Gas oil cracking activities

Gas Oil Cracking by the Dual Zeolite Catalyst. After the steam pre-treatment, the gas oil cracking activity of REY was about 100 times greater than the activity of the pure matrix catalyst. 

Activity per Unit Surface Area for Gas Oil Cracking. A second order kinetic conversion parameter (conversion + 100 - conversion) was used (13) to monitor gas oil cracking activity. The activity relationship as a function of surface area and catalyst composition is described in Figure 4. As expected, activity increased linearly with surface area. Activity per unit surface area depended on composition and increased with increasing alumina content. 

The distribution of A1 spedes of varying coordination (tetrahedral, pentacoordinated and octahedral) can be influenced by changing the conditions of hydrothermal pretreatment of amorphous silica-alumina catalysts. However, for a given composition, activity per unit surface area and selectivity were independent of pretreatment conditions. Thus, gas oil cracking activity and selectivity in amorphous silica-alumina cannot be... 

A new class of hi alumina silica-aluminas has been prepared with hi pore volume and with controllable pore size. For 20 wt % Si02 content materials steam treatment at 760°C serves to substantially increase the gas oil cracking activity. Steam stability at 870°C has also been demonstrated for these unique materials. These samples are prepared by recrystallization of co-gels of aluminum and silicon alkoj compounds losing a two-step procedure. AmorjAious alumina shows similar physical properties to those of the silica-alumina co-gels vhen re-crystallized in an analogous manner. 

If water was added to the 15% Si02 co-gel to fill the pore voids a partially recrystallized boehmite was formed with a surface area of 464 m /g and with a pore volume of 1.8 oc/g. If water was added to the 15% Si02 co-gel to form a slurry and then dried and calcined at 500 a partially recrystallized bodunite was formed with a surface area of 334 m /g. steam treatment at 760 of this second, small pore, bodunite-like silica-alumina resulted in no change in the surface area. The gas oil cracking activity of the steamed sample was definitely hi er than that for the amorphoias co-gel, i.e., a Micro Activity Test (MAT) Activity Number of 38 (see Table 1.). 

In conclusion, it can be said that gas-oil cracking activity does not depend only on the unit cell size. During dealumination... 

After separation from its quartz matrix, the beneficiated rectorite dries into aggregates of flakes resembling mica particles. Similar materials are obtained also after drying the product of the pillaring reaction. Prior to evaluation for gas oil cracking activity, the pillared rectorite samples were crushed and sized into 20x60 mesh (flake-like) particles and calcined. Typical chemical composition of these clay catalysts is given in Table I. 

The activity of a cracking catalyst declines with time on stream. A case of gas oil cracking has the rate equation, dC 8.5C ... 

Finally, the variation of the yields of gasoline and diesel versus A1 per unit cell allow us to conclude that highly steam-dealuminated HY zeolites behave, from the point of view of gas-oil cracking, like a well-dispersed active alumina. 

Comparison of the catalytic properties of H-Beta and H-Y zeolites for cracking n-heptane and gasoil shows that zeolite Beta should have more than one type of channel with different dimensions. For gas-oil cracking, zeolite Beta is less active and produces more coke and less gasoline than zeolite HY. 

Figure 7. Comparison between H-Beta zeolites (open circles and dashed lines) and HY zeolites (continuous lines) for gas-oil cracking (a) First-order activity constant by specific surface area vs, Si/Al ratio (b) and (c) Average total conversion vs. gas-oil ratio for a H-Beta with Si/Al=27 and a HY Si/Al=35, and for a H-Beta with Si/Al=10 and a Hy with Si/Al=7.7 respectively. Solid circles correspond to the H-Beta steamed at 750 C and 1 atmosphere of water pressure.

H-Beta are more active for n-heptane cracking than HY-zeolites with the same Si/Al ratio, while for gas-oil cracking the opposite occurs. Nevertheless we have not looked here to mesoporosity of the zeolites which may be critical for explaining the activity in gasoil cracking. Steaming causes a smaller decreases in activity of H-Beta than on HY zeolite. H-Beta gives a lower ratio than... 

Figure 8. Correlation between catalyst activity for gas-oil cracking and Br nsted acidity of Ca, Mn, and REX zeolites...

Thus, the rates of activity decline are substantially constant for these two cases, and the gasoline production is similar with both operations. This is true even though the initial activity of the catalyst employed for cracking the heavy gas oil falls toward the terminal activity of the catalyst applied to the light gas oil cracking operation. 

Cruz et al. (36) also found that AFS preferentially dealumi-nates the surface of zeolite Y crystals to a depth of about 100 A and produces an extra-framework-Al-free zeolite. They found that the activity for n-heptane cracking is the same as for a steamed dealuminated sample, while the gas oil cracking was lower, being controlled by the outer shell. 

The decomposition of organic templates in SAP0-37 and the evolution of the hydroxyl groups upon calcination as well as the stability of the framework have been followed by IR spectroscopy. Moreover, activity and selectivity to n-heptane and gas-oil cracking allow us to discuss the acidity character of SAP0-37 as compared to USY zeolites. 

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