STAR process^® – Most reliable dehydrogenation technology for propylene and isobutylene production

The STAR process® (Steam Active Reforming) is a commercially established techno logy for the production of propylene and isobutylene.

The technology is used to dehydrogenate lower paraffins (propane or butanes) into their corres ponding olefins (propylene or butylenes), which can be further processed to valuable downstream products (see possible applications below).

Main Advantages

Low maintenance fixed bed reactor type

• No moving catalyst

• No hot switching valves

• Simple and robust operation

High availability and reliability

• Independent parallel reactor trains

• Wide operational window makes trips less likely

Shortest start-up and overall shut-down time in the unlikely event of a reactor trip

• Shorter re-start from “hot stand-by”

• Demonstrated plant availability of 98%

Catalyst

• STAR catalyst^® – high yield and long lifetime: The STAR catalyst^® consists of a platinum promoted basic calcium and zinc aluminate which is very stable in the presence of steam at high temperatures. It shows high selectivity at near equilibrium conversion. Regeneration is simple and sustainable by simply using air to burn off coke deposits and to re-oxidize the precious metal. No chemicals are required for catalyst activation or coke suppression. Before delivery to site thyssenkrupp Uhde will qualify the performance of the catalyst in its test facilities. In order to continuously improve the performance of the STAR process^® plants thyssenkrupp Uhde has established a continuous catalyst development program together with its production partner.

How does the STAR process^® work?

Process description

Typically, the feedstock is first sent to a feed preparation unit to separate any heavier components or possible contaminants.

The remaining paraffin is fed to the reaction section where it is heated up and mixed with process steam before it is sent to the externally heated and catalyst-filled reformer tubes. After reacting inside the catalyst bed the hot reactor effluent is cooled down in several steps, recovering energy for feed preheating and steam generation.

Subsequently, all the steam contained in the process gas is condensed and the heat is recovered by heating the distillation columns in the fractionation unit.

The remaining dry process gas is compressed and partially condensed. The liquid phase is directly fed to the fractionation unit while gaseous components are fed to the gas separation unit. In a cryogenic process light uncondensables are removed. Optionally high-purity hydrogen can be generated by applying pressure swing adsorption (PSA).

The fractionation unit of a dehydrogenation plant consists of a stripper column to remove light uncondensables, which are fed to the gas separation unit, and a splitter column to separate olefin product and unconverted paraffin. For C4 applications such a splitter column may not be required depending on the downstream products. Finally, unconverted paraffin is recycled back to the feed preparation unit.

References

> 70 steam reformers built