Method and apparatus for treating nitrogen oxide-containing gas streams using a combined electrochemical-sorbent approach

Claim 1

A method for treating a gaseous stream containing NO x , comprising: (a) passing the gaseous stream through a sorbent body comprised of an alkali metal salt, an alkali metal oxide, an alkaline earth metal salt, an alkaline earth metal oxide, or a mixture thereof, at a temperature of less than about 500° C., for a period of time to remove substantially all of the NO x contained in the gaseous stream; followed by (b) heating the sorbent body to a temperature greater than about 600° C., producing an effluent comprising a concentrated stream of NO x and channeling the effluent therefrom to a solid-oxide electrochemical cell to electrochemically reduce the effluent to N 2 and O 2 .

Claim 2

A method for treating a gaseous stream containing NO x , comprising: (a) passing the gaseous stream through a sorbent body comprised of an alkali metal salt, an alkali metal oxide, an alkaline earth metal salt, an alkaline earth metal oxide, or a mixture thereof, at a temperature of less than about 500° C., for a period of time to remove substantially all of the NO x contained in the gaseous stream; followed by (b) heating the sorbent body to a temperature greater than about 600° C., producing an effluent comprising a concentrated stream of NO x and channeling the effluent therefrom to a solid-oxide electrochemical cell to electrochemically reduce the effluent to N 2 and O 2 .

Claim 14

An apparatus for the removal of nitrogen oxides from a feed gas and subsequent catalytic dissociation thereof, comprising: an inlet means for introducing the feed gas into the apparatus; a gas line enabling passage of the feed gas from the inlet means to a first sorbent cell comprised of an alkaline earth metal salt, an alkaline earth metal oxide, an alkali metal salt, an alkali metal oxide, or a mixture thereof; a heating means for heating the sorbent cell, causing desorption of nitrogen oxide-containing effluent; a means for carrying the nitrogen oxide-containing effluent from the sorbent cell to a solid-oxide electrochemical cell; and a solid-oxide electrochemical cell comprising a first, cathodic face through which the effluent is introduced, a second, anodic face, and, contained therebetween, an oxygen ion conducting metal oxide; and a means for applying a dc potential across the solid-oxide electrochemical cell.

Claim 15

An apparatus for the removal of nitrogen oxides from a feed gas and subsequent catalytic dissociation thereof, comprising: an inlet means for introducing the feed gas into the apparatus; a gas line enabling passage of the feed gas from the inlet means to a first sorbent cell comprised of an alkaline earth metal salt, an alkaline earth metal oxide, an alkali metal salt, an alkali metal oxide, or a mixture thereof; a heating means for heating the sorbent cell, causing desorption of nitrogen oxide-containing effluent; a means for carrying the nitrogen oxide-containing effluent from the sorbent cell to a solid-oxide electrochemical cell; and a solid-oxide electrochemical cell comprising a first, cathodic face through which the effluent is introduced, a second, anodic face, and, contained therebetween, an oxygen ion conducting metal oxide; and a means for applying a dc potential across the solid-oxide electrochemical cell.

Claim 26

An apparatus for the removal of nitrogen oxides from a feed gas and subsequent catalytic dissociation thereof, comprising: an inlet means for introducing the feed gas into the apparatus; a gas line enabling passage of the feed gas from the inlet means to two or more sorbent cells, wherein the cells are comprised of an alkaline earth metal salt, an alkaline earth metal oxide, an alkali metal salt, an alkali metal oxide, or a mixture thereof; a heating means for heating the sorbent cells, causing desorption of nitrogen oxide-containing effluent; a means for carrying the nitrogen oxide-containing effluent from the sorbent cells to a solid-oxide electrochemical cell; and a solid-oxide electrochemical cell comprising a first, cathodic face through which the effluent is introduced, a second, anodic face, and, contained therebetween, an oxygen ion conducting metal oxide; and a means for applying a dc potential across the solid-oxide electrochemical cell.

Claim 27

An apparatus for the removal of nitrogen oxides from a feed gas and subsequent catalytic dissociation thereof, comprising: an inlet means for introducing the feed gas into the apparatus; a gas line enabling passage of the feed gas from the inlet means to two or more sorbent cells, wherein the cells are comprised of an alkaline earth metal salt, an alkaline earth metal oxide, an alkali metal salt, an alkali metal oxide, or a mixture thereof; a heating means for heating the sorbent cells, causing desorption of nitrogen oxide-containing effluent; a means for carrying the nitrogen oxide-containing effluent from the sorbent cells to a solid-oxide electrochemical cell; and a solid-oxide electrochemical cell comprising a first, cathodic face through which the effluent is introduced, a second, anodic face, and, contained therebetween, an oxygen ion conducting metal oxide; and a means for applying a dc potential across the solid-oxide electrochemical cell.