Chemical composition impregnation

Chromium-containing wood preservatives and their chemical compositions are Hsted ia Table 13 (199). Chromium compounds have a triple function ia wood preservation (200). Most importantiy, after impregnation of the wood the Cr(VI) compounds used ia the formulations react with the wood extractives and the other preservative salts to produce relatively insoluble complexes from which preservative leaches only very slowly. This mechanism has been studied in the laboratory (201—206) and the field (207). Finally, although most of the chromium is reduced to chromium (ITT), there is probably some slight contribution of the chromium (VT) to the preservative value (208). 

Preparation of the composite materials with the FAU and BEA nanodomains has been reported previously [3,4]. The procedure was based on the impregnation of the parent materials with concentrated template solutions and subsequent recrystallization in the hydrothermal conditions. Amorphous aluminosilicates of chemical composition 13%Al20387%Si02 (13A187Si) and 6%Al20394%Si02 (6A194Si) were used as the parent materials for the FAU and BEA composites, respectively. 

Ronning, Holmen, and coworkers—Ce doping of Cu/Zn/Al catalysts improves stability. Ronning et al,339 explored the impact of ceria addition to Cu/ZnO catalysts. Catalysts were prepared by co-precipitation of Cu, Zn, and Al from their corresponding nitrates. Ceria was incorporated into the catalyst by impregnation of cerium nitrate either before or after calcination (6 hours at 350 °C or 400 °C). The chemical compositions of the resulting catalysts are reported in Table 62. 

Based on the activity test results, new experimental series with different impregnations on the same carrier are typically carried out in order to optimise the chemical composition for a given carrier. 

Alternatives to impregnation procedures coating procedures are another possibility for the application of different chemical compositions to a carrier -body. A sequential procedure can though lead to an onion like structure of the deposited components, which may not always be desirable, but for some applications one may also exploit this concept. In combination with impregnation procedures, coating procedures may prove to be most powerful and efficient... 

This chapter reports the study of the chemical composition of the polysulfide fraction in dicyclopentadiene and styrene modified materials, the mechanical properties of modified materials, and their use in the preparation of composite materials by the impregnation of polypropylene and glass-fiber fabrics. 

Our experiments are carried out in the presence of various types of micro-porous solids. They consist principally of alumina (CA), silica (CS), and activated charcoal (EC). For irradiation purposes with fission fragments, uranium is incorporated as an oxide by impregnation or coprecipitation methods. Microporous solids with variable uranium content are made available in this way with, as supporting phase, alumina (CAU), silica (CSU), and activated charcoal (ECU) 8, 9), respectively. Quite apart from the chemical composition, the knowledge of the physical structure of these solids is particularly important. For this reason a series of systematic measurements have been carried out on these solids of granulometry between 15 and 30 mesh. 

The catalyst is made by impregnating the beads with aqueous solutions of salts of some rare earth metals and of salts of the desired precious metals such as Pt, Pd and Rh these impregnated beads are then dried and calcined. The distribution of precious metals over the bead radius must be achieved with care, to balance the mass transfer requirements with the poison resistance requirements (Figs. 24-26). The distribution of the active component over the pellet radius can be measured by an Energy Dispersive X-ray (EDX) scan on an individual pellet. However, since in the application a relatively broad distribution in diameters occurs, special procedures have been developed to determine some kind of average distribution of the active components over the pellet radius. The most common procedure is the attrition test, in which a known mass of pellets of known diameter distribution is immersed in a liquid that neither dissolves the active components nor the carrier. The pellets are stirred for a defined time, and are separated from the attrited powder. The powder mass is determined, and its chemical composition analyzed by sensitive methods. 

An overview of the effect of the precipitation variables on morphology, chemical composition and performance in selective propene oxidation is given in Table 1.1. The precipitated catalysts without La addition to the solution showed a much lower selectivity than the selectivity of the catalysts prepared by impregnation reported in the Arco patents, which is 40-50% in comparable experimental conditions. At most, a selectivity of 8% was... 

The paper presents data on development of Mn oxide catalysts for selective oxidation of lean methane mixtures with air to produce CO2 and generate heat. To obtain catalysts, new approaches to the synthesis of polyoxide materials based on Mn were adopted. Catalysts were modified by doping with La, Ce, Ba and Sr nitrates which were deposited from solutions onto the stabilized 2%Ce/0-Al2O3 support (of surface area 100 m /g and pellet diameter 4-5 mm). By varying the components of the impregnation mixture, it was possible to optimize the chemical composition and ratio of elements in the multi-component catalysts (at Ba Sr La Ce Mn = 1 1 1 7 10 ratio). The catalyst composition conformed to the oxide stoichiometry in the perovskite structure. 

Palladium was deposited onto three different supports by incipient-wetness impregnation, as described elsewhere [16]. The supports, supplied by Condea GmbH, possess the following chemical composition AI2O3, Ba-Al203 and La-ALOs. The concentration of Ba and La, respectively, was 3 wt% for both supports. A Pd(N03)2 solution (Alfa Aesar, 8.41 wt%) was used as the metal precursor. The concentration of the solution was calculated to obtain a washcoat with a metal loading of 2.5 wt %. 

Electric Matches are small resin-impregnated paper strips on which conductive brass strips are laminated with a wire loop affixed over one end. Two layers of priming material—Formula 12—followed by a chlorate/charcoal/lacquer mixture for flame and fire transfer and protective coatings of clear lacquer form a bulb resembling a book-match tip. Ignition is achieved by a current of 500 mA for a minimum of SO msec. This is only one example out of a series of electric matches, which are manufactured to various current input requirements and also wifli different chemical compositions. 

Generally supported bimetallic catalysts are being prepared using the same procedures as for the production of monometallic supported catdysts, viz., impregnation, deposition-precipitation, and ion exchange. These procedures, however, usually result in supported catalyst precursors of a non-uniform chemical composition of tiie individual active particles. The variation of the cherrucal composition is mainly due to a lack of interaction between the two metals to be alloyed during the various steps of the preparation procedure. 

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