Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
1999-06-11
2001-05-22
Wood, Elizabeth D. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S332000, C502S335000, C502S336000, C502S340000, C502S341000, C502S342000, C502S344000, C502S353000, C502S355000
Reexamination Certificate
active
06235678
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a catalyst composition for an oxidative dehydrogenation of organic compounds having alkane functionality to organic compounds having alkene functionality. The present invention also relates to a catalytic process for the oxidative dehydrogenation of alkanes to alkenes.
BACKGROUND OF THE INVENTION
Unsaturated alkenes are useful as monomers and comonomers for the formation of commercially valuable polymers. The conversion of lower value saturated hydrocarbons into higher value unsaturated hydrocarbons is economically desirable. Oxidative dehydrogenation of saturated hydrocarbons to form unsaturated hydrocarbons has been accomplished using catalysts in high temperature gas phase reactions.
Numerous catalysts which can be used for the oxidative dehydrogenation of saturated or paraffinic hydrocarbons have been reported. Mixed nickel and tin oxides have been disclosed in U.S. Pat. No. 3,745,194; U.S. Pat. No. 3,801,671; and U.S. Pat. No. 5,086,032. Complex metal oxide catalyst including vanadium and aluminum for oxidative dehydrogenation of hydrocarbons has been disclosed in U.S. Pat. No. 4,046,833.
Catalysts, having crystalline structures, useful for the oxidative dehydrogenation of saturated hydrocarbons to form unsaturated hydrocarbons are known. U.S. Pat. No. 5,772,898 discloses a metallo manganese oxide having a hollandite structure and an intracrystalline pore system.
U. S. Pat. No. 4,777,319 discloses a catalyst for oxidative dehydrogenation of hydrocarbons using metal vanadate compounds which are described as having crystalline structures. U.S. Pat. No. 5,139,988 discloses an iron-antimony containing oxide catalyst in which the iron antimonate is crystalline. U.S. Pat. No. 4,973,793 discloses crystalline catalyst compositions having iron, oxygen and at least one other metallic element. U.S. Pat. No. 4,658,074 also discloses crystalline catalysts having iron, oxygen and at least on other metallic element.
Calcination is commonly used as one step in the process of preparing catalysts useful for oxidative dehydrogenation. U.S. Pat. No. 3,860,534 disclosed high temperature calcinations at 700° C. to 900° C.
A desire still exists in the art to develop catalyst that will promote a high conversion of alkane starting material with high selectivity to an alkene product material of the same carbon number so as to enable the attainment of a high yield of product per pass.
SUMMARY OF THE INVENTION
One embodiment of this invention is a catalyst in an oxide form containing aluminum, vanadium and antimony which is useful for the oxidative dehydrogenation of organic compound having at least two adjacent carbon atoms each having at least one hydrogen atom. The catalyst composition is represented by the formula A
a
B
b
Sb
c
V
d
Al
e
O
x
wherein A is an alkali or alkaline earth metal; B is one or more optional elements selected from zinc, cadmium, lead, nickel, cobalt, iron, chromium, bismuth, gallium, niobium, tin and neodymium; and a is 0 to 0.3, b is 0 to 5, c is 0.5 to 10, d is 1, e is 3 to 10, 7≦a+b+c+d+e≦25, and x is determined by the valence requirements of the elements present. The catalyst is prepared by a low temperature process with a calcination temperature below about 650° C. The catalyst is prepared by a process comprising at least a step of heating the catalyst to its calcination temperature using a heating velocity of less than 15° C./minute. The catalyst is substantially amorphous, i.e. without any long range lattice order. The preferred catalyst compositions promote a high conversion of alkane starting material with high selectivity to alkene product material of the same number of carbon atoms to enable production yields of up to 30% per reactor pass.
According to one embodiment of the present invention the catalyst can be on a support material. The support material may be an inorganic compound that is substantially free of alumina or aluminum.
The oxidative dehydrogenation process includes a step of contacting an organic compound containing alkane functionality with the catalyst in a reactor, in the presence of an oxygen containing gas, in the gas phase at an elevated temperature for a time sufficient to convert a portion of the organic compound of alkane functionality to an organic compound containing alkene functionality. The oxidative process may be applied to any organic compound having at least two adjacent bonded carbon atoms each having at least one hydrogen atom.
DETAILED DESCRIPTION OF INVENTION
The subject matter of the present invention is an improved catalyst for a process of oxidative dehydrogenation of compounds having at least two adjacent carbon atoms each having at least one hydrogen atom. The oxidative dehydrogenation process converts alkanes to alkenes. The process is applicable to, but not limited to, for example, ethane, propane, butane, isobutane, pentane, isopentane, hexane and ethylbenzene. The oxidative dehydrogenation process may proceed even in the presence of one or more additional functional groups in the compound to be dehydrogenated. The oxidative dehydrogenation process of the present invention is applicable even in the presence of one or more of the following functional groups: nitrile, alkyl halide, ether, ester, aldehyde, ketone, carboxylic acid and alcohol.
The process of the present invention is useful for the oxidative dehydrogenation of compounds which typically contain from 2 to 20 carbon atoms, have a boiling point below about 350° C., and optionally may contain other elements, in addition to carbon and hydrogen, such as halogen, nitrogen and sulphur. Preferred compounds have from 2 to 12 carbon atoms and most preferred compounds have from 2 to 6 carbon atoms.
The oxidative dehydrogenation process is also applicable to the direct dehydrogenation of an alkane to an alkadiene or to the dehydrogenation of an alkene to an alkadiene. For example, the process can convert isopentane to isopentene or convert isopentane, through an isopentene intermediate, to isoprene.
CATALYST COMPOSITION
The catalyst composition is represented by the formula A
a
B
b
Sb
c
V
d
Al
e
O
x
wherein A is an alkali or alkaline earth metal; B is one or more optional elements selected from zinc, cadmium, lead, nickel, cobalt, iron, chromium, bismuth, gallium, niobium, tin and neodymium; and a is 0 to 0.3, b is 0 to 5, c is 0.5 to 10, d is 1, e is 3 to 10, 7≦a+b+c+d+e≦25, and x is determined by the valence requirements of the elements present.
Catalyst precursors may be prepared by conventional physical methods utilizing mixing, co-precipitation, impregnation and filtration. Preferred starting materials are water soluble metal salts which include, but are not limited to, metal nitrates, chloride, oxalates and hydroxides. For metal salts in which the metal is an anionic ion, an ammonium cation may be used as a counterion.
The catalyst of the present invention can be produced by preparing one or more solutions or slurries, preferable aqueous solutions or slurries, each containing one or more of the starting materials. For example, a slurry of an alumina precipitate is formed by adjusting the pH of an aluminum salt solution with ammonium hydroxide. The remaining solutions or slurries are mixed, with pH adjustment as needed, to form a mixed metal precipitate. The mixed metal precipitate is added to the alumina slurry and the resulting solids are recovered by filtration, dried and calcined in a non-reducing atmosphere to prepare an oxide form of the catalyst.
Some catalysts are further impregnated prior to calcination with one or more Group I and/or Group II elements. A compound of the Group I or Group II element, for example potassium hydroxide, may be dissolved in water and impregnated onto the catalyst by incipient wetness. Typically water that is substantially free of dissolved metals, for example de-ionized water, may be used. Alternatively semi-conductor grade water may be used to dissolve the compound of the Group I or Group II element in order to reduce the
Mamedov Edouard A.
Shaikh Shahid N.
Akin Gump Strauss Hauer & Feld L.L.P.
Saudi Basic Industries Corporation
Wood Elizabeth D.
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