Influence of the physico-chemical properties of CeO2–ZrO2 mixed oxides on the catalytic oxidation of NO to NO2

2010 ◽  
Vol 256 (24) ◽  
pp. 7706-7712 ◽  
Author(s):  
Idriss Atribak ◽  
Noelia Guillén-Hurtado ◽  
Agustín Bueno-López ◽  
Avelina García-García
Keyword(s):  
Catalytic Oxidation ◽  
Mixed Oxides ◽  
Chemical Properties ◽  
Physico Chemical ◽  
Oxidation Of No

The effect of origin and physico-chemical properties on the kinetics of reduction of mixed NiO-Fe2O3 oxides with hydrogen

1986 ◽  
Vol 51 (10) ◽  
pp. 2098-2108 ◽  
Author(s):  
Milan Pospíšil ◽  
Jan Topinka
Keyword(s):  
Mixed Oxides ◽  
Mutual Influence ◽  
Spinel Phase ◽  
Chemical Properties ◽  
Inhibitory Effect ◽  
Chemical Parameters ◽  
Physico Chemical ◽  
Preliminary Annealing ◽  
Kinetics Of ◽  
Kinetics Of Reduction

We investigated the effect of origin and some physico-chemical parameters on the kinetics of reduction with hydrogen of two series of mixed NiO-Fe2O3 oxides differing by their composition, the character of their precursors (mixed crystalline nitrates and coprecipitated hydroxides) and their decomposition temperature.This effect manifested itself by different magnitudes of specific surfaces of the mixed oxides and coherent regions of present phases as well as by different oxidizing abilities of the surface and differences in morphology and phase composition of corresponding samples in both series investigated. Nonlinear or nonmonotonous composition dependences of physico-chemical parameters investigated point to a mutual influence of individual components, which is also a function of the system origin and which modifies its reactivity during its reduction with hydrogen. The kinetics of the reduction was studied thermogravimetrically at 320-410 °C. The reduction of oxides of the hydroxide origin is catalytically accelerated by primarily reduced nickel, whereas in corresponding samples of the nitrate series, the total NiO is bound to the spinel phase and the reduction is delayed. Experimental IR spectra, the effect of preliminary annealing and DTA of the mixed oxides point to an inhibitory effect of water, which is constitutionally bound in trace admixtures of the goethite phase, on the kinetics of reduction of samples in the hydroxide series.

scholarly journals The Influence of the Preparation Method on the Physico-Chemical Properties and Catalytic Activities of Ce-Modified LDH Structures Used as Catalysts in Condensation Reactions

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6191
Author(s):  
Alexandra-Elisabeta Stamate ◽  
Rodica Zăvoianu ◽  
Octavian Dumitru Pavel ◽  
Ruxandra Birjega ◽  
Andreea Matei ◽  
...  
Keyword(s):  
Preparation Method ◽  
Mixed Oxides ◽  
Condensation Reaction ◽  
Chemical Properties ◽  
Precipitation Method ◽  
Synthesis Methods ◽  
Molar Ratios ◽  
Base Catalysts ◽  
Physico Chemical ◽  
Co Precipitation

Mechanical activation and mechanochemical reactions are the subjects of mechanochemistry, a special branch of chemistry studied intensively since the 19th century. Herein, we comparably describe two synthesis methods used to obtain the following layered double hydroxide doped with cerium, Mg3Al0.75Ce0.25(OH)8(CO3)0.5·2H2O: the mechanochemical route and the co-precipitation method, respectively. The influence of the preparation method on the physico-chemical properties as determined by multiple techniques such as XRD, SEM, EDS, XPS, DRIFT, RAMAN, DR-UV-VIS, basicity, acidity, real/bulk densities, and BET measurements was also analyzed. The obtained samples, abbreviated HTCe-PP (prepared by co-precipitation) and HTCe-MC (prepared by mechanochemical method), and their corresponding mixed oxides, Ce-PP (resulting from HTCe-PP) and Ce-MC (resulting from HTCe-MC), were used as base catalysts in the self-condensation reaction of cyclohexanone and two Claisen–Schmidt condensations, which involve the reaction between an aromatic aldehyde and a ketone, at different molar ratios to synthesize compounds with significant biologic activity from the flavonoid family, namely chalcone (1,3-diphenyl-2-propen-1-one) and flavone (2-phenyl-4H-1benzoxiran-4-one). The mechanochemical route was shown to have indisputable advantages over the co-precipitation method for both the catalytic activity of the solids and the costs.

scholarly journals Synthesis and investigation of the physico-chemical properties of catalysts based on mixed oxides CexZr1−xO2

2015 ◽  
Vol 8 (2) ◽  
pp. 222-227 ◽  
Author(s):  
S. Nousir ◽  
R. Maache ◽  
S. Azalim ◽  
M. Agnaou ◽  
R. Brahmi ◽  
...  
Keyword(s):  
Mixed Oxides ◽  
Chemical Properties ◽  
Physico Chemical

Analysis of the Behaviour of Different Mixed Oxides in the Treatment of Cl-VOC Containing Gas Streams

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Beatriz de Rivas ◽  
Rubén López-Fonseca ◽  
Miguel A Gutierrez-Ortiz ◽  
Jose I Gutiérrez-Ortiz
Keyword(s):  
Mixed Oxides ◽  
Active Oxygen Species ◽  
Manganese Content ◽  
Chemical Properties ◽  
Active Oxygen ◽  
Oxygen Species ◽  
Product Selectivity ◽  
Gas Streams ◽  
Physico Chemical ◽  
Catalytic Behaviour

The present work deals with the catalytic behaviour of a series of ceria and manganese-based catalysts for the deep single combustion chlorinated compounds in air. Our attention is focused on both activity and product selectivity of Ce/Zr and Mn/Zr in the oxidation of 1,2-dichloroethane (1,000 ppm) and trichloroethylene (1,000 ppm). This study also makes an attempt to establish a correlation between physico-chemical properties and catalytic performance.Both series of mixed oxides exhibited a noticeable activity in the combustion of both compounds, Ce0.5Zr0.85O2, Ce0.5Zr0.5O2 and Mn0.4Zr0.6O2 being the samples with the most promising catalysts. A remarkable acidity and readily accessible active oxygen species played a key role in determining the catalytic behaviour. As for the product selectivity, CO2, CO, HCl and Cl2 were the main products. The yield of CO2 and Cl2 was favoured as cerium or manganese content was increased. However, selectivity to chlorine was noticeably limited by the addition of stream in favour of HCl.

scholarly journals Effect of Neodymium on the Physico‐chemical Properties and N 2 O Decomposition Activity of Co(Cu)−Al Mixed Oxides

ChemCatChem ◽  
2019 ◽  
Vol 11 (22) ◽  
pp. 5580-5592 ◽  
Author(s):  
Phuoc Hoang Ho ◽  
Magdalena Jabłońska ◽  
Marek Nocuń ◽  
Giuseppe Fornasari ◽  
Francesca Ospitali ◽  
...  
Keyword(s):  
Mixed Oxides ◽  
Chemical Properties ◽  
Physico Chemical
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