-Hinshelwood (L-H, Mechanism S2) mechanisms, with the latter dominating at low temperatures. Nb doping considerably reduces the sulfate formation and the initial SO2 adsorption on the NbMnCeOx surface, while decreasing the average oxidation state of Mn and shielding it from electronic attack from S4+ in SO2. This study highlights the synergistic effect of Nb and Mn in bolstering acidic sites in CeO2-based catalysts and proposes the reaction mechanisms for improving the low-temperature and sulfur-resistant NH3-SCR performance.

Mechanism of biochar-Cu-based catalysts construction and its electrochemical CO2 reduction performance

Electrochemical CO2 reduction can convert CO2 into high-value-added products for special forms of energy storage and efficient carbon utilization for renewable electricity. To investigate the influence of biochar-Cu-based catalysts properties on electrochemical CO2 reduction performance, Cu is loaded onto rice husk-based biochar by impregnation method combined with pyrolysis and calcination in this study. The three synthesized biochar-Cu-based catalysts are tested for activity and electrochemical CO2 reduction performance in Flow Cell. The results show that biochar's properties, such as its high specific surface area, rich pore structure, and adjustable pore structure, provide sufficient sites for CO2 reduction. Urea can relatively increase the copper loading by 44 %, but it will also increase the clustering of copper. In the reduction performance test, the current density of char-Cu-700 is 2.08 times higher than that of char-Cu and 1.45 times higher than char-Cu-N at a reduction potential of -0.45 (V vs. RHE). The current density enhancement of the catalyst loaded on biochar with Cu particle size of 10 nm is about 50 % higher than that of the catalyst with a particle size of 20 nm. It indicates that the smaller the particle size of Cu at the nanoscale, the lower the average coordination of surface atoms and the greater the catalyst's reactivity. This study provides novel ideas for synthesizing biochar-Cu-based catalysts, lays part of the theoretical foundation for using biochar-Cu-based catalysts for electrochemical CO2 reduction, and provides experimental support for optimizing the catalyst structure.

Removal of Cr(VI) from electroplating wastewater by CoNi-LDH@NHCS electrode and its electrocatalytic ammonia production

Excess Cr(VI) and nitrates from industrial processes can pose a serious threat to humans and the environment. In this study, a CoNi-layered double hydroxide@nitrogen doped hollow carbon sphere (CoNi-LDH@NHCS) electrode was prepared and used for Cr(VI) removal by capacitive deionization (CDI) as well as waste CoNi-LDH@NHCS electrodes were used for ammonia production (NO3RR). The CoNi-LDH@NHCS electrode could remove up to 98.66 % of 10 ppm Cr(VI). In the actual electroplating wastewater, the removal of Cr(VI) by CoNi-LDH@NHCS electrode was 73.91 %, which showed good deionization performance. Density-functional theory calculations show that the oxygen atoms in the Cr(VI) anion and the hydrogen atoms on the surface of the electrode form hydrogen bonds and are adsorbed on the surface of the electrode under the effect of polarity, and the OH bonds on the surface of the electrode are elongated or even dehydrogenated and eventually form Cr(III)-OH. We also produced a high ammonia yield of 30.51 mg h−1mgcat−1 by using the CoNi-LDH@NHCS electrode that was discarded after the adsorption cycle as a catalyst for electrocatalytic nitrate reduction. This work enabled the sustainable use of electrode materials in addition to offering an effective technique for removing Cr(VI) from electroplating wastewater.

Laser ablation-induced convenient fabrication of surfactant-free platinum nanospheres with clean surface structures for enhanced electrocatalytic methanol oxidation

Platinum (Pt) is the most promising catalyst for hydrogen oxidation and oxygen reduction. However, the residual surface-stabilizing agents capped on Pt-based nanomaterials via traditional chemical approaches will significantly reduce their catalytic activity. Herein, a new one-step strategy for the facile synthesis of surfactant-free Pt nanospheres with clean surface structures is developed by laser ablation of Pt target in distilled water. The distinctive advantage is that the pure water-dispersed Pt nanospheres can be obtained without any extra purification procedures, and the obtained catalyst exhibits enhanced electrocatalytic activity compared with Pt nanospheres capped with polyvinyl pyrrolidone or cetyl trimethyl ammonium bromide, which are most regular stabilizers or surfactants in traditional nanoparticles synthesis method. Importantly, the mass-normalized cyclic voltammetry (CV) curves for the methanol oxidation reaction show that the measured value of peak current is nearly 610 and 1050 times higher than that of Pt/PVP and Pt/CTAB samples. Moreover,the chronoamperometric (CA) measurements reveals that the steady-state current density is about 1.28 mA/cm2, while which of Pt/PVP and Pt/CTAB are 1.07 and 0.017 μA/cm2, respectively. It is no doubt that the application of laser beam as an environmental friendly tool for sculpting pure functional metal-based nanomaterials is a breakthrough in the additive problems that arise from standard chemical fabrication.

Electrochemical CO2 reduction to syngas on copper mesh electrode: Alloying strategy for tuning syngas composition

Electrochemical CO2 reduction to synthetic fuels and commodity chemicals using renewable energy offers a promising approach to mitigate CO2 emissions and alleviate energy crisis. Copper-based catalysts show potential for electrochemical CO2 reduction applications, while they face the key challenges of high potential, sluggish kinetics, and poor selectivity. In this work, Cu-Zn, Cu-Co, Cu-Cd, and Cu-In bimetallic catalysts are synthesized via the electrodeposition method for electrochemical CO2 reduction to syngas with adjustable CO/H2 ratios. The bimetallic catalysts are characterized using various techniques to reveal their crystalline structures, morphologies, and elemental compositions. The structure-property-activity relationships of these catalysts are investigated to identify optimal candidates for electrochemical CO2 reduction applications. The findings reveal that the bare Cu mesh catalyst exhibits poor CO2 reduction activity, and the products are dominated by hydrogen evolution reaction (HER). The bimetallic catalysts exhibit improved CO2 reduction performance, with the Cu-Zn and Cu-Cd catalysts showing excellent activity, and the CO/H2 ratio in syngas can be tuned over a wide range by adjusting the applied potential. The Cu-Zn and Cu-Cd catalysts demonstrate outstanding performance with Faradic efficiencies of ∼90 % and ∼80 % towards syngas production with CO/H2 ratios of ∼2.0 and ∼1.5 at −0.81 and −1.01 V vs. RHE, respectively, making the produced syngas suitable for various industrial applications. Stability tests over 450 min show that the Cu-Zn and Cu-Cd catalysts maintain stable catalytic activity, syngas selectivity and CO/H2 ratio, making them robust candidates for syngas production. The results will provide valuable insights into the design of robust catalysts for electrochemical CO2 reduction, offering a promising path toward sustainable syngas production.

Facile growth of a heteroepitaxial layer on perovskite oxide surfaces for active and durable fuel cell cathodes

Polycrystalline perovskite oxide particles are promising candidates for cathode materials in solid oxide fuel cells. However, their limited activity and stability pose significant challenges for practical applications. In this study, we demonstrate a novel approach to achieve both high activity and durability in a PrBaCo2O5+δ catalyst through a simple epitaxial layer growth strategy. We found that an amorphous precursor of the highly durable catalyst SmBa0.5Ca0.5CoCuO5+δ can spontaneously adhere to the surface of PrBaCo2O5+δ particles. Upon heat treatment, it grows along the perovskite lattice, forming a heteroepitaxial layer with just a few atomic layers thickness. This heterostructure enhances the operational stability of PrBaCo2O5+δ transforming a 78% decrease over 100 h into a 7% increase. After 100 h, the power output density of the cell with the modified sample is more than 500% higher than that of unmodified PrBaCo2O5+δ. This work presents a new strategy for fabricating heteroepitaxial layers on polycrystalline ceramic catalysts and introduces a pioneering approach for developing high-performance oxygen reduction catalysts and related materials.

Design and Implementation of a Cost-Effective, Safe, and Precise Lean-Rich Generating System for NOX Storage Reduction Catalyst Evaluation: Performance Analysis, Statistical Modeling, and Multiple Response Optimization – A Guideline for Future Research and Application

Mixing is a critical factor in chemical reaction engineering, particularly in the development of new catalysts for pollutant removal, such as NOx storage reduction catalysts. Comprehensive performance evaluation in laboratory experiments requires high-quality test gases. Several techniques have been developed for generating these gases, each with specific advantages and limitations. This research presents a simple, safe, and cost-effective gas generation system for laboratory applications, including evaluating adsorbents and catalysts, particularly NOx storage reduction catalysts, and for toxicological studies using precise dynamic methods like gas stream mixing and evaporation. Components of the dynamic system—including gas cylinders, connections, mixing chambers, rotameters, the quartz reactor with preheating chamber, bubbler systems, and tubular heaters—are comprehensively described. Statistical modeling and optimization were employed to determine the optimal operating conditions. The optimal conditions were identified as NO (924 ppm), O₂ (15%), CO (9999 ppm), and a space velocity of 105,921 h⁻¹. Additionally, the system's ability to generate various mixtures of gases (NO, O₂, and CO) and vapors (toluene and water) was assessed. The system was further evaluated under fan-on and fan-off modes to assess its performance under varying turbulent conditions. A detailed analysis was performed to determine the relative errors, time to reach steady-state conditions, and actual concentrations produced under different expected concentrations (NO: 100-200 ppm, O₂: 3-15%, CO: 500-10000 ppm, toluene: 64-8999 ppm, relative humidity: 0.14-22.69%), space velocity (70,000-140,000 h⁻¹), bubbler flow rates (10-600 mL/min), and saturator temperatures (5-20°C). Fundamental equations for calculating conversion, selectivity, and yield of a component of interest, carbon-messing, and carbon balance in the mixture are also provided.

The Ru/CeO2‐NaOH‐NaI Solvent‐free Catalytic System for the Hydroesterification of C2H4, CO, and C2H5OH

AbstractEthyl propionate can be produced from CO, C2H4, and CH3CH2OH as raw materials by ethylene hydroesterification in one step. In this paper, a solvent‐free composite catalytic system (Ru/CeO2‐NaI‐NaOH) is developed to catalyze the hydroesterification of C2H4, CO, and C2H5OH. The formation and inhibition mechanisms of 3‐pentanone and acetal are studied, and the pathway for the generation of ethyl propionate has also been analyzed. The factors that influence the performance of catalytic system were researched, such as catalyst reduction temperature, the addition of Ru/CeO2, reaction temperature, reaction time, the partial pressure of CO, and so forth. In Ru/CeO2‐NaOH‐NaI heterogeneous catalytic system, at the experiment conditions of 3 MPa and 180 °C, the C2H4 conversion and the ethyl propionate selectivity are 66.7% and 92.0%, respectively after 4 h reaction. This work presents a strategy for the production of propionate by ethylene hydroesterification, catalyzed by a heterogeneous catalytic system.

In-situ CeO2/CuO heterojunction electrocatalyst for CO2 reduction to ethylene.

CeO2/CuO heterojunction composite catalysts were synthesized using a one-step method, achieving the introduction of Ce species on nanoscale copper oxide (CuO) particles during the hydrothermal process. On one hand, this protects the nanostructure of the substrate from damage and prevents the agglomeration of CuO nanoparticles. On the other hand, the bimetallic synergistic effect between Ce and Cu effectively improves the conductivity and catalytic activity of the catalyst, significantly enhancing the selectivity of the catalyst for electrochemical reduction of CO2 to C2H4, while effectively suppressing the competing hydrogen evolution reaction (HER). By regulating the amount of CeO2 introducing, a series of CeO2/CuO composite catalysts were designed. The results showed that the 15% CeO2/CuO catalyst exhibited the best selectivity and catalytic activity for C2H4. At a low overpotential of -1.2 V, the 15% CeO2/CuO catalyst demonstrated a current density of 14.2 mA cm⁻² and achieved a Faradaic efficiency for ethylene as high as 65.78%, which is 2.85 times the current density (j = 4.98 mA cm⁻²) and 3.27 times the Faradaic efficiency for ethylene (FEC2H4 = 20.13%) of the undoped catalyst at the same potential. This work provides a feasible basis for achieving efficient CO2RR to C2 products, and even multi-carbon products.

Cross-Electrophile Coupling: Principles, Methods, and Applications in Synthesis.

Cross-electrophile coupling (XEC), defined by us as the cross-coupling of two different σ-electrophiles that is driven by catalyst reduction, has seen rapid progression in recent years. As such, this review aims to summarize the field from its beginnings up until mid-2023 and to provide comprehensive coverage on synthetic methods and current state of mechanistic understanding. Chapters are split by type of bond formed, which include C(sp3)-C(sp3), C(sp2)-C(sp2), C(sp2)-C(sp3), and C(sp2)-C(sp) bond formation. Additional chapters include alkene difunctionalization, alkyne difunctionalization, and formation of carbon-heteroatom bonds. Each chapter is generally organized with an initial summary of mechanisms followed by detailed figures and notes on methodological developments and ending with application notes in synthesis. While XEC is becoming an increasingly utilized approach in synthesis, its early stage of development means that optimal catalysts, ligands, additives, and reductants are still in flux. This review has collected data on these and various other aspects of the reactions to capture the state of the field. Finally, the data collected on the papers in this review is offered as Supporting Information for readers.

Developing Robust Ceria-Supported Catalysts for Catalytic NO Reduction and CO/Hydrocarbon Oxidation

Developing Robust Ceria-Supported Catalysts for Catalytic NO Reduction and CO/Hydrocarbon Oxidation

Copper oxide nanoparticles-decorated cellulose acetate: Eco-friendly catalysts for reduction of toxic organic dyes in aqueous media

In this study, we aimed to gain insight into the potential of catalytic reduction using copper oxide nanoparticles decorated cellulose acetate as a biosupport (CuxO@CA) for the removal of specific pollutants. The prepared catalyst was submitted to a series of spectroscopy techniques for characterization purposes. The results of the catalytic tests on methylene orange (MO) and methylene blue (MB) solutions suggest that the elimination efficiency may be influenced by several factors, including the catalyst dose and the concentration of the pollutant. Kinetic studies were also carried out, and the value of the rate constant Kapp derived from the pseudo-first-order kinetics was found to be highest for the prepared catalyst in a very short reaction time. The CuxO@CA catalyst was tested on a combination of MO/MB dyes, and the results indicated that it exhibited the highest catalytic activity in reducing and degrading these organic dyes in aqueous solutions, which is an encouraging outcome. Furthermore, the prepared catalyst demonstrated promising catalytic performance and exhibited the potential for recycling multiple times without significant loss of activity, which could be advantageous for large-scale production and practical use in water treatment.

Impact of Alkali Metals on CeO2-WO3/TiO2 Catalysts for NH3-Selective Catalytic Reduction and Lifetime Prediction of Catalysts

Ce-based catalysts have been widely used in the removal of nitrogen oxides from industrial flue gas because of their good catalytic performance and environmental friendliness. However, the mechanism of alkali metal poisoning in Ce-based catalysts remains to be further studied. This work involves the preparation of the K/Na-poisoned CeWTi catalyst via the impregnation method for assessing its performance in NO removal. Experiments show that both K and Na exhibit detrimental effects on the CeWTi catalyst, and the loading of alkali metal reduces the specific surface area and pore volume of the catalyst. Furthermore, the presence of alkaline metals results in a notable decline in the CeWTi acid concentration, particularly in Lewis acid sites. Concurrently, the levels of Ce3+, oxygen vacancies, and reducing agents on the catalyst surface decrease, leading to diminished reduction capability and eventual catalyst deactivation. The application of a BP neural network for catalyst activity prediction yielded an average relative error of approximately 0.73%, indicating enhanced accuracy in prediction outcomes. This work explored the cause of alkali metal poisoning of the CeWTi catalyst and provided an effective prediction method for the lifetime of CeWTi catalyst, which provided theoretical guidance for the engineering application of Ce-based catalysts.