IRPC Rewind: ExxonMobil unveils liquid-phase isomerization advances for paraxylene production
At the International Refining and Petrochemical Conference (IRPC) in Houston, Texas, ExxonMobil presented breakthrough results in its liquid-phase isomerization (LPI) process, highlighting energy efficiency, improved yields and strong commercial performance. The presentation, titled “Liquid-Phase Isomerization Process for Paraxylene Production”, was delivered by Alejandra Rivas Cardona, Business Development Manager for ExxonMobil’s Aromatic Catalyst Licensing organization, and Jeff Pryor, Market Development for ExxonMobil.
The LPI process was introduced as a complementary—or in some cases, alternative—technology to conventional vapor-phase isomerization (VPI). ExxonMobil emphasized that LPI operates in the liquid phase, reducing energy-intensive vaporization and condensation steps while enabling lower-temperature operation.
“This technology was designed not as a replacement, but as a strategic enhancement to VPI,” said Rivas Cardona. “It can debottleneck existing xylene loops, reduce energy consumption and increase material efficiency without requiring major infrastructure changes.”
Commercial success and proven longevity. ExxonMobil shared case studies from commercial plants, including one that has been in operation for nearly a decade. Results consistently demonstrated ultra-low xylene losses—below 0.3 weight percent—across the full catalyst cycle.
Another unit, where LPI was installed in parallel with a VPI reactor achieved:
- Lower xylene losses
- Increased ethylbenzene conversion
- Reduced energy consumption across the system.
In one heavy naphtha-fed operation, the plant achieved 101% of baseline paraxylene production capacity while simultaneously cutting energy use:
- Fuel gas down 3%
- Steam down 9%
- Power down 3%
- Cooling water down 3%.
The combined OPEX savings were calculated at 4%, with the project delivering a payback in less than two years.
Pryor emphasized the broader implications: “The xylene loop is one of the largest energy consumers in the aromatics chain. By shifting to liquid-phase operation, we can cut that energy demand dramatically—more than 50% in some cases—while improving paraxylene yields.”
The LPI process also leverages ExxonMobil’s proprietary zeolite catalyst, which does not rely on precious metals, reducing both costs and logistical challenges for customers.
Looking ahead. The company framed LPI as a flexible solution for both revamps of existing complexes and new grassroots units, particularly where ethylbenzene-lean feeds are used. In such cases, ExxonMobil noted, LPI could even serve as a full replacement for vapor-phase isomerization.
In closing, Rivas Cardona summarized the message to refiners and petrochemical operators: “If greater efficiency, fewer byproducts, and reduced energy use are important to you, LPI technology delivers those results while fitting seamlessly into your current setup.”
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