Patent ID: 7435286

Claim:
A method for reducing mercury in mercury-containing gas to a desired level, the method comprising: preparing a sorbent having a sorbent composition; wherein preparing the sorbent comprises reacting a base activated carbon with at least one promoter selected from the group consisting of molecular halogens, halides, and combinations thereof to yield a promoted halogenated carbon comprising active sites wherein the active sites comprise halide covalently-bound to the base-activated carbon; injecting the sorbent into a mercury-containing gas stream at at least one sorbent injection location and at a sorbent injection rate, wherein the mercury-containing gas stream is a combustion gas or a gasification gas, and wherein the composition of the mercury-containing gas may vary with time; optionally co-injecting an alkaline sorbent into the mercury-containing gas stream at at least one alkaline injection location and at an alkaline injection rate; collecting greater than 70 wt % of the mercury in the mercury-containing gas on the sorbent to produce a cleaned gas; monitoring the mercury content of the cleaned gas; and controlling, in response to the monitored mercury content of the cleaned gas, which may vary with the composition of the mercury-containing gas and operating conditions, the sorbent injection rate, the alkaline injection rate, the sorbent composition, or a combination thereof so that the mercury content of the cleaned gas is maintained at substantially the desired level with minimal operating cost.