Washcoat Material Research Articles

NiO ELECTRO-DEPOSITION TECHNIQUE OF γ-Al2O3 WASHCOAT ON FeCrAl SUBSTRATE BY USING SULPHAMATE TYPE SOLUTION

Electro-deposition process to develop surface layer on the substrate material in Catalytic converter (CATCO) become interesting area due to that process was purposed to improve the physical properties of substrate material. Currently, precious metals such as Platinum (Pt), Palladium (Pd), and Rodium (Rd) were used due to excellent oxidation resistant but it limited and easily oxidized. Therefore, Nickel Oxide (NiO) catalyst used as electro-deposition material. NiO electro-deposition technique that called by EL was conducted by using NiO as cathode and FeCrAl as substrate and -Al2O3 as washcoat material. This technique was performed by variation times of 15, 30, 45, 60 and 75 minutes, current density of 8 A/dm2. The results shows that Coating layer of NiO and -Al2O3 has been developed on surface of FeCrAl substrate. The coating layer was increase the surface roughness which showed by surface morphology data that coated FeCrAl substrate has uneven surface and some particles has been embedded on that surface. The composition of raw material was consists of Fe for 74.13wt%, Cr of 20.25 wt% and Al of 5.62 wt%. Meanwhile, for composition of EL samples was 52.56- 63.54wt% for Fe element, Al for 3.56-11.89 wt%, Cr for 14.97-18.56 wt%, O for 2.47-11.78 wt%, C for 8.33-11.85 wt%, Na for 0.11-0.48 wt% and Ni for 0.17- 1.58 wt%. Higher elements of the EL samples potential to improve the thermal stability at high temperature due to CATCO operate at high temperature of 600-8500C and in extreme condition.

Nano-oxides washcoat for enhanced catalytic oxidation activity toward the perovskite-based monolithic catalyst.

In order to explore a superior washcoat material to give full play to the catalytic activity of perovskite active components on the monolithic catalysts, three novel types of LaCoO3/washcoat/cordierite monolith catalysts were prepared by a facile two-step procedure which employed the cordierite honeycomb ceramic as the monolith substrate, the nano-oxides (ZrO2, ɤ-Al2O3, TiO2) as the washcoat, and the perovskite of LaCoO3 as the active components. The blank cordierite, powdered LaCoO3, semi-manufactured monolithic catalysts (washcoat/cordierite), and manufactured monolithic catalysts (LaCoO3/washcoat/cordierite) were characterized by XRD, SEM, XPS, N2 adsorption-desorption, H2-TPR, and ultrasonic test, and their catalytic activities and catalytic stability were evaluated by the toluene oxidation test. The research results indicate that the nanoparticles coated on the cordierite substrate as the washcoat can give full play to the catalytic ability of the LaCoO3 active components and also showed high catalytic stability. However, the catalytic properties of the monolithic catalysts vary notably with the species of nano-washcoat. Among all the catalysts, the porous honeycomb surface structure, uniform distribution, high ratio of surface adsorbed oxygen, and strong reducing ability together give the LaCoO3/ZrO2/cordierite monolithic catalyst the highest catalytic activity on the oxidation of toluene at low temperature, which could be attributed to the excellent interactions of perovskite and nano-ZrO2 washcoat. Therefore, the nano-oxides, especially the nano-ZrO2, have a broad practical application potential for toluene oxidation at low temperature as the washcoat of perovskite-based monolithic catalysts.

Characterization of the Evolution of Noble Metal Particles in a Commercial Three-Way Catalyst: Correlation between Real and Simulated Ageing

Ageing of automotive catalysts is associated to a loss of their functionality and ultimately to a waste of precious resources. For this reason, understanding catalyst ageing phenomena is necessary for the design of long lasting efficient catalysts. The present work has the purpose of studying in depth all the phenomena that occur during ageing, in terms of morphological modification and deactivation of the active materials: precious metal particles and oxidic support. The topic was deeply investigated using specific methodologies (FT-IR, CO chemisorption, FE-SEM) in order to understand the behavior of metals and support, in terms of their surface properties, morphology and dispersion in the washcoat material. A series of commercial catalysts, aged in different conditions, have been analyzed, in order to find correlations between real and simulated ageing conditions. The characterization highlights a series of phenomena linked to the deactivation of the catalysts. Pd nanoparticles undergo a rapid agglomeration, exhibiting a quick loss of dispersion and of active sites with an increase of particles size. The evolution of the support allows highlighting also the contribution of chemical ageing effects. These results were also correlated with performance tests executed on synthetic gas bench, underlining a good correspondence between vehicle and laboratory aged samples and the contribution of chemical poisoning to vehicle aged ones. The collected data are crucial for the development of accelerated laboratory ageing protocols, which are instrumental for the development and testing of long lasting abatement systems.

Effects of ammonia concentration in hydrothermal treatment on structure and redox properties of cerium zirconium solid solution

Cerium zirconium solid solution is a key washcoat material for automotive three-way catalysts (TWCs). However, improving the redox ability and high temperature thermal stability of cerium zirconium solid solution is still a challenge. In this paper, the cerium zirconium solid solution was prepared by a coprecipitation-hydrothermal method, and the effects of the ammonia concentration on their structures and redox properties were investigated. The results show that when the ammonia concentration is 0.8 mol/L, the aged sample (1100 °C/10 h) of cerium zirconium solid solution has the highest specific surface area of 23.01 m2/g. Additionally, the increase of ammonia concentration improves the uniformity of phase compositions and increases the oxygen vacancies. When the ammonia concentration reaches 0.4 mol/L, the cerium zirconium solid solution exhibits the best redox activity, with the lowest reduction temperature of 565 °C. Therefore, increasing ammonia concentration in the hydrothermal treatment is beneficial to the thermal stability and redox performance of cerium zirconium solid solution.

Detailed experimental investigation of the NOx reaction pathways of three-way catalysts with focus on intermediate reactions of NH3 and N2O

In this work possible reaction pathways of NOx were investigated for a three-way catalyst on a synthetic gas test bench with a focus on intermediately produced NH3 and N2O. NH3 formation during a typical lean-to-rich transient was verified. Further experiments were carried out in Ar atmosphere allowing to directly determine the N2 selectivity. It could be shown that the catalyst's oxygen storage capacity (OSC), which is implemented by addition of CeO2 to the washcoat material, plays a significant role and that NO can fill the oxygen storage in the absence of O2. Further, no nitrogen species were found to be stored. Also, intermediately produced NH3 was oxidized by stored oxygen with a high selectivity to N2. As soon as the OSC was fully exhausted, NH3 dissociated, leading to the formation of N2 and H2. The presence of side products and secondary emissions strongly depends on the actual operating conditions.

Experimental Investigation on Reduction of NO<sub>X</sub> Emission Using Zeolite Coated Converter in CI Engine

In the recent times, the issues of reduction of harmful pollutants emitted from an internal combustion engine have gained large prominence as a part of climate change and global warming. Automobile and power generation systems are identified to be one of the largest contributors to atmospheric pollution. Some of the major pollutants emitted from an engine are Oxides of Nitrogen (NOx), Carbon monoxide (CO), Unburnt Hydrocarbon (UBHC) and soot particles. This project work presents a new wash coat material is in the catalytic converter to be used for compressed ignition engine. Zeolite coated in the catalytic converter insists of aluminium oxide to reduce the emission. The objective of this project work is to control the NOx emission and to develop a low-cost three way catalytic converter. This catalytic converter is assembled in the exhaust manifold region of a single cylinder four stroke diesel engine. The emission from the engines is measured using a five gas analyzer and the results are tabulated.

Catalytic Converter Developed By Washcoat Of γ-Alumina On Nickel Oxide (Nio) Catalyst In FeCrAl Substrate For Exhaust Emission Control : A Review

Automobile exhaust emission control is one of the trending issues in automobile research field. The existing catalytic converter using the noble metals of platinum (Pt), palladium (Pd) and rhodium (Rd) recently were in limited supply and higher in cost. There is a need for the automotive industry to produce ultra-low emitting vehicles at a reasonable cost. The objective of this study is to investigate the effectiveness of methods of fabrication of modified catalytic converter by approaching FeCrAl as a substrate which treated using ultrasonic bath technique to improve the exhaust emission control. The modified catalytic converter preparation will involve the ultrasonic bath process of FeCrAl foil which has fabricated as metallic monolith coated by γ-Al 2 O 3 powder. Nickel as catalyst material will be prepared using electroplating process. The oxidation test will be conducted using a tube and automatic furnace in temperature of 1100°C for 100 hours. Mitsubishi 4G93 1800cc Petrol E.F.I with a multi -gas analyzer equipped with a hydraulic dynamometer will be used for emission measurements of HC, CO, and NO x in varying speed and load for both conditions with and without catalytic converter. The result will expect the γ-Al 2 O 3 as the washcoat material that fully embedded to FeCrAl substrate with the combination of ultrasonic and electroplating technique will effectively convert the CO, NO x and HC to CO 2 , NO 2 and H 2 O which means that catalytic converter is effective to improve exhaust emission control of diesel engine. The FeCrAl substrate as a metallic catalytic converter which coated by γ-Al 2 O 3 using ultrasonic and nickelelectroplating technique may improve the exhaust emission control.

Vanadium and tungsten release from V-based selective catalytic reduction diesel aftertreatment

Vanadium-based selective catalytic reduction (V-SCR) catalysts are currently used for the reduction of nitrogen oxides (NOx) in worldwide diesel applications including Euro IV, V, and VI as well as U.S. nonroad Tier 4 Final. Although V-SCR catalysts are attractive because of their high NOx conversion, low cost, resistance to sulfur poisoning, and ability to reduce hydrocarbon emissions, there is concern that V-SCR washcoat material (e.g., vanadium and tungsten) and its derivatives may be released into the atmosphere, potentially harming human health and the environment. In this study, vanadium and tungsten release measurements are made with both a reactor- and engine-based approach in order to determine the potential release of these metals from diesel exhaust aftertreatment systems that contain a V-SCR catalyst. Results for a commercially available V-SCR reveal that both V and W release begin at 500 °C, and both reactor- and engine-based methods are capable of measuring qualitatively similar release. Emissions with the engine-based method are higher at all temperatures evaluated, likely due to this method's ability to capture particle-phase and vapor-phase emissions which become particle-bound after their evolution from the catalyst surface. Certification relevant data (NRTC and NRSC) from a nonroad engine is used to understand probable emissions from V-SCR aftertreatment architectures. Finally, results from a V-SCR catalyst formulated for improved thermal durability illustrate that it is possible to increase the maximum temperature for V-SCR catalysts. This comprehensive understanding of the temperature dependence of vanadium and tungsten volatility can be used to further analyze the full impact of diesel aftertreatment on exhaust emissions and their impact on human health and environmental toxicity.

Disassembly of Small Engine Catalytic Converters and Analysis of Washcoat Material for Platinum Group Metals by X-Ray Fluorescence Spectrometry

Disassembly of Small Engine Catalytic Converters and Analysis of Washcoat Material for Platinum Group Metals by X-Ray Fluorescence Spectrometry

Electrically Conductive Honeycomb Monolith of Nanolaminated Ti3AlC2: Preparation and Characterization

Nanolaminated Ti3AlC2 honeycomb monolith with parallel and uniform holes has been prepared through a facile extrusion route by using Ti3AlC2 powder as the main raw material. The fabricated honeycomb monolith has high compressive strength of 133 ± 11 and 59 ± 9 MPa, along and perpendicular to the extrusion direction, respectively. It also has good electrical conductivity, and excellent match of thermal expansion coefficient with the washcoat material of γ-Al2O3. These combined properties endow the honeycomb monolith a promising candidate as catalysis substrate for cleaning vehicle exhaust.

Preparation and characterization of a novel washcoat material and supported Pd catalysts

A nanosized Ce0.5Mn0.5O1.5 powder was successfully synthesized by macromolecule surfactant modified method and then it was used as the cordierite honeycomb washcoat of VOCs combustion catalysts. The effect of Ce-Mn-O powder with different Ce/Mn molar ratio on the catalytic activity and the cohesive ability of washcoat on the cordierite honeycomb substrate was also investigated. The structure and catalytic properties of Ce0.5Mn0.5O1.5 washcoat were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), differential thermal analysis and thermo-gravimetric analysis (TG/DTA), and N2 adsorption and desorption techniques. The results indicated that the Ce0.5Mn0.5O1.5 powder belongs to a novel washcoat with the advantages of strong cohesiveness, high surface area and without agglomeration even after 1000°C calcination. The total oxidation temperature for toluene, acetone and ethyl acetate over the 0.1 wt % Pd/Ce0.5Mn0.5O1.5/cordierite honeycomb catalysts was at 200, 220 and 220°C, respectively. Compaired with the catalysts without Ce0.5Mn0.5O1.5 washcoat, the catalyst with Ce0.5Mn0.5O1.5 as washcoat on the cordierite honeycomb could improve the dispersion of PdO and shows a good catalytic activity for toluene, acetone and ethyl acetate.

Dynamics of oxygen storage and release on commercial aged Pd-Rh three-way catalysts and their characterization by transient experiments

The present work has provided new fundamental information on the effects of aging (mileage, km) of a commercial Pd-Rh (9:1, w/w) three-way catalyst (TWC) on (a) the H2 chemisorption, (b) the redox properties of washcoat material, and (c) the dynamic oxygen storage and release properties of TWC. Hydrogen chemisorption in the 25–400°C range was found to decrease with increasing aging of TWC. On the other hand, H2 chemisorption performed at 200 and 400°C resulted in a significantly larger amount of chemisorbed hydrogen (exceeding the monolayer value based on the noble metals) compared to that obtained after chemisorption at 25°C. This is due to the onset of a hydrogen spill over process in the 200–400°C range. The features of H2-TPD spectra were found to strongly depend on the aging of TWC. Hydrogen chemisorption at 25°C followed by TPD after a given pre-treatment of the catalyst surface might be considered as a procedure for a good estimate of the metal dispersion of a commercial Pd-Rh TWC. The redox properties of the oxygen storage components of the washcoat of a commercial Pd-Rh TWC were found to drastically change with increasing aging of TWC. It was found that the oxygen storage capacity (OSC) of the TWC investigated decreases significantly with catalyst aging in the 0–56,000km range and in the temperature range of 500–750°C. In the case of fresh TWC, the presence of 20ppm SO2 or 10% CO2 in a 1.5% O2/He gas mixture used for oxygen storage (oxidizing gas) was found to result in a large decrease in the amount of dynamic OSC measured by alternating switches between oxidizing and reducing feed gas compositions. The shift in time of the peak maximum of the transient response of CO2 obtained during the switch O2/He → He → CO/He (t) can be ascribed to the alteration of the kinetics of the oxygen back-spillover process and not to the kinetics of CO oxidation on the metal surface.

Catalytic activity of oxide-supported Pd catalysts on a honeycomb for low-temperature methane oxidation

Low-temperature methane oxidation over oxide-supported Pd catalysts coated on a metal or ceramic honeycomb was investigated for gas turbine applications. Al 2O 3 and SnO 2 were used as washcoat material, and a Fe–Cr–Al alloy and cordierite were adopted as metal and ceramic honeycombs, respectively. Pd catalysts on the honeycomb were prepared by varying washcoat loading and washcoat calcination temperature. It was found that the catalytic activities of Pd/SnO 2 on metal and ceramic honeycombs improved with increasing washcoat loading and precalcination temperature of the washcoat material. Especially, significant enhancement of the catalytic activity appeared for Pd/SnO 2/ceramic honeycomb as the washcoat loading increased from 150 to 200 g/l. The catalytic activity of the honeycomb catalysts was examined under high pressure and space velocity. The temperature at which the increase in CH 4 conversion became noticeable was shifted to higher temperature compared to the experiments at lower space velocity and ambient pressure. CH 4 conversion over the honeycomb catalysts fluctuated as the catalyst bed inlet temperature was raised. Pd/SnO 2/ceramic honeycomb exhibited the highest stable activity for low-temperature methane oxidation.

Characterization of alumina supported Pd catalysts modified by rare earth oxides using X-ray photoelectron spectroscopy and X-ray diffraction: enhanced thermal stability of PdO in Nd/Pd catalysts

Thermal stability of palladium oxides on industrially manufactured alumina supported catalysts modified by Nd, La and Ba oxides was investigated using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Catalysts were prepared by mechanical mixing of washcoat material with Pd precursor compound. A stepwise thermal reduction in high vacuum was performed in order to investigate the effect of noble metal loading, stabilizers and aging on the thermal stability of PdO. One of the pseudo-binary compounds of Nd 2O 3/PdO, Nd 4PdO 7, was successfully manufactured and characterized by XRD and XPS. The presence of Nd 4PdO 7 as a surface compound was identified by its unusually high binding energy of the Pd 3d 5/2 photoelectron peak (337.6 eV). PdO formed as a result of the decomposition of the alumina supported Nd 4PdO 7 upon aging in air at 950°C exhibited clearly higher thermal stability than pure PdO supported on alumina. La, Ba and Nd oxides were also found to enhance the thermal stability of PdO.

Preparation, evaluation and characterization of copper catalysts for ethanol fuelled diesel engines

Copper-based monolithic honeycomb catalysts for ethanol fuelled diesel engines have been prepared and evaluated. The washcoat consisted either of alumina or titania. Two different methods to apply the active material were used; incipient wetness impregnation and deposition precipitation. The catalysts have been evaluated in a laboratory reactor and have been characterised using SEM, XRPD, TEM, TPR, XPS, BET surface area and pore-size distribution measurements. Both the choice of washcoat material as well as the preparation method is of importance. Titania as washcoat gave a better performing catalyst than alumina in this case. Deposition precipitation gave a better catalyst than incipient wetness impregnation when alumina was used as washcoat, as well as at low temperatures for titania catalysts.