A catalyst system includes a first catalytic composition and a second catalytic composition. The first catalytic composition includes a homogeneous solid mixture, which includes a first catalytic material disposed on a first substrate. The pores of the solid mixture have an average diameter of greater than about 45 nanometers. The second catalytic composition includes at least one of a zeolite or a second catalytic material disposed on a second substrate. The second catalytic material includes an element selected from the group that includes tungsten, titanium, and vanadium.