P2GS.2 - Gas Adsorption and Sensing Mechanism Studies by Measu ring Enthalpy of Porous Materials with QCM
Quartz crystal microbalance (QCM) loaded with different porous materials was used as a new tool to measure adsorption isotherms for calculating adsorption enthalpy. The QCM devices enable to measure the adsorption isotherms and monitor the dynamic process for the adsorption of CO2 on ZIF-8.,UIO-66 and SBA-15-NH2 which represent three different adsorption mechanism. The adsorption isotherms of the CO2 on ZIF-8 followed the Kraussius-Clapelon equation with the characteristic energy of 15.6
... ergy of 15.6 kJ.mol-1.This adsorption enthalpy approximates the result of BET test(14.6~14.9kJ. mol-1) and the Gaussian calculation software(14.8kJ), and according with previous studies about 15~20kJ.mol-1 (belong to physical absorption). The adsorption enthalpy of CO2 on UIO-66 was 38~42 kJ.mol-1, conforming with previous studies about 40kJ.mol-1 (belong to weak chemical absorption).The SBA-15-NH2 was choose as a strong chemical adsorption on CO2 to explore the accuracy of this method. Fortunately, the figure obtained is in keeping with the theoretical value (greater than 80 kJ mol-1) . As a result, the above three adsorption enthalpy measured by QCM are consistent with that calculated from the earlier adsorption theory. This will open a new route to judge if the material is suitable for adsorptive and sensing materials.