Oxygen carrying materials with surface modification for redox-based catalysis and methods of making and uses thereof

Patent metadata

Field	Value
Publication number	US-2020215515-A1
Application number	US-201816622627-A
Country	US
Kind code	A1
Filing date	Jun 14, 2018
Priority date	Jun 15, 2017
Publication date	Jul 9, 2020
Grant date	—

Abstract

Redox catalysts having surface medication, methods of making redox catalysts with surface modification, and uses of the surface modified redox catalysts are provided. In some aspects, the redox catalysts include a core oxygen carrier region such as CaMnO3, BaMnO3-δ, SrMnO3-δ, Mn2SiO4, Mn2MgO4-δ, La0.8Sr0.2O3-δ, La0.8Sr0.2FeO3-δ, Ca9Ti0.1Mn0.9O3-δ, Pr6O11-δ, manganese ore, or a combination thereof; and an outer shell having an average thickness of about 1-100 monolayers surrounding the outer surface of the core region. The outer shell can include, for example a salt selected such as Li2WO4, Na2WO4, K2WO4, SrWO4, Li2MoO4, Na2MoO4, K2MoO4, CsMoO4, Li2CO3, Na2CO3, K2CO3, or a combination thereof.

First claim

1 . The redox catalyst according to claim 2 wherein:
(a) the core region comprises an oxygen carrier selected from the group consisting of CaMnO 3 , BaMnO 3-δ , SrMnO 3-δ , Mn 2 SiO 4 , Mn 2 MgO 4-δ , La 0.8 Sr 0.2 O 3-δ , La 0.8 Sr 0.2 FeO 3-δ , Ca 9 Ti 0.1 Mn 0.9 O 3-δ , Pr 6 O 11-δ , manganese ore, and a combination thereof; and
(b) the outer shell comprises a salt selected from the group consisting of Li 2 WO 4 , Na 2 WO 4 , K 2 WO 4 , SrWO 4 , Li 2 MoO 4 , Na 2 MoO 4 , K 2 MoO 4 , CsMoO 4 , Li 2 CO 3 , Na 2 CO 3 , K 2 CO 3 , and a combination thereof.

2 . A redox catalyst comprising:
(a) a core region having an outer surface, the core region comprising an oxygen carrier, and (b) an outer shell having an average thickness of about 1-100 monolayers surrounding the outer surface of the core region, the outer shell comprising a metal salt.

3 . The redox catalyst according to claim 2 , wherein the metal salt is selected from the group consisting of metal carbonates, metal phosphates, metal tungstates, metal molybdates, metal vanadates, metal halides, and a combination thereof.

4 . The redox catalyst according to claim 2 , wherein the outer shell comprises an alkaline earth metal tungstate selected from the group consisting of tungstates having a formula BWO 4 , B 2 WO 5 , B 3 WO 6 , and a combination thereof, where B is selected from the group consisting of Mg, Ca, Sr, and Ba.

5 . The redox catalyst according to claim 2 , wherein the outer shell comprises an alkali metal tungstate selected from the group consisting of Li 2 WO 4 , Na 2 WO 4 , K 2 WO 4 , Cs 2 WO 4 , and a combination thereof.

6 - 7 . (canceled)

8 . The redox catalyst according to claim 2 , wherein the outer shell comprises a halide salt having a formula AX,
where A is Na, K, Li, Rb, or Cs, and where X is F, Cl, Br, or I.

9 . The redox catalyst according to claim 2 , wherein the outer shell comprises a molybdate salt having a formula A 2 MoO 4 ,
where A is Li, Na, K, or Cs.

10 . The redox catalyst according to claim 2 , wherein the outer shell comprises a molybdate salt having a formula BMoO 4 ,
where B is Mg, Ca, Sr, Ba, a transition metals such as Fe or Mn, or a rare earth oxide.

11 . The redox catalyst according to claim 2 , wherein the shell comprises a metal carbonate, metal phosphate, metal vanadate, metal sulfate, metal halide, a combination thereof, or a combination thereof with one or more other mixed oxides.

12 . The redox catalyst according to claim 2 , wherein the shell comprises Ca, Sr, and/or Ba added to the shell as a tungstate or as an oxide in conjunction with an alkali tungstate.

13 . The redox catalyst according to claim 2 , wherein the oxygen carrier comprises a perovskites of the form AMnO 4 or AFeO 3 where A may be Ca, Sr, Ba, La, lanthanides or combination thereof.

14 . The redox catalyst according to claim 2 , wherein the oxygen carrier comprises a perovskite of the form Ca x A 1-x Mn y B 1-y O 3-δ , where A=Sr, Ba, La, Sm, or Pr and B=Ti, Fe, Mg, Co, Cu, Ni, V, Mo, Ce, or Al.

15 . The redox catalyst according to claim 2 , wherein the oxygen carrier is a nonstoichiometric perovskite including the Ruddlesden-Popper phases of the form A n+1 BnO 3n+1 where A is Ca, Sr, Ba, La, other lanthanides, or combination thereof, and B is Ti, Fe, Mn, Mq, Co, Cu, Ni, V, Mo, Ce, Al, or a combination thereof.

16 . The redox catalyst according to claim 2 , wherein the oxygen carrier is a nonstoichiometric mixed oxide including Brownmillerite (A 2 B 2 O 5 ), Spinel AB 2 O 4 , and cubic A 1-x B x O 2-δ where A is Ca, Sr, Ba, La, other lanthanides, or combination thereof, and B is Ti, Fe, Mn, Mq, Co, Cu, Ni, V, Mo, Ce, Al, or a combination thereof.

17 . The redox catalyst according to claim 2 wherein the oxygen carrier comprises a perovskite of the form ABO 3 , or other mixed oxide core material in the form of A x B y O z , where A is Sr, Ba, La, Sm, Pr, other lanthanides, or a combination thereof, and B is Ti, Fe, Mn, Mg, Co, Cu, Ni, V, Mo, Ce, or Al, or a combination thereof, and
wherein the shell layer is protected from destructive interactions with the oxygen carrier during redox cycling by stabilizing the oxygen carrier phase through one or both of:
a.) limiting a temperature of cycling for pretreatment and operation to the range of 500-800° C.; and
b) using A and B site substituents/dopants to stabilize the ABO 3 perovskite or other mixed oxide core materials.

18 - 21 . (canceled)

22 . The redox catalyst according to claim 2 , wherein the oxygen carrier comprises MnO 2 , Mn 2 O 3 , Mn 3 O 4 , MnO, or a combination thereof.

23 . The redox catalyst according to claim 2 , wherein the oxygen carrier comprises mixed manganese silica oxides.

24 . (canceled)

25 . The redox catalyst according to claim 2 , wherein the oxygen carrier comprises monometallic or mixed metal oxides containing first row transition metals Cu, Ni, Co, Fe, Mn or combinations or mixtures thereof.

26 - 27 . (canceled)

28 . The redox catalyst according to claim 2 , wherein the oxygen carrier comprises manganese ores containing significant amounts of the minerals pyrolusite (MnO 2 ), braunite, (Mn 2+ , Mn 3+ 6 )(SiO 12 ), psilomelane (Ba,H 2 O) 2 Mn 5 O 10 , Birnessite (Na 0.3 Ca 0.1 K 0.1 )(Mn 4+ ,Mn 3+ ) 2 O 4 , and/or bixbyite (Mn,Fe) 2 O 3 and/or Mn/Fe Spinel (Mn,Fe) 3 O 4 , or combinations or mixtures thereof.

29 . The redox catalyst according to claim 2 , wherein the oxygen carrier comprises bulk oxides including M 2-x SiO 4 structured materials (commonly known as Olivines) where M may be Mn, Fe, Mg, or a mixture thereof, in an amount effective to enhance the physical strength of the redox catalyst particles to provide additional oxygen carrying capacity, and/or catalyze thermal naphtha cracking.

30 . (canceled)

31 . The redox catalyst according to claim 2 , wherein the shell is in the form of a molten or solid shell or surface decorations fully or partially covering the core.

32 . (canceled)

33 . The redox catalyst according to claim 2 , wherein the oxygen carrier is active for oxidative dehydrogenation of methane, ethane, or propane at a temperature of about 500° C. to about 850° C.

34 - 35 . (canceled)

36 . The redox catalyst according to claim 3 , wherein a ratio of cation to anion in the shell is about ¼ to 4 times a stoichiometric cation to anion ratio.

37 - 40 . (canceled)

41 . A method of making a redox catalyst according to claim 2 , the method comprising
(a) forming a precursor comprising the oxygen carrier and the salt, wherein the salt comprises an alkaline or rare earth tungstate selected from the group consisting of BWO 4 , B 2 WO 5 , and B 3 WO 6 where B is Mg, Ca, Sr, Ba, or a rare earth element; and wherein the oxygen carrier is substantially free of alkali metals and metal oxides; (b) heating the precursor to an elevated temperature above a Tamman temperature of the salt to allow facile surface transport and “wetting” of the salt to form the shell that fully or partially covers the surface of the core.

42 . The method according to claim 41 , wherein the resulting tungsten containing phase is selected to not melt at reaction conditions to optimize its mechanical, chemical, and hydrodynamic properties.

43 . (canc

Assignees

• Univ North Carolina State

Inventors

• Li Fanxing
• Neal Luke Michael
• Gao Yunfei
• Yusuf Seif
• Dudek Ryan

Classifications

• B01J2235/00

  Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J35/733

  Perovskite-type · CPC title

• Y02E60/50

  Fuel cells · CPC title

• Y02P20/52

  using catalysts, e.g. selective catalysts · CPC title