1. Answer BOTH parts a) and b). ) a) During the industrial preparation of a Pt/Al2O3 catalyst by wet impregnation, hydrated tetraammine platinum(II) chloride is used as the platinum precursor. A batch of granulated Al2O3 is immersed in a large excess of impregnating solution, and the pH is adjusted to 11.5 before the suspension is stirred for 1 hour. After isolating the solid by filtration, it is dried at 110 C for 10 hours and calcined in air at 500 C for 2 hours. i) Why is the pH of the impregnating solution adjusted to a value of 11.5? Why have these calcination conditions been selected? iii) Why does this preparative method not include a reduction step? b) Why are washcoated monolith catalysts used for controlling the emissions from internal combustion engines