Catalyst regeneration cycle lengths

Greater cycle lengths are also on the horizon. Where one-year cycle lengths between regenerations were typical for the early generations of EB isomerization catalysts, customers now expect two-year life as a minimum, and the demand for... 

In commercial aging simulations, KINPTR s deactivation model is used to predict cycle lengths (time between catalyst regenerations) and reactor inlet temperature requirements with time on stream to maintain target reformate... 

MCM-22 is a commercial catalyst with a production history of over seven years, and operation history of over five years. Catalyst performance in these applications has been outstanding. In MCM-22 s first ethylbenzene commercial application at Denka s Chiba Styrene Monomer Company Ltd., a cycle length of over three years has been demonstrated without any significant aging of the catalyst or change in yields. Like ZSM-5, MCM-22 is regenerable, and is environmentally inert. 

The catalysts are non-corrosive and operate at mild conditions, allowing for all carbon-steel construction. The reactors can be designed for 2-6 year catalyst cycle length, and the catalyst is fully regenerable. The process does not produce any hazardous effluent. 

In the MTG process the gasoline reactors have to be operated in a cyclic way as the HZSM-5 ages due to coking. When the reaction zone has moved through the catalyst bed and MeOH or DME is found in the reactor effluent, the reactor will be taken off stream for regeneration (ref. 6). The cycle length at a... 

All catalysts, operated either in laboratory or conmiercially, are deactivated during their use. Deactivation is very important in commercial operation because it influences the choice of the operational conditions and fixes the cycle length between regenerations and the total life of the catalyst. Some catalysts remain active for a decade (catalysts for oxidation of SO2 and for ammonia synthesis) whereas others must be regenerated after a few minutes of operation (catalysts for fluidized bed hydrocarbon cracking). 

The reactor was a tube of 446 stainless steel with an internal diameter of % in. and of 20 in. total length. The catalyst bed was the central 2 in., and a furnace surrounding the tube controlled the temperature to 1°. A sliding thermocouple in a central well of 3 -in. o.d. measured the bed temperature. The catalyst bed volume was 10 cc., and the rest of the reactor was filled with stainless steel spacers to reduce the dead space. Steam was heated to 650° in a preheater and mixed with the reacting gas or air at the top of the reactor, which was operated at atmospheric pressure. The supply of gas and steam was measured by flow meters and controlled by solenoid valves activated by a timer so that the catalyst could be fed on hourly or half-hourly cycles with steam and hydrocarbon or steam and air. In this way, any carbon laydown could be measured by analyzing for carbon dioxide in the air from the second (regeneration) cycle. 

Pilot plant development of Triolefin Process technology, requiring about four years, including establishing preferred feed composition, purification techniques, catalyst composition, catalyst activation and regeneration procedures, process conditions, and cycle length. Catalyst life was also determined in repeated cycles and certain design premises (e,g, temperature differential in the reactor) were demonstrated to be valid. 

An efficient scheme for regenerating the catalyst should be worked out with a cycle length of at least one month. 

As time progresses, the catalyst in the HDS reactor decays because of metal (vanadium and nickel) and coke depositions. The deposition of these metals occurs nonuniformly along the length of the reactor (more deposits occur near the reactor inlet than at the reactor outlet). In normal plant operations, the catalyst activity decline is counterbalanced by a rise in feed temperature, a reduction in the amount of quench fluids fed to the reactor or both, so as to achieve the same quality product. The process is terminated upon the attainment of a maximum allowable temperature (MAT) anywhere in the reactor. The catalyst bed is then regenerated. The time required to achieve the MAT is often called the reactor cycle life. 

Catalyst residence time or process period). Catalyst residence time in a moving-bed or fluid unit, or process period in a fixed-bed unit, is the length of time a catalyst particle is used to crack oil in each cycle before it is regenerated. Catalyst residence time is equal to the ratio of the amount of catalyst in the reactor to the catalyst-circulation rate. In moving-bed units, it is essentially the same for all catalyst particles, whereas in fluid units there is a variation, as already discussed. 

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