New sample carrier systems for thermogravimetric analysis under forced flow conditions and their influence on...

For thermogravimetric analysis, it has been shown that, depending on the type of sample container, different kinetic results could be obtained despite regarding the same reaction under constant conditions. This is due to limiting macrokinetic effects which are strongly dependant on the type of sample carrying system. This prompted the need for sample containers which deliver results minimally limited by diffusive mass transport. In this way, two container systems were developed, both characterized by a forced flow stream through a solid, porous bed: one from bottom to top (counter-current flow) and one from top to bottom (co-current flow). Optical test measurements were performed, the results indicating that reaction proceedings are almost fully independent of the geometrical shape of the sample containers. The Boudouard reaction was investigated with a standard crucible and the new developed systems; the reaction rates determined differed significantly, up to a factor of 6.2 at 1373 K.