Impregnation Method Research Articles

Nanostructured Ni–Co catalysts: Effect of impregnation sequence and complexing agent

This paper explores the synthesis by the impregnation method using citric acid and the characterization of bimetallic Nickel–Cobalt (Ni–Co) catalysts, focusing on their application in ethanol steam reforming leveraging the demonstrated improved stability and catalytic activity observed in previous works when Co is introduced into Ni catalysts. The study aims to investigate the effects of the sequence of incorporation of Ni and Co in the catalyst support in order to optimize the catalytic performance. The results indicate that the optimal sequence for introducing Co and Ni significantly enhanced the catalytic performance in ethanol steam reforming and it was associated to a higher Ce+3/Ce+4 ratio and a stronger active site-support interactions that modified the CNT growth mechanism, preventing increasing pressure drop through the reactors. The best catalytic performance corresponded to the system, Co/Ni/MgAl2O4–CeO2, in which Co was incorporated after Ni.

Effect of transition and alkali metals on Mo2C/Al2O3 catalysts for syngas to higher alcohols

Direct production of higher alcohols remains a great challenge in syngas conversion process. Herein, MMo2C/Al2O3 and KMMo2C/Al2O3 catalysts promoted by different transition metals M (M=Co, Fe, Cu, Ni, Zn, Nb) and alkali metal (K) were prepared by impregnation method to investigate the effect on CO hydrogenation to higher alcohols under milder reaction conditions (300°C, 3.0 MPa). The catalysts were characterized with XRD, H2-TPR, and XPS. It was found that the addition of transition metals and K resulted in the decrease of low-valent Mo species on the catalyst surface, which facilitated the generation of Mo4+ during the reaction. Increase in Mo4+ content facilitates the conversion of CO to CO*, which provides more CO insertion sites for the generation of alcohols. Moreover, the introduction of K also enhances the interaction of transition metals with Mo, which accelerates the formation of alcohols in the reaction. Meanwhile, the transition metal and Mo2C work together to promote the dissociative adsorption of CO. The production of higher alcohols is facilitated by the synergistic effect of the two mentioned above. Overall, the KCoMo/Al2O3 and KFeMo/Al2O3 catalysts exhibited high selectivity for higher alcohols, reaching 73.9 % and 71.3 % for C2+OH in the alcohol products, respectively. CO conversion of KFeMo/Al2O3 catalyst can reach 84.9 % with excellent stability in the reaction. Moreover, the possible pathways of the reaction were obtained by in-situ DRIFT characterization.

Synergistic Effect of NiAl-Layered Double Hydroxide and Cu-MOF for the Enhanced Photocatalytic Degradation of Methyl Orange and Antibacterial Properties

This study synthesized NiAl-layered double hydroxide (LDH)/Cu-MOF photocatalyst using a simple impregnation method involving NiAl-LDH and Cu-MOF. The successful synthesis was confirmed through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potential measurements, thermogravimetric analysis (TGA), ultraviolet diffuse reflectance spectroscopy (UV-DRS), N2 adsorption at −196 °C, and electrochemical impedance spectroscopy (EIS). Photocatalysts based on NiAl-LDH, Cu-MOF, and NiAl-LDH/Cu-MOF were used to remove methyl orange (MO) dye from contaminated water. The impact of various factors, including pH, dye concentration, and photocatalyst amount, on MO degradation efficiency was assessed. FTIR analysis was conducted both before and after dye degradation. The optimal degradation conditions were a photocatalyst dose of 25 mg and a pH of 3. Kinetic studies indicated that the degradation of MO dye onto NiAl-LDH/Cu-MOF followed a pseudo-first-order and an L–H or Langmuir–Hinshelwood model. The value of R2 = 0.94 confirms the validity of pseudo-first-order and Langmuir–Hinshelwood (L–H) kinetic models for the photocatalytic degradation of MO dye. This study highlights the importance of developing novel photocatalysts with improved degradation efficiency to protect the water environment. Antibacterial activity was also performed with antibacterial sensibility testing by disk diffusion to determine minimal inhibitory and bactericidal concentrations. In short, NiAl-LDH/Cu-MOF can be helpful for various biomedical and industrial applications.

Green Approach for the Synthesis of 2-Phenyl-2H-indazoles and Quinazoline Derivatives Using Sustainable Heterogeneous Copper Oxide Nanoparticles Supported on Activated Carbon and OER Study.

This research work reports the synthesis of copper oxide (CuO) nanoparticles supported on activated carbon by a simple impregnation method using 2-propanol as a green solvent, followed by calcination. The synthesized CuO@C is used as an efficient heterogeneous nanocatalyst for the synthesis of 2H-indazoles and quinazolines utilizing commercially available 2-bromobenzaldehydes, primary amines, and sodium azide under ligand-free and base-free conditions. The present methodology demonstrates the formation of new N-N, C-N, and C═N bonds under one-pot reaction conditions using PEG-400 as a green solvent. The reaction pathways are supported by control experiments and mechanistic elucidation. Further, the synthesized catalyst was characterized by a range of microscopic and spectroscopic techniques such as powdered X-ray diffraction, fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray, UV-vis, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and BET-BJH analysis. Importantly, the study focused on the recyclability of the catalyst and successfully showed gram-scale production. Significantly, our active catalyst exhibited an outstanding performance in the oxygen evolution reaction, with an overpotential of 290 mV and a swallow Tafel slope of 91 mV dec-1.

Efficient Toluene Decontamination and Resource Utilization through Ni/Al2O3 Catalytic Cracking.

Volatile organic compounds (VOCs), particularly aromatic hydrocarbons, pose significant environmental risks due to their toxicity and role in the formation of secondary pollutants. This study explores the potential of catalytic pyrolysis as an innovative strategy for the effective remediation and conversion of aromatic hydrocarbon pollutants. The research investigates the high-efficiency removal and resource recovery of the VOC toluene using a Ni/Al2O3 catalyst. The Ni/Al2O3 catalyst was synthesized using the impregnation method and thoroughly characterized. Various analytical techniques, including scanning electron microscopy, X-ray diffraction, and N2 adsorption-desorption isotherms, were employed to characterize the Al2O3 support, NiO/Al2O3 precursor, Ni/Al2O3 catalyst, and the resulting solid carbon. Results indicate that Ni predominantly occupies the pores of γ-Al2O3, forming nano/microparticles and creating interstitial pores through aggregation. The catalyst demonstrated high activity in the thermochemical decomposition of toluene into solid carbon materials and COx-Free hydrogen, effectively addressing toluene pollution while recovering valuable resources. Optimal conditions were identified, revealing that a moderate temperature of 700 °C is most favorable for the catalytic process. Under optimized conditions, the Ni/Al2O3 catalyst removed 1328 mg/g of toluene, generated 915 mg/g of carbon material, and produced 1234 mL/g of hydrogen. The prepared carbon material, characterized by its mesoporous structure and high specific surface area graphite nanofibers, holds potential application value in adsorption, catalysis, and energy storage. This study offers a promising approach for the purification and resource recovery of aromatic volatile organic compounds, contributing to the goals of a circular economy and green chemistry.

The adsorption and separation of tungsten and molybdenum by chitosan and chitosan-D301: Experiments and DFT theoretical calculation

The adsorption and separation of tungsten and molybdenum are important for efficient recycling of W-Mo resources, which requires green and efficient adsorbents. In this paper, Chitosan (CS)-D301 material was obtained by impregnation method and was applied to adsorb and separate W and Mo in solutions. The adsorption optimization results indicated that W was adsorbed by CS-D301, the separation factor of W/Mo increased to 26.45 compared with that of CS 21.34. The desorption efficiency was still above 94 % after five adsorption–desorption cycles. FT-IR, XPS and DFT theoretical calculations indicated that the surface group N+-R of CS-D301 showed more affinity for W, making it easier to selectively adsorb W over Mo than CS only. N was the surface-active adsorption site, and the adsorption process belonged to chemical adsorption with an adsorption energy of Eads = −957.64 kcal/mol. CS-D301 was expected to become green adsorbent for efficient separation of W and Mo to support resource recovery, protection and sustainable development.

Catalytic hydrogenation of waste-derived lipids: A route to producing sustainable drop-in biofuels by using Re/TiO2 catalysts

The urgent threat of climate change compels modern society to transition to alternative energy sources swiftly. The production of sustainable liquid biofuels capable of substituting fossil-derived fuels is a topic of great interest. This study explores the effectiveness of Re/TiO2 catalysts in producing drop-in biofuels from waste-derived feedstock. Specifically, four Re-based catalysts supported on different TiO2 materials, namely TiO2 P25, TiO2 FSP, TiO2 M, TiO2 COTIOX were synthesized using the wet impregnation method, characterized and tested in the hydrodeoxygenation reaction of fatty acids, to uncover fundamental insight into this process. These catalysts exhibited varying levels of effectiveness. Apart from Re/TiO2 COTIOX, which showed the lowest conversion of fatty acids (30 %), the other three catalysts allowed over 98 % conversion of fatty acids into hydrocarbons after 6 h reaction, at 35 bar of H2, under solvent-free conditions and without pre-reduction of the catalyst. Notably, Re/TiO2 P25 was the most effective, attaining this remarkable result at 300 °C. The remaining catalysts, Re/TiO2 FSP and Re/TiO2 M, required higher temperatures (350 °C) to achieve complete hydrogenation of fatty acids into hydrocarbons. These effective catalysts also demonstrated great recoverability, reusability, and robustness, successfully converting waste-derived lipids, such as grease recovered from urban sewage sludge and waste cooking oil, into hydrocarbons. These findings underscore Re/TiO2 as a promising robust catalyst for waste-derived lipids hydrogenation, enabling the efficient production of drop-in biofuels and paving the way for innovative solutions in the renewable energy landscape.

Reusable superhydrophobic fluorinated cellulose-graphene composite aerogels for selective oil absorption

Although some progress had been made in the adsorption of graphene aerogels, more research was needed on their elasticity and recyclability. In this paper, a superhydrophobic fluorinated cellulose and graphene composite aerogel (FCGA) was prepared by a simple two-step impregnation method. Firstly, nano-cellulose was introduced into the graphene aerogel to inhibit the excessive accumulation of graphene lamellae and increase the specific surface area. The surface of the composite aerogel was then impregnated with silanol and fluorinated functional groups by a two-step impregnation method, resulting in a superhydrophobic aerogel with remarkable elasticity. The introduction of cellulose and silane provided the aerogel with excellent elasticity and recovery from cyclic adsorption. The successful grafting of the fluorophobic groups of PFDMS onto the graphene oxide strengthened the framework of the graphene aerogel, making FCGA a good candidate for repeated selective oil absorption. It could be restored to the original height after compression to 50% and 80% strain decompression. FCGA could efficiently absorb oil in water and had a high organic adsorption capacity. And the adsorption capacity of different oils/organic solvents reached 22,480 mg/g∼36,700 mg/g. Its absorption efficiency remained above 98.5% under distillation cycles. Due to its high elasticity, it retained more than 90% of its cyclic adsorption capacity through the squeeze cycle. As a simple, low-cost recovery method, its reusability was already better than most known adsorption elastic materials. The prepared composite aerogel had the advantages of simple preparation, low density (0.014 g/cm3), superhydrophobicity (water contact angle 153.3°), excellent adsorption properties, and recyclability. Therefore, FCGA had a very promising application in circulating selective oil absorption.

Deciphering the structural origin for the remarkable CO oxidation activities of the CuO-based catalysts with diverse morphological CeO2 supports

In this work, octahedral, cubic, particle-like, spherical and rod-shaped nano-CeO2 supports were synthesized by hydrothermal method. CuO/CeO2 catalysts were then prepared via an ultrasonic-assisted impregnation method, employing these differently shaped CeO2 supports. The resulting catalysts were tested for their performance in CO oxidation. The findings revealed that the CuO active sites significantly influenced the oxygen storage and release capacity of CeO2, thereby improving its catalytic activity for low-temperature CO oxidation. The key factors affecting the CO oxidation performance of CuO/CeO2 catalysts with different CeO2 morphologies were investigated through various characterizations. It was found that the specific surface area was not the primary factor in determining catalytic activity. Instead, the exposed crystal planes played a crucial role. By adjusting the crystal plane exposure of CeO2, the supported 1CuO/CeO2 catalysts exhibited different crystal surface configurations. Notably, the 1CuO/CeO2-S catalyst, with exposed (100) and (110) crystal planes, and the 1CuO/CeO2-P catalyst, with exposed (111), (100), and (110) planes, exhibited higher surface defect concentrations. This increased defect concentration facilitated the formation of Cu+ species, enhancing the redox properties and further improving the overall catalytic performance of CO oxidation.

Efficient Catalytic Hydrocracking of Crude Palm Oil Over EDTA Template-assisted SiO2-Al2O3/NiMo Catalysts

The development of hydrocracking catalysts for crude palm oil (CPO) is a challenging process due to its limited textural or pore accessibility and low acidity properties. Therefore, this study aims to develop a series of SiO2-Al2O3-x/NiMo catalysts using different Al mass (x = 5, 10, 25 g) assisted with EDTA to enhance their physicochemical properties. During the procedures, bimetallic NiMo species were dispersed into SiO2-Al2O3-x using the wet impregnation method. The structural, textural, surface morphology, particle size distribution, and acidity properties of the products were then assessed. Catalytic activity of catalysts on hydrocracking of CPO was evaluated at 350 °C for 2 h, H2 gas pressure of 20 bar, and mixed at 1500 rpm. The results showed that increasing Al mass caused an increment in the total acidity, acid site density, and surface area of SiO2-Al2O3-x. In addition, SiO2-Al2O3-25 provided better support properties, allowing preferable NiMo dispersion. Hydrocracking assessment showed that CPO conversion was increased at higher Al mass, producing the highest bio-aviation and biogasoline fractions yield. Based on these results, SiO2-Al2O3-x/NiMo successfully enhanced CPO conversion of unloaded SiO2-Al2O3-x, as well as increased the yield of bio-aviation and biogasoline fractions.

Cs-Ba-Ru/La2O3-MgO Catalysts from Microdrop-Confined Pyrolysis for Superior NH3 Synthesis under Mild Conditions.

Support modification is an important way to improve the activity of the Ru/MgO-based NH3 synthesis catalyst. This work synthesized 24 composite MgO-based supports of MOx-MgO (M = La, Zn, etc.) via a microdrop-confined pyrolysis (MDCPy) method and then prepared the corresponding Cs-Ba-Ru/MOx-MgO catalysts using the impregnation method. Under the same NH3 synthesis conditions, the activity of the Cs-Ba-Ru/MOx-MgO catalysts composed of 17 elements such as Pr was significantly lower than that of Cs-Ba-Ru/MgO, while the activity of the Cs-Ba-Ru/MOx-MgO catalysts composed of four elements such as Nd was comparable to that of Cs-Ba-Ru/MgO, and the activity of the Cs-Ba-Ru/MOx-MgO catalysts composed of three elements such as La was significantly higher than that of Cs-Ba-Ru/MgO. Among them, it is clear that La2O3-MgO composite supports have the most significant effect on the improvement of NH3 synthesis performance. Through the optimization of the La/Mg ratio and loading of Ru, the optimal activities achieved ∼7 mol(NH3)/g(Ru)/h with corresponding Ru loading of 0.25-0.5 wt % under mild conditions as follows: H2/N2 ratio of 3:1, temperature of 400 °C, pressure of 3 MPa and a weight hourly space velocity (WHSV) of 96.0 L/gcat/h. In addition, the CsBa-Ru/La2O3-MgO catalyst showed good stability.

Enhancing glycerol dry reforming performance through metal promoters: A study on 10Ni/La.Al catalyst with Mo, Sn, and Cd additions

The effect of metal promoters (Mo, Sn, and Cd) on the performance of the 10Ni/La.Al nanocrystalline catalyst in Glycerol Dry Reforming (GDR) was investigated. 2x.10Ni/La.Al (x = Mo, Sn, and Cd) catalysts were prepared using the solid-state method and 10 wt.% Ni and 2 wt.% Mo, Sn, and Cd were added to the catalyst using the impregnation method. The catalysts were characterized by BET, X-ray diffraction, temperature-programmed reduction (TPR), oxidation (TPO), Raman, and scanning electron microscopies (SEM) techniques. It was found that adding Mo caused an increase in glycerol conversion and improved the long-term stability of the 10Ni/La.Al. Furthermore, catalysts with different amounts of promoter loading (2, 4, and 6 wt%) were synthesized to evaluate the optimum amount of Mo. 4Mo.10Ni/La.Al was selected to achieve 58 % glycerol conversion and the best stability.

Efficiency and mechanistic insights of photocatalytic degradation and sterilization utilizing g-C3N4/WO3-x Z-scheme heterojunction under full-spectrum light

Designing highly efficient full-spectrum responsive Z-scheme heterojunction for wastewater decontamination and disinfection is urgently essential. Herein, a novel Z-scheme g-C3N4/WO3-x heterojunction was successfully synthesized by a facile wet impregnation method for the highly efficient photocatalytic degradation and sterilization. Benefiting from the accelerated charge separation, broadened light absorption to near infrared region, and appropriate band energy, optimized g-C3N4/WO3-x heterojunction exhibited photocatalytic degradation of 86.3 % and 97.4 % tetracycline in 2 h under visible light and full-spectrum light, respectively. Meanwhile, 6.5-log of Escherichia coli strains could also be inactivated by optimized g-C3N4/WO3-x heterojunction within 45 min and 15 min under visible light and full-spectrum light, respectively. Impressively, it also exhibited desirable anti-interference ability and satisfying photocatalytic degradation capacity with various key experimental parameters. The plausible degradation pathways of TC and the main active species involved in the photocatalysis were investigated based on liquid chromatography-mass spectrometer (LC-MS) and electron paramagnetic resonance (EPR) analysis. Mineralization process of TC was further confirmed by three-dimensional fluorescence spectra (3D EMMs). Besides, Toxicity Estimation Software Tool (T.E.S.T.) and Ecological Structure-Activity Relationships (ECOSAR) program were applied to predict the noxiousness of TC and its potential intermediates. The results suggested that the excitotoxicity of intermediates generally decreased relative to the pristine TC. Finally, we propose a plausible enhancement mechanism of photocatalytic degradation and sterilization. This work sheds a new light on the design of novel full-spectrum responsive Z-scheme heterojunction for environmental remediation.

Bacterial cellulose-based Janus energy storage phase change composite aerogel for efficient interfacial solar vapor generation

Interfacial solar evaporation systems based on Janus structures exhibit potential application prospects in terms of salt tolerance. However, intermittent and unstable light conditions limited the evaporation rate and water production performance of the evaporators. The introduction of energy storage phase change (ESPC) composite materials into the interface solar evaporators can effectively solve this problem. In this work, bacterial cellulose (BC) is selected as the matrix material, sodium alginate (SA) and multi-walled carbon nanotubes (MWCNTs) are added as functional fillers, and porous composite aerogels are prepared using direct freeze-drying. On this basis, Janus porous composite aerogel (J-BCS/CNT) with ESPC function is further constructed by depositing paraffin onto the upper layer of the aerogel through a unilateral vacuum impregnation method. The aerogel exhibits strong photothermal conversion capabilities and excellent thermal management properties. The addition of appropriate amount of MWCNTs enables it to obtain high latent heat storage and release functions, providing energy for operation in dark conditions. Under the solar irradiation of 1.5 kW m−2, J-BCS/CNT40% aerogel exhibits a high evaporation rate of 1.95 kg m−2h−1 in pure water and 0.67 kg m−2h−1 under dark conditions. The salt evaporation resistance test shows that the aerogel has excellent purification capabilities in high-concentration salt water (20 wt%) solutions. More importantly, the long-term energy storage-release tests of J-BCS/CNT in 3.5 wt% saline water indicate that the aerogel reveals excellent sustainability and latent heat release functions.

Effects of Ni Loadings on the Structure and Morphology of Carbon Nanotubes Using Nickel Doped Iron Oxide Catalysts

AbstractIron oxide and their different doped iron oxide catalyst have been used for decades and are considered as efficient catalysts in several synthesis schemes including synthesis of carbon nanotubes. The iron oxide of the catalyst is abundant in nature, high catalytic activity at low over potentials, stability in basic media and low cost, making it environmentally and economically attractive. Nickel doped iron oxide catalyst have not been reported in the literature. Doping of nickel over iron oxide catalyst, different percentage 1 %, 5 %, 10 % and 20 % were done by impregnation method. The samples were characterized by X‐Ray powder Diffraction (XRD), Fourier‐Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Energy Dispersive X‐ray (EDX) and Thermo Gravimetric Analysis (TGA). Nickel doped iron oxide was used as catalyst for the synthesis of carbon nanotubes (CNTs) and doping changed the morphology of carbon nanotube (CNTs). FTIR results confirmed the doping and presence of different functional groups. Chemical vapor deposition (CVD) was carried out for the synthesis of multiwall carbon nanotubes (MWCNTs) on nickel doped iron oxide catalyst for different percentage (1 %, 5 %, 10 % and 20 %) separately. CVD assembly was carried in tube furnace and the reaction was checked at two different temperature i.e 700 °C and 750 °C and using methane and compressed natural gas (CNG) as precursors. The catalyst was activated in the furnace at 800 °C for an hour. Methane and argon were used in proportion 2 : 1 inside the furnace. SEM showed formation of CNTs at 750 °C with CNG precursor. Formation of CNTs increased with increasing doping with this CNTs was confirmed by SEM.

Preparation and Electrochemical Properties of High Specific Surface Carbon Aerogel/SnO2 Anode Materials for Li-Ion Batteries

Lithium-ion batteries have consistently been a focal point of research in the field of energy. Traditional graphite anodes no longer meet the increasing demands for energy density. SnO2, with its high theoretical capacity, environmental friendliness, and safety, has emerged as a promising anode material for the next generation. However, issues such as volumetric expansion and agglomeration during charge–discharge cycles hinder its practical application. Addressing these challenges, this paper combines the high capacity of SnO2 with conductive and highly porous carbon aerogels, comparing the performance differences between composite anodes prepared by vacuum impregnation and hydrothermal methods. The results show the following: (1) high specific surface area carbon aerogels are beneficial for enhancing performance; (2) vacuum impregnation yields relatively higher initial capacity and better cycle stability; and (3) hydrothermal synthesis results in a higher loading of SnO2.

Role of Ca in Ni-Ca/Fumed-SiO2 Catalysts for CO2 Catalytic Conversion to Methane

AbstractThis study investigates the role of calcium in facilitating the carbon dioxide methanation reaction over nickel supported on fumed-SiO2 catalysts. The wet impregnation method was used to prepare Ni/fumed-SiO2 catalysts with three different Ca loadings for CO2 conversion. As part of the investigation into the effects of Ca concentration and reaction conditions on the structural and morphological properties of the catalysts, various techniques including XRD, BET, SEM, TPR and TEM were used for both fresh and used catalyst samples. The findings showed that the addition of 0.5% Ca increases the catalyst reducibility, promotes dispersion of Ni sites on the surface of fumed SiO2 support and prevents the metal from agglomerating. Evaluation of catalytic results showed that the performance of 10%Ni-0.5Ca/fumed-SiO2 was superior to the other tested catalysts, with CO2 conversion and CH4 yield of 76% and ~ 40% at 650 °C, respectively.

Mechanistic investigation of the suppressed N2O formation during the low-temperature NH3-SCR over the Sb-modified Mn/Ti catalyst

The formation of N2O during the NH3-SCR reaction over the Mn-based is one of the crucial factors limiting the industrial application of Mn-based catalysts. In this work, the Sb-modified Mn/Ti catalyst was prepared by the ultrasonic assistance impregnation method to control the formation of N2O during the NH3-SCR reaction. The preferred Mn3Sb/Ti catalyst had over 80 % NOx conversion at 150–300 °C, and more than 80 % N2selectivity at 150–250 °C, which were higher than that of the Mn/Ti catalyst at the same temperature window. A series of performance experiments showed that the Sb modification inhibited the oxidation of NH3to N2O and suppressed the N2O produced by the E-R mechanism in the NSCR reaction, which is the main pathway for N2O generation. Moreover, the presence of NO inhibited the oxidation of NH3 to generate N2O over the Mn3Sb/Ti catalyst. Based on the physical–chemical characterizations and DFT calculations, it was revealed that the introduced Sb species achieves a trade-off between redox ability and surface acidity over the Mn3Sb/Ti catalyst, which is beneficial to enhance the NH3-SCR performance and simultaneously suppress the over-oxidation of NH3. The high content of Mn3+caused by the electron transfer through the redox cycle of Sb3++Mn4+→Sb5++Mn3+ was beneficial in decreasing the N2O formation.The formation of NH speciesis inhibited on the Mn3Sb/Ti catalyst with a higher energy barrier of the NH2* conversion to NH* species due to the Sb modification. Meanwhile, the energy barrier of NH3*→NH2* is decreased and the energy barrier of NH2*+NO → N2 + H2O is lower than that of NH2*→NH* over the Sb-modified catalyst, indicating that the NH3-SCR reaction is more favorable than the formation of N2O on the Mn3Sb/Ti catalyst.

The impact of support selection and Co loading amount on the catalytic performance for methane combustion

Methane (CH4) is a key component of natural gas and is essential for energy production and utilization. However, due to its strong greenhouse effect, efficient catalytic combustion methods are needed to convert it into CO2 and H2O. This study systematically evaluates the catalytic performance of Co, CoO, and Co3O4 in methane catalytic combustion, particularly highlighting the superior activity of Co3O4. To improve catalytic efficiency, this paper examines the effects of SiO2, Al2O3, and CeO2 as support materials using co-precipitation and impregnation methods. The results show a significant improvement in the catalytic activity of Co3O4 supported on CeO2, attributed to CeO2's unique redox properties and high oxygen storage capacity. Additionally, the study explores the impact of different loading amounts (5%, 10%, 15%, 20%) of Co3O4(x)-CeO2 catalysts on their performance. The optimal 10%wt Co3O4–CeO2 catalyst achieves methane conversion rates of 10%, 50%, and 90% at temperatures of 376 °C, 473 °C, and 578 °C, respectively, demonstrating exceptional stability during a 20-h stability test and the ability to adapt to fluctuations in CH4 concentrations in low-oxygen environments, while also exhibiting significant catalytic activity across a range of methane concentrations from 0.5% to 2.5%. These findings provide important theoretical and experimental guidance for the application of cobalt-based catalysts in CH4 combustion, paving the way for future catalyst design and optimization.

A New Approach for Improving Flame Retardancy of Automotive Interior Upholstery

This study presents the flame retardant (FR) performance of chemically treated automotive upholstery fabrics using two different impregnation methods of Resin Transfer Molding (RTM) and supercritical carbon dioxide (scCO2). Referring to the related standards, untreated seat fabric obtained from seat upholstery of a bus (neat fabric, NF) and treated fabric samples underwent burning rate (BR) and limiting oxygen index (LOI) tests to compare effect of treatment and impregnation methods on FR performance. Thermal analysis was also conducted on the samples considering onset degradation temperatures and char yields. The results showed that BR and LOI of all samples were in acceptable range and treatment provided enhancement in FR performance of NF. The treated sample using scCO2 method gave the highest LOI value of 32% and the lowest BR of 21 mm/min subtending to 18.5% increase in LOI and 30% reduction in BR compared to those of NF. The performance of treatment in RTM was worse than that of scCO2 and better than that of NF. The results confirm that both treatment and methods used in this study give promising results for safety against fire in transportation vehicles.