Regenerating Caustic During Mercaptan Extraction Processes

REGEN® and REGEN® ULS | Treatment Solutions

Developed by Merichem®, REGEN® and REGEN® ULS (ULTRA-LOW SULFUR) reduce the consumption of caustic by allowing for the regeneration and reuse of the caustic solution. In this process, sodium mercaptides are oxidized to disulfide oil (DSO), recovering sodium hydroxide for reuse in the mercaptan treating process.

REGEN® Advantages

  • Reduces consumption of caustic by allowing caustic solution to be re‑used
  • Mercaptides are oxidized to disulfide oil (DSO), thus recovering sodium hydroxide
  • REGEN® ULS allows the return stream of regenerated caustic to have negligible DSO allowing ultra-low sulfur specifications to be met
  • Several design options available based on the treatment need

We offer multiple solutions for handling spent caustic:

MERICON | Spent Caustic Treatment

Treatment solutions for processing spent caustics


Spent Caustic Management

Removes spent caustic products safely and reliably from your facility for beneficial reuse.

About Spent Caustic Management »

REGEN® Applications

  • All Caustic Streams Used in Mercaptan Removal Processes

How It Works

Coupled with THIOLEX technology, REGEN® regenerates the mercaptide-rich caustic purged from the THIOLEX system, returning a lean caustic stream for additional mercaptan removal. Depending on the stringency of the treated product specifications, gravity separation and/or solvent washing may be employed to minimize the impact of disulfide oil (DSO) back‑extraction.

Ideal for high-sulfur Coker LPG streams and LPG products requiring <5 wppm total sulfur, REGEN® ULS regenerates mercaptide-rich caustic and returns a lean caustic with minimal DSO content. This results in minimal DSO back-extraction into the LPG and ultra-low sulfur levels in the treated product

Established Performance

For nearly 75 years, Merichem® has provided innovative technology and equipment to the oil and gas industry. With proven solutions, we’ve helped our customers eliminate the obstacles to performance and profitability.

Comprehensive and Committed

In addition to a range of proprietary treatment technologies, Merichem® offers engineering, design, fabrication, analytics, testing and service support to help our customers meet their specifications, performance and warranty requirements.

Proven Flexibility, Global Reach

With extensive capabilities and a flexible array of supply chain options, Merichem® has helped customers all over the world address some of their most challenging treating problems.

We have licensed more than 170 REGEN® and REGEN® ULS units worldwide


North America

  • 5 AMINEX Units
  • 21 AQUAFINING Units
  • 126 LO-CAT® Units
  • 70 MERICAT Units
  • 13 MERICAT II / J Units
  • 2 MERICON Units
  • 19 NAPFINING Units
  • 26 REGEN® Units
  • 153 THIOLEX Units

South America

  • 3 AMINEX Units
  • 14 AQUAFINING Units
  • 8 LO-CAT® Units
  • 4 MERICAT Units
  • 6 MERICAT II / J Units
  • 8 MERICON Units
  • 12 NAPFINING Units
  • 8 REGEN® Units
  • 26 THIOLEX Units


  • 6 AMINEX Units
  • 23 AQUAFINING Units
  • 29 LO-CAT® Units
  • 21 MERICAT Units
  • 10 MERICAT II / J Units
  • 5 MERICON Units
  • 14 NAPFINING Units
  • 6 REGEN® Units
  • 43 THIOLEX Units


  • 1 AQUAFINING Units
  • 3 LO-CAT® Units
  • 1 MERICAT Units
  • 1 MERICAT II / J Units
  • 4 NAPFINING Units
  • 1 REGEN® Units
  • 2 THIOLEX Units


  • 18 AMINEX Units
  • 44 AQUAFINING Units
  • 52 LO-CAT® Units
  • 59 MERICAT Units
  • 22 MERICAT II / J Units
  • 20 MERICON Units
  • 32 NAPFINING Units
  • 20 REGEN® Units
  • 121 THIOLEX Units


  • 2 AQUAFINING Units
  • 9 LO-CAT® Units
  • 2 MERICON Units
  • 2 NAPFINING Units
  • 1 THIOLEX Units