14 research outputs found
Mesoporous CuO/TiO2 catalysts prepared by the ammonia driven deposition precipitation method for CO preferential oxidation: Effect of metal loading
No full textSupported CuO catalysts onto a highly crystalline mesoporous TiO2 material are produced via an ammonium driven deposition precipitation method and tested for prefere degrees ntial oxidation of CO in H-2-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 degrees 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
Data_Bifunctional Nickel-Nitrogen-Doped-Carbon-Supported Electrocatalyst for CO2 Reduction
No full textThe folder contains the processed data of figures 1, 2, 3, 4, 5 that appear in:
Choukroun, D.; Daems, N.; Kenis, T.; Van Everbroeck, T.; Hereijgers, J.; Altantzis, T.; Bals, S.; Cool, P.; Breugelmans, T., Bifunctional Nickel–Nitrogen-Doped-Carbon-Supported Copper Electrocatalyst for CO2 Reduction. The Journal of Physical Chemistry C 2020, 124, 1369-1381.The processing method is described in the article (10.1021/acs.jpcc.9b08931)
Copper-based critical raw material-free three-way catalysts : an exploration of supports and synergies
No full textAbstract: One of the big problems with gasoline-powered cars is that the exhaust gas contains pollutants which are detrimental for human health and the environment. For this reason cars are equipped with a three-way catalytic converter which has the function to convert carbon monoxide (CO), hydrocarbons and nitrogen oxides (NOx) to molecules that are not harmful for human health. The materials that are used to do this are the platinum group metals (PGMs), platinum, palladium and rhodium, which are very rare, expensive, critical raw materials. The increasing demand for new cars and progressively stricter emission standards drives the price even higher. So, there is a need to reduce the amount of PGMs in three-way catalytic converters and replace them by materials that are more common and cheap. A good candidate to do this is copper oxide (CuO) because it is common and shows some catalytic activity. While it is not as active as the PGMs it can be used in much larger quantities for compensation. To keep the CuO particles small, which is more efficient, they need to be supported on a material with a large surface area. Furthermore, the catalytic activity can be altered by interactions with other materials. For this thesis CuO is deposited on different support materials such as alumina, titania and ceria. The catalytic performance of the final materials are evaluated against its characteristics. Another part of the research focuses on the precipitation of copper with other elements is to obtain intimate mixtures of metal oxides and mixed metal oxides. The spinel-type materials are evaluated against pure CuO to find synergies between the different elements. A final study makes use of layered double hydroxides to obtain mixtures of metal oxides and mixed metal oxides. Again, we evaluate how certain properties and elements in the composition affect the catalytic performance. At the end of the thesis the conclusions are presented and the developed materials are compared to a commercial three-way catalyst. Furthermore, the limitations of this work are discussed and an outlook on the future of the automotive industry is presented and how the developed materials can play a role in this
Behavior of Control and Inhibitive Polyaspartic Coatings Using Alkylammonium and Zinc Phosphate Corrosion Inhibitors in Soil
No full textThis study is part of an anti-corrosion coating development project at CHEMSYSTEMS. The corrosion performance was assessed through erosion, immersion and soil corrosion experiments. The erosion results have previously been published. This article discusses the impact of soil on control polyaspartic coatings used to protect concrete and the modified polyaspartic coating intended to protect underground steel substrates. The modified polyaspartic coating was boosted with a micaceous iron oxide barrier, a liquid alkylammonium corrosion inhibitor, a powdered zinc phosphate corrosion inhibitor and a novel hardener. The surface finish of the steel samples was of a milled and blasted nature (SA 2.5). The coating was applied directly to the metal without the application of a primer or second layer of coating. The average thickness of the coating was 220±10 µm as a direct-to-metal protection system. The experiments were conducted in soil at room temperature (RT) and 35°C over 30 days. The experimental results of the control polyaspartic coating loaded on steel substrates exhibited severe blistering. The polyaspartic coating dispersed with a liquid alkylammonium inhibitor also exhibited blistering, whereas the modified polyaspartic coating with a zinc phosphate corrosion inhibitor showed an adequate degree of resistance to the impact of soil under the evaluated conditions. The results confirmed that the presence of a zinc phosphate corrosion inhibitor in combination with a micaceous iron oxide barrier improved the resistance of the coating to the evaluated soils in which it was positioned and at the investigated temperatures
Copper-Containing Mixed Metal Oxides (Al, Fe, Mn) for Application in Three-Way Catalysis
No full textMixed oxides were synthesized by co-precipitation of a Cu source in combination with Al, Fe or Mn corresponding salts as precursors. The materials were calcined at 600 and 1000 °C in order to crystallize the phases and to mimic the reaction conditions of the catalytic application. At 600 °C a mixed spinel structure was only formed for the combination of Cu and Mn, while at 1000 °C all the materials showed mixed spinel formation. The catalysts were applied in three-way catalysis using a reactor with a gas mixture containing CO, NO and O2. All the materials calcined at 600 °C displayed the remarkable ability to oxidize CO with O2 but also to reduce NO with CO, while the pure oxides such as CuO and MnO2 were not able to. The high catalytic activity at 600 °C was attributed to small supported CuO particles present and imperfections in the spinel structure. Calcination at 1000 °C crystallized the structure further which led to a dramatic loss in catalytic activity, although CuAl2O4 and CuFe2O4 still converted some NO. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, H2-Temperatrue Programmed Reduction (H2-TPR), N2-sorption and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX)
Copper-containing mixed metal oxides (Al, Fe, Mn) for application in three-way catalysis
No full textAbstract: Mixed oxides were synthesized by co-precipitation of a Cu source in combination with Al, Fe or Mn corresponding salts as precursors. The materials were calcined at 600 and 1000 degrees C in order to crystallize the phases and to mimic the reaction conditions of the catalytic application. At 600 degrees C a mixed spinel structure was only formed for the combination of Cu and Mn, while at 1000 degrees C all the materials showed mixed spinel formation. The catalysts were applied in three-way catalysis using a reactor with a gas mixture containing CO, NO and O-2. All the materials calcined at 600 degrees C displayed the remarkable ability to oxidize CO with O-2 but also to reduce NO with CO, while the pure oxides such as CuO and MnO2 were not able to. The high catalytic activity at 600 degrees C was attributed to small supported CuO particles present and imperfections in the spinel structure. Calcination at 1000 degrees C crystallized the structure further which led to a dramatic loss in catalytic activity, although CuAl2O4 and CuFe2O4 still converted some NO. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, H-2-Temperatrue Programmed Reduction (H-2-TPR), N-2-sorption and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX)
NO reduction with CO on metal nanoparticles/layered double hydroxides heterostructures obtained via the structural memory effect
No full textAbstract: Nitrogen oxides are notorious air pollutants and the catalytic reduction of NOx by CO for removing NOx has attracted extensive attention. Herein, we present a series of ZnCu-layered double hydroxides (LDH) decorated with nanoparticles of metals (Me: In, Zn or Au) and the derived oxides as novel catalysts for NO reduction by CO. MeNP/ZnCu heterostructures were successfully prepared by taking advantage of the structural reconstruction of ZnCu LDH, via the structural memory effect, in the aqueous solutions of Me salts. X-ray diffraction (XRD), FTIR spectroscopy, H2-Temperature programmed reduction (H2-TPR), transmission electron microscopy TEM, X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy have been used to characterize the structural, chemical composition, optical and nano/micromorphology of MeNP/ZnCu catalysts and the mixed oxides derived after the thermal treatment. Results indicate that on MeNP/ZnCu the reduction of NO by CO was 3 times higher than that of ZnCu while CO conversion was above 90%. Further, MeNP/ZnCu and the derived oxides demonstrated good stability in subsequent catalytic cycles while NO conversion was influenced by the molar ratio O2/CO. These findings indicate that the memory effect of the LDH can be effective as a simple strategy in the development of novel LDH-based heterostructured catalysts
Bifunctional nickel-nitrogen-doped-carbon-supported copper electrocatalyst for <tex>CO_{2}$</tex> reduction
No full textAbstract: Bifunctionality is a key feature of many industrial catalysts, supported metal clusters and particles in particular, and the development of such catalysts for the CO2 reduction reaction (CO2RR) to hydrocarbons and alcohols is gaining traction in light of recent advancements in the field. Carbon-supported Cu nanoparticles are suitable candidates for integration in the state-of-the-art reaction interfaces, and here, we propose, synthesize, and evaluate a bifunctional Ni\u2013N-doped-C-supported Cu electrocatalyst, in which the support possesses active sites for selective CO2 conversion to CO and Cu nanoparticles catalyze either the direct CO2 or CO reduction to hydrocarbons. In this work, we introduce the scientific rationale behind the concept, its applicability, and the challenges with regard to the catalyst. From the practical aspect, the deposition of Cu nanoparticles onto carbon black and Ni\u2013N\u2013C supports via an ammonia-driven deposition precipitation method is reported and explored in more detail using X-ray diffraction, thermogravimetric analysis, and hydrogen temperature-programmed reduction. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDXS) give further evidence of the presence of Cu-containing nanoparticles on the Ni\u2013N\u2013C supports while revealing an additional relationship between the nanoparticle\u2019s composition and the electrode\u2019s electrocatalytic performance. Compared to the benchmark carbon black-supported Cu catalysts, Ni\u2013N\u2013C-supported Cu delivers up to a 2-fold increase in the partial C2H4 current density at 121.05 VRHE (C1/C2 = 0.67) and a concomitant 10-fold increase of the CO partial current density. The enhanced ethylene production metrics, obtained by virtue of the higher intrinsic activity of the Ni\u2013N\u2013C support, point out toward a synergistic action between the two catalytic functionalities
Mesoporous CuO/TiO\u2082 catalysts prepared by the ammonia driven deposition precipitation method for CO preferential oxidation : effect of metal loading
No full textAbstract: Supported CuO catalysts onto a highly crystalline mesoporous TiO2 material are produced via an ammonium driven deposition precipitation method and tested for prefere degrees ntial oxidation of CO in H-2-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 degrees 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
Towards Highly Loaded and Finely Dispersed CuO Catalysts via ADP: Effect of the Alumina Support
No full textTo meet current economic demands enforcing the replacement of platinum-group metals, extensively used in three-way-catalytic converters (TWC), research is driven towards low-cost and widely available base metals. However, to cope with their lower activity, high metal loadings must be coupled with increased dispersion. Herein, a series of CuO/Al2O3 samples is produced and the effect of different alumina supports’ properties on CuO dispersion, speciation and eventually on the TWC performance is studied. The alumina samples are synthesized via different methods, including soft-templating routes and flame spray pyrolysis, and compared with a commercial one, while CuO used as the catalytic active phase is added through ammonia-driven deposition–precipitation. As found, the large surface area and low crystallinity of the aluminas produced by soft-templating routes favor strong metal–support interaction, generating highly dispersed and strongly bonded CuO species at low loading and copper-aluminate phases at high loading. Notably, the use of amorphous mesoporous alumina completely prevents the formation of crystalline CuO even at 15 wt% Cu. Such high metal loading and dispersion capacity without the application of elevated calcination temperatures is one of the best reported for nonreducible supports. Catalytic evaluation of this material reveals a pronounced enhancement of oxidation activity with metal loading increase
