# A new green method for purifying acetylene with the help of Zeolite molecular sieve

I'm investigating for a green method for purification of acetylene in order to reduce the environmental impacts in manufacturing plants. In the current method mercuric chloride is used in the purification material that is indeed harmful to the environment. The main impurities consists of:

1- Phosphine (Maximum concentration must be 200 ppm)

2- Arsine,

3- Hydrogen sulfide, (Maximum concentration must be 100 ppm)

4- Ammonia

5- water.

Recently, I read that Zeolite molecular sieves are used to purify many gases in industry. Further information can be found in the article below:

https://www.honeywell-uop.cn/wp-content/uploads/2011/07/UOP-Adsorbents-for-purification-of-olefin-and-polymer-process-streams-brochure.pdf

If I noticed correctly, this porous material absorbed different gases with respect to its amount of pore diameter. Gases that their molecular sizes are similar or smaller than the pore diameter will be absorbed while other gases will pass from this material. I wonder that if we could use this material for purifying acetylene. Since the size of the gas molecules in the acetylene gas mixture are different, this seems practical.

What is your suggestion?

Do you think that Zeolite molecular sieves can be a solution for purifying acetylene? Do you know any papers or articles that is relevant to this subject?

Thank you very much.

• I get some 70 hits on Web of Science for 'Acetylene AND Zeolite'... Aug 18 at 15:25
• Thanks for your comment. Yes, but I didn't found any resources about purifying acetylene using Zeolite sieve. One example of using zeolite for separating acetylene is in this article: epubs.stfc.ac.uk/manifestation/51157539/STFC-AAM-2021-016.pdf Aug 18 at 16:57

## 1 Answer

With respect to "What is your suggestion?", I note that apparently hydrogen peroxide does not readily react with acetylene, see comments here, for example, to quote:

A hydrogen peroxide (H2O2) solution reacts with calcium carbide (CaC2), so as to generate the mixed gas of oxygen (O2) and acetylene (C2H2).

However, the created mix of acetylene and hydrogen peroxide appears per a recent 2018 work to present an enhanced explosion hazard (see "Water Vapor and Hydrogen Peroxide as Promoters of Acetylene Explosive Decay"), where "the acetylene explosiveness is largely determined by humidity" implying the further employment of a drying agent.

Also, on phosphine with hydrogen peroxide, to quote a source:

Reactive oxygen species for lipid peroxidation may therefore be derived from direct reaction of PH3 with H2O2 as an alternative hypothesis to their respiration-linked formation.

Also, $$\ce{H2S}$$ and $$\ce{AsH3}$$ both react with $$\ce{H2O2}$$ see, for example, "Catalyzed oxidation of arsenic(III) by hydrogen peroxide on the surface of ferrihydrite: an in situ ATR FTIR study".

As such, I would suggest a possible hydrogen peroxide scrubbing step, per the manner described in the literature, as a feasible green but apparently, not completely safe, route.

• Thank you very much for your idea about using hydrogen peroxide for oxidizing agent as a new green method. It can be a very valuable and green method. Thanks. I will investigate about it. After I read your message, I was wondering that can Ozone (another oxidizing compound of oxygen) be used too? (for example ozonated water scrubber) thanks. Aug 19 at 8:51
• Just an idea similar to the method you have suggested. In the patent below you can observe the purifying method that used sulfuric acid as the absorbing material ( currently used in acetylene production). But the idea of the writer is similar to your suggestion. That is recovering sulfuric acid by using oxidizing agents such as hydrogen peroxide. Actually in this procedure, the impurities(in this article only phosphine), first absorbed by sulfuric acid and then oxidized. So, they will be prevented from returning back to gas stream. In this article solvated phosphine is converted to phosphite. Aug 19 at 14:46
• freepatentsonline.com/2313022.html Aug 19 at 14:47
• No, ozone is too reactive (see this youtube.com/watch?v=ViMocu_iPOU ). Also, ozone and water creates the hydroxyl radical which attacks acetylene (see "Ozonation of Water: Role of Hydroxyl Radicals as Oxidizing Intermediates" at science.org/doi/10.1126/science.190.4216.782). Also, one came not use a precursor to H2O2 like the HO2 radical (see digital.library.unt.edu/ark:/67531/metadc1706551/m2/1/…). Aug 19 at 16:22
• Thanks so much for your attention. Aug 20 at 9:49