(225c) Adsorption of CO and NO By Na-FAU Zeolites: Effects of Si/Al Ratio, Oxygen and Humidity

NO, and CO are toxic and noxious gas molecules. They emitted from exhaust gas diesel in particular in non-road vehicle and they cause great damage to people worker’s health. Therefore, it is urgent to design effective gas trap to remove them. The catalytic processes are great method to control the NO and CO emission. However, during the first minutes of using the vehicle, the temperature is too low to allow the catalysis to be effective. Consequently, NO and CO emissions into the ambient work atmosphere namely are observed. Otherwise, water which is in large amount into the exhaust gas diesel, generated competitive reaction and adsorption with pollutants. Therefore, the adsorption of NO and CO with water on faujasites were investigated. The density functional theory was used to perform a screening on several monovalent cation on faujasites structure with different Si/Al ratio to reach the bonding characteristics and adsorption energies. Experimental investigations were carried out to achieve equilibrium constants and they allowed calculating the isosteric heat of each gas/zeolite couple. Breakthrough curve were carried out to understand the behaviour of these gas mixture in dynamic situation (figure 1). This work showed DFT is effective tool to make a screening. The computational work has been validated by experimental data. In order to develop industrial trap, dynamic approach allowed showing the practicability of the trap but unfortunately observing chemical surface reaction and the formation of by-products. However, an industrial application is possible but other zeolites have to be investigated to reduce the weight of the trap.

Figure 1: The experimental setup used to study the adsorption and desorption of NO and CO on several adsorbents. The symbols FRC (Flow Regulator Controller) denote the sensors that control the composition of the stream. P stands for pressure, RH for the relative humidity and T for the temperature of the pipes. Inside the furnace, TRC (Temperature Regulator Controller), refers to the temperature in the furnace.