By: Dhaval Prajapati10BPE078

MEROX: Mercaptan Oxidation.

MEROX unit reduces LPG sulfur content to meet customers product specifications.

MEROX IntroductionMEROX Introduction

What does MEROX process consist of?

MEROX IntroductionMEROX Introduction

Mercaptan Sulfur Extraction SectionUtilization of caustic solution to extract mercaptans sulfur from LPG products as they are converted to mercaptides.

Caustic Regeneration SectionUtilization of catalyst and air to regenerate caustic solution as the mercaptides are converted furthermore to insoluble disulfides.

• The Merox process requires an alkaline environment which, in some of the process versions, is provided by an aqueous solution of sodium hydroxide (NaOH), a strong base, commonly referred to as caustic.

• In other versions of the process, the alkalinity is provided by ammonia, which is a weak base.

• The catalyst in some versions of the process is a water-soluble liquid. In other versions, the catalyst is impregnated onto charcoal granules.

The most common mercaptans removed are:

• Methanethiol - CH3SH [m-mercaptan]

• Ethanethiol - C2H5SH [e- mercaptan]

• 1-Propanethiol - C3H7SH [n-P mercaptan]

• 2-Propanethiol - CH3CH(SH)CH3 [2C3 mercaptan]

• Butanethiol - C4H9SH [n-butyl mercaptan]

• tert-Butyl mercaptan - C(CH3)3SH [t-butyl mercaptan]

• Pentanethiol - C5H11SH [pentyl mercaptan]

Blockage of Merox unit equipment due to salt formation

Mr. LPGH2S

SulfurSulfur Extraction Extraction

Prewash Drum

Extractor

Regenerated Caustic

Contaminated Caustic

Treated Product

San

d F

ilter

Caustic Settler

LPG

SulfurSulfur Extraction Extraction

NaOH(Caustic)

SulfurSulfur Extraction Extraction

H2S + 2NaOH Na2S + 2H2O

Legend

Mercaptans

NaOH Solution

Hydrocarbon

SulfurSulfur Extraction Extraction

RSH + NaOH NaSR + H2O

NaSR(Mercaptide)

SulfurSulfur Extraction Extraction

RSH(Mercaptans)

O

X

I

D

I

Z

E

R

Process AirContaminated Air

Contaminated Caustic

Disulfide Oil

CausticHeater

Regenerated Caustic

To atmosphere

60 PSIG Steam

To Crude

Caustic RegenerationCaustic Regeneration

Disulfide Separator

VentTank

Catalyst Add. Pot

CatalystO2

NaSR+ + ½ H2O ½ RSSR + NaOH

RSSR(Disulfides)

Caustic RegenerationCaustic Regeneration

NaSR(Mercaptides)

Merox Catalyst

41

References

• [1] Treating Technology Solutions (http:/ / www. uop. com/ refining/ 1110. html)

• [2] Merox Process for Mercaptan Extraction (http:/ / www. uop. com/ objects/ 3 Extract Merox Mercap. pdf)

Mr. LPG