Michigan State University

Jayantha Amarasekera

Thomas J Pinnavaia

Christine A Polansky

Malama Chibwe

Taehyun Kwon

Emmanuel D Dimotakis

A process for removing and then capturing noxious sulfur oxides from gas streams, particularly from the flue gases of coal-burning power plants, using Ni-containing heated layered double hydroxide (LDH) as recyclable sorbents. The sorbent compositions contain metal components that form stable metal sulfites and sulfates at one temperature, but are decomposed at a higher temperature to regenerate the sorbent material.

Process using recyclable sorbents for the removal of sox from flue gases

The use of base/clay composites materials as sorbents for the removal of SO.sub.2 and SO.sub.3 (SO.sub.x) from flue gas and other sulfur containing gas streams is described. The base is either an alkaline earth metal carbonate (eg. CaCO.sub.3) or hydroxide (eg. Ca(OH).sub.2) is incorporated onto the clay by precipitating from corresponding metal oxide (eg. CaO) in an aqueous clay slurry. A second metal oxide or oxide precursor, preferably selected from transition metal ions, capable of promoting the oxidation of sulfur dioxide to sulfur trioxide, is incorporated to the base/clay composite during the synthesis in the form of finely divided metal oxide powder, metal oxide sol, water soluble metal salt or as clay-intercalated metal cation. The use of clay as dispersing agent for both the basic oxide and the second metal oxide component decreases the particle agglomeration of base particles and increases the rate of SO.sub.x uptake compared to the bulk bases in current use.

Method for the preparation of highly reactive clay composites for the

A process for removing noxious sulfur oxides, nitrous oxides, and chlorine from gas streams, particularly from flue gases of coal-burning power plants, using layered double hydroxide (LDH) sorbents are described. The sorbents are particularly useful for SO.sub.2 absorption at temperatures in the range 100 to less than 400.degree. C. The SO.sub.2 gas absorbs into the hydrotalcite structure as SO.sub.3.sup.2- anions by replacing most of the gallery CO.sub.3.sup.2- anions. The adsorbed SO.sub.2 is driven-off by calcination at elevated temperatures (500.degree. C.) and the LDH sorbents are regenerated by hydrolyzing the calcined product optionally in the presence of CO.sub.2 or CO.sub.3.sup.2-.

Process of using layered double hydroxides as low temperature recyclable

The preparation and the use of base/clay composites materials as sorbents for the removal of SO.sub.2 and SO.sub.3 (SO.sub.x) from flue gas and other sulfur containing gas streams is described. The base is either an alkaline earth metal carbonate (e.g. CaCO.sub.3) or hydroxide (e.g. Ca(OH).sub.2) and is incorporated onto the clay by hydrating a dry physical mixture of an alkaline earth metal oxide, a smectite clay and a second metal oxide, or metal oxide precursor to form a powdered composite material. The second metal oxide, preferably selected from transition metal ions, act as an oxidation catalyst for the conversion of sulfur dioxide to sulfur trioxide. The use of clay as dispersing agent for both the basic oxide and the catalytic oxide component decreases the particle agglomeration of base particles and increases the rate of SO.sub.x uptake compared to the bulk bases in current use.

Hydrated lime clay composites for the removal of SO.sub.x from flue gas

A method for preparing and using compositions including a smectite clay and a base or base precursor which reacts with SO.sub.x in a hot flue gas is described. The base or base precursor is preferably the dispersed phase in the bulk phase of the clay. The compositions are heated to form the base which reacts with SO.sub.x in the flue gas.

Composite clay materials for removal of SO.sub.x from gas streams

Composite clay materials for removal of sox from gas streams

A method for preparing smectite clay alkaline earth metal hydroxide and carbonate composite materials is described. The method uses low amounts of the clay added to water to which is added calcium oxide or calcium hydroxide. Optionally the calcium carbonate is formed in situ by exposure to air or to carbon dioxide in the solution. The product is dried to form the composite material which is used to remove SO.sub.x from flue gases.

Clay composites for removal of SO.sub.x from flue gas streams

Clay composites for the removal of SO.sub.x from flue gas streams

Processes for removing noxious oxides from gas streams, particularly from flue gases of coal-burning power plants, using heated layered double hydroxide (LDH) sorbents are described. The sorbent compositions contain metal components, incorporated into the sorbents either by isomorphous replacement of all or part of M.sup.II and /or M.sup.III ions in layers of LDH structures or by impregnation as a metal salt, to promote the oxidation of sulfur dioxide.

Layered double hydroxide sorbents for the removal of SO.sub.x from flue

Processes for removing noxious sulfur oxides from gas streams, particularly from flue gases of coal-burning power plants, using heated layered double hydroxide (LDH) sorbents are described. The sorbent compositions contain metal components, incorporated into the sorbents either by isomorphous replacement of all or part of M.sup.II and/or M.sup.III ions in layers of LDH structures or by impregnation as a metal salt, to promote the oxidation of sulfur dioxide.

A process of removing noxious sulfur oxides from gas streams using heated layered double hydroxide (LDH) sorbents is described. The sorbent compositions contain metal components incorporated into the galleries of the LDH structures in the form of metal-containing oxo-anions, to promote the oxidation of sulfur dioxide.

Process using sorbents for the removal of SO.sub.x from flue gas

This disclosure describes the synthesis of layered double hydroxide compositions interlayered by polyoxometalate anions with Keggin-type structures and having the formula [M.sub.1-x.sup.ll M.sub.x.sup.lll (OH).sub.2 ]A.sub.x/n.sup.n-.yH.sub.2 O, wherein, M.sup.ll is a divalent metal and M.sup.lll is a trivalent metal, A is an anionic polyoxometalate of negative charge n, x range between 0.12 to 0.8, and y is a positive number. The products exhibit well-defined XRD peaks corresponding to uniformly crystalline layered products with basal spacing values.gtoreq.14 .ANG..

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East Lansing, MI, United States of America

Jayantha Amarasekera