Time-Resolved Kinetic Analysis of the Direct Formation of Nitrogen-Containing Aromatics from Biomass Chars

The fate of nitrogen during pyrolysis or combustion is an important consideration in the utilization of biomass. Important source of nitrogen in biomass are proteins and amino acids, which can react catalytically with the carbohydrates by reactions characterized as Maillard chemistry. Of particular interest in the char formation are effects due to the Maillard chemistry involving proline. The effects of proline on the maturation of char were studied. The first products to evolve were predominantly water and CO₂. The second products were Amadori products due to the interaction of proline and glucose and dominated by the aliphatic nitrogen heterocycle, 1-(1′pyrrolidinyl)-2-propanone. The next products were typical carbohydrate products. The final products were nitrogen aromatics. The formation of volatile aromatics ≥ 350°C was significant. They were accompanied by the accelerated formation of aromatics in the char when proline was present. This has implications for the char combustion phase when high temperature can potentially generate even more aromatics from the char. This is an abstract of a paper presented at the ACS Fuel Chemistry Meeting (San Diego, CA Spring 2005).