Effect Of Cu Loading Research Articles

Copper-loaded sustainable MOFs as photocatalysts for dye removal

This work presents the effect of Cu loading, using incipient wetness impregnation method, on sustainably synthesized MIL-100(Fe), NH2-MIL-53(Al), Zr-BDC and NH2-Zr-BDC MOFs and their photocatalytic removal efficiency on target dye, rhodamine B (RhB), from aqueous solutions. Several Cu ratios have been tested, finding that 2 wt% of Cu load becomes optimum in terms of metal distribution and catalytic performance. Powder X-ray diffraction patterns (XRD) showed no difference from the parent supports in the case of MIL-100(Fe), NH2-MIL-53(Al) and Zr-BDC, whereas extra peaks are induced by Cu impregnation in NH2-Zr-BDC. In addition, several techniques indicate that Cu strongly interacts with the MOF in Cu@NH2-Zr-BDC, exhibiting the lowest bandgap of the series, the lowest photoluminescence intensity and a notable predominance of Cu in the oxidation state 2+. The above evidences lead Cu@NH2-Zr-BDC to behave as the most effective catalyst in the removal of RhB, reaching removal efficiency as high as 93 %, being able to efficiently and selectively remove basic dyes from mixed samples, such as RhB and MB, but not for acidic dyes like MO, and also showing a very good performance (46 % photodegradation) in real waste water from Hawassa textile factory, in Ethiopia. Moreover, this catalyst can be recycled 3 times by simple washing and drying. Scavengers test suggested that h+ is the most active species in the photocatalytic degradation.

Effect of Cu content on the wear resistant behavior of arc-sprayed laminated-structured Cu–TiN/TiO2 composite coating

The wear and corrosion effects in marine or coastal environments are critical issues that seriously deteriorate the service performance of marine infrastructure. Thus, development of an effective and long-lasting wear-resistant and corrosion-resistant protective coating is highly desirable. By controlling the diameter ratio of different heterogeneous metal wires during the supersonic arc spraying process, a laminated-structured Cu-TiN/TiO2 metal-ceramic composite coating with a Cu content of 8.3 % -66.6 % was fabricated. The effects of Cu loading on the microstructure, morphology, mechanical properties, and wear resistance of composite coating were analyzed. The results of scanning electron microscopy and nanoindentation tests indicated that the composite coating exhibited a dense microstructure, with tight interlayer bonding, and a gradient change in hardness and Young's modulus with Cu loading. The friction and wear tests under different loads and wear environments shown that the composite coating had excellent wear resistance. The composite coating with 8.3 % Cu loading had stronger resistance to plastic deformation and abrasive wear under dry sliding friction with 5 N and 10 N loads. The composite coating with 35.8 % Cu loading shown the most significant lubrication and friction reduction effect of Cu under dry sliding friction at a larger load of 20 N, showing the best wear resistance. The wear test under 10 N load with 3.5 wt% NaCl corrosion solution shown that the composite coating with 8.3 % Cu load had a more prominent role in resisting corrosion wear. These results may guide the preparation of high hardness, wear and corrosion resistant Cu-TiN/TiO2 metal-ceramic composite coating with appropriate Cu loading capacity through simple and effective preparation methods and easily customized raw materials, according to different wear and corrosion conditions.

In situ formation of CuxO/ZnO photocatalysts for efficient simultaneous oxidation of As (III) and adsorption of As (V): Effect of Cu loading.

The introduction of Cu ions onto ZnO leads to alterations in the electrical, optical, and magnetic characteristics of ZnO. These transformations, in turn, result in heightened photocatalytic activity and enhanced stability when employed in the degradation of both organic and inorganic pollutants. Here, a novel photocatalytic-adsorbent system is developed using zinc oxide (ZnO) nanostructures modified with Cu (II) ions in an aqueous solution containing 40mg/L of As (III). The system utilizes UV-A light (365nm) as the irradiation source, and the weight percentage of Cu (II) in the composite varies from 0 to 20%. The experimental results reveal significant adsorption of As (III), ranging from 20 to 50%, depending on the solution's Cu (II) content. Remarkably, the ZnO10%Cu composite exhibits the highest photocatalytic activity, achieving 40% adsorption and complete oxidation of As (III) within 25min of irradiation. Characterization of the composite after the photocatalytic treatment reveals the effective adsorption of As (V) within its structure. Furthermore, no traces of Cu (II) ions are detected in the solution after the reaction, indicating their successful adsorption onto the ZnO surface as Cu (I) and Cu (II) ions. This research marks a significant advancement in harnessing innovative materials for efficient arsenic removal, offering promising insights into the development of novel photocatalytic-adsorbent systems.

Copper loading effect on active species formation over Cu/SSZ-13 catalysts for selective catalytic oxidation of high-concentration NH3

Cu/SSZ-13 catalysts not only exhibit superior SCR performance but also possess excellent selective catalytic oxidation (SCO) ability to remove NH3 escaped from engine exhaust gas fueled by NH3. To elucidate the effect of Cu loading on Cu/SSZ-13 catalysts, a series of Cu/SSZ-13 catalysts were prepared through wet impregnation method to remove high-concentration NH3 (5000 ppm). The SCO activity test results showed that when Cu loading increased from 1% to 10%, there was an obvious improvement effect on NH3 conversion performance at low temperature. Cu10/SSZ-13 catalyst reached a high NH3 conversion of 96% at 250 °C, and N2 selectivity was higher than 86% in the whole temperature range. However, when further increasing Cu loading from 10% to 20%, there was no distinctive difference in NH3 conversion and N2 selectivity. The characterization results indicated that there were abundant active species, adsorbed oxygen species, and acid sites on the surface of Cu10/SSZ-13 catalyst. The [Cu(OH)]+ and isolated Cu2+ species in zeolite channels of Cu10/SSZ-13 catalyst rather than CuO species on the surface played a key role in NH3-SCO reactions. Since 20% Cu loading would result in a significant decrease in isolated Cu2+ species, it resulted in both [Cu(OH)]+ species in zeolite channels and superfluous Cu species on zeolite surface being main active species in NH3-SCO reactions. In-situ DRIFTS experiments suggested that NH3-SCO reactions over Cu/SSZ-13 catalysts followed the internal selective catalytic reduction (i-SCR) mechanism.

Study on desulfurization performance of Cu modified red mud-fly ash sorbent

In this paper, fly ash, red mud and Cu(NO3)2·3H2O were used to prepare Cu modified red mud-fly ash sorbent (CuRMFA) by hydration impregnation method, and the sorbent was used to remove SO2 from coal-fired flue gas. The effects of Cu loading and removal conditions (temperature, O2 concentration and NO concentration) on the desulfurization ability of sorbent were studied. The desulfurization performance and mechanism of CuRMFA were analyzed by experimental results and characterizations. The experimental results show that the sorbent CuRMFA can meet the ultra-low emission standard of SO2, and the optimal load of Cu is 20 mg/g. The optimal removal conditions were 500 ℃, 5% O2, 50 mg/m3 NO and 500 mg/m3 SO2, and when the desulfurization efficiency was greater than 93%, the breakthrough time and sulfur capacity were 65.5 min and 230.88 mg/g, respectively. The CuRMFA mainly removes SO2 by chemical reaction, and the desulfurized product exists in the form of SO42-. The conversion of Cu+ to Cu2+ can enhance the electron transfer, enhance the adsorption oxygen conversion and catalytic oxidation performance, which plays an important role in improving the desulfurization performance of the CuRMFA. That Cu modified RMFA is beneficial to form active component 2MgO·SiO2 and decompose of (CaO)12·(Al2O3)7, and can promote the uniform dispersion of active component, which is conducive to reducing the activation energy of desulfurization reaction and speeding up the reaction process.

Supported Cu catalysts on UiO-66 toward enhanced methanol selectivity by CO2 hydrogenation: Effect of Cu loading

The xCu/MOF catalysts were synthesized by incipient-wetness impregnation of copper precursor on UiO-66 support, in which the Cu loadings were 5, 10, and 20% (wt.%). To gain insight into the properties of the materials, a range of techniques, including XRD, TEM, TGA, N2 physisorption, CO2-TPD, EDS, N2O chemisorption, XPS, IR, and NMR, were employed. The effectiveness of catalysts was evaluated for synthesizing methanol through CO2 hydrogenation under various Gas Hourly Space Velocities (GHSVs) and reaction conditions, including pressures of 10 and 30 bar, CO2/H2 ratios of 1:3, and CO2/H2/N2 ratios of 1:3:0.14 M, all conducted at a temperature of 250 °C. The active site in the Cu/UiO-66 catalyst is the interface between Cu+ nanoparticles (NPs) with Zr oxide SBU [Zr6O4(OH)4(−CO2) and the defects related to unsaturated Zr sites of the Zr-Oxo cluster due to the increase of Cu NPs occupying missing linker defects of the MOF structure. 20Cu/MOF catalyst, with the highest copper loading, showed the best methanol formation rate and CO2 conversion due to the strong metal-support interaction and the highest amount of the missing linker defects of the MOF structure.

Effect of Cu loading on the performance and kinetics of Cu/SAPO-34 catalysts for selective catalytic reduction with NH3

A series of X%Cu/SAPO-34 (X = 1.0, 2.0, 4.0 and 6.0) catalysts were prepared by ultrasonic impregnation method for selective catalytic reduction (SCR) of NOx with ammonia. The effect of different Cu loadings on the selective catalytic reduction of NO by molecular sieve catalysts was examined on a fixed-bed reactor. Catalyst physicochemical properties were characterized and analyzed using XRD, TEM, NH3-TPD, H2-TPR, and in situ DRIFTS. Catalysts were used in reaction kinetics studies from the perspective of transient and steady-state kinetics. Cu/SAPO-34 catalyst with 4% Cu loading had the best denitrification efficiency and wide activity window. Copper species were highly dispersed on the catalyst surface. Cu/SAPO-34 catalyst with 4% Cu loading had rich acidic sites and excellent redox performance. Cu/SAPO-34 catalysts with 4% Cu loading possess minimal activation energy and were lower than commercial catalysts. According to the results of in situ IR, transient and steady-state analysis, the Cu/SAPO-34 catalyst with 4% Cu loading in the NH3-SCR reaction process was mainly E-R mechanism, and there was L-H mechanism.

Ethanol dehydrogenation to acetaldehyde with mesoporous Cu-SiO2 catalysts prepared by aerosol-assisted sol–gel

Copper based catalysts are central for carrying dehydrogenation reactions. However, these materials are prone to deactivation by sintering and coke deposition. Irreversible sintering occurring during reaction (under the effect of temperature) is known to decrease both activity and selectivity, where the unwanted dehydration activity of the support might also play an important role. From this perspective, the quite unreactive silica supports may be attractive. However, using classical catalyst preparation methods (e.g. impregnation), it is a challenge to obtain a stable and homogeneous dispersion of Cu over SiO2 owing to the weak support-active phase interactions. Taking a sidestep, aerosol-assisted sol–gel is a promising alternative for the facile preparation of mesostructured metallosilicates with high metal dispersion. Here we report Cu-SiO2 made by the aerosol-assisted sol–gel method and exploited in the ethanol non-oxidative dehydrogenation to acetaldehyde. These catalysts are compared with a series of catalysts made by impregnation to investigate, through a thorough characterization survey, the effect of the synthesis procedure as well as the effect of Cu loading. We show that aerosol-made catalysts do not suffer heavy sintering, reach high ethanol conversions with acetaldehyde selectivity above 75%, and only slowly deactivate upon time due to a (reversible) coking phenomenon.

Stepwise conversion of methane to methanol over Cu-mordenite prepared by supercritical and aqueous ion exchange routes and quantification of active Cu species by H2-TPR

Copper-exchanged mordenite prepared by supercritical ion exchange (SCIE) and aqueous ion exchange (AIE) were investigated in stepwise conversion of methane to methanol. Increasing the oxygen activation temperature and methane reaction time enhances the methanol yield of copper-exchanged mordenite prepared by SCIE (Cu-MORS). The reducibility of Cu-MORS was compared with those of Cu-MORA prepared by aqueous ion exchange (AIE) using H2-TPR. It was demonstrated for the first time that deconvoluted H2-TPR profile coupled with effects of Cu loading and oxygen activation temperature on methanol yield data can be used to distinguish the active Cu sites from inactive ones based on their reduction temperature. The copper species responsible for methane activation were found to be reduced below 150 °C by H2 in both Cu-MORS and Cu-MORA. From the stoichiometry of the reaction of H2 with Cu2+ species, the average number of copper atoms of active sites were calculated as 2.07 and 2.80 for Cu-MORS and Cu-MORA, respectively. Differences in structure of copper species caused by the synthesis routes were also detected by in-situ FTIR upon NO adsorption indicating a higher susceptibility of Cu-MORS towards autoreduction. The results demonstrated the potential of TPR based methods to identify copper active sites and suggested the importance of site selective ion exchange in order to controllably synthesize active Cu species in zeolites.

Bimetallic iron–copper and iron–nickel nano-catalysts over ceria support for medium temperature shift reaction

Iron/ceria catalysts promoted by copper or nickel, were studied in medium temperature shift (MTS) reaction for hydrogen production and purification. Samples were characterized by X-Ray Diffraction (XRD), N2 adsorption-desorption (BET), temperature programmed reduction (TPR), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and transmission electron microscope (TEM) analysis. Among xFe/CeO2 (x = 2, 5, 8, 10 wt%) samples, 8Fe/CeO2 showed the best performance, due to appropriate amount and good dispersion of active phase on the support (45% CO conversion at 390 °C). Then, to enhance the CO conversion, 2% of Ni or Cu were added to the catalyst. However CO conversion using Cu promoter was lower than Ni containing one, (25 and 45%, at 300 °C, respectively.), but due to better reducibility and lack of methane production, copper was selected as promoter. Eventually, the effect of Cu loading (2, 4, 8, 12 wt %) was also investigated, and 8Fe–8Cu/CeO2, with >80% CO conversion at 390 °C, showed the best performance with appropriate stability.

Heterogeneous photo-Fenton-like degradation of emerging pharmaceutical contaminants in wastewater using Cu-doped MgO nanoparticles

A facile thermal decomposition method was utilized to synthesize mesoporous Cu-doped MgO nanoparticles. These Cu-MgO nanoparticles were shown to be efficient photo-Fenton-like catalysts for degrading emerging pharmaceutical contaminants in wastewater and completely oxidized salicylic acid within 1 h under optimized conditions. Tetracycline was shown to be converted to other intermediates with a large portion of it undergoing full mineralization. Batch experiments were conducted to demonstrate the effects of Cu loading on MgO, overall catalyst loading, and H2O2 concentration on the salicylic acid and tetracycline conversion and rate constants. Quenching experiments revealed that both •OH radicals or HO2•/•O2- radicals were involved in the reaction, with the latter showing a higher contribution. The surface dissolution of MgO was shown to increase solution pH which completely prevented Cu from leaching out while retaining high activity. The catalyst reusability was shown to be satisfactory with high activity and conversion being preserved over five cycles.

Mesoporous CuO/TiO2 catalysts prepared by the ammonia driven deposition precipitation method for CO preferential oxidation: Effect of metal loading

Supported CuO catalysts onto a highly crystalline mesoporous TiO2 material are produced via an ammonium driven deposition precipitation method and tested for preferential oxidation of CO in H2-rich gases. The effect of Cu loading on the oxidation activity is investigated by producing samples with final Cu content varying between 2.5 and 10 wt%. According to the analysis results, the chemical nature of the CuO species differs in each sample depending on the Cu loading. All materials tested are highly selective towards CO oxidation up to 160 °C. The 5 wt% Cu loaded material demonstrates the optimum CO-PROX performance, which is ascribed to the formation of finely dispersed and easily reducible copper oxide nanoparticles. Stability and durability of the latter sample are assessed by performing multiple testing cycles corresponding to >100hrs on stream as well as by the separate and combined addition of CO2 and H2O in the feeding stream.

TiO2-carbon nanotubes composite supported MnOx-CuO catalyst for low-temperature NH3-SCR of NO: Investigation of SO2 and H2O tolerance

A series of titania-carbon nanotubes (TiO2-CNTs) supported MnOx-CuO catalysts were prepared and investigated for NH3-SCR of NO at low temperature. It was observed that the addition of Cu and/or CNTs to Mn/TiO2 has a beneficial effect in improving the activity of the catalyst. In addition, the effect of Cu loading was also studied and found that the catalyst with 5 wt% Cu (Mn-Cu5/Ti-CNTs) exhibited the best NH3-SCR performance. Remarkably, the Mn-Cu5/Ti-CNTs showed excellent resistance to SO2/H2O in comparison to the Mn/TiO2 catalyst. The addition of CNTs has increased the specific surface area, total pore volume, and reduced the average pore size of the catalyst. Meanwhile, the Cu loading has enhanced the Mn4+ species and chemisorbed oxygen species on the surface of the catalyst. Besides, the incorporation of both Cu and CNTs have decreased the catalyst reduction temperature and increased the amount and strength of acidic sites on the catalyst. All these factors contributed to the superior NH3-SCR activity and SO2/H2O resistance of the catalyst.

Modification of TiO2/AC catalyst for visible light degradation of ionic liquid contaminated wastewater: Effect of Cu loading on the characterization and efficiency

The emergence of ionic liquids (ILs) as a green substitute for the conventional volatile organic compound has attracted many researchers to keep synthesizing and improving ILs formula for enhanced performance in various industrial application. Due to the various possible combinations of cations and anions, the properties of the formulated ILs varies which directly affecting its toxicity and degradability. One of the major concerns over the use of ILs is the potential water pollution caused by cross contamination during the industrial processes. The present study reports on the photodegradation of 1-butyl-3-methylimidazolium chloride ([C 4 mim][Cl]), which is a common IL used in industry. The effect of Cu 2+ loading on the performance of TiO 2 /Activated carbon composite photocatalyst was studied. The modification of TiO 2 with Cu 2+ managed to shift the absorption edge of TiO 2 towards visible light region, with enhanced performance as compared to the pristine TiO 2 . Less agglomeration rate of the Cu-TiO 2 /AC in comparison to TiO 2 and TiO 2 /AC revealed the important role of metal dopant in suppressing the growth rate during the calcination process. The presence of activated carbon (AC) as support for the powdered TiO 2 has improved the diffusion rate of [C 4 mim][Cl]. The Cu-TiO 2 /AC composite photocatalyst containing 0.1 wt% of Cu showed the highest total degradation compared to other photocatalysts which is in agreement with the characterization analysis of the composite photocatalyst.

Effect of Cu loading on the structural evolution and catalytic activity of Cu–Mg/ZnO catalysts for dimethyl oxalate hydrogenation

Proper Cu loading introduced into the Cu–Mg/ZnO system facilitates strengthening of the Cu–Zn synergistic effect and optical surface chemical properties.

Synergistic effect of Cu loading on Fe sites of fly ash for enhanced catalytic reduction of nitrophenol

A novel Cu catalyst was developed using water-washed coal fly ash (WFA) as a support material for catalytic reduction of p-nitrophenol (p-NP) in the presence of NaBH4. Cu/WFA showed ~ × 105 times higher estimated rate constant kobs-p-NP/CCu (L min−1 gCu−1) compared with Cu/SiO2, Cu/Al2O3, and other Cu catalysts previously reported. Surprisingly, we obtained a significant lower price value (Price’/K) (0.027–0.068 USD/L min−1) for Cu/WFA in comparison with other Cu catalysts and precious metallic catalysts (Pd, Au, Ag, and Pt). Various surface analyses and additional experiments using Fe/SiO2, Cu/Fe2O3/SiO2, and Cu/HCl-treated WFA demonstrated that Cu(0) nanoparticles were well loaded on the surface of WFA, where Fe elements were abundant, resulting in a dramatic enhancement of the Cu/WFA catalytic activity. Particularly, X-ray photoelectron spectroscopy revealed the abundance of Cu(0)/Fe(III) and Cu(0)/Fe(II) in the WFA surface. This indicates that Cu(0) was the main driving force for the activation of Had molecule, and that the reduction of Fe(III) to Fe(II) by NaBH4 can accelerate the reduction of Cu(II) to Cu(0). Recycling and phytotoxicity tests showed that Cu/WFA can be applied as a reusable catalyst with low environmental impact, revealing the remarkable potential of non-precious metal/WFA catalyst in the field of environmental remediation.

Decomposition of Nitrous Oxide over Cu/TiO2 Catalysts: The Effect of Cu Loading, TiO2 Structure, and Reaction Conditions

Decomposition of nitrous oxide (N2O) over titania (TiO2) supported copper (Cu) catalyst was investigated with the existence of oxygen and water vapor. The catalytic activity of TiO2 was promoted by copper loading. It was found that there are optimum levels of copper loading on TiO2, and these values are correlated to the specific surface area of TiO2 support being used. The relationship between the catalytic activity for decomposition of N2O and the crystal structure of TiO2 was also investigated. The result revealed that Cu/TiO2 catalysts with the rutile structure has a higher activity toward N2O decomposition than those with the anatase structure. In this research, Cu(5wt%)/TiO2 prepared from TiO2 JRC-TIO-4 (reference catalyst provided by Catalysis Society of Japan) which was mainly constituted of rutile showed the highest activity for N2O decomposition and it could decompose N2O completely at 650℃. The catalytic activity was inhibited by the existence of oxygen. However, there was no influence of water vapor to the catalytic activity of Cu/TiO2 for N2O decomposition.

In-situ degradation of polybrominated diphenyl ethers from thermal desorption off-gas over structured Fe-based/γ-Al2O3/Al plate-type catalyst

Thermal desorption was an efficient method for removal of decabromodiphenyl ether (BDE-209) from contaminated soil, but some less brominated diphenyl ethers (tri- to hepta-BDEs) with high toxicity were detected in the effluent gas. Herein, a novel anodic alumina supported Fe-based catalyst was developed and applied for in-situ degradation of gaseous polybrominated diphenyl ethers (PBDEs). The produced Fe/γ-Al2O3/Al catalyst was able to degrade PBDEs in the effluent gas, while a low activity with degradation efficiency of 70.1% was observed. As such, Cu was added into the Fe-based catalyst, and the effects of Cu loading on gaseous PBDEs degradation were systematically examined. A proper copper loading was found to increase the active Fe3O4 sites, thus improving the catalytic activity. Meanwhile, the degradation of gaseous PBDEs by Fe-based catalysts follows a pseudo-first-order model. A 90.2% PBDEs degradation efficiency was achieved at 375 °C on the optimized Fe/Cu/γ-Al2O3/Al catalyst, which demonstrated that the anodic alumina supported Fe and Cu was an excellent catalyst for gaseous PBDEs degradation system. Thus, this study provides a promising method and catalyst to achieve in-situ degradation of gaseous PBDEs.

Effect of Copper Doping Over GdFeO3 Perovskite on Soot Oxidation Activity

A series of Fe substituted (B-site doping) by Cu on the GdFeO3 perovskite materials (GdFe1−xCuxO3±δ, x = 0 to 0.3) were synthesized using EDTA-Citrate method. The effect of Cu loading on the physio-chemical investigations of the obtained samples was carried out using X-ray Diffraction technique, BET surface area analysis, FESEM/EDS, TEM analysis, XPS, H2-TPR, and Soot-TPR. The performance of perovskites towards soot oxidation was analyzed in detail using TGA equipment. The results of the XRD pattern shows that upto10 mol% of Cu doping was dissolved into the lattice of GdFeO3. H2-TPR results reveal that the samples with Cu loading exhibit the successive reductions of Cu2+, Fe3+, and Fe2+ which implies the presence of multiple oxidation states in the perovskite. This induces the oxygen vacancies in the doped samples (due to charge compensation) leading to an increase in soot oxidation activity. According to the XPS results it was observed that the surface composition of Gd is in +3, Fe in +2 and +3 and Cu in +2 oxidation states. Moreover, the O1s peaks of the doped samples clearly evidenced an increase in adsorbed oxygen species when compared to the un-doped one. Among the doped samples, 10 mol% of Cu loading in GdFeO3 showed the higher activity of oxygen species. The T50% (temperature at 50% conversions) of the samples was in the order of GFCu30% < GFCu10% < GFCu5% < GFCu15% < GdFeO3 < bare soot.

Effects of Cu loading and zeolite topology on the selective catalytic reduction with C3H6 over Cu/zeolite catalysts

The objective of this study is to investigate the catalytic performance of Cu-zeolite catalysts supported on various types of zeolites (chabazite, MFI, and BEA) for selective catalytic reduction with C3H6. 2Cu/ZSM-5 exhibited a nearly 70% de-NOx performance at 360°C, Cu/SSZ-13 and Cu/BETA exhibited less than 60%. The loading of Cu also exhibited different de-NOx performances, which were related to the chemical states of Cu. The isolated Cu2+ ion was favorable to the NOx reduction compared to the bulk CuOx species. The effects of O2, CO2 concentrations and hydrothermal aging were investigated for the 2Cu/ZSM-5 catalyst.