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All sources NASA NTRS DOE OSTI

NASA NTRS1988

High temperature regenerative H.sub.2 S sorbents

Efficient, regenerable sorbents for removal of H.sub.2 S from high temperature gas streams comprise porous, high surface area particles. A first class of sorbents comprise a thin film of binary oxides that form a eutectic at the temperature of the gas stream coated onto a porous, high surface area refractory support. The binary oxides are a mixture of a Group VB or VIB metal oxide with a Group IB, IIB or VIII metal oxide such as a film of V-Zn-O, V-Cu-O, Cu-Mo-O, Zn-Mo-O or Fe-Mo-O coated on an alumina support. A second class of sorbents consist of particles of unsupported mixed oxides in the form of highly dispersed solid solutions of solid compounds characterized by small crystallite size, high porosity and relatively high surface area. The mixed oxide sorbents contain one Group IB, IIB or VIIB metal oxide such as copper, zinc or manganese and one or more oxides of Groups IIIA, VIB or VII such as aluminum, iron or molybdenum. The presence of iron or aluminum maintains the Group IB, IIB or VIIB metal in its oxidized state. Presence of molybdenum results in eutectic formation at sulfidation temperature and improves the efficiency of the sorbent.

Flytani-Stephanopoulos, Maria↗

NASA NTRS1993

Hot gas, regenerative, supported H.sub.2 S sorbents

Efficient, regenerable sorbents for removal of H.sub.2 S from moderately high temperature (usually 200.degree. C.-550.degree.C.) gas streams comprise a porous, high surface area aluminosilicate support, suitably a zeolite, and most preferably a sodium deficient zeolite containing 1 to 20 weight percent of binary metal oxides. The binary oxides are a mixture of a Group VB or VIB metal oxide with a Group IB, IIB or VIII metal oxide such as V-Zn-O, V-Cu-O, Cu-Mo-O, Zn-Mo-O or Fe-Mo-O contained in the support. The sorbent effectively removes H.sub.2 S from the host gas stream in high efficiency and can be repetitively regenerated at least 10 times without loss of activity.

Voecks, Gerald E.↗

DOE OSTI2020

Materials Data on Fe2MoO4 by Materials Project

Fe2MoO4 is Spinel-like structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Mo2+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent MoO6 octahedra, and edges with four equivalent FeO6 octahedra. All Mo–O bond lengths are 2.17 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six equivalent MoO6 octahedra and corners with six equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There is two shorter (1.92 Å) and two longer (1.95 Å) Fe–O bond length. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four equivalent MoO6 octahedra. All Fe–O bond lengths are 2.17 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Mo2+ and two Fe3+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mo2+ and three Fe3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Fe2Mo3O8 by Materials Project

Fe2Mo3O8 is beta indium sulfide-derived structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Mo+3.33+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with three equivalent FeO4 trigonal pyramids, an edgeedge with one FeO6 octahedra, and edges with four equivalent MoO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Mo–O bond distances ranging from 2.06–2.20 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 trigonal pyramids that share corners with three equivalent FeO6 octahedra and corners with nine equivalent MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–64°. There is one shorter (1.93 Å) and three longer (1.98 Å) Fe–O bond length. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent MoO6 octahedra, corners with three equivalent FeO4 trigonal pyramids, and edges with three equivalent MoO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are three shorter (1.98 Å) and three longer (2.24 Å) Fe–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mo+3.33+ and one Fe3+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mo+3.33+ and two Fe3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mo+3.33+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to three equivalent Mo+3.33+ and one Fe3+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Fe2Mo4O7 by Materials Project

Fe2Mo4O7 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are eight inequivalent Mo2+ sites. In the first Mo2+ site, Mo2+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with three FeO4 tetrahedra, edges with two FeO6 octahedra, and edges with two equivalent MoO5 square pyramids. There are a spread of Mo–O bond distances ranging from 2.07–2.09 Å. In the second Mo2+ site, Mo2+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with three FeO4 tetrahedra, edges with two FeO6 octahedra, and edges with two equivalent MoO5 square pyramids. There are a spread of Mo–O bond distances ranging from 2.10–2.20 Å. In the third Mo2+ site, Mo2+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with three FeO4 tetrahedra, edges with two FeO6 octahedra, and edges with two equivalent MoO5 square pyramids. There are a spread of Mo–O bond distances ranging from 2.06–2.09 Å. In the fourth Mo2+ site, Mo2+ is bonded to five O2- atoms to form MoO5 square pyramids that share corners with three FeO4 tetrahedra, edges with two FeO6 octahedra, and edges with two equivalent MoO5 square pyramids. There are a spread of Mo–O bond distances ranging from 2.10–2.19 Å. In the fifth Mo2+ site, Mo2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.15–2.19 Å. In the sixth Mo2+ site, Mo2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.15–2.19 Å. In the seventh Mo2+ site, Mo2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are one shorter (2.14 Å) and three longer (2.19 Å) Mo–O bond lengths. In the eighth Mo2+ site, Mo2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.15–2.19 Å. There are four inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with four FeO6 octahedra and corners with six MoO5 square pyramids. The corner-sharing octahedra tilt angles range from 59–60°. There are a spread of Fe–O bond distances ranging from 2.03–2.08 Å. In the second Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with four FeO6 octahedra and corners with six MoO5 square pyramids. The corner-sharing octahedra tilt angles range from 59–60°. There are a spread of Fe–O bond distances ranging from 2.03–2.08 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four MoO5 square pyramids. There are a spread of Fe–O bond distances ranging from 2.11–2.35 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four MoO5 square pyramids. There are a spread of Fe–O bond distances ranging from 2.11–2.35 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mo2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OFe3Mo tetrahedra. In the second O2- site, O2- is bonded to one Mo2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OFe3Mo trigonal pyramids. In the third O2- site, O2- is bonded to one Mo2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OFe3Mo tetrahedra. In the fourth O2- site, O2- is bonded to one Mo2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OFe3Mo trigonal pyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mo2+ and one Fe3+ atom. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mo2+ and one Fe3+ atom. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mo2+ and one Fe3+ atom. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mo2+ and one Fe3+ atom. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mo2+ and one Fe3+ atom. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mo2+ and one Fe3+ atom. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mo2+ and one Fe3+ atom. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Mo2+ and one Fe3+ atom. In the thirteenth O2- site, O2- is bonded in a square co-planar geometry to four Mo2+ atoms. In the fourteenth O2- site, O2- is bonded in a square co-planar geometry to four Mo2+ atoms.

36 MATERIALS SCIENCE↗