Temperature oxygen regeneration

NOj, levels in the FCC flue gas typically range from 50-500 ppm. Nitrogen content of the feed, excess oxygen, regenerator residence time, dense phase temperature, and CO promoter all influence the concentration of NO. ... 

Sirotherm resins tend to be slowly oxidized by dissolved oxygen in raw water at the elevated temperature of regeneration this may be controlled by vacuum... 

This model of the active site and the deactivation mechanism are consistent with the fact the treatment by O2 or He at elevated temperatures cannot regenerate the catalyst. Although the carbonate most likely decomposes by 300°C, the decomposition only results in the formation of adsorbed oxygen. No hydroxyl is formed. Thus, the active site is not regenerated. 

Figure 16.7 Low temperature oxygen separation from air Oxygen permeation flux through a BCFZ hollow fiber membrane as a function of time at 500 °C. At this temperature a continuous decrease of the oxygen flux is observed. For regeneration, the fiber was heated to 925 °C, kept at this temperature for 1 h in air, then cooled down to 500 °C for the next run. Experimental details Air flow rate on the shell side= 150 mL min He flow rate on the core side = 30 mL min 0.43 cm effective membrane area.

In the absorbent cycle of the Wellman-Lord Process, as in all alkali-based SO2 removal processes, some oxidation to sulfate occurs due to oxygen in the gas stream, hr addition, at the temperature of regeneration, disproportionation is possible by the following reaction ... 

The first process utilizes a bed of nickel catalyst which has been regenerated with hydrogen to reduce the nickel content to metallic form. The finely divided metal then reacts with impurities and retains them in the bed, probably as nickel oxide in the case of oxygen or as physisorbed compounds for other impurities. Periodically, the bed is regenerated at elevated temperature using hydrogen to restore the metallic content. The nickel process can be used and regenerated indefinitely. 

Two other methods worth discussing are wet air oxidation and regeneration by steam. Wet oxidation may be defined as a process in which a substance in aqueous solution or suspension is oxidized by oxygen transferred from a gas phase in intimate contact with the liquid phase. The substance may be organic or inorganic in nature. In this broad definition, both the well known oxidation of ferrous salts to ferric salts by exposure of a solution to air at room temperature and the adsorption of oxygen by alkaline pyrogallol in the classical Orsat gas analysis would be considered wet oxidations. 

Unexpected concentration of oxygen can occur when compressed air is dried or purified by pas.sing it over certain types of molecular sieves. Nitrogen is absorbed preferentially after regeneration, and the air first produced may be rich in oxygen. This can widen flammability limits and lower auto-ignition temperatures. At least one explosion has occurred as a result. If possible, use Type 3A molecular sieves [21]. 

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