FCC catalysts

Fig. 5. Effect of fines particle size on (a) bubble size for FCC catalyst, of Pp = 1250 kg/m, decreases with increa sing fines content, U = 0.1 m/s and...

Fig. 8. (a) Schematic for an FCC unit showing where the various fluidization regimes are found and (b) a corresponding phase diagram for Group A powder (FCC catalyst) where the numbers on the curves represent the superficial soHd velocity in m/s. A represents the bubbling regime B, the turbulent ... 

Fig. 10. Expansion curve for FCC catalyst in a 0.15-m inner diameter column showing the fluidization regimes where the numbers on the lines correspond...

Bed-to-Surface Heat Transfer. Bed-to-surface heat-transfer coefficients in fluidized beds are high. In a fast-fluidized bed combustor containing mostly Group B limestone particles, the dense bed-to-boiling water heat-transfer coefficient is on the order of 250 W/(m -K). For an FCC catalyst cooler (Group A particles), this heat-transfer coefficient is around 600 W/(600 -K). 

Coke deposition is essentially independent of space velocity. These observations, which were developed from the study of amorphous catalysts during the early days of catalytic cracking (11), stiU characteri2e the coking of modem day 2eohte FCC catalysts over a wide range of hydrogen-transfer (H-transfer) capabihties. 

The activation energy for burning from a coked zeoHte has been reported as 109 kj/mol (29) and 125 kj/mol (30 kcal/mol) has been found for coke burning from a H-Y FCC catalyst. Activation energies of 167 kJ/mol (40 kcal/mol) (24) and 159 kJ/mol (25) have been reported for the burning of carbon from a coked amorphous siUca-alumina catalyst. 

Multiftmctional SO removal catalyst systems have been ia commercial use siace 1985 ia the United States. Such systems have successfully reduced SO emissions in the FCCU regenerator by 50% when the regenerator is operating in the complete CO combustion mode (45). Modern-day additives can achieve a 50% SO reduction with only IS—2% of the additive in the circulating inventory, an amount small enough not to interfere with the cracking characteristics of the bulk FCC catalyst (45). 

L. L. Upson, "How to Design Your Own FCC Catalyst," presented at Katalistiks SthMnnualFCC Symposium, Budapest, Hungary, June 1987. 

A rare-earth chloride, mischmetal FCC catalysts kon metallurgy principal component... 

B lanthanum concentrate. La—Ln chloride FCC catalysts b minor component... 

Octane-Enhancing Zeolitic FCC Catalysts, Julius Scherzer... 

Aluminum distribution in zeolites is also important to the catalytic activity. An inbalance in charge between the silicon atoms in the zeolite framework creates active sites, which determine the predominant reactivity and selectivity of FCC catalyst. Selectivity and octane performance are correlated with unit cell size, which in turn can be correlated with the number of aluminum atoms in the zeolite framework. ... 

Davison Division of W.R. Grace Co. developed micro-spheroidal FCC catalyst. 

Mobil Oil developed USY and ReY FCC catalyst. Last TCC unit completed. 

Except for sulfur, all these contaminants poison the FCC catalyst, causing it to lose its ability to produce valuable products. Sulfur in the feed increases operating costs because additional feed and product treatment facilities are required to meet product specifications and comply with environmental regulations. 

These metals permanently poison the FCC catalyst by lowering the catalyst activity, thereby reducing its ability to produce the desiretl products. Virtually all the metals in the FCC feed are deposited on the cracking catalyst. Paraffinic feeds tend to contain more nickel than vanadium. Each metal has negative effects. 

Alkaline earth metals in general, and sodium in particular, are detrimental to the FCC catalyst. Sodium permanently deactivates the catalyst by neutralizing its acid sites. In the regenerator it causes the zeolite to collapse, particularly in the presence of vanadium. Sodium comes from two prime sources ... 

Schcr/cr, J., and McArthur, D. R, Nitrogen Resistance of FCC Catalysts, presented at Katalistiks 8th Annual FCC. Symposium, Venice, Italy, 1986,... 

A complete discussion of FCC catalysts would fill another book. This chapter provides enough information to select the proper catalyst and to troubleshoot the unit s operation. The key topics discussed are ... 

FCC catalysts are in the form of fine powders with an average particle size in the range of 75 microns. A modern cat cracking catalyst has four major components ... 

Zeolite, or more properly, faujasite, is the key ingredient of the FCC catalyst. It provides product selectivity and much of the catalytic activity. The catalyst s performance largely depends on the nature and quality of the zeolite. Understanding the zeolite structure, types, cracking mechanism, and properties is essential in choosing the right catalyst to produce the desired yields. 

Zeolites employed in the manufacture of the FCC catalyst are synthetic versions of naturally occurring zeolites called faujasites. There are about 40 known natural zeolites and over 150 zeolites that have been synthesized. Of this number, only a few have found commercial applications. Table 3-1 shows properties of the major synthetic zeolites. 

FCC catalyst vendors are now able to manufacture catalysts with a sodium content of less than 0.20 wt%. Sodium is commonly reported as... 

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