**3. Experimental**

#### *3.1. Fuel Sample and Char Preparation*

The raw material used in this work is abundantly available lignite from the Rhenish area, which was pre-processed and pre-dried for the use in a 2300 MWth lignite power plant. The pre-drying was performed via a fluidized bed with internal waste heat utilization [19]. The ultimate and proximate analysis of the fuel sample is shown in Table 1. The mean Sauter diameter of the sample is about 140 μm.

**Table 1.** Proximate and ultimate analyses of the char samples, oxygen calculated by difference.


The chars for the TGA experiments were prepared by devolatilizing the raw fuels in a muffle furnace at 900 ◦C for 7 min according to DIN 51720 or ISO 562:2010, respectively. Generally, the kinetics of the gasification strongly depend on the duration of the pyrolysis and the temperature gradient used during the heat up [20]. Devolatilizing the samples according to DIN 51720 leads to significantly higher heating rates than any possible pyrolysis in the TGA, but still is slower than heating rates one can expect in a fluidized bed gasifier.
