Oxygen, atomic added gases

Other workers have added THF or H2O to the carrier gas stream in efforts to affect the requisite vapor pressure increase in Ba(/3-diketonate)2 compounds. " The objective of all these experiments was to coordinatively saturate the barium atom in the vapor phase by incorporation of the lone pair electrons on the oxygen atoms of the neutral ligands into the bonding sphere of the metal. At the temperatures demanded for vapor transport, the equilibrium for dissociation of these ligands is rather unfavorable therefore, any anticipated gain will be minimal. 

Figure 118. Conversion of nitrogen oxides reached over a NO.x reduction catalyst at 498 K for different classes of hydrocarbons and oxygenates added to the exhaust gas, as a function of the number of carbon atoms in the molecule of the organic component (catalyst and test as for Fig. 116 except that the NO.x concentration is fixed at 270 vol.ppm and that various hydrocarbons or oxygenates are added to a fixed concentration of 3200 vol.ppm C ). Reprinted from ref [72] with kind permission of Elsevier Science.

The enzyme in question is one of the oldest zinc protein enzymes, carbonic anhy-drase. This enzyme effectively hammers an extra oxygen atom onto CO carbon dioxide, making COf, the three-oxygen carbonate ion. The added oxygen pins down the gas so it can dissolve better in water. In the normal enzyme, zinc holds water still, so its oxygen can be added to CO. The cadmium enzyme uses cadmium to do the same thing. 

Af/ads is the heat of adsorption from the gas phase, which takes into account the dispersion interaction of hexene with the oxygen atoms in the wall of the zeolite pores. This energy depends both on the size of the reactant (hexene in this case) and the size o .the pores in the zeolite (Figure 8a and 8b) and is estimated with the configurational-bias Monte Carlo method (CB-MC). - The CB-MC method differs from conventional Monte Carlo (see Monte Carlo Simulations for Polymers) in so far as.ti guest species is grown atom by atom inside the host rather than inserted as a complete molecule. ... 

The reaction of ethylene with adsorbed oxygen atoms to form carbon dioxide is inhibited by adding a few parts per million of ethylene dichloride to the process gas. The chlorine atoms cover a significant proportion of the silver surface, and the rate of oxygen adsorption is reduced. This can deactivate the catalyst. Moreover, at high levels of chloride in the process gas, the catalyst eventually becomes chlorided and thus deactivated. The alkaline promoter in the catalyst can store chlorine and help control deactivation, but it can also lead to a small decrease in selectivity. The effect of chlorine on silver can be reversed by the addition of methane or ethane to the feed. ... 

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