Simultaneous Measurements of Isotherms and Heats of Adsorption in a Sensor Gas Calorimeter

Unpublished AIChE shall not be responsible for statements or opinions contained in papers or printed in its publications. Abstract This paper describes a novel calorimeter applicable for the simultaneous measurement of adsorption isotherms and the corresponding heats of adsorption. The calorimeter is based on a new metrological principle as a gas surrounding the adsorption vessel containing the sorbens material and the sorptive gas, is used as a sensor for the heat flux from or to the vessel. Indeed, if heat is released from inside the adsorption vessel to the sensor gas, its temperature and pressure will increase what can be monitored accurately. Hence such an instrument can be called a sensor gas calorimeter (SGC). The device can be used at temperatures from –200 °C up to 100 °C and from vacuum (10-3 Pa) up to 1 MPa. The calorimetric sensitivity as well as the time constants of the system can be adopted to special applications by a proper choice of the sensor gas and/or by adjustment of its pressure. As the only material in contact with the sorptive gas phase is stainless steel, even corrosive gases like ammonia or sulphur dioxide can be used. The measurement procedure and the theory of the instrument are outlined. As an example, data of the isotherms and heats of adsorption of n-butane, being a representative component of gasoline, on activated Carbon (AC) at various temperatures are presented and discussed to a certain extend.