Isobutylene Process by Lummus Technology

Technology for dehydrogenation of isobutane to make high-purity isobutylene. The CATOFIN process uses specially formulated proprietary catalyst from Süd-Chemie.

Isobutylene Process by Lummus Technology

The CATOFIN reaction system consists of parallel fixed-bed reactors and a regeneration air system. The reactors are cycled through a sequence consisting of reaction, regeneration and evacuation/purge steps. Multiple reactors are used so that the reactor feed/product system and regeneration air system operate in a continuous manner.

Fresh isobutane feed is combined with recycle feed from the downstream unit, vaporized, raised to reaction temperature in a charge heater (1) and fed to the reactors (2). Reaction takes place at vacuum conditions to maximize feed conversion and olefin selectivity.

After cooling, the reactor effluent gas is compressed (3) and sent to the recovery section (4), where inert gases, hydrogen, and light hydrocarbons are separated from the compressed reactor effluent. Condensed liquid from the recovery section is sent to a depropanizer (5), where the remaining propane and lighter components are separated from the C4s.The bottoms stream containing isobutane, isobutylene, and other C4s is sent to the downstream unit (usually an MTBE unit). The unconverted isobutane is recycled back from the downstream MTBE unit to the CATOFIN reactors.

After a suitable period of onstream operation, feed to an individual reactor is discontinued and the reactor is reheated/regenerated. Reheat/regeneration air heated in the regeneration air heater (7) is passed through the reactors. The regeneration air serves to restore the temperature profile of the bed to its initial onstream condition in addition to burning coke off the catalyst. When reheat/regeneration is completed, the reactor is re-evacuated for the next onstream period.

The low operating pressure and temperature of CATOFIN reactors, along with the robust Süd-Chemie catalyst, allows the CATOFIN technology to process isobutane feedstock without fouling of process equipment. The simple reactor construction, with its simple internals, results in a very high on-stream factor.

Yields and product quality: Isobutylene produced by the CATOFIN process is typically used for the production of MTBE. The consumption of isobutane (100%) is 1.14 metric ton (mt) per mt of isobutylene product.

Licensor: Lummus Technology

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