Abstract: A cyclic process for the removal of NOx from a NOx containing feed gas, and optionally removal mercury vapour and/or sulfur dioxide is provided. A process is also provided by which an iron chelate absorbent may be thermally regenerated.

Abstract: Sulphur dioxide is removed from gas streams by contacting the gas stream with an absorbing medium containing an amine capable of forming an amine salt, heat stable salt and sulfite. The level of heat stable salt is selected such that during the regeneration process of the sulphur dioxide rich amine, the pH of the absorbing medium is at a selected level or below when the level of sulfite in the absorbing medium has been reduced to a specified value. The amine that absorbs the sulphur dioxide has a pKa less than that of sulfite. If the absorbent includes a diamine, then the spent absorbing medium is regenerated under conditions such that at least one amine group remains in salt form.

Abstract: A process for recovering CO2 from a feed gas stream comprises treating the feed gas stream with a regenerated absorbent comprising at least one tertiary amine absorbent having a pKa for the amino function of from about 6.5 to about 9 in the presence of an oxidation inhibitor to obtain a CO2 rich stream and subsequently treating the CO2 rich stream to obtain the regenerated absorbent and a CO2 rich product stream. The feed gas stream may also include SO2 and/or NOx.

Abstract: NO is removed from a gas stream by reacting NO with an absorbent to form a metal nitrosyl complex. The metal nitrosyl complex is reacted with sulfite and/or bisulfite to produce recoverable reaction products containing nitrogen and/or sulfur and to regenerate the reagent. The recoverable reaction products are then separated from the regenerated reagent.

Abstract: A process for recovering CO2 from a feed gas stream comprises treating the feed gas stream with a regenerated absorbent comprising at least one tertiary amine absorbent having a pKa for the amino function of from about 6.5 to about 9 in the presence of an oxidation inhibitor to obtain a CO2 rich stream and subsequently treating the CO2 rich stream to obtain the regenerated absorbent and a CO2 rich product stream. The feed gas stream may also include SO2 and/or NOx.

Abstract: NO is removed from a gas stream by reacting NO with an absorbent to form a metal nitrosyl complex. The metal nitrosyl complex is reacted with sulfite and/or bisulfite to produce recoverable reaction products containing nitrogen and/or sulfur and to regenerate the reagent. The recoverable reaction products are then separated from the regenerated reagent.

Abstract: The invention relates to a method of confining sulfur dioxide for storage or transportation under safe conditions. The method of the invention comprises the steps of (a) contacting a sulfur dioxide-containing gas stream with an absorbing medium comprising water and a water-soluble amine absorbent having at least one amine group with a pKa value greater than about 7 and at least one other amine group with a pKa value less than about 6.5 so that the at least one amine group with a pKa value greater than about 7 irreversibly absorbs sulfur dioxide in salt form rendering the amine absorbent non-volatile and the at least one other amine group with a pKa value less than about 6.5 reversibly absorbs sulfur dioxide, to thereby saturate the absorbing medium with sulfur dioxide against a partial pressure of sulfur dioxide of no more than about 1 atmosphere at 25° C.; and (b) charging the absorbing medium saturated with sulfur dioxide obtained in step (a) into a container for storage or transportation.

Abstract: Processes are disclosed for converting heat stable amine salts to heat regenerable amine salts using a modified electrodialysis zone. The processes of the present invention can be used to reduce the level of heat stable salts in a lean solvent stream in an acid gas removal process and can be integrated with the acid gas removal process to utilize process streams as a source of ions.

Abstract: Processes for the removal of sulfur dioxide from gas streams, e.g., stack gases, are disclosed wherein the absorption occurs in the presence of a diamine. The first amine group, i.e., stronger amine group, of the diamine is in salt form, having sulfite anions associated therewith, and absorbs by a sulfite/bisulfite absorption mechanism. The second amine groups absorbs sulfur dioxide in free base form. The sulfite salt on the first amine group is maintained by controlling the level of heat stable salts in the absorbent. Both the first and second amine groups can be conveniently regenerated together, e.g., by steam stripping.

Abstract: Processes are provided for the removal of sulfur dioxide from gas streams using aqueous lime or limestone slurries containing an additive comprising an amine. The amines have an available alkalinity of at least 0.5 meq/gram at a pH between 3.0 and 5.5. The amines are highly soluble in the slurry and can have a low volatility, thereby reducing amine losses with the gas product. Furthermore, amines which are absorbed on the calcium sulfate or calcium sulfite by-products can be recovered by water-washing with a water make-up stream.

Abstract: Sulphur dioxide is removed from gas streams by contacting the gas stream with an absorbing medium containing less than about 80 wt. % of water and the spent absorbing medium subsequently is regenerated by removing absorbed SO.sub.2. The absorbing medium comprises amine salt absorbent having at least two amine groups, at least one of which is a salt and at least one of which has a pKa of about 4.5 to 7.3. The absorption is at a temperature of less than about 60.degree. C. The spent absorbing medium is regenerated under conditions such that at least one amine group remains in salt form.

Abstract: Components are removed from gas streams by contact in a contact zone with finely-divided droplets of reversible liquid sorbent wherein a portion of the droplets is coalesced, which droplets contain a concentration of component sorbed greater than that predicted by vapor-liquid equilibrium at the condition of the gas stream at the exit of the contact zone.