It is stressed, that the signal m/z = 61 occurred to be most representative of acetone in this experiment, implying that more than only the hydrogen atom of the hydroxyl group is substituted by a deuterium atom. A minor maximum in the evolution of H2 and HD below or around 300 °C is observed in both samples, but only in the larger crystallite size sample a continuous increase from the beginning of the temperature ramp is observed in the D2 signal. The evolution of D2 may originate from either the elimination of two deuterium atoms along the C-O bond of 2-propanol, when the hydrogen atoms at these positions have been exchanged before or from a deuterium atom in a 2-propanol molecule at the hydroxyl position and a deuterated hydroxyl group on the catalyst's surface. In the first case, the signal of acetone should increase simultaneously, which is not the case: acetone evolution is observed from 230 °C. In the latter case, the evolution of D2 does not necessarily imply simultaneous evolution of acetone as the second deuterium atom does not originate from 2-propanol, which would remain adsorbed as an alcoholate and is therefore compatible with the observation made here. In the higher temperature region from approximately 280 °C, the course of the HD and D2 signals are similar, showing that they originate from the same mechanism. The signal of H2 decreases very slowly starting from the beginning of the plateau at 400 °C. Both observations are compatible with hydrogen and deuterium atoms being exchanged more over time. In the smaller crystallite size sample, the delay in temperature between acetone and H2, HD and D2 evolution is much smaller and all hydrogen and/or deuterium containing species evolve from the same temperature, implying there is no such low temperature D2 evolution mechanism as in the larger crystallite size sample.