3 replies to this topic

[rosneft]

Hi, 

 

I wasn't sure if this post should be in this section or student section since its research. I am currently measuring CO2 solubility in Glycols for modeling and I have noticed for one of my measurements, the TEG has changed colour (Yellow). It may have also become more viscous however I don't have a visco-meter to check.

 

The system was left at 70C and 3400 PSI with excess CO2 for two days.

 

I was wondering if anyone has seen this before?

Is there esterification taking place?

 

Many Thanks in Advance

[Pilesar]

Glycols do decompose and can react to form ethers, esters, cyclic compounds, and polymers. You also likely had some impurities in your feedstock. I do not know what you have after subjecting your material to high pressure for an extended period of time, but you should exercise caution in handling any unknown chemical (especially dried residue) as there may be some explosive potential.

[rosneft]

Thank you for the reply. I'm developing solubility curves for model tuning. The TEG is 99% purity from Sigma. What percentage degradation do you expect? Is it necessary for GC analysis to determine what new components are formed, or is it guessable? The solubility doesn't seem to be affected which leads me to believe the quantity is far too low.

[Pilesar]

My knowledge is from designing an EO/EG plant almost 30 years ago. My research back then revealed that the critical properties of EG/DEG/TEG were not known because the material would degrade before the critical properties could be determined. I assumed this was more a phenomenon of high temperature. Unless there is a known industrial use for TEG at 3400 psi you may not find much in a literature search. After two days at super-high pressure you observed changed inherent properties of color and viscosity which suggests a different chemical, but I do not guess what is formed. With unnamed impurites and an unknown chemical formed, extra caution seems warranted until you know what you have.