Manufacture of Catalysts

Nickel carbonate is used in the manufacture of catalysts, in the preparation of colored glass (qv), in the manufacture of certain nickel pigments, and as a neutralizing compound in nickel electroplating solutions. It also is used in the preparation of many specialty nickel compounds. 

Niobium is used as a substrate for platinum in impressed-current cathodic protection anodes because of its high anodic breakdown potential (100 V in seawater), good mechanical properties, good electrical conductivity, and the formation of an adherent passive oxide film when it is anodized. Other uses for niobium metal are in vacuum tubes, high pressure sodium vapor lamps, and in the manufacture of catalysts. 

Ca.ta.lysts, A more important minor use of chromium compounds is ia the manufacture of catalysts (Table 14). Chromium catalysts are used ia a great variety of reactions, including hydrogenations, oxidations, and polymerizations (229—231). Most of the details are proprietary and many patents are available. 

Uses. In specialty reactions as a source of Cr manufacture of catalysts polymerization of olefins curing agent for urethane resins... 

Alumina-supported nickel catalysts are an excellent example for the advantages of and the problems associated with coprecipitation processes for the manufacture of catalysts. Such catalysts are accessible via several pathways, as impregnation, deposition/precip-itation, coprecipitation from alumina gels, and more conventional coprecipitation routes. Also, for coprecipitation, different routes are possible, the first examples originating from the 1920s [48]. Starting from the nitrate solutions of nickel and aluminum, there are at least three different routes ... 

Undercooling is the driving force in freeze drying. An aqueous salt solution is introduced dropwise into an immiscible liquid (hexane or a petroleum fraction such as kerosene) cooled below 243 K. The individual droplets are frozen instantaneously and the solid particles are decanted or filtered. The frozen particles are then sublimed in a vacuum to obtain a homogeneous powder of fairly uniform particle size. Important parameters in freeze drying are the final temperature of the salt solution and the cooling rate. These can be controlled to some extent, but only on a small scale. Hence the method is not very suited for large-scale manufacture of catalysts. 

Chromium 50d X X The leather tanning industry manufacture of catalysts pigments and paints fungicides the ceramics and glass industries photography chrome alloy chromium metal production chrome plating corrosion control 111, 23,3231, 3512,3521,3522, 361,362,372, 38, 94... 

The manufacture of catalysts and special glasses from rare earths... 

Use Mordant for dyeing, pigments, manufacturing of alizarin, chrome alum, oil purification, pickling, manufacture of catalysts, leather tanning, synthetic perfumes, photography, process engraving and li-... 

During the course of crystallization, but especially in the subsequent recrystallization process the physico-chemical properties of the samples vary to a considerable extent with respect of the nature of the gallium, the crystal size and shape, and the perfection of the lattice, although the overall composition of the Ga-ZSM 5 samples as well as their structure remains essentially unchanged. The manufacturing of catalysts with desired properties on the basis of Ga-ZSM 5 has to take into account these circumstances. 

All features depend on the application and the feed properties. Capacities, although strongly influenced by the material as well as the pellet size and shape, may be as low as a few hundred kg/h and, on the high end, exceed 80 t/h. As visible from the dies shown in Fig. 8.50, most of the extrusion channels in pellet mills are cylindrical bores however, as depicted in the center of this Fig. (8.50), square openings (and others) are provided for specific applications (for example, the manufacturing of catalyst carriers). As a typical product of pellet mills, Fig. 8.56 presents some cylindrical animal feed pellets. 

Extruders are also used in the production of sintered industrial parts. Of special importance is their application for the manufacture of catalyst carriers (Section 6.3.2, Figs. 6.3-20 and 6.3-21). The use of wear-resistant alloys for all parts that come in contact with the material to be extruded make the extruders suitable for the processing of highly abrasive catalysts, other chemicals, and minerals, such as molecular sieves, high-purity aluminas, and kaolin carriers. Interchangeable die plates allow the extrusion of an almost unlimited variety of sizes and shapes on the same basic machine that is then equipped with a variable-speed screw-drive to adjust retention time, pressure, and production rate. 

Fig. 6.3-21 Special extruder for the manufacture of catalysts or catalyst carriers. A hinged die holder allows the quick exchange of extrusion plates (courtesy Bormot, Uniontown, OH, USA)...

Purity The purity of activated carbon is essential for the performance of the final catalyst. Impurities of activated carbon originate from the raw material and the process conditions. Ash contents of up to 20% can be possible. Wood-based activated carbons have ash contents as low as 1 wt% [7]. The ash content can be lowered further by acid treatment of the activated carbon [8]. Typically, the ash consists of alkaline and alkahne earth metal oxides, silicates, and smaller amounts of other compounds (e.g., iron). The presence of the alkaline and alkaline earth metal oxides makes those carbons more basic in nature, so that some additional adjustments are necessary during catalyst manufacturing to meet the constant quality requirements. Since the supports are used in catalysts, the presence of catalytically active compounds that could have a potential influence on the performance of the final catalyst has to be considered as well. For the manufacture of catalysts, activated carbon based on wood, peat, nut shells, and coconut are commonly used. Due to a relatively high sulfur content in activated carbons derived from coal, those carbons are typically not used as catalyst support. 

Pyrometallurgy Manufacture of catalysts Building manufacture Manufacture of ceramics Potter s manufacture Pharmaceutical manufacture Production of explosives Polymers... 

Klabunovskii, E.I., Mordovin, V.P., Pisarev, Yu.N., and Artem ev, V.A. (1997) Manufacture of catalyst for conversion of methanol into hydrogen-carbon monoxide mixture, Pat. Russian Federation 2087189, 20.08.1997, Chem. Abstr. 1998,128, 90728g. 

There is no generally-acknowledged method or measuring unit to specify the extrusion behaviour of ceramic bodies. In order to obtain an adequately precise description of the extrusion behaviour, numerous specific methods do exist, which have to be chosen according to the material, for example for bodies to produce bricks and tiles or bodies for the manufacture of catalyst converters, as well as methods relating to specific application requirements, be it for example for the purposes of production, quality control or development of the body. 

Washing and adsorption The belt filters are used for washing and dewatering of fine solids in the manufacture of catalysts, zeolites, alumina and other crystalline substances, and so on. The belt filter requires the associated equipment — several vacuum pumps and separation drums. Through-circulation tray driers and through-circulation rotary driers are used to dry solids. All these are continuous crosscurrent processes. These could be replaced with a moving-bed, Hildebrand (screw) conveyer or Kennedy extractor [18], each of which is a countercurrent process. Their potential for PI has not been explored. 

Personal correspondence and discussions with senior engineers and representatives of manufacturers of catalysts (Catalyst India Ltd, Mont-Edison at JakartaX Refractory materials (ACE-Calderys Relractories, SKG Relractories), fabricators of mechanical equipments (VK Engineers, India and many others). Scrubbing systems and Candle Demisters-(Evergreen Technologies) ... 

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