Sorbent and processes for removing nitrogen oxides, sulfur oxides and hydrogen sulfide from gas streams

Claim 1

A process for the removal of nitrogen oxides and sulfur oxides from a sorbent containing them, comprising: (a) removing said nitrogen oxides from a sorbent comprising: (i) a gamma alumina substrate having a surface area between 100 m 2 /g and 500 m 2 /g and a pore volume between 0.4 and 0.8 cc/g, said gamma alumina substrate having a bimodal pore size disribution comprising micropores and macropores, said micropores having an average pore diameter d 1 in the range of between 30 and 400 Angstroms and said macropores having an average pore diameter d 2 in the range of between 80 and 3000 Angstroms, (ii) an alkali metal component, said substrate impregnated with the alkali metal component and the amount of said alkali metal component being between 50 and 400 μg per m 2 of said substrate; by contacting said nitrogen oxides and sulfur oxides containing sorbent with a stream of air heated to a temperature of above 532° C. and carrying said removed oxides away in a hot air stream; and (b) subsequently, contacting said sulfur oxides containing sorbent with a regenerant stream of methane which reacts with the sorbed sulfur oxides to produce a stream of elemental sulfur and carrying said stream of elemental sulfur away.