Patent ID: 7632479

Claim:
A process for producing ammonia and sulfuric acid from a first stream comprising ammonium sulfate, the process comprising the steps of: (i) heating the first stream comprising ammonium sulfate thereby producing ammonia and a decomposition product comprising sulfate salt selected from the group consisting of bisulfate salt, pyrosulfate salt and a combination thereof; (ii) recovering the ammonia produced in step (i); (iii) adding water to the decomposition product produced in step (i) to produce a second stream comprising a chemical selected from the group consisting of sulfate salt, bisulfate salt, sulfuric acid and a combination thereof; (iv) separating sulfate salt from sulfuric acid in the second stream produced in step (iii) to obtain a third stream comprising sulfuric acid and a fourth stream comprising one or more than one sulfate salt, wherein said separating comprises acid retardation; and (v) recovering the sulfuric acid obtained in step (iv), wherein the first stream comprising ammonium sulfate originates from a stream produced by pretreatment of a lignocellulosic feedstock with sulfuric acid and wherein sulfate present in the stream comprising ammonium sulfate originates, in whole or in part, from sulfuric acid added during said pretreatment.