Cracking catalysts representative types

Steam pre-treatment of fluid cracking catalysts has been conventionally employed to represent the deactivation occurring in a commercial FCC unit. Appropriate steam pre-treatment methods have been developed so that the activity and selectivity of the steam pre-treated catalyst is equivalent to a commercially deactivated catalyst (12). However, a unique steaming method may not be suitable for catalysts of varying compositions (12). Two steaming methods designed to simulate deactivation in a commercial unit of the two types of catalysts used in this work were employed. Super-D was treated for 8 hours at 732 C with a steam pressure of 2 atmospheres. The catalysts containing ZSM-5 were treated for 12 hours at 827°C with a steam partial pressure of 0.2 atmosphere. 

Figure 1 shows the matrix surface area of conunercially aged Ecat for four types of cracking catalyst. Each set of data represents one type of cracking catalyst deactivated in different conunercial FCC units. The four types of catalysts were chosen fOT their wide range of matrix surface areas. Although the fresh catalyst matrix surface area for each catalyst type is similar, the equilibrium matrix surface area decreases by as much as fifty percent with increasing Na The variation of matrix surface could be attributed to other... 

This section provides brief descriptions of industrial processes in which noncatalytic gas-solid reactions play a major role. Although by no means complete, the discussion includes both traditional processes, such as the blast furnace for the production of iron from ore and the regeneration of fluidized-bed catalytic cracking catalyst, and newer processes such as the dry capture of SO2 from flue gas and the production of silicon for semiconductor applications. Each of the three primary reactor types is represented in the processes described. 

A preliminary overall picture of cracking catalyst structures is available in the first three horizontal rows of the composite plot of Fig. 2 and the corresponding data of Table I. Isotherms presented in the lowest row are discussed in Sec. IV. Only the general features of these representative types of cracking catalysts are indicated here, since the detailed plots of individual isotherms will be considered in subsequent sections on sintering. Cracking catalysts of principal interest are represented by three types silica-magnesia silica-alumina and activated clay. 

The CF and GF represent the coke- and gas-forming tendencies of an E-cat compared to a standard steam-aged catalyst sample at the same conversion. The CF and GF are influenced by the type of fresh catalyst and the level of metals deposited on the E-cat. Both the coke and gas factors can be indicative of the dehydrogenation activity of the metals on the catalyst. The addition of amorphous alumina to the catalyst will tend to increase the nonselective cracking, which forms coke and gas. 

As far as catalyst design is concerned, results seem to indicate that the specific coke caused by CCR will be higher for zeolite cracking than for matrix-type cracking. The foregoing adds support to our earlier statement that it is essential to test catalysts with a representative resid feedstock in order to obtain a realistic assessment of the delta coke of the catalyst. 

Many reactions that are catalyzed by a solid in a process that is heterogeneous have as the essential step the adsorption of the reactants on the solid surface. The preparation of catalysts having surface characteristics that make them more effective in this type of interaction is currendy a very important area of chemistry. In the cracking of hydrocarbons as represented by the equation... 

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