Laboratory steam deactivations

These results on commercially-aged samples show that silica is transported from the cracking catalyst particles to the Additive R particles during commercial-unit aging, just as it is during a laboratory steam deactivation. More Importantly, the data show that silica deactivates Additive R in a commercial unit (loss of SOx capability) just as it does in a laboratory deactivation. 

Laboratory steam deactivations represent a significant compromise in the effort to simulate equilibrium catalyst. Since hydrothermal deactivation of FCC catalysts is not rapid in commercial practice, deactivation of the fresh catalyst in the laboratory requires accelerated techniques. The associated temperatures and steam partial pressures are often in substantial excess of those encountered in commercial units. In some instances, the effect of contaminant metals is measured by an independent test not affiliated with steam deactivation. In subsequent yields testing, interactions between different modes of deactivation may be overlooked. Finally, single mode deactivation procedures can not reproduce the complex profile of ages and levels of deactivation present in equilibrium catalyst. 

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. 

Since the oxidation of SO to SO is a step in the operation of SOx catalysts, an increase in oxygen concentration should favor the reaction, and thereby increase the efficiency of SOx catalysts. The evidence indicates that this occurs. Baron, Wu and Krenzke (9) have shown that an increase in excess oxygen from 0.9% to 3.4% resulted in a 20% reduction in SOx emissions. This was for a steam-deactivated catalyst in a laboratory unit at 1345 F (no combustion promoter). 

We have found that Additive R has very good metals tolerance. Laboratory metals-impregnation studies show that 5,000 ppm Ni + V (33% Ni, 67% V) has no effect on the SOx reduction capability of Additive R. At a higher metals level of 10,000 ppm Ni + V (33% Ni, 67% V), Additive R loses only 9% of its SOx reduction capability. This is seen in Figure 5 for DA-250 + 10% Additive R + 0.37% CP-3. In this study, the DA-250 and Additive R were impregnated with metals then CP-3 was added and the 3-component blend steam deactivated at 1350 F, 100% steam, 15 psig, 8 hours. 

Deactivation of Additive R, during laboratory steaming of a blend of... 

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... 

In an effort to understand hew the petroleum industry addresses the problem of fresh FOC catalyst evaluation, a survey of testing philosophies from 15 companies was conducted. The objective was to identify the merits of various steaming procedures as well as catalyst testing. The results of the survey shew that each laboratory has a unique testing program, with wide differences being practiced in both steam deactivation and Micro Activity (MAT)... 

Recent work on laboratory catalyst deactivation in the presence of Ni and V by cyclic propylene steaming (CPS) has shown that a number of conditions affect the dehydrogenation activity and zeolite destruction activity of the individual metals. These conditions include find metal oxidation state, overall exposure of the metal to oxidation, the catalyst composition, the total metal concentration and the NiA ratio. Microactivity data, which show dramatic changes in coke and hydrogen production, and surface area results, which show changes in zeolite stability, are presented that illustrate the effect each of these conditions has on the laboratory deactivation of metals. The CPS conditions which are adjustable, namely final metal oxidation state and overall exposure of the metal to oxidation are used as variables which can control the metal deactivation procedure and improve the simulation of commercial catalyst deactivation. In particular, the CPS procedure can be modified to simulate both full combustion and partial combustion regeneration. 

In the laboratory, the two deactivation mechanisms can be separated by steaming the cracking catalyst and Additive R separately. In this case, there can be no transfer of silica from the cracking catalyst to Additive R during the steaming. The Additive R only loses surface area. The steamed components are then blended together for SOx activity measurements. 

In Table II, the product yields of REY-PILC are compared with PILC, a commercial equilibrium catalyst, and with the same commercial catalyst that had been deactivated in the laboratory to near constant conversion. The addition of REY to PILC maintained activity in the presence of steam while coke yield was reduced and the LCO/HCO ratio was slightly higher than for either of the commercial catalysts. This suggests that the microstructure of the PILC after pretreatment D will still convert large molecules into gasoline range products instead of generating coke as seen in PILC alone. 

The catalyst used in this study corresponds to a fresh commercial catalyst used in one FCC unit of ECOPETROL S.A. This solid is hydrothermal deactivated at the laboratory in cycles of oxidation-reduction (air-mixture N2/Propylene) at different temperatures, different times of deactivation, with and without metals (V and Ni), and different steam partial pressures. Spent catalysts (with coke) are obtained by using microactivity test unit (MAT) with different feedstocks, which are described in Table 10.1. 

FCC catalyst, supplied by Grace Davison, at three different cat-to-oil ratios, 4,6, and 8. The feed was injected at a constant rate of 3 g/min for 30 seconds. The catalyst to oil ratio was adjusted by varying the amonnt of catalyst in the reactor. Two catalysts used for this evaluation were laboratory deactivated using the cyclic propylene steaming (CPS) method [6]. Properties of these catalysts after deactivation are listed in Table 12.3. 

Conventional laboratory deactivations (high-temperature steam... 

To determine if we could simulate in the laboratory the effect of sodium on conunercially deactivated FCC catalysts, we prepared catalysts containing Na in the range of 0.22 to 0.41 wt% by modifying the catalyst washing procedure and deactivated the samples at 1088 K fa- 4 hours under 1 atm of steam This steaming procedure is commonly used to prepare deactivated catalysts with physical properties (zeolite and matrix surface areas and unit cell size) that match conunercial Beats. 

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