Straw – Evolved Gas Analysis (STA-FT-IR)

Straw is a generic term for threshed, dried corn stalks and the leaves of plants used to produce oils and fibers.

In addition to its use in agriculture, straw also has the potential to become important as an energy carrier in the future. To characterize its thermal behavior, 28.6 mg of powdered straw was measured in a nitrogen atmosphere at a heating rate of 20 K/min.

The TGA curve depicts three steps at 110°C, 298°C and 356°C (each characterized by its DTG peak temperature) plus a drawn-out step in the temperature range above 400°C. The corresponding mass losses are 5% for the first step, 33.4% and 25.3% for the two overlapping ones in the middle, and 10.7% for the last effect. At around 740°C, there is still a residue of 25.6%.

A library search of the corresponding FT-IR spectra shows that the first TGA step (110°C) is caused by dehydration, whereas the steps at 298°C and 356°C pertain to the evolution of water, CO, CO2, formic acid, acetic acid and ethane. Furthermore, methane was found at approx. 534°C. The traces of water, carbon monoxide and methane are plotted here together with the TGA and DTG curves. For a better overview, the DSC-signal is not displayed here.
The NETZSCH Proteus®® software allows for FT-IR traces to be easily imported. (measurement with PERSEUS®® STA 449 F1 /F3 )