In this paper, a general dynamic model of a pseudo-homogeneous catalytic plug flow reactor (PFR) is developed, which does not apply the traditional assumption of negligible difference between enthalpy and internal energy inside its energy balance.Such Drive Hub a model is then compared to a second dynamic PFR model, whose energy conservation equation identifies internal energy with enthalpy.The aim is that of quantitatively investigating the real suitability of the identification of these two thermodynamic quantities (internal energy and enthalpy) in PFR modeling problems.The Claus process is selected as a meaningful case study for Figure Skating - Blades the aforementioned purposes.