Analysis of VOCs in Biogas

Natural gas is generally odourless and easily detected through the presence of odourants such as THT (tetrahydothiophen), Gasodor S-Free (methyl- and ethylacrylates) and TBM (tert-Butylthiol). The presence of odourants is important for detection of leaks which can be a safety issue.

Biogas produced by fermentation of organic sources contains volatile organic compounds (VOC) either from
by-products of the fermentation or by the sources directly. The presence of these VOCs can produce a significant odour. This strong odour that is produced can mask the effects of the odourants therefore causing a safety issue.

To prevent this, the VOCs in biogas are removed through an activated carbon filter. The VOCs are adsorbed by the filter medium. The filter medium adsorption medium has a limited capacity so has to be replaced periodically, this can be expensive to keep replacing therefore it’s important to know the point of exchange. Using our GC-IMS instruments allows monitoring of the VOCs after passing through the filter medium. The results of this investigation showed that:

  • The VOC load can be analyzed directly in biogas. No further sample is necessary
  • The reduction of VOC load due to passing through the active carbon filter can be determined
  • Selected VOCs can be detected after filtering. the intensity correlates to the filter status ‘used’/’fresh’
  • The level of the odourizing agent THT can be determined

For more in depth information on the results of this study and how our GC-IMS instrument was used please contact us and send us an enquiry.