Catalysts discharge

Cobalt catalysts discharged from oxo -process reactors are frequently pyrophoric, owing to the presence of the carbonylcobalt. 

Figure 11.6 Examples of methanol synthesis converters (a) tube-cooled, low-pressure reactor A nozzles for charging and inspecting catalyst B outer wall of reactor as a pressure vessel C thin-walled cooling tubes D port for catalyst discharge by gravity (b) quench-cooled, low-pressure reactor, A,B,D, as in (a) C ICI lozenge quench distributors (Twigg, 1996, pp. 450, 449 reproduced with permission from Catalyst Handbook, ed. M.V. Twigg, Manson Publishing Company, London, 1996.)...

TEM/EDX investigations were carried out on samples of catalyst B taken from the upper bed region exposed to molten carbonate for 0, 50, 100 and 1000 hours. Representative examples of this catalyst, discharged after 2500 hours from all three regions of the bed, were also probed using this technique. 

Figures 3.5 and 3.6 show typical EDX spectra obtained from a sample of catalyst B after 1000 hours of use in a molten carbonate environment. Figure 3.5. shows the spectrum recorded from the nickel aggregate Figure 3.6. shows that recorded from the alumina support. Inspection of all the data reveals that up to and including 50 hours of operation, potassium covered both the support and the nickel areas of the catalyst. However, for catalysts discharged after 100 hours, potassium is associated primarily with the alumina support.

J—housing g-support ring J—Inlet pipe connection dlKhars pipe connection 4—geTe —catalyst discharge pipe connection —porcelain balls ... 

E - Gas from external start up heater F - Quench gas inlets G — Pyrometer H - Catalyst discharge noaale... 

Traditional Air-Met Battery (for instance, with carbon catalysts) Discharge Process ... 

Preheat burners are usually designed to increase the temperature of the contaminated gases to the required catalyst discharge gas temperature without regard to the heating value of the contaminants (especially if considerable concentration variation occurs). 

The metal supported catalysts were characterized by FTIR spectroscopy, TEM analyses, surface area and metal dispersion determinations. The 5% Ru/Nb205 catalysts, discharged after the activity tests, were subjected to pulse NO chemisorption in a ZnSe DRIFTS cell at 423 and 523 K. 

Catalytic stability of a Pd/H-Mordenite catalyst for C5/C6 hydroisomerization was tested in a laboratory reactor for 1000 hours. The content, chemical composition and structure of the coke formed on the catalyst discharged from a pilot reactor working in an accelerated condition was characterized using XRD, EPR, MAS-NMR, FTIR and TPO techniques. The catalyst shows stable catalytic activity and selectivity during 1000 hours. The nature of the coke and its combustion behavior depended upon time on stream and varied with the catalyst bed length. As time on stream increased, coke initially formed on palladium metals and then moved to acidic sites on the support where polyaromatic or pseudographite-like structures were formed through further acid catalyzed reactions. 

The pilot-reactor was a stainless steel cylinder with 4.5m in length and 0.25m in diameter. It loaded 100 kg of 0.5 wt% Pd/H-mordenite catalysts. The coked catalysts, discharged from the inlet, central and outlet sections in the catalyst bed were represented as D, Dc and Do respectively. The catalyst activity was defined as iCs/ZCs or iCJZCf, while selectivity was defined as 2,2 dimethylbutane (2,2 DMB) yield because of its high concentration and octane ratings. 

Table 2 Elemental analysis of coke on Pd/HM catalyst discharged from various sections of the reactor.

Figure 2. FTIR spectrum of the coke separated from the coked Pd/HM catalyst discharged from the central section of the of the polite reactor.

For example, the life of catalyst in some plants is less than a year, the shortest period being less than 100 days (as plant A in Table 8.33), it is often suspected that the catalyst itself is not good or has poor anti-poisoning property. In reality, any metal catalyst, including the Fe catalyst that all can not resist to sulfur poisoning. Metal catalysts can not have anti-sulfur poisoning ability. In order to prove this view, the sulfur content is measured in waste catalysts discharged from these plants, as shown in Table 8.33, to identify the cause of short life. 

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