Catalytic reforming catalyst

It follows that regeneration may consist of either (i) removal of IS sometimes poisons, most often inhibitors or fouling agents, e.g., coke (hydrogenation catalysts, e.g., selective hydrogenation of pyrolysis gasoline) or (ii) redispersion of the active species (platinum catalysts) or (iii) both (hydrodesulfurization or catalytic reforming catalysts). 

The deactivation of catalytic reforming catalysts was studied in Platforming units. The deactivation was measured by the increase in the operation temperature necessary to obtain a specified performance in processes using Pt-Re and Pt-Sn catalysts. The statistical analysis produced an equation capable to predict the deactivation degree in terms of the operation parameters and properties of the feed. 

In the past decade, Pt/H-MOR was considered as the begiiming of a new family of catalysts for the hydroisomerization of C5/C6 n-paraffms. More recently, Pt/H-BEA has been used. In this study, catalysts containing H-MOR and H-BEA zeolites loaded with 0.35-0.55 wt% Pt as well as 0.05-0.25 wt% Pd or Ir combined with 0.35 wt% Pt are tested for n-hexane hydroconversion. It is known that commercial hydroisomerisation and catalytic reforming catalysts normally contain 0.35-0.40 wt%Pt. 

J. P. Franck and G. Martino, in J. Figueiredo and M. Nijhoff, eds. Deactivation and Regeneration of Catalytic Reforming Catalysts In Progress in Catalyst Deactivation, Martinus Nijhoff, The Hague, the Netherlands, 1982, pp. 355. 

Catalytic reforming catalysts contain highly dispersed platinum (Pt), the activity of which is inhibited by sulfur. Therefore, an upstream hydrotreater lowers the sulfur content of reformer feeds to <1 wppm. In addition to Pt, modem multi-metallic catalysts contain highly dispersed rhenium (Re) and in some cases tin (Sn). 

In addition, salts deactivate reforming and catalytic cracking catalysts. 

For example, in the case of light Arabian crude (Table 8.16), the sulfur content of the heavy gasoline, a potential feedstock for a catalytic reforming unit, is of 0.036 weight per cent while the maximum permissible sulfur content for maintaining catalyst service life is 1 ppm. It is therefore necessary to plan for a desulfurization pretreatment unit. Likewise, the sulfur content of the gas oil cut is 1.39% while the finished diesel motor fuel specification has been set for a maximum limit of 0.2% and 0.05% in 1996 (French specifications). 

Catalytic cracking is a key refining process along with catalytic reforming and alkylation for the production of gasoline. Operating at low pressure and in the gas phase, it uses the catalyst as a solid heat transfer medium. The reaction temperature is 500-540°C and residence time is on the order of one second. 

The predominant feeds for reforming are straight-mn naphthas from cmde stills. Naphthas from catalyst crackers and naphthas from code stills are also used. Typical compositions are summarized in Table 5. Typical operating conditions for catalytic reforming are 1.135—3.548 MPa (150—500 psi),... 

C, 0.356—1.069 m H2/L (2000—6000 fU/bbl) of Hquid feed, and a space velocity (wt feed per wt catalyst) of 1—5 h. Operation of reformers at low pressure, high temperature, and low hydrogen recycle rates favors the kinetics and the thermodynamics for aromatics production and reduces operating costs. However, all three of these factors, which tend to increase coking, increase the deactivation rate of the catalyst therefore, operating conditions are a compromise. More detailed treatment of the catalysis and chemistry of catalytic reforming is available (33—35). Typical reformate compositions are shown in Table 6. 

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