Deactivation methods

The catalysts used in the pilot unit are both equilibrium catalysts from the FCCU at the Statoil Mongstad refinery, and impregnated and deactivated fresh catalysts from different vendors. The catalysts have been impregnated with nickel and vanadium naphthenates. The amount of metals has varied over the years, but the nickel to vanadium ratio has usually been 2 3. The deactivation procedure has also changed over the years, as new deactivation methods have been developed and existing deactivation methods have been improved. 

The scope of the present study is to investigate the time extension of the conventional and the advanced CPS deactivation methods. Moreover, the impact of the deposited metals and their oxidation state during laboratory deactivation on the final properties of the deactivated samples is under research. The correlation of acidity changes during the deactivation with the catalytic performance is inquired for the understanding of the complex phenomenon of deactivation due to interrelation of the several variables in the process. 

In general, although proper metal aging is still an open issue, it seems that severe hydrothermal conditions during ReDox cycles with an emphasized reducing step is the direction to optimization of the artificial deactivation methods. The development of such a simulative lab-deactivation protocol will undoubtedly be very essential and a major contribution in the FCC research field. 

The route of catalyst deactivation via a cyclic metal impregnation and deactivation method has produced significant improvements in approaching realistic vanadium and nickel profiles over the catalyst particles. From electron microprobe analyses of Ni and V loaded catalyst it has been established that after pore volume saturation, Ni and V are rather homogeneously distributed over the catalyst. 

As described by Gerritsen et al [23] in the Cyclic Deactivation method the catalyst is deactivated by several Reaction and Regeneration (coke burning) cycles. As we will discuss in the next section of this paper, this is essential for the realistic aging of the metals. 

A possible explanation for this is that while dealumination in a commercial unit is fastt migration of non-framework alumina from the zeolite structure will be a function of temperature and steam partial pressure [24], This is an area in which the Cyclic Deactivation method approaches the commercial conditions much closer than traditional steaming methods. 

The foregoing combined with the observations made in 3.2 lead us to conclude that we need to try to simulate the deactivated catalyst as close as possible, preferably using the Cyclic Deactivation method. 

This method was directly derived from Saegusa s deactivation method 47). 

Sensitized photolysis is a much more efficient method to produce triplet nitrenes than the collisional deactivation method. This technique, which populates the triplet state of a nitrene exclusively by energy transfer, employs triplet sensitizers such as aromatic ketones with a high intersystem-crossing efficiency. Energy is... 

With time the interest for a better simulation of the commercial situation started to dominate the development of new more realistic test and deactivation methods. Realistic information on what to expect of the catalyst tested became the real target. 

Here the Cyclic Deactivation method approaches the commercial conditions much more closely than traditional steaming methods. 

A polymeric coating which is covalently bonded to the surface of capillary wall is the most significant approach among the surface deactivation methods. This... 

The rapid deactivation of catalyst was related to the break-point of the first pretreatment catalyst, and could be predicted by the metal capacity measurement for an accelerated deactivation method with Boscan crude oil. 

For the activity-limited operation the catalyst resistance to poisons with the ven feedstock will be the most important selection criterion. For the delta-coke-limited operation, a reduction of the commercial delta coke of the catalyst is crucial. Commercial delta coke consists of various components, which are discussed in this paper along with methods for their evaluation. In both cases the use of realistic catalyst deactivation methods and feedstock will be essential in order to arrive at the correct catalyst choice. 

The catalysts were impregnated with 5000 ppm V by the traditional Mitchel pore volume impregnation method and by the cyclic deactivation method. With the pore volume method (PV) the vanadium is distributed homogeneously over the catalyst. With the cyclic deactivation method (CD), the vanadium profile over the particle is as in commercial practice. 

Figure 11 shows that a high-accessibility system will give the best zeolite protection when evaluated by the realistic cyclic deactivation method. This has been confirmed in commercial operations (Figure 12). The FCC catalyst ability to rapidly deactivate the deposited metals will be an important factor in resid cracking.

Vanadium interacts with nickel in a manner which inhibits the deactivation behavior of nickel. Metals-resistant catalysts must therefore be evaluated in the presence of both nickel and vanadium. Also, the mobility of vanadium is reduced in the presence of nickel. In general, cyclic deactivation will be the preferred deactivation method in order to simulate the actual metal distribution and interactions on the catalyst and the correct metal age distribution. 

Other variants of technical interest include blocked reactive groups, that can be activated by heat or atmospheric moisture. Microencapsulation of polyisocyanates is also becoming a deactivation method. 

The catalyst deactivation method in [48] included the intensive mechanical impact both on a polymer solution and on a reaction mixture in a high molecular compound precipitation process. The physical gel is destroyed in this case and the results of the insoluble ds-l,4-polyisoprene fraction analysis indicates the gel-fraction content is formed by chemically crosslinked molecules (a chemical gel ). This effect is confirmed by the data of the insoluble fraction content in polyisoprene, which has been synthesised using different methods (Figure 3.24). The results of dynamic and static measurements of the insoluble fraction content are comparable, thus indicating, the formation of chemically linked branched structures. 

As for the sepetration of - C2 hydrocarbons, the most selective adsorbent to be used as stationary phase is aluminum oxide. With aluminum oxide it is possible to separate all C1-C4 hydrocarbons with high resolution, see Fig. 7-25. The retention behavior of C.) - C2 hydrocarbons on aluminum oxide depends on the deactivation method used. Most widely used is deactivation with KCI which results in a relatively apolar AI2O3 surface. Also other deactivating salts can be used, altering the polarity of AI2O3 surfaces... 

---