Microcalorimetiy adsorption

Another thermal analysis method available for catalyst characterization is microcalorimetiy, which is based on the measurement of the heat generated or consumed when a gas adsorbs and reacts on the surface of a solid [66-68], This information can be used, for instance, to determine the relative stability among different phases of a solid [69], Microcalorimetiy is also applicable in the measurement of the strengths and distribution of acidic or basic sites as well as for the characterization of metal-based catalysts [66-68], For instance, Figure 1.10 presents microcalorimetry data for ammonia adsorption on H-ZSM-5 and H-mordenite zeolites [70], clearly illustrating the differences in both acid strength (indicated by the different initial adsorption heats) and total number of acidic sites (measured by the total ammonia uptake) between the two catalysts. 

Using different probe molecules such as ammonia and sulfiir dioxide, the acid-base properties of the samples were determined by adsorption microcalorimetiy. 

Flow adsorption calorimetry is recognized as an important method to study adsorption/desorption phenomena at solid-fluid interfaces. According to a review by Groszek [37], flow adsorption microcalorimetiy is now developed to a point where it provides accurate and reliable adsorption and desorption data for events occurring at the solid-liquid or gas-solid interface over a wide range of temperatures, pressures and solution concentrations. 

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