controlling methyl mercaptan 1

[mruby]

There was considerable discussion of sulfides control in an exhaust gas stream in thread127-72509 but the specific subject of methyl mercaptan remains illusive. We are trying to control methyl mercaptan using a two-stage scrubber - first stage is acid and second stage is caustic with NaOH/ClO2 (see thread127-157289 for details). Methyl mercaptan cuts through both like a hot knife through butter. The alternatives we are looking into are replacement of the oxidizer in either the caustic or the acid scrubber (if we used the acid scrubber we would raise the pH to about 4.5) with a proprietary hydrogen peroxide plus catalyst solution or with potassium permanganate. We have had real difficulty finding anyone who has successfully controlled methyl mercaptan using wet scrubbing. Papers in the literature seem to be all over the map as to the correct pH for max solubility. Would appreciate any comments on the alternative scrubbing solutions that might be successful.

 

[mechtimeng]

Mr. Ruby,

I am familar with running Merichem Treaters used to treat debutanizer bottoms, and straight run gasoline at an FCC.

If you're looking to control methyl mercaptans using a Caustic scrub, it's going to be important to control the levels of H2S in your gas stream. If your levels of H2S are high that's going to hinder the mercaptan extraction process. Just from what I have been an to interpret from your post, it sounds as though that may be the case.

You might want to consider trying to scrub the H2S out of your gas stream prior to running it through your caustic scrubber.

Finally if all else fails, you might want to contact UOP and see if you can't talk to one of their process guys.

Good Luck....