An ammonia and isocyanic acid measuring method for soot containing exhaust gases [An article from: Analytica Chimica Acta]

This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
The set-up and operating principle of an analyzer, which can be used without any filter for the continuous measurement of ammonia (NH"3) and isocyanic acid (HNCO) in soot containing exhaust gases is described. Ammonia and isocyanic acid are dissolved in a buffer solution, in which ammonia is measured directly with an ammonia-sensitive electrode. The sum of ammonia and isocyanic acid is measured with the same method after hydrolysis of HNCO to NH"3 and CO"2. Ammonia and isocyanic acid concentrations of up to ~500ppm can be measured with a mean relative error of 3.6% at a standard deviation of 4.0%. The investigation of the urea thermohydrolysis, which is an important step in the selective catalytic reduction (SCR) of nitrogen oxides in Diesel exhaust gases, revealed the emission of toxic isocyanic acid besides ammonia from the SCR catalyst.