A sulfur recovery unit (SRU) and method including converting hydrogen sulfide to elemental sulfur via the SRU having a reaction furnace and three catalytic reactors including a first catalytic reactor, a second catalytic reactor, and a third catalytic reactor disposed operationally in series, wherein catalyst in the first catalytic reactor consists of alumina catalyst, and wherein catalyst in the second catalytic reactor consists of a first layer of alumina catalyst, a second layer of hydrogenation catalyst, and a third layer of titania catalyst.