Copper Loading Research Articles

Achieving simultaneous Cu particles anchoring in meso-porous TiO2 nanofabrication for enhancing photo-catalytic CO2 reduction through rapid charge separation

A facile solvo-thermal approach was successfully employed to prepare titanium oxide (TiO2) nano-aggregates with simultaneous copper particles anchoring. The as-synthesized composite could convert CO2 into CH4 and CO products under simulated solar irradiation. The impact of copper loading amounts on the photo-reduction capability was evaluated. It was found proper amount of Cu loading could enhance the activity of CO2 photo-reduction. As a result, the optimal composite (TiO2-Cu-5%) consisting of TiO2 supported with 5% (mole ratio) Cu exhibits 2.2 times higher CH4 yield and 3 times higher CO yield compared with pure TiO2. Conduction band calculated from the band gap and valence X-ray photoelectron spectroscopy (XPS) indicated TiO2 nano-aggregates have suitable band edge alignment with respect to the CO2/CH4 and CO2/CO redox potential. Furthermore, with involving of Cu particles, an efficient separation of photo-generated charges was achieved on the basis of photocurrent response and photoluminescence spectra results, which contributed to the improved photo-catalytic performance. The present work suggested that the Cu-decorated TiO2 could serve as an efficient photo-catalyst for solar-driven CO2 photo-reduction.

Efficient hydrogen generation of vector Z-scheme CaTiO3/Cu/TiO2 photocatalyst assisted by cocatalyst Cu nanoparticles

Herein, the CaTiO3/Cu/TiO2 all-solid-state Z-scheme heterojunction is successfully designed via Cu nanoparticles situating at the interface between CaTiO3 and TiO2 with a new synthesis route. Interestingly, TiO2 nanosheets are generated in-situ on the surface of CaTiO3 in the second step hydrothermal reaction. The lifetimes of photoexcited carriers, photoluminescence emission spectra and transient photocurrent response tests have confirmed that the efficient Z-scheme charge transmission path of the CaTiO3/Cu/TiO2 is beneficial to facilitate the separation of photogenerated carriers and reduce their recombination efficiency. As expected, the hydrogen generation rate of CaTiO3/Cu/TiO2 is increased to 23.550 mmol g-1h−1 with the appropriate amount of copper loading, which is about 981 times and 93 times higher than that of pristine CaTiO3 (0.024 mmol g-1h−1) and CaTiO3/TiO2 (0.253 mmol g-1h−1), respectively. Furthermore, the CaTiO3/Cu/TiO2 sample shows good stability in cycle experiments. Particularly, experimental results show that the non-noble metal Cu nanoparticles can be an effective electron mediator. And these merits strongly demonstrate that the CaTiO3/Cu/TiO2 composites have potential application in photocatalytic field. This study can provide fundamental guidance for designing rationally efficient non-noble metal vector Z-scheme system photocatalysts with outstanding photocatalytic H2 generation performance.

Enhanced Activity for CO Preferential Oxidation over CuO Catalysts Supported on Nanosized CeO2 with High Surface Area and Defects

Nanosizedceria (n-CeO2) was synthesized by a facile method in 2-methylimidazolesolution. The characterization results of XRD, N2 adsorption-desorption, Raman and TEM indicate that n-CeO2 shows a regular size of 10 ± 1 nm, a high surface area of 130 m2·g−1 and oxygen vacancies on the surface. A series of CuO/n-CeO2 catalysts (CuCeOX) with different copper loading were prepared for the preferential oxidation of CO in H2-rich gases (CO-PROX). All CuCeOX catalysts exhibit a high catalytic activity due to the excellent structural properties of n-CeO2, over which the 100% conversion of CO is obtained at 120 °C. The catalytic activity of CuCeOX catalysts increases in the order of CuCeO12 < CuCeO3 < CuCeO6 < CuCeO9. It is in good agreement with the order of the amount of active Cu+ species, Ce3+ species and oxygen vacancies on these catalysts, suggesting that the strength of interaction between highly dispersed CuO species and n-CeO2 is the decisive factor for the activity. The stronger interaction results in the formation of more readily reducible copper species on CuCeO9, which shows the highest activity with high stability and the broadest temperature “window” for complete CO conversion (120–180 °C).

Preparation of a Gangue-Based X-type Zeolite Molecular Sieve as a Multiphase Fenton Catalyst and Its Catalytic Performance.

In this study, a series of X-type zeolite molecular sieve catalysts, modified with copper (Cu-X), were prepared by an alkali fusion–hydrothermal synthesis using coal gangue from Inner Mongolia. These catalysts were used in the degradation of the methylene blue dye by a Fenton-like reaction. Characterization results showed that Cu is considered to be present in the surface structure of the zeolite in the form of doped Cu ions and metal oxide. It is believed that Cu2+ is the main active site involved in the Fenton reaction. The X-ray photoelectron spectroscopy (XPS) spectra indicated that Cu2+ and Cu+ coexist in the catalysts and participate together in the Fenton reaction. The degradation of methylene blue by the Cu-X catalysts was investigated to determine the optimal catalytic conditions in terms of six aspects: catalyst dosage, initial solution concentration, initial pH of the solution, H2O2 dosage, copper loading, and reaction temperature. The experimental results showed that CX-1.0 had excellent activity and stability for the degradation and decolorization of the methylene blue dye, which could completely degrade the dye within 90 min, and the total organic carbon removal rate reached as high as 97.8%. Electron spin resonance (ESR) and radical capture experiments showed that •OH played a dominant role in the Fenton-like reaction. Combined with XPS, ESR, and catalytic tests, the redox cycle of Cu+/Cu2+ was found to be accelerating the generation of reactive radicals in the Fenton system.

Comparative study on the effect of different copper loading on catalytic behaviors and activity of Cu/ZnO/Al2O3 catalysts toward CO and CO2 hydrogenation

The ternary Cu/ZnO/Al2O3 (CZA) catalysts having different Cu loading were prepared by the co-precipitation method. Then, they were used in CO and CO2 hydrogenation to produce methanol under atmospheric pressure at 250 °C. The high Cu loading CZA catalyst (CZA-H) resulted in the enhancement of structural features and textural properties (e.g., BET surface area and the crystallite size of copper species). Furthermore, the conversion of CO and CO2 over CZA-H catalyst was apparently higher than that of the CZA-L (low Cu loading) catalyst. The major product of CO hydrogenation obtained from both catalysts was methanol, whereas in CO2 hydrogenation, the main product was CO. Deactivation of catalysts was also crucial during CO and CO2 hydrogenation. Therefore, the spent catalysts were determined to identify the nature of carbon formation. It revealed that amorphous and graphitic cokes were present. These cokes have different mechanisms in the elimination from the surface leading to influencing the deactivation process. The spent CZA-L was found to have higher carbon content, which was around 2.3% and 3.1% for CO and CO2 hydrogenation, respectively. Besides the amorphous coke, the graphitic coke was also observed in CZA-L after time on stream for 5 h.

Liquid phase hydrogenation of furfural to biofuel over robust NiCu/Laponite catalyst: A study on the role of copper loading

Sustainable production of biofuel and chemical feedstock through catalytic hydrogenation has now received increased attention due to the expeditious depletion of crude oil. In the present investigation, we developed a cost-effective and base metal-based NiCu/Laponite catalyst for liquid-phase hydrogenation of furfural into fuel range components. The robust catalysts were prepared by a simple co-impregnation method with constant loading of 5 wt% NiO with different wt.% of CuO (x) loadings (where x = 8, 10, 12 & 14%) on the Laponite support. The textural properties, surface acidity, and reduction of the synthesized catalysts were studied by employing various physicochemical characterizations such as XRD, N2 sorption analysis, NH3-TPD, H2-TPR, and TGA. The obtained results revealed that optimum loading of 12% CuO and 5% NiO catalyst aids fine dispersion of copper and nickel oxide on the surface of the support. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images displayed the delamination of Laponite particles and dispersion of Ni-Cu catalyst on the support surface. The hydrogenation efficiency of the synthesized catalysts was tested in a bench top stainless steel autoclave reactor by liquid phase reaction condition of furfural at 150–210 °C under 10–25 bar H2 pressure for 1–6 h. The excellent activity of 5Ni-12Cu/Laponite catalysts was compared and correlated with the physicochemical characteristics of the catalyst.

Chrysanthemum flower like silica with highly dispersed Cu nanoparticles as a high-performance NO2 adsorbent

Atmospheric NO2 removal is urgent and necessary due to its negative effects on the eco-system. Here we developed the chrysanthemum flower-like silica (KCC-1) loaded with highly dispersed copper nanoparticles for efficient NO2 removal under ambient conditions. We carefully studied the NO2 removal performance of Cu-KCC-1 materials with different copper loadings (0, 5, 10, and 15 wt%) and demonstrated the Cu0 nanoparticles (10 wt%) boosted the NO2 removal capacity of KCC-1 by up to 51 times. KCC-1 loaded with 10 wt% of copper was verified to be the best-performing adsorbents, featuring an efficient NO2 removal capacity of 3.63 mmol/g and a moderate NO release (11.3%), which was primarily attributed to the presence of Cu0 nanoparticles. The mechanistic study unveiled that the loaded Cu0 particles served as active adsorption sites for NO2 molecules and reduced the NO2 dissociation by covering the sites primarily responsible for NO2 dissociation (i.e., oxygen vacancies). This work affords a promising adsorbent for NO2 abatement under ambient conditions. The new knowledge established in developing adsorbents for NO2 would promote future research in this emerging and niche area of air pollution control.

A new catalytic approach for aerobic oxidation of primary alcohols based on a Copper(I)-thiophene carbaldimines

• Novel in situ copper(I) iodide schiff base catalysts. • High activity for the aerobic oxidation of benzylic, allylic and aliphatic alcohols. • Quantitative yields for benzaldehyde in 3 h with a catalyst loading of 2.5 mol%. • Diol oxidation to the corresponding lactol. We report here novel Cu(I) thiophene carbaldimine catalysts for the selective aerobic oxidation of primary alcohols to their corresponding aldehydes and various diols to lactones or lactols. In the presence of the in situ generated Cu(I) species, a persistent radical (2,2,6,6-tetramethylpiperdine-N-oxyl (TEMPO)) and N-methylimidazole (NMI) as an auxiliary ligand, the reaction proceeds under aerobic conditions and at ambient temperature. Especially the catalytic system of 1-(thiophen-2-yl)-N-(4-(trifluoromethoxy)phenyl)methanimine (ligand L2 ) with copper(I)-iodide showed high reactivity for all kind of alcohols (benzylic, allylic and aliphatic). In the case of benzyl alcohol even 2.5 mol% of copper loading gave quantitative yield. Beside high activity under aerobic conditions, the catalysts ability to oxidize 1,5-pentadiol to the corresponding lactol (86% in 4 h) and N-phenyldiethanolamine to the corresponding morpholine derivate lactol (86% in 24 h) is particularly noteworthy.

Promoting Effect of Copper Loading and Mesoporosity on Cu-MOR in the Carbonylation of Dimethyl Ether to Methyl Acetate

Cu-mordenite (Cu-MOR) catalysts with different copper loadings were prepared, characterized and examined in continuous, gas-flow synthesis of methyl acetate (MA) by dimethyl ether (DME) carbonylation. Improved activity and selectivity were observed for Cu-MOR catalysts with up to 1 wt% Cu and X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) spectroscopy and temperature-programmed reduction with hydrogen (H2-TPR) were used to elucidate the state of copper in the catalysts. Moreover, mesoporous MOR catalysts (RHMs) were prepared by mild stepwise recrystallization with X-ray powder diffraction (XRPD) and ammonia temperature-programmed desorption (NH3-TPD) demonstrating the retained MOR structure and the acid property of the catalysts, respectively. The RHM catalysts showed improved lifetime compared to pristine MOR giving a yield up to 78% MA with 93% selectivity after 5 h on stream (GHSV = 6711 h−1). Under identical reaction conditions, 1 wt% Cu-RHM catalysts had an even higher catalytic activity and durability resulting in a MA yield of 90% with 97% selectivity for 7–8 h of operation as well as a lower coke formation.

One-pot synthesis of highly dispersed mesoporous Cu/ZrO2 catalysts for NH3-SCR

Catalysts consisting of highly dispersed copper on a mesoporous ZrO2 support were synthesised via a one-pot sol-gel synthesis and were tested for the selective catalytic reduction of NOx by NH3. The copper dispersion was investigated by XRD and TEM, which showed no discernible copper oxide particles up to 6 wt% Cu, while they were detected at 15 wt% Cu.NH3 adsorption and the SCR reaction were followed in situ by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) on mesoporous ZrO2 and on one-pot synthesized 3 wt% Cu/ZrO2. Cu was found to improve the NH3 adsorption capacity of the catalyst by enhancing the Lewis functionality.The catalysts were efficient for SCR at low temperature, at 150 °C 75% of NO was converted over 6 wt% Cu/ZrO2 at water-free conditions. Increasing the copper loading while maintaining the dispersion improved NOx conversion.

Copper immobilized on biomimetic assembled calcium carbonate/carboxymethylcellulose hybrid: a highly active recoverable catalyst for CuAAC reactions

A novel copper immobilized on biomimetic assembled carboxymethylcellulose/calcium carbonate hybrid (CuII@CMC/CaCO3) as an efficient heterogeneous catalyst for the synthesis of 1,2,3-triazoles has been described herein. The fabrication of CuII@CMC/CaCO3 is accomplished through a bioinspired mineralization process using sodium carboxymethylcellulose (CMC-Na) as the template and ion exchange agent, while the metathesis, nucleation, assemble, hybridization, and immobilization of Cu(II) occurred by successful treatment with CaCl2, Na2CO3, and CuSO4 in water at room temperature. The resultant CuII@CMC/CaCO3 hybrid was well characterized by various analyses such as FT-IR, XRD, SEM, EDX, EDX-mapping, TEM, and TGA techniques. In the presence of low copper loading of CuII@CMC/CaCO3 hybrid, benzylic halides, azide, and alkynes proceeded smoothly to afford 1,4-disubstituted 1,2,3-triazoles in high yields. The catalyst can be conveniently recovered from the reaction mixture by filter and reused for at least 5 consecutive runs with a slight drop in its catalytic activity. The remarkable activity and stability of the catalyst may be attributed to the coordination of both carboxyl and hydroxyl groups of the hybrid of CMC/CaCO3.

Influence of Copper Locations on Catalytic Properties and Activities of Cu/SAPO-34 in C3H6-SCR

Herein, Cu-modified SAPO-34 catalysts with various copper loadings are synthesized via a pH-controlled ion-exchange method. Cu exists predominantly as isolated cations at lower loadings, located at octahedrally coordinated sites in the ellipsoidal cavity of SAPO-34 zeolites, while CuO is gradually generated on the external surface at higher loadings. Our results reveal that the isolated Cu cations are the active sites for C₃H₆-SCR. The presence of CuO species enhances the C₃H₆ activation ability of the catalysts, which thus, improves the C₃H₆-SCR performance at medium and low temperatures (below 400 °C). At high temperatures, however, the formation of CuO accelerates the nonselective oxidation of C₃H₆ and causes activity decline. These findings suggest that the active temperature window for hydrocarbons-selective catalytic reduction (HC-SCR) reactions over Cu/SAPO-34 catalysts can be tailored by tuning the proportion of various copper species to fit the need in real applications, which provide new insights into understanding and designing highly efficient Cu-based zeolite catalysts.

Exceptional Catalytic Activity of Cu−Zn/ZrO2 Mixed Metal Oxide towards the Oxidation Reaction

AbstractHerein, we report the catalytic activity of the copper and zinc doped ZrO2‐based mixed metal oxide system towards the oxidation reaction. To study this attribute, different weight % loadings of copper and zinc supported on zirconia catalysts were synthesized by co‐precipitation followed by the hydrothermal method. The synthesized catalysts were characterized by various physicochemical methods. X‐ray analysis revealed that mainly cubic zirconia (111) planes were formed, and up to 0 to 25 wt.% Cu and Zn were doped in the zirconia lattice. Also, elemental mapping revealed uniform dispersion of Cu, Zn, Zr, and O elements. The catalytic activity of the synthesized catalyst was studied for olefin epoxidation and alcohol oxidation reactions using aqueous tert‐butyl hydrogen peroxide as an oxidant. Among all the synthesized catalysts, 2 wt.% doping of 1 : 1 Cu: Zn on ZrO2 gave almost complete olefin conversion with the best selectivity towards epoxides under optimized reaction conditions. Furthermore, the selected catalyst showed excellent substrate scope for different olefins and alcohol oxidation. Also, the catalyst was successfully recycled up to five cycles without affecting the conversion and selectivity.

Fabricated CuO–ZnO/nanozeolite X heterostructure with enhanced photocatalytic performance: mechanism investigation and degradation pathway

ZnO-CuO/Nanozeolite X catalysts (ZC/ZXN), coated using different amounts of copper and zinc loading, were synthesized to enhance the photocatalytic activity ZnO in the photo-degradation of Methyl Orange (MO). The catalysts is characterized by XRD, FT-IR, DRS, SEM, and EIS techniques. Owing to the effective mole ratio of the semiconductors in the hybridized photocatalysts, the resulting showed the photo-catalyst containing 12.3 wt% CuO and 3.7 wt% ZnO/ZXN (ZC4/ZXN) can create excellent degradation ability. Mott–Schottky plot in (Na2SO4, 0.1 M) medium indicates p-n junction with a flat band potential of 0.56 and 1.26 eV Ag/AgCl for ZnO and CuO, respectively. EIS measurements showed the values of RCT 27.9 Ω for ZC4/ZXN. A lower charge transfer resistance of ZC4/ZXN is indicative of recombination suppression by improved charge transport to the solution. Response surface methodology (RSM) was selected for optimization and investigation of the combined variables and interaction effects. The quadratic model was well fitted to the experimental data (with values of 0.9824 and 0.9619 for R2 and R2adj). Based on the experimental design results, the photodegradation of MO was mostly affected by the variables of pH, catalyst dosage, initial dye concentration, and irradiation time, respectively. The degradation compounds formed during the photo-degradation process were analyzed by the GC–MS technique. During the degradation, MO was converted to benzene sulfonic acid, N, Ń-dimethyl-p-phenylenediamine, etc.

Unraveling the nature of active sites onto copper/ceria-zirconia catalysts for low temperature CO oxidation

The aim of this research is an attempt to shed some light on the understanding of the nature of the active sites and the generated synergies in the copper/ceria-zirconia formulations for low temperature CO oxidation by means of the creation of copper entities with different physico-chemical nature. For this reason, several CuOx/ceria-zirconia catalysts, with different Cu contents and different methods to incorporate copper species, were synthesized. Focus was specially put in this case trying to link the results of CO oxidation catalytic tests with the CO-temperature programmed reduction profiles/approximate estimations and selected characterization parameters in order to find out correlations among catalysts’ properties/reducibility and catalytic behaviors, especially those corresponding to the nature and roles of the different CuOx species in contact with ceria-based support on catalytic activity.Results reveal a significant improvement in CO conversion compared to the ceria-zirconia support by adding a small amount of copper loading (as low as 0.5 %), emphasizing the paramount role of copper incorporated by the method of IWI. From 0.5 up to 2% of copper loading, an interesting increase gradual trend in activity and reducibility can be noted. It should be mentioned that all the catalysts obtained by this procedure are more catalytically active towards CO oxidation than 1%Pt/Al2O3 at low temperatures (T < 130 °C). CO-TPR results show that the reducibility of these catalysts is in line with their CO oxidation activity. The method of preparation has been revealed as a critical variable in the catalytic performance, and quite similar catalytic activities can be reached from different synthesis methods and different copper contents, due to the similar nature and type of CuOx species generated over the catalysts’ surface, identified by the CO-TPR profiles and the rest of characterization data. Finally, IWI method seems to be the best one among those tested, thus combining superior areas of both α and β contributions assigned on CO-TPR profiles, which seem to be critical in the interpretation of the catalytic behaviors.

Effective and Stable Zeolite Imidazole Framework-Supported Copper Nanoparticles (Cu/ZIF-8) for Glycerol to Lactic Acid

The dehydrogenation and isomerization of glycerol to produce lactic acid is an important way to realize the effective utilization of biodiesel by-products. Currently, precious metal catalysts have been widely used in the preparation of lactic acid from glycerol. In this paper, Cu-supported zeolitic imidazolate framework (ZIF-8) crystals of different loadings were synthesized by the reaction of zinc nitrate, copper nitrate and 2-aminobenzophenone at room temperature, and were applied to the reaction of glycerol to lactic acid. Characterizations including XRD, XPS, SEM, TEM, BET, FT-IR, UV–vis DRS, CO2-TPD and TG were carried out to evaluate the morphology and properties of the catalysts. The results showed that the lattice structure of body centered cubic of the materials was successfully formed, and nano-copper was distributed uniformly on the supports, which provided abundant active alkaline sites. In addition, the catalytic reactions achieved good results under optimum copper loading and reaction conditions, which the glycerol conversion and lactic acid yield can reach 97.5% and 84.2%, respectively.

Size-activity threshold of titanium dioxide-supported Cu cluster in CO oxidation

Development of non-noble metal cluster catalysts, aiming at concurrently high activity and stability, for emission control systems has been challenging because of sintering and overcoating of clusters on the support. In this work, we reported the role of well-dispersed copper nanoclusters supported on TiO2 in CO oxidation under industrially relevant operating conditions. The catalyst containing 0.15 wt% Cu on TiO2 (0.15 CT) exhibited a high dispersion (59.1%), a large specific surface area (381 m2/gCu), a small particle size (1.77 nm), and abundant active sites (75.8% Cu2O). The CO oxidation activity measured by the turnover frequency (TOF) was found to be enhanced from 0.60 × 10−3 to 3.22 × 10−3 molCO·molCu−1·s−1 as the copper loading decreased from 5 to 0.15 wt%. A CO conversion of approximately 60% was still observed in the supported cluster catalyst with a Cu loading of 5 wt% at 240 °C. No deactivation was observed for catalysts with low copper loading (0.15 and 0.30 CT) after 8 h of time-on-stream, which compares favorably with less stable Au cluster-based catalysts reported in the literature. In contrast, catalysts with high copper loading (0.75 and 5 CT) showed deactivation over time, which was ascribed to the increase in copper particle size due to metal cluster agglomeration. This study elucidated the size-activity threshold of TiO2-supported Cu cluster catalysts. It also demonstrated the potential of the supported Cu cluster catalyst at a typical temperature range of diesel engines at light-load. The supported Cu cluster catalyst could be a promising alternative to noble metal cluster catalysts for emission control systems.

THE EFFECTIVENESS OF ADSORBENTS FOR SELECTIVE RECOVERY OF GOLD FROM COPPER-BEARING CYANIDE LEACH SOLUTIONS

Recovery of gold from copper-rich gold ores has proved challenging. Dissolved copper in cyanide-deficit leach solutions severely interferes with adsorption of gold resulting in low recoveries onto activated carbon or ion exchange resins. This study reports the efficiency of different adsorbents for selective recovery of gold from the copper-containing cyanide leachate. Activated carbon (NORIT GAC 1240), mixed base (Purogold A193), strong base (Dowex 21K XLT, Purogold A194) and weak base (Purogold S992) resins were tested as the adsorbents. The pregnant leach solution (PLS), which contained 28.2 mg/L Au and 2804 mg/L Cu was obtained from the cyanidation of a roasted copper-rich gold ore. The activated carbon showed a superior capacity for gold loading, succeeded by Purogold S992. On the other hand, Purogold S992 (weak base) achieved the highest degree of selectivity for gold over copper with the lowest copper adsorption. Mixed and strong base resins had the highest copper loadings. These findings demonstrated that Purogold S992 could be suitably used for selective recovery of gold from leach solutions containing a high level of copper.

The ammonia storage and ammonia species reactivity within Cu-ZSM-5 with different copper electronic states

Three Cu-ZSM-5 catalysts having different copper species: 1) the isolated Cu2+ ions, 2) the structures of Cu2+ ions with extra-lattice oxygen (ELO), and 3) the CuO-like nanoparticles, were comparatively studied for their ammonia storage capacity under NH3-Ar, NH3-O2-Ar, and NH3-NO-O2-Ar (SCR-like) feeds. EPR, DR UV–vis, DRIFT techniques and TPD modes were used to evaluate the effect of Cu-state in the O2-activated catalysts on their ammonia storage capacity and conversion of the adsorbed ammonia under Ar, O2-Ar, or NO-O2-Ar feeds. Several types of NH3-species were generated in the NH3-saturated and SCR-treated catalysts. It was shown that NH3-species within the NH3-saturated catalysts, which contained the Cu-structures with ELO or CuO-like nanoparticles, were more reactive compared with the catalyst with isolated Cu2+ ions. For the first two samples, the ammonia sorption capacity determined from the sorption-desorption dynamics at given temperature (25, 200, 300 °C) was higher than amount of the TPD(Ar)-desorbed ammonia under Ar. It is due to selective oxidation of some amount from the coordinated NH3-species, for which ELO of Cu-structures is consumed, the process is accompanied by reduction of Cu2+ to Cu+. The total quantity of the TPD-desorbed ammonia as well as the amount of ammonia coordinated in [Cu(NH3)n]2+ complex decreased with increasing sorption temperature and under O2-Ar or NO-O2-Ar feeds used for TPD mode. Regardless of Cu-states in the catalysts, the molar ratio of the ammonia storage capacity to copper loading was shown by the sorption-desorption dynamics to be ca. 2 at 200 °C, versus 4 typical of the catalyst saturated at 25 °C. These values are consistent with DR UV–vis data, showing a.b. at 14100-14500 cm−1 and 15700−15800 cm−1, respectively. The NH3-TPD(Ar) mode with the NH3-saturated catalysts showed the molar ratio of the TPD-desorbed ammonia to copper loading (ν(NH3)/ν(Cu) equal to 2 for the sample with isolated Cu2+ions; but for two others, the ν(NH3)/ν(Cu) was < 1. Finally, this work is trying to manifest the role of isolated Cu2+ ions and Cu-structures with ELO for SCR-activity.

Antibacterial and photocatalytic properties of SiO2-CuxO films with high copper loading and crystallized CuxO nanoparticles

SiO2-CuxO composites may have potential applications in antibacterial and dye degradation. However, it is still a challenge to prepare SiO2-CuxO films with well crystallized CuxO nanoparticles and high Cu/Si molar ratios under alkaline condition at relatively low temperature. Herein, by using PVP stabilized alkaline silica sol and ethanolic solution of copper acetate, a series of SiO2-CuxO composite films with high Cu/Si molar ratios were successfully prepared via a facile two-step process of dip coating and annealing. The microstructure and crystalline phase of the composite films were finely controlled by changing the amount of PVP, the concentration of copper solution and the calcination temperature. The results showed that film prepared with 1 mol/L copper acetate solution and calcined at 500 °C exhibited the best antibacterial activity, adsorption and photocatalytic performance toward methylene blue in solutions. The prepared films could be conveniently used in antibacterial field and the treatment of organic wastewater.