2.2.5. Temperature-programmed Desorption (NH3-TPD)

NH3-TPD analyses of samples were carried out using lab-made equipment at CATMAT laboratory, Ca' Foscari University of Venice in order to study the acidity of the catalysts. First, 100 mg of the catalyst was charged in a quartz reactor and degassed in He with a flow rate of 40 mL/min at 500 ◦C for 90 min. The catalyst was then cooled to room temperature (25 ◦C) prior to adsorption of ammonia. Then, the adsorption of 5% NH3/He with a flow rate of 40 mL/min at 25 ◦C for 30 min was performed. The physisorbed ammonia was removed from the catalyst surface by passing He (40 mL/min) at room temperature for 10 min. The desorption profile of NH3-TPD was recorded using a Micrometrics TPD-TPR 2900 analyzer equipped with a thermal conductivity detector TCD (Gow-Mac 24-550 TCD instrument CO, Bethlehem, PA, USA) from 25 to 1000 ◦C at a heating rate of 10 ◦C/min under the flow of He (40 mL/min).
