Equilibrium catalyst fraction

Correlation of Equilibrium Catalyst Fraction Properties with Fraction Densitv/Age... 

Table IV. Digisorb Analyses of Coked and Regenerated Equilibrium Catalyst Fractions...

The comparison of physical properties of laboratory-steamed catalyst with those of equilibrium catalyst fractions given in Table VII indicates that a wide range of steaming temperatures is necessary to reproduce the equilibrium catalyst deactivation profile for lab steaming times of one day or less. These results indicate that an improved catalyst aging procedure for simulating... 

The results for residual carbon on equilibrium catalyst fractions (Figure 2) and for cumene cracking on regenerated equilibrium fractions (Table V) also indicate that cracking activity shows little dependence on zeolite content following completion of framework dealumination (minimum unit cell size). 

Assuming non-selective adsorption and observing that the equilibrium catalyst Fraction A exhibits a crystallinity of 28% with a micropore volume of 0.075 cc/g, the expected increase in density due to a given change in micropore volume, Ampore, is ... 

A decrease in the 0 to 40 microns fraction of the equilibrium catalyst or an increase in average particle size... 

Coke Deposition. The properties of catalyst fractions separated in coked condition from spent equilibrium catalyst are summarized in Tables III and IV. The distribution of catalyst fractions along with the percent carbon found on each coked fraction is given in Figure 2. The activity for coke deposition falls off sharply with increase in density. Only the three lightest fractions show a coke make that is significantly above the minimum coke make exhibited by the heavier fractions. The fact that the lightest fractions are the most active is consistent with the notion that they are the youngest. The distribution of catalyst... 

Figure 4), by which time dealumination is largely complete. There follows a steady rate of zeolite destruction which results in an additional 42% loss of crystalline zeolite (relative to fresh catalyst) over the next 80 days (see Figure 4, Fractions B-F). Fraction F, representing the end point of the USY catalyst distribution, retains only 38% of the crystallinity characteristic of fresh catalyst. Fractions A-D, representing the major portion of this equilibrium catalyst, exhibit relative crystallinity retentions ranging from 83 to 66%.

Comparison with Lab Steam Deactivations. Catalyst fractions which exhibit 50% or greater loss in micropore volume/crystallinity comprise less than 15% of equilibrium catalyst. The major portion of this particular equilibrium catalyst is remarkably similar to the material which results from increasingly severe laboratory steam deactivations at 815°C or less (Tables VI and VII). Dealumination is rapid, the associated crystallinity loss is small, and the matrix surface area shows little change. Crystallinity retention falls below 70% only after dealumination is complete. 

A successful separation by density into fractions of increasing age has been obtained for the USY equilibrium catalyst of this study. The nickel level on each catalyst fraction, which is expected to furnish a stable age marker, increases with increasing density/age. The observed decrease in the V/Ni ratio with increasing age is indicative of interparticle vanadium migration. The trend of increasing Ni level with increasing density has been used to correlate increases in density with "Ni days" in the unit. 

In Figure 5 the iso-C4/total C4 ratio as a function of conversion is illustrated, reflecting the ability of the catalysts to produce branched species and thus to affect, in particular, the octane number of the gasoline fraction. It is evident that MCM-41 produces a much lower amount of branched products compared with the equilibrium catalyst. 

Dual particle traps can frequently be separated from equilibrium catalyst if their densities are slightly different. The two fractions can then be analyzed for vanadium. If the trap is preferentially picking up vanadium, then it confirms that the technology is working even if there is too little trap in the inventory to improve the microactivity or if another variable is at work reducing microactivity. We have found the ratio of vanadium on the two fractions to be an effective means of confirming trap performance. We refer to this ratio as the Pick-up Factor (PUF) and express it as follows ... 

As predicted by theory, the position of the ring/chain equilibrium was found to be independent of the nature of the redistribution catalyst employed (acid or base) (4,13,24- ) and of the specific inert solvent used (26). Russian authors (4,27) equilibrated mixtures of eyelosiloxanes comprised of dimethylsiloxane (75 mole %) and either trifluoropropylmethyl, cyanoethylmethyl, or cyanopropylmethyl siloxane (25 mole %) in acetone at a siloxane repeating unit concentration of 0.833 moles/A. They measured the dipole moments of the respective cyclosiloxanes, [(CH3)9SiO]3[Si(CH3)R0j>, to be 2.76 for R = trifluoropropyl, 3.45 for R cyanoethyl, and 3.58 in the case of R cyanopropyl. The equilibrium weight fraction of rings,... 

Instead of the static methods implied above for determining the equilibrium mole fractions and pressure, flow methods can be used in which the reactant gases are made to flow at measured rates through a reaction chamber (for example, a long tube) in which they are allowed a sufficient residence time to reach equilibrium. The effluent gas is then analysed. Flow methods are especially useful for reactions which are slow in the absence of a solid catalyst the reaction chamber is then loosely packed with solid catalyst. 

Equilibrium catalyst attrition index and average particle size distribution (APS) indicate changes in the rate of catalyst attrition. Further analysis of APS for any catalyst that is carried forward into the fractionator, present in the slurry, or which leaves the unit via the regenerator stack can identify problems associated with catalyst quality or cyclone operation. Problems include operation at greater than design feed, catalyst rates or cyclone maloperation. APS is also important in predicting the fluidization properties of the catalyst inventory. 

A catalyst is a material that accelerates a reaction rate towards thennodynamic equilibrium conversion without itself being consumed in the reaction. Reactions occur on catalysts at particular sites, called active sites , which may have different electronic and geometric structures than neighbouring sites. Catalytic reactions are at the heart of many chemical industries, and account for a large fraction of worldwide chemical production. Research into fiindamental aspects of catalytic reactions has a strong economic motivating factor a better understanding of the catalytic process... 

AH (A)-menthol is made by synthetic methods. One method involves the cyclization of (+)-citroneIlal (68). Using a mild acid catalyst, (+)-citroneIlal [2385-77-5] undergoes an ene-reaction to produce a mixture of isopulegols (142). Catalytic hydrogenation of the isopulegol mixture gives a mixture of menthol and its isomers. The (A)-menthol is obtained after efficient fractional distillation and the remaining isomers can be equilibrated, usually with sodium menthol ate or aluminum isopropoxide. An equilibrium mixture is obtained, comprised of 62 wt % (A)-menthol, 23 wt % (+)-neomenthol, 12 wt % (+)-isomenthol, and 3 wt % (+)-neoisomenthol. The equilibrium mixture can be distilled to recover additional (+)-mentbol. 

A closer analysis of die equilibrium products of the 1 1 mixture of methane and steam shows the presence of hydrocarbons as minor constituents. Experimental results for die coupling reaction show that the yield of hydrocarbons is dependent on the redox properties of the oxide catalyst, and the oxygen potential of the gas phase, as well as die temperamre and total pressure. In any substantial oxygen mole fraction in the gas, the predominant reaction is the formation of CO and the coupling reaction is a minor one. 

This refers to the total gas flow through a plane of catalyst where Nx is the mole fraction of X in the gas passing through the plane, NWeq is the mole fraction of X at equilibrium under conditions at this point in the catalyst bed, and dv is the incremental catalyst volume. 

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