Preparation of Highly Dispersed Pd-Supported Catalysts for Hydrogenation Processes by Microemulsion Method

Preparation of nano-dispersed palladium particles on alumina support is described here using reverse microemulsion (water-in-oil) method. This synthesis protocol leads to a narrow Pd particle size distribution with particles of average size, which were significantly smaller compared to those prepared by classical impregnation method. It is shown that the particle size could be effectively controlled both by the microemulsion chemical composition such as concentration of PdCl2 and the water/surfactant molar ratio and by the catalyst reduction process. Under the optimal reaction conditions, a Pd/Al2O3 catalyst with a homogeneous distribution of Pd particles of average size ~2.2 nm was obtained

Precipitated K-promoted Co-Mn-Al mixed oxides for direct NO decomposition: Preparation and properties

Direct decomposition of nitric oxide (NO) proceeds over Co-Mn-Al mixed oxides promoted by potassium. In this study, answers to the following questions have been searched: Do the properties of the K-promoted Co-Mn-Al catalysts prepared by different methods differ from each other? The K-precipitated Co-Mn-Al oxide catalysts were prepared by the precipitation of metal nitrates with a solution of K2CO3/KOH, followed by the washing of the precipitate to different degrees of residual K amounts, and by cthe alcination of the precursors at 500 degrees C. The properties of the prepared catalysts were compared with those of the best catalyst prepared by the K-impregnation of a wet cake of Co-Mn-Al oxide precursors. The solids were characterized by chemical analysis, DTG, XRD, N-2 physisorption, FTIR, temperature programmed reduction (H-2-TPR), temperature programmed CO2 desorption (CO2-TPD), X-ray photoelectron spectrometry (XPS), and the species-resolved thermal alkali desorption method (SR-TAD). The washing of the K-precipitated cake resulted in decreasing the K amount in the solid, which affected the basicity, reducibility, and non-linearly catalytic activity in NO decomposition. The highest activity was found at ca 8 wt.% of K, while that of the best K-impregnated wet cake catalyst was at about 2 wt.% of K. The optimization of the cake washing conditions led to a higher catalytic activity.Web of Science97art. no. 59

Co-Mn-Al mixed oxides promoted by K for direct NO decomposition: Effect of preparation parameters

Fundamental research on direct NO decomposition is still needed for the design of a sufficiently active, stable and selective catalyst. Co-based mixed oxides promoted by alkali metals are promising catalysts for direct NO decomposition, but which parameters play the key role in NO decomposition over mixed oxide catalysts? How do applied preparation conditions affect the obtained catalyst's properties? Co4MnAlOx mixed oxides promoted by potassium calcined at various conditions were tested for direct NO decomposition with the aim to determine their activity, stability and selectivity. The catalysts were prepared by co-precipitation of the corresponding nitrates and subsequently promoted by KNO3. The catalysts were characterized by atomic absorption spectrometry (AAS)/inductive coupled plasma (ICP), X-ray photoelectron spectrometry (XPS), XRD, N-2 physisorption, temperature programmed desorption of CO2 (TPD-CO2), temperature programmed reduction by hydrogen (TPR-H-2), species-resolved thermal alkali desorption (SR-TAD), work function measurement and STEM. The preparation procedure affects physico-chemical properties of the catalysts, especially those that are associated with the potassium promoter presence. The addition of K is essential for catalytic activity, as it substantially affects the catalyst reducibility and basicity-key properties of a deNO catalyst. However, SR-TAD revealed that potassium migration, redistribution and volatilization are strongly dependent on the catalyst calcination temperature-higher calcination temperature leads to potassium stabilization. It also caused the formation of new phases and thus affected the main properties-S-BET, crystallinity and residual potassium amount.Web of Science97art. no. 59

Utilization of Ammonium Alum for Manufacture of a Fertilizer.

Utilization of ammonium alum for preparation of a Ca-N-S fertilizer and elimination of thalium from the alum

Direct Decomposition of NO Over Co-Mn-Al Mixed Oxides: Effect of Ce and/or K Promotors.

In this contribution, the effect of K and/or Ce on activity of Co-Mn-Al mixed oxides was stud-ied, as presence of Ce could increase mobility of oxygen in the transition metals oxides.\

Co-Mn Mixed Oxides Preared by Magnetron Sputtering on Meshes as Catalysts for Oxidation of Organic Compounds.

The catalysts with various Mn content were examined by XRD, SEM, FUR. XPS, and Ih-TPR. tested in the gas-phase oxidation of model organic compound (ethanol) and compared with pelletized commercial Co-Mn- Al mixed oxide catalyst (Astin 2-100, Czech Republic, Co:Mn:Al molar ratio of 4:1:1 )

Aluminum Sieves Supporting Cobalt-Manganese Mixed Oxides as Catalysts for Deep Ethanol Oxidation.

It can be concluded that conditions of sieves pretreatment substantially affect properties of the deposited oxides, and consequently, the catalitic activity of the prepared catalysts

Activity of K-Promoted Co-Mn-Al Mixed in Direct Decomposition of No and Deep Oxidation of Ethanol.

In this study, Co-Mn-Al mixed oxides modified by K were prepared by co-precipitation of a solution of metal nitrates with the aqueous solution of K2CO3 and KOH, washing the precipitates to different level of K concentrations and finally calcined at chosen temperature, usually 500 °C. The catalysts were characterized by AAS, nitrogen physisorption (Sbet), TPR-H2, XRD, and TPD- CO2. In case of direct NO decomposition, the catalysts pre-calcined at 700 °C were tested for direct NO decomposition in inert gas (650 °C, 0.5 g, 1000 ppm NO/N2, 49 ml min"1). Deep oxidation of ethanol was carried out under following conditions: 0.2 g, 760 ppm of ethanol in air, 4 000 ml h'1, the temperature ramp of 2 °C min'1

Properties of the Combustion Catalyst Obtained from Filtracni technika, s.r.o. in November 2000

Physical-chemical properties of an industrial Pt catalyst and its activity in combustion of toluene were evaluated

Aktivita směsných oxidů přechodných kovů nanesených na nosič Al2O3/Al při úplné oxidaci VOC

The MII-(Mn)-Al and MII-Cu-(Mn)-Al LDH precursors (MII = Ni and/or Co) were deposited on Al2O3/Al support during hydrothermal reaction in aqueous solutions containing divalent metal cations. Only a slight incorporation of Mn into deposited solid was observed. The obtained LDH films consisted of thin platelet crystals oriented nearly perpendicularly to the support; their morphology did not change even after heating at 500 °C, when mixed oxides were formed. The deposited mixed oxides containing Cu showed reduction peaks at the lowest temperatures, and, from that reason, the Cu-containing catalysts, namely the Ni-Cu-(Mn)-Al sample was the most active in the total oxidation of ethanol