Manganese Oxide Nanoarchitectures for Broad-Spectrum Removal of Toxic Gases in Air-Filtration Applications

Patent metadata

Field	Value
Publication number	US-2017197197-A1
Application number	US-201615383938-A
Country	US
Kind code	A1
Filing date	Dec 19, 2016
Priority date	Jan 8, 2016
Publication date	Jul 13, 2017
Grant date	—

Abstract

High-surface-area, ultraporous manganese oxide (MnOx) xerogels and aerogels exhibit outstanding filtration performance for multiple, chemically distinct toxic gases, including ammonia, sulfur dioxide and hydrogen sulfide. These MnOx materials use multiple mechanisms for small molecule capture/catalysis including molecular sieving and oxidative decomposition, and function in a wide range of humidity conditions.

First claim

What we claim is:

1 . A method of filtering toxic gases, said method comprising:
adding fumaric acid to an aqueous solution of NaMnO 4 in a 1:3 mole ratio to form a fluid-filled porous gel of MnOx in which the oxide domains also contain Na + and thereby form Na-MnOx; exposing the MnOx gel with a manganese oxide nanoarchitecture to a toxic gas and air mixture; and removing the toxic gas from the toxic gas and air mixture at room temperature via an oxidative mechanism that converts the toxic gas to an innocuous adsorbed substance.

2 . The method of filtering toxic gases of claim 1 wherein the manganese oxide nanoarchitecture has an interior surface area >200 m 2 g −1 .

3 . The method of filtering toxic gases of claim 2 wherein the MnOx gel has a void structure comprising pores that are sized from 2-150 nm.

4 . The method of filtering toxic gases of claim 3 wherein the MnOx gel has an average manganese oxidation state between +3 and +4.

5 . The method of filtering toxic gases of claim 4 further comprising the steps of:
rinsing the Na-MnOx gel with an acid solution to protonate the oxide and form H-MnOx and remove Na + ; and
rinsing the gel in water to remove residual acid.

6 . The method of filtering toxic gases of claim 5 further comprising the step of:
drying the fluid-filled porous gel under ambient-pressure conditions to generate a densified xerogel MnOx material.

7 . The method of filtering toxic gases of claim 5 further comprising the steps of:
exchanging the fluid in the pores of the fluid-filled porous gel for CO 2 ,
removing said CO 2 under supercritical conditions to render a dry, low-density MnOx aerogel.

8 . A high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders comprising:
a manganese oxide nanoarchitecture comprising an interior surface area >200 m 2 g −1 .

9 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 8 wherein the MnOx gel has a void structure comprising pores that are sized from 2-150 nm.

10 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 9 wherein the MnOx gel has an average manganese oxidation state between +3 and +4.

11 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 8 wherein the MnOx gel is capable of removing ammonia from a contacting gas mixture at sorption capacities >1.0 mol NH 3 kg −1 MnOx for H-MnOx compositions and >1.5 mol NH 3 kg −1 MnOx for Na-MnOx compositions under dry conditions.

12 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 8 wherein the MnOx gel is capable of removing ammonia from a contacting gas mixture at sorption capacities >2 mol NH 3 kg −1 MnOx for H-MnOx compositions and >1 mol NH 3 kg −1 MnOx for Na-MnOx compositions under humid conditions or wherein the humidity is about 80% relative humidity.

13 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 8 wherein the MnOx gel is capable of removing sulfur dioxide from a contacting gas mixture at sorption capacities >0.5 mol SO 2 kg −1 MnOx for H-MnOx compositions and >1 mol SO 2 kg −1 MnOx for Na-MnOx compositions under dry conditions.

14 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 8 wherein the MnOx gel is capable of removing sulfur dioxide from a contacting gas mixture at sorption capacities >2 mol SO 2 kg −1 MnOx for H-MnOx compositions and >3 mol SO 2 kg −1 MnOx for Na-MnOx compositions under wet conditions or wherein the humidity is about 80% relative humidity.

15 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 8 wherein the MnOx gel is capable of removing hydrogen sulfide from a contacting gas mixture at sorption capacities >0.3 mol H 2 S kg −1 MnOx for H-MnOx compositions and >1.5 mol H 2 S kg −1 MnOx for Na-MnOx compositions under dry conditions.

16 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 8 wherein the MnOx gel is capable of removing hydrogen sulfide from a contacting gas mixture at sorption capacities >0.5 mol H 2 S kg −1 MnOx for H-MnOx compositions and >9 mol H 2 S kg −1 MnOx for Na-MnOx compositions under wet conditions or wherein the humidity is about 80% relative humidity.

17 . The high-surface-area, highly porous manganese oxide (MnOx) in the form of xerogel or aerogel monoliths or powders of claim 8 wherein the MnOx gel is capable of removing >35% of HD mustard agent from a liquid-phase application.

Assignees

• Us Gov Sec Navy

Inventors

• Long Jeffrey W
• Wallace Jean M
• Peterson Gregory W

Classifications

• B01J20/3085

  Chemical treatments not covered by groups B01J20/3007 - B01J20/3078 · CPC title

• B01J20/06

  comprising oxides or hydroxides of metals not provided for in group B01J20/04 · CPC title

• B01D53/50

  Sulfur oxides (B01D53/60 takes precedence) · CPC title

• B01J20/28085

  being more than 50 nm, i.e. macropores · CPC title

• B01J20/3071

  Washing or leaching · CPC title