Ultra-pure gases

To produce polymer on a planar CrOx/SiO2/Si(100) model catalyst in a flow of ethylene, one needs to consider that a sample of 1 cm2 exposes no more than 1014 highly reactive chromium ions, which makes the model extremely sensitive to deactivation by impurities such as water or acetylene. Hence, working with ultra-pure gases, cleaned by filters close to the position of the model catalyst, is crucial [90],... 

The rate of ion formation in flames has been studied by many techniques and shown to be a complex phenomenon which must take account of thermal and chemiionization, of charge transfer and ion recombination. The ionization may be dominated by an added substance of low ionization potential, or it may be the natural ionization of a hydrocarbon flame. This natural ionization is of widespread importance, and it has been suggested that even in so-called pure hydrogen flames, the background ionization is due to traces of hydrocarbon. Other experiments with ultra-pure gases have yielded strange, though unconfirmed, results. 

If large samples of air are taken from the interior of the car, ultra-pure gas must be added to balance the draw-off. 

Adsorption and desorption on and off materials are negligible in the case of metals, in the case of plastic materials, however, as they are used for seals, membranes, valve seats, they develop values that have to be noted. Plashes are able to adsorb considerable amounts of gases and vapours and to desorb them again. Even the plashc material itself can desorb volahle components such as softening agents. Therefore, care has to be taken that independent from the applicahon the amoimt of plastic components in the ultra-pure gas systems is as low as possible. 

Unlike the RDE technique, which is quite popular for characterizing catalyst activities, the gas diffusion electrode (GDE) technique is not commonly used by fuel cell researchers in an electrochemical half-cell configuration. The fabrication of a house-made GDE is similar to the preparation of a membrane electrode assembly (MEA). In this fabrication, Nation membrane disks are first hot-washed successively in nitric acid, sulphuric acid, hydrogen peroxide, and ultra-pure water. The membranes are then coated with a very thin active layer and hot-pressed onto the gas diffusion layer (GDL) to obtain a Nation membrane assembly. The GDL (e.g., Toray paper) is very thin and porous, and thus the associated diffusion limitation is small enough to be ignored, which makes it possible to study the specific kinetic behaviour of the active layer [6],... 

On-Site Generation of Chlorine Gas and Caustic and/or Ultra-Pure High-Strength Hypochlorite... 

Figure 5 is the on-site ultra-pure hypoehlorite generation system sehematic (13). The same eleetrolyzer unit is used in the two sehematics (Figs. 5 and 6), except there are a few minor differences in the new schematic shown in Fig. 6, the chlorine gas and... 

TG-DTG measurements were made with a DuPont Model 951 thermo-gravimetric analyzer equipped with a 1091 disk memory. Weight loss data were obtained as a function of time and temperature. Samples were heated from room temperature to 900°C at a rate of 10°C/min. The purge gas was ultra-pure nitrogen, typically at... 

The most common industrial method to make ultra-pure hydrogen is by steam-methane reforming (SMR) using a catalyst at the temperature 890-950° C. The reformed gas is then subjected to a high temperature water gas shift (WGS) reaction at 300-400°C. The WGS reactor effluent typically contains 70-80% H2, 15-25% CO2, 1-3% CO, 3-6% CH4, and trace N2 (dry basis), which is fed to a PSA system at a pressure of 8-28 atm and a temperature of 20 0°C for production of an ultrapure (99.99+ mol%) hydrogen gas at the feed pressure. Various PSA systems have been designed for this purpose to produce 1-120 million cubic feet of H2 per day. 

A simple, but representative, example of the application of THERDAS to the investigation of chemical vapour deposition (CVD) processes is the production of ultra-pure silicon by the thermal decomposition of SiHCl3 gas. In this process, it is of technological and ecological importance to establish the optimum temperatures for the maximum yield of pure silicon from the decomposition reaction. 

CCRIS 6831 EINECS 232-2634 Plots 100SCO HSDB 5351 Monosilane Silane Silicane Silicon tetrahydride UN2203. Used as a doping agent, source of ultra-pure silicon for eiectronics fabrication. Gas mp = -185 bp = -112 d" = 0.68 dec. in H2O, insoluble in organic solvents. 

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