Semiregenerative processes

The consequence of these different performances suggest that for semiregenerative processes a Pt-Re catalyst is better than a Pt-Sn catalyst, but if a continuous regeneration unit is considered then a Pt-Sn catalyst should be preferred. 

The semiregenerative process operates for long periods, and then the catalyst has to be regenerated. The time between regeneration is called cycle. Typically, a cycle is in the range of 3 months to 3 years. During normal operation, the shutdown for regeneration is due to the coke deposition. 

In many processes, regeneration occurs by shutting down the unit and regenerating the catalyst (Semi-regenerative). Figure 3-5 shows a Chevron Rheiniforming semiregenerative fixed three-bed process. 

In normal nonregenerative or semiregenerative operations, yield losses are allowed to increase until it is economic to regenerate or replace the catalyst. Normally, yield losses are not allowed to increase beyond 2 vol %. In view of the improved yield stability of the platinum-rhenium catalysts it is now possible to operate at much lower yield losses or to operate to much lower activity levels than has been common in the past. The ability to increase temperature rise during the process cycle to high levels should be considered in the design of new plants using this catalyst. 

Catalytic reforming is the major source of benzene and xylenes as well as of toluene. There are three basic types of processes semiregenerative, cyclic, and continuous. 

FIGURE 2 Toluene manufacture by a semiregenerative reforming process. 

The curve obtained from these equations is shown in fig. 6 together with that obtained for semiregenerative Pt-Re/Al203 CR catalysts. It is clear the difference in deactivation behaviour for both catalysts. Pt-Sn catalysts show a monotonic decrease in activity, whereas Pt-Re catalysts have a fast initial deactivation but then it stabilizes out from around 11 to 45 Blls/lbcat (aproximately 50 to 200 days) followed by a slow deactivation process. 

Several commercial reforming processes are available for license worldwide. A list of reforming processes with a summary of key process features is presented in Table 3. Several commercial processes are available, dominated by UOP and Axens Technologies for semiregenerative and continuous reforming. Other licensors included Houdry Division, Chevron, Engelhard, ExxonMobil, and Amoco, but none of them is currently... 

Axens Octanizing Aromizing Semiregenerative CCR dual forming for conventional process revamp Over 100 licensed units... 

The total capacity of the semiregenerative units exceeded 5.0 million b/d while CCR units reached 3.8 million b/d. The simultaneous use of CCR technology and bimetallic catalysts has given UOP a unique position in the field of catalytic reformer process licensing. Recent catalyst formulations have improved both aromatic and reformate yields. UOP has improved the performance of the conventional platforming process by incorporating a CCR system. The process uses stacked radial-flow reactors and a CCR section to... 

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