Impregnated tungsten

FIGURE 7.27. Coiled cathodes of porous impregnated tungsten for laser resonators. By courtesy of Plansee AG, Austria. 

Using of a source Cs nozzles with the contents of tungsten up to 75 % were investigated. The distributions received for a product without impregnation and after impregnation by tungsten are shown on fig. 1. 

The SCR catalyst designed for FCCU regenerator flue gas service is a homogenous monolith, typically made from 1 mm thick material. Some catalysts are extruded clays that receive a wash coat of titanium dioxide before impregnation of the vanadium and tungsten metals. Another type involves painted plates of expanded metal... 

Thorium nitrate is a reagent for measuring fluorine and for making thori-ated tungsten filaments. Thorium nitrate containing 1% cerium nitrate is the impregnating liquid in making incandescent gas mantles. 

Tungsten-based hydrotreating catalysts have been studied much less than the classical molybdenum-based catalysts. It is expected, however, that phosphorus addition should lead to similar effects in both cases since tungsten is chemically similar to molybdenum. Atanasova et al. (101) reported that phosphorus increases the thiophene HDS activity, especially that of a sequentially impregnated NiW—P/Al catalyst. Halachev et al (135) found that a maximum hydrogenation activity for naphthalene conversion is attained when the catalyst contains 0.6 wt% P2O5. Cruz Reyes et al (58) reported that phosphorus on a W/Al catalyst notably enhances gas oil HDS and pyridine HDN. 

These catalysts consist of the oxides of vanadium, chromium, molybdenum or tungsten deposited by co-precipitation or by impregnation on a silica or silica—alumina support. The catalysts require an activation process before use, and for those containing chromic oxide this consists of... 

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