Sulfur and Nitrogen Compounds in Rectified Methanol from Foul Condensate Stripping, 2004 International Chemical Recovery Conference

Gas chromatography mass spectrometry was used to identify volatile organic impurities in rectified methanol, derived from foul condensate stripping at kraft pulp mills. They were also analyzed for total and ammonium nitrogen. The methanol samples were derived from the mills pulping different raw materials, i.e. spruce, eucalyptus, and birch wood chips. Altogether, more than 150 different compounds were identified or partially characterized. These included various aliphatic alcohols and ketones, terpenes, sulfur and nitrogen compounds, and other types of compounds. The sulfur compounds included sulfides, thiols, thiophenes, and bis(methylthio)alkanes. Many of the identified novel or rare sulfur compounds, such as 4-mercapto-4-methyl-2-pentanone and 1-(methylthio)ethanethiol, may significantly contribute to the pungent odor of the rectified methanols.

Ammonia was the main nitrogen compound, making up 85–95% of the total nitrogen content of 10–20 g/l in the methanols. In addition, several organic nitrogen compounds were identified or partially characterized. The high nitrogen content needs to be taken into account when selecting combustion sites and technology for methanol as that may contribute to the mill’s overall nitrogen oxide emissions.