Clay catalyst, activated poisoning

To achieve these criteria, we needed to establish standard processing and characterization procedures for FCC catalysts. In particular, a process for making microspheres of controlled size distribution and shape, independent of composition, had to be defined. Also, an approach for obtaining the intrinsic attrition rate of commercial grade and experimental catalysts had to be adapted from a method for alumina. This paper describes these methods and shows that the substitution of CP alumina for part of the clay in a commercially viable FCC formulation can improve attrition behavior and enhance catalytic activity, especially in the presence of Ni+V poisoning. 

The activity of rhodium catalyst samples was monitored at 100 C for 7 hours, during which period the activity declined. All the catalysts reach a constant activity after 200 minutes fi om the start of the reaction approximately (Fig. 3). The percentage of residual activity (percentage of the final activity versus the maximum value reached) for the catalysts supported on zeolites (Rh/ZEDIP, 71% Rh/ZESEP, 83 % Rh/ZEDIX, 76% and Rh/ZESEX, 57%) indicates the resistance to poisoning. The deactivation of Rh/BENPIL (36%) is relatively rapid particularly during the first hour of reaction as mentioned, and this can be related to the formation of heavy secondary products formed in the MIBK formation route [20]. These molecules remain within the pores of the pillared clay sample, and therefore they block the access of the reactant to the active centres, hence causing a decrease in the activity of the catalyst. 

As sulfur-containing organic molecules are known catalyst poisons because of strong adsorption, acylation of thioethers is difficult to obtain. The reaction between thioanisole and AAN can, however, be performed in the presence of ion-exchange resins that are more robust to deactiva-tion. The process is carried out in a Parr autoclave in 1,2-dichloro-ethane at 70°C. Under these conditions, other acid catalysts such as sulfated zirconia and KIO clay do not show any noticeable activity. Only the cation exchange resin catalysts, which contain Bronsted sites, are effective. Among these, Amberlyst-15 shows maximum conversion because it... 

This method was first reported by Heinemann et al. [1] for the polymerization of ethylene with the catalysts depicted in Figure 3.15 in the presence of clays with different types of organic modifications. Figure 3.16 compares the ethylene uptake curves with homogeneous and clay-supported MBI catalyst. Lower activity and more stable polymerization rate were observed for the clay-supported system. As water present on the clay surface acts as a catalyst poison [71], the low polymerization activity observed for the clay-supported system was attributed to water traces remaining on the organoclay surface. 

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