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How is the dual focus on increasing butylene and propylene production being met?

Jan-2024

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Kandasamy Sundaram, Lummus Technology, kandasamy.sundaram@lummustech.com

On-purpose propylene routes are satisfying the demand to some extent. FCC and olefin conversion technology satisfy some additional capacity in addition to thermal cracking. Butene-1, Butene-2, and isobutene have different markets. Due to the decline in the MTBE market, isobutene is not requested by our clients. The dimerisation of ethylene is meeting some demand.

Jan-2024
Cai Zeng, Clariant Catalysts, Cai.Zeng@clariant.com

Petrochemicals customers are now looking for unique and extremely reliable technology for co-processing butane and propane to meet both increasing butylene production and propylene demand. Catalysts such as Clariant’s highly selective Catofin catalyst and the company’s patented metal-oxide HGM allow for thermodynamically advantaged reactor pressure and temperature to achieve a high conversion rate and maximised yield. One example is the Hengli Group’s world’s largest mixed-feed dehydrogenation plant in China using the Catofin technology. The plant is designed to process 500 KTA of propane and 800 KTA of iso-butane feeds to produce propylene and iso-butylene.

Jan-2024
Stefan Jäger, Clariant Catalysts, Stefan.Jaeger@clariant.com

In traditional refining, the catalytic cracker (FCC) is the source for light olefins such as propylene and butylenes. In many countries, demand for gasoline is shrinking as individual transportation is the most influenced section during the energy transition, moving to lean consumption engines, plug-in hybrids or fully electric-driven solutions. Thus, the product slate behind FCC calls for more distillates and light olefins and less gasoline. Cracking technology providers can offer revamp solutions to follow these requirements (second riser and modified catalyst solution). Clariant can offer adsorbents and catalysts to clean these streams, delivering high-purity light olefins over the fence or utilising these olefins in the refinery grid toward fuels or even chemicals.

Jan-2024
Alvin Chen, BASF, alvin.u.chen@basf.com

While butylene pricing is often quite stable (typically either very high or very low), propylene pricing has seen significant volatility over the past few years. One approach that many refiners have adopted, to address the dual focus on butylene and propylene production, is to formulate a base FCC catalyst with moderate overall LPG= selectivity and an emphasis on strong C₄= selectivity. Such a catalyst coupled with judicious usage of ZSM-5 offers excellent C₄= selectivity during times when C₃= value is low. However, it still allows the refiner to capture short-term C₃= opportunities while maintaining a strong C4= yield.

One strategy for the optimum base catalyst is to optimise the acid site distribution on the catalyst by increasing total surface area while reducing acid site density, allowing similar catalytic activity with reduced hydrogen transfer. Since it is known that butylenes are more sensitive than propylene to hydrogen transfer effects, a catalyst with this approach will target both products depending on process conditions and externally added ZSM-5. BASF applies this catalyst design approach in the Multiple Frameworks Topologies (MFT) technology, where secondary zeolite frameworks are also used to further improve butylenes to propylene flexibility. Catalysts like Fourte and Fourtune for VGO applications and Fortitude for resid applications are examples of the MFT catalyst technology for FCC units.

It should not be forgotten that operating conditions, such as catalyst-to-oil ratio and reactor outlet temperature, also have an impact on butylenes to propylene distribution, with butylenes favoured at mild severity conditions, while propylene is favoured at high severity conditions.

Jan-2024