New Trends in Automotive Exhaust Gas Purification Materials: Improvement of the Support against Stability of the Active Components

2019 ◽  
Vol 950 ◽  
pp. 185-189 ◽  
Author(s):  
Aleksey A. Vedyagin ◽  
Vladimir O. Stoyanovskii ◽  
Roman M. Kenzhin ◽  
Pavel E. Plyusnin ◽  
Yury V. Shubin ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Incipient Wetness Impregnation ◽  
Exhaust Gas ◽  
Active Components ◽  
Commercial Alumina ◽  
Zirconium Oxides ◽  
Catalytic Fields ◽  
Physicochemical Methods ◽  
Aging Regime ◽  
Three Way Catalysis

Lanthanum and zirconium oxides are well known to be applied as an additive to improve the properties of the commercial alumina. Such modified aluminas are widely used in different catalytic fields including three-way catalysis. In the present research we have paid attention to the possible effects of the doping on the catalytic performance and stability of bimetallic Pd-Rh catalysts. The samples were prepared via an incipient wetness impregnation of the commercial supports, tested in CO oxidation under prompt thermal aging regime and characterized by physicochemical methods.

scholarly journals Preparation and Characterization of Cu-Mn-Ce@γ-Al2O3 to Catalyze Ozonation in Coal Chemical Wastewater-Biotreated Effluent

2019 ◽  
Vol 16 (8) ◽  
pp. 1439
Author(s):  
Yue Teng ◽  
Ke Yao ◽  
Wenbin Song ◽  
Yongjun Sun ◽  
Haoliang Liu ◽  
...  
Keyword(s):  
Reaction Time ◽  
Calcination Temperature ◽  
Catalytic Performance ◽  
Catalytic Ozonation ◽  
Operating Conditions ◽  
Operating Parameters ◽  
Incipient Wetness Impregnation ◽  
X Ray Diffraction ◽  
Calcination Time ◽  
Catalyst Dosage

Cu-Mn-Ce@γ-Al2O3 was prepared by incipient wetness impregnation and used to catalyze ozonation in a coal chemical wastewater-biotreated effluent. The preparation factors that considerably affected the catalytic performance of Cu-Mn-Ce@γ-Al2O3, specifically metal oxide loading percentage, calcination temperature, and calcination time, were examined. The catalyst was characterized by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, and Brunauer-Emmett-Teller analysis. The optimal catalytic ozonation operating parameters, such as ozone dosage, catalyst dosage, pH, and reaction time, were also investigated. Results showed that an optimized catalyst consisted of 17.0% CuO, 3.0% MnO2, and 2.0% CeO2 (wt.%). The optimal calcination temperature and calcination time were 600 °C and 5 h. The optimal catalytic ozonation operating parameters, including ozone dosage, catalyst dosage, pH, and reaction time, were 7, 80.0 mg/L, 20.0 mg/L, 7 and 50 min, respectively. The COD removal of biotreated effluent increased to 61% under these optimal operating conditions. Meanwhile, ozonation alone resulted in only 20% removal. This work proposes the use of easily available Cu-Mn-Ce@γ-Al2O3 catalyst and might drive the advancement of catalytic ozonation for chemical wastewater purification.

Effect of silver on the catalytic hydrodechlorination of tetrachloromethane over silica-supported palladium-silver catalysts

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Magdalena Bonarowska ◽  
Zbigniew Kaszkur ◽  
Zbigniew Karpiński
Keyword(s):  
Gas Phase ◽  
Palladium Catalysts ◽  
Catalytic Performance ◽  
Incipient Wetness Impregnation ◽  
Significant Extent ◽  
Silver Addition ◽  
Catalytic Hydrodechlorination ◽  
Silver Catalysts ◽  
Supported Palladium ◽  
Incipient Wetness

AbstractTwo silica-supported palladium based catalysts characterized by overall metal loadings 10 wt.%, and atomic Pd : Ag ratios of 100 : 0 and 70 : 30, were prepared by incipient wetness impregnation, subjected to reduction in hydrogen and characterized by XRD. It was found that incipient wetness co-impregnation of silica resulted in the formation of a catalyst characterized by relatively small metal crystallites (~11 nm) and significant extent of Pd-Ag alloying. The catalytic performance was investigated in the hydrodechlorination of tetrachloromethane in the gas phase. Silver addition to palladium in the co-impregnated catalysts had very pronounced effect, vastly decreasing the overall activity (conversion) and also the selectivity towards hydrocarbons, propensity characteristic for the monometallic palladium catalysts working in CCl4 hydrodechlorination carried out in the gas phase. Instead, large amounts of C2HxCly dimeric products were formed. These dimers are considered as possible coke precursors. Post-reaction samples of both catalysts contained large amount of carbon which entered the Pd and Pd-Ag phases. This carbon can be easily removed by treatment with hydrogen at 450ºC.

Activity of yFe-10Cu/H-Sep and xCu/H-Sep for the Selective Catalytic Reduction of NO with Propylene

2012 ◽  
Vol 518-523 ◽  
pp. 281-284
Author(s):  
Qing Ye ◽  
Hai Ping Wang ◽  
Hai Xia Zhao ◽  
Shui Yuan Cheng ◽  
Tian Fang Kang
Keyword(s):  
Catalytic Reduction ◽  
Catalytic Performance ◽  
High Dispersion ◽  
High Catalytic Activity ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Promotional Effect ◽  
Scr Of No ◽  
Metal Support Interaction ◽  
Metal Support

Cu supported on acid-treated sepiolite catalysts (xCu/H-Sep, x = 0  20.0 wt%) or Cu-Fe mixed supported on acid-treated sepiolite catalysts (yFe-10Cu/H-Sep, y = 0  20.0 wt%) were prepared by the incipient wetness impregnation method. The xCu/H-Sep and yFe-10Cu/H-Sep catalysts were characterized by means of XRD, BET, XRF, XPS, and H2-TPR techniques, and their catalytic activities were evaluated for the SCR of NO with propylene. XPS and XRD results indicate that there was the co-presence of Cu+-Cu2+ and Fe2+-Fe3+ over the surfaces of yFe-10Cu/H-Sep catalysts, and there was a strong interaction between Cu, Fe and sepiolite. High promotional effect of iron additive on the catalytic performance of Cu/H-Sep catalyst were found in C3H6-SCR of NO reaction. The highest activity of 65% NO conversion was obtained over 15Fe-10Cu/H-Sep catalyst at 280 oC under the condition of 1000 ppm NO, 1000 ppm C3H6, and 5% O2. The high catalytic activity of 15Fe-10Cu/H-Sep catalyst for NO reduction was due to its high reducibility to activate C3H6 to selectively reduce NO in the presence of excess O2. The high dispersion of copper oxides and strong metal-support interaction over 15Fe-10Cu/H-Sep catalyst also improve its catalytic performance.

STUDY ON NANO COPPER-BASED CATALYSTS FOR THE HYDROGENATION OF METHYL 3-HYDROXYPROPIONATE TO 1, 3-PROPANEDIOL

2009 ◽  
Vol 16 (03) ◽  
pp. 343-349 ◽  
Author(s):  
YUZHOU YING ◽  
KANKA FENG ◽  
ZHIGUO LV ◽  
ZHENMEI GUO ◽  
JINSHENG GAO
Keyword(s):  
Fixed Bed ◽  
Side Reaction ◽  
Catalytic Performance ◽  
Fixed Bed Reactor ◽  
Precipitation Method ◽  
Active Components ◽  
Analysis Technique ◽  
Co Precipitation ◽  
Nano Catalysts ◽  
Adsorption Desorption

Nano copper-based catalysts were prepared by co-precipitation method and the performance of catalytic hydrogenation for methyl 3-hydroxypropionate (MHP) to 1, 3-propanediol (1, 3-PDO) on the nano catalysts were studied under a high-pressure microcontinuum fixed-bed reactor. The effects of structure, texture, and composition of the catalysts on the catalytic performance were investigated by characterizing the catalysts with XRD, TG–DTG, SEM, and N 2 adsorption/desorption analysis technique. The results showed that addition of promoters enhanced the activity and selectivity of copper-based catalysts, which promoted the dispersion of the active components effectively and stabilized the active center of the catalysts. Especially, the copper-based catalyst of loaded P could restrain side-reaction effectively and improve selectivity obviously, the conversion of MHP and the selectivity of 1, 3-PDO could be 91.30% and reach 90.15%, respectively.

scholarly journals Effect of Preparation Mode on the Properties of Mn-Na-W/SiO2 Catalysts for Oxidative Coupling of Methane: Conventional Methods vs. POSS Nanotechnology

2016 ◽  
Vol 18 (2) ◽  
pp. 93 ◽  
Author(s):  
I.Z. Ismagilov ◽  
E.V. Matus ◽  
V.V. Kuznetsov ◽  
M.A. Kerzhentsev ◽  
S.A. Yashnik ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Oxidative Coupling Of Methane ◽  
Molar Ratio ◽  
High Dispersion ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Polyhedral Oligomeric Silsesquioxanes ◽  
Preparation Mode ◽  
Slurry Method ◽  
Conventional Methods

<p>Reflectance spectroscopic methods the electronic, redox and structural properties of Mn-Na-W/SiO<sub>2</sub> catalysts prepared by the incipient wetness impregnation method and mixture slurry method were studied in detail. Since POSS nanotechnology (POSS = polyhedral oligomeric silsesquioxanes) has attracted attention as tooling for synthesis of catalysts with novel properties and functionalities, we expanded this method for the preparation of Mn-Na-W/SiO<sub>2</sub> catalyst. The physicochemical and catalytic properties of Mn-Na-W/SiO<sub>2</sub> catalysts prepared by conventional methods and POSS nanotechnology were examined comparatively. In all studied Mn-Na-W/SiO<sub>2</sub> catalysts both individual oxides (MnO<sub>x</sub>, WO<sub>3</sub>) and bimetal oxide phases (Na<sub>2</sub>WO<sub>4</sub>, MnWO<sub>4</sub>) are found in addition to oxide particles of high dispersion. The UV-Vis Diffuse Reflectance indicates that Na<sup>+</sup> cations facilitates stabilization of octahedrally coordinated Mn<sup>3+</sup><sub>Oh</sub> cations in the isolated state, while Mn<sup>3+</sup><sub>Oh</sub> promote the disordering of W<sup>6+</sup> cations in the supported system. The Mn-Na-W/SiO<sub>2</sub> prepared using metal-POSS precursors marks out presence of unglobular SiO<sub>2</sub> particles, higher dispersion of MnO<sub>x</sub> and MnWO<sub>4</sub> particles and more easily reducible metal-oxide species. The catalysts prepared by incipient impregnation method and mixture slurry method have practically similar catalytic performance while the catalyst prepared by POSS nanotechnology method shows lower activity and selectivity. At 800‒850 °C the increase of C<sub>2</sub> hydrocarbons yield from 4 to 15% and the rise of molar ratio С<sub>2</sub>Н<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> from 0.2 to 1 are observed when impregnation or mixture slurry method are used for catalyst preparation instead of POSS nanotechnology method.</p>

Reduction of Carbon-Monoxide Content from Four Stroke Petrol Engine by using Subsystem

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
A. Godwin Antony ◽  
K. Radhakrishnan ◽  
K. Saravanan ◽  
V. Vijayan
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Reduction ◽  
Aluminium Oxide ◽  
Catalytic Performance ◽  
Petrol Engine ◽  
Exhaust Gas ◽  
Emission Standard ◽  
System A ◽  
Physical Effects ◽  
Co Emission

A method for removing carbon monoxide from exhaust gas of a petrol engine through catalytic reduction by the use of catalyst in presence of cuprous aluminium oxide is performed. This method feeds cuprous oxide into exhaust gas proportionately to the product of revolution number of petrol engine. The catalytic performance of cuprous aluminium oxide catalyst for carbon monoxide hydro generation and addition of promoter cuprous aluminium results in slide modification silencer. Many methods are used to control the emission rate but it is not getting reduced and for efficient benefits we are using a mechanical device called emission sub system. A lit was created mainly to reduce CO from the exhaust of the vehicle. It reduces the physical effects and global warming. To meet the emission standard bs6 CO emission may reduce the effect of toxic content present in the exhaust.

Manipulation of Pt-Ni Tetrahexahedral Nanoframes Using a Gaseous Etching Method

MRS Advances ◽  
2018 ◽  
Vol 3 (18) ◽  
pp. 943-948 ◽  
Author(s):  
Yiliang Luan ◽  
Lihua Zhang ◽  
Chenyu Wang ◽  
Jingyue Liu ◽  
Jiye Fang
Keyword(s):  
Driving Force ◽  
Surface Defects ◽  
Catalytic Performance ◽  
High Reactivity ◽  
Etching Time ◽  
Industry Research ◽  
Catalytic Fields ◽  
Metallic Complex ◽  
Annealing Operation

ABSTRACTNanosized Platinum (Pt) nanocrystals (NCs) have been extensively investigated in catalytic fields because of their high reactivity due to the unique electron structure. However, the rarity and the high cost of Pt limit its applications in industry. To reduce the usage of Pt in catalytic industry, research interests have been extended to Pt-based nanoalloys. Among various nanostructures, nanoframes (NFs) showed promising catalytic performance even with a lower metallic loading dose. Herein, we report a facile and robust method to transfer the Pt-Ni tetrahexahedral (THH) NCs into THH NFs in which carbon monoxide (CO) plays a role of the “etching reagent”. The driving force of the etching is a formation of gaseous metallic complex, Ni(CO)4, known as Mond Process, preferentially dealloying nickel atoms along <100> directions of the Pt-Ni THH NCs. It is determined that the resultant Pt-Ni THH NFs possess an open, stable and high-index preserved nanostructure, in which the outside atomic layers are composed of only Pt atoms with surface strains. Compared to a solution-based etching process, this approach requires less etching time and generates a well-defined structure. The associated thermal annealing operation also releases extra internal stress, making the NFs more stable with fewer surface defects. Such Pt-Ni THH NFs show interesting potentials in the improvement of stability and activity as advanced catalysts.

Catalytic Performance of Nanosized Pt–Au Alloy Catalyst in Oxidation of Methanol and Toluene

2007 ◽  
Vol 7 (11) ◽  
pp. 3795-3799
Author(s):  
Ki-Joong Kim ◽  
Yong-Hwa Kim ◽  
Ho-Geun Ahn
Keyword(s):  
Flow Rate ◽  
Catalytic Performance ◽  
Exhaust Gas ◽  
Complete Oxidation ◽  
Feed Flow Rate ◽  
Group Viii ◽  
Alumina Support ◽  
Oxidation Activity ◽  
Oxidation Of Methanol ◽  
Monolith Catalyst

The alloy formed between a group-VIII metal such as platinum and a group-IB metal such as gold changes the catalytic behavior compared to the monometallic phase, increasing the selectivity toward certain products and also decreasing the deactivation rate. Pt–Au alloy nanoparticles coated on alumina support were found to be catalytically very active for complete oxidation of methanol and toluene. Furthermore, the nanosized Pt–Au particles were added to ZnO/Al2O3 on monolith catalyst. Also, effect of various parameters such as concentration of methanol and toluene and feed flow rate was investigated. Au particles were sized in 20∼30 nm and Pt particles were well dispersed. In case of alumina supported powder catalyst, complete oxidation of methanol occurred at a temperature lower than that of toluene. From oxidation activity of monolithic honeycomb with Pt and Au particles, the conversion of methanol was increased with increasing the concentration of methanol, but conversion of toluene showed a decreasing tendency as the concentration of toluene increased. Also, conversion of methanol over honeycomb catalyst was not largely affected by feed flow rate, while conversion in toluene oxidation was decreased rapidly as feed flow rate was increased. As a result, the Pt-Au/ZnO/Al2O3/M catalyst used is likely to efficiently treat a large volume of exhaust gas containing VOCs.

scholarly journals Single-atom Sn-Zn pairs in CuO catalyst promote dimethyldichlorosilane synthesis

2019 ◽  
Vol 7 (3) ◽  
pp. 600-608 ◽  
Author(s):  
Qi Shi ◽  
Yongjun Ji ◽  
Wenxin Chen ◽  
Yongxia Zhu ◽  
Jing Li ◽  
...  
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Utilization Efficiency ◽  
Single Atom ◽  
Electronic Interaction ◽  
Active Components ◽  
Functional Theory ◽  
Low Concentrations ◽  
Sn Substitution

Abstract Single-atom catalysts are of great interest because they can maximize the atom-utilization efficiency and generate unique catalytic properties; however, much attention has been paid to single-site active components, rarely to catalyst promoters. Promoters can significantly affect the activity and selectivity of a catalyst, even at their low concentrations in catalysts. In this work, we designed and synthesized CuO catalysts with atomically dispersed co-promoters of Sn and Zn. When used as the catalyst in the Rochow reaction for the synthesis of dimethyldichlorosilane, this catalyst exhibited much-enhanced activity, selectivity and stability compared with the conventional CuO catalysts with promoters in the form of nanoparticles. Density functional theory calculations demonstrate that single-atomic Sn substitution in the CuO surface can enrich surface Cu vacancies and promote dispersion of Zn to its atomic levels. Sn and Zn single sites as the co-promoters cooperatively generate electronic interaction with the CuO support, which further facilitates the adsorption of the reactant molecules on the surface, thereby leading to the superior catalytic performance.

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