Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2002-08-07
2004-01-06
Solola, Taofiz A (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
active
06673949
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a process for the epoxidation of hydrocarbons. This process comprises reacting at least one hydrocarbon with oxygen, in the presence of a mixture comprising at least two elements selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Fe, Co, Ni, Sn, Pb, Sb, Bi and Se, on a support with a BET surface area of less than 200 m
2
/g. The present invention also relates to catalysts suitable for the epoxidation of hydrocarbons. These catalysts comprise a mixture comprising at least two elements from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Fe, Co, Ni, Sn, Pb, Sb, Bi and Se, on a support with a BET surface area of less than 200 m
2
/g.
Epoxides are an important starting material in the polyurethane industry. There are a number of processes given for preparing these, some of which have also been converted to the industrial scale. Currently, the direct oxidation of ethylene with air or with gases which contain molecular oxygen in the presence of a silver-containing catalyst, as described in EP-A2-933 130, is used for the industrial preparation of ethylene oxide. In order to prepare longer-chain epoxides on an industrial scale, hydrogen peroxide or hypochlorite in the liquid phase are generally used as oxidizing agents. EP-A1-0 930 308 describes, for example, the use of ion exchanged titanium silicalites as a catalyst with these two oxidizing agents.
Another class of oxidation catalysts, which enables propylene to be oxidized to the corresponding epoxide in the gas phase, was disclosed recently in, for example, U.S. Pat. No. 5,623,090. Here, gold on anatase is disclosed as a catalyst, oxygen serves as the oxidizing agent and this is used in the presence of hydrogen. The system is characterized by extraordinarily high selectivity (i.e. S>95%) with respect to propylene oxidation. The low conversion and deactivation of the catalyst are,
Very little information is disclosed in the literature about other active components, apart from gold and silver, for the selective direct oxidation of propylene and higher alkenes in the gas phase.
Since none of the published catalysts has previously exhibited satisfactory results with regard to activity and selectivity for the direct oxidation of propylene to propylene oxide, other active components are being sought as alternatives to the known silver and gold-containing catalysts. An important prerequisite is that the oxidation process does not go to completion, and form the corresponding acid or the aldehyde or ketone. Rather, any suitable the oxidation process must terminate at the epoxide stage.
A few mixtures of elements from groups 3-10 or 14-16 in the Periodic System of Elements according to IUPAC 1986 have already been disclosed in the literature.
For example, mixtures of iron, cobalt and nickel on a variety of supports are used to prepare ammonia. To provide an example of the very extensive literature, reference is made here only to the review by M. Appl [Indian Chem. Eng., 1987, 7-29]. Furthermore, mixtures of iron and cobalt are also known and described as being suitable for the oxidation of cyclohexane to adipic acid. See, for example, U.S. Pat. No. 5,547,905. The formation of epoxides is not disclosed by this reference, however.
It has now surprisingly been shown that propylene oxide can be prepared by the direct oxidation of propylene with oxygen or air, using mixtures of different elements. This is all the more unusual because the oxidation remains at the epoxide stage, and does not produce the corresponding acids, ketones or aldehydes.
SUMMARY OF THE INVENTION
The invention provides a process for the epoxidation of hydrocarbons. This process comprises
(1) reacting
(a) at least one hydrocarbon,
with
(b) oxygen, or air or nitrous oxide or other gaseous oxidents (preferably oxygen)
in the presence of
(c) a mixture comprising at least two elements selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Fe, Co, Ni, Sn, Pb, Sb, Bi and Se, on an inert support with a BET surface area of less than 200 m
2
/g.
Said elements may be present as such or in the form of chemical compounds. The present invention also relates to suitable epoxidation catalysts for hydrocarbons. These epoxidation catalysts comprise:
(i) a mixture comprising at least two elements selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Fe, Co, Ni, Sn, Pb, Sb, Bi and Se,
(ii) on an inert support with a BET surface area of less than 200 m
2
/g. Said elements may be present as such or in the form of chemical compounds.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the expression hydrocarbon is understood to cover unsaturated or saturated hydrocarbons, such as, for example, olefins or alkanes which may also contain heteroatoms such as N, O, P, S or halogen atoms. These organic hydrocarbon components which are to be oxidized in accordance with the present invention may be acyclic, monocyclic, bicyclic or polycyclic, and may be monoolefinic, diolefinic or polyolefinic. In the case of organic hydrocarbon components with two or more double bonds, the double bonds may be conjugated or non-conjugated. It is preferred that the hydrocarbons which are oxidized in accordance with the present invention, form oxidation products with partial pressures which are low enough, at the reaction temperature, to enable constant removal of the product from the catalyst.
Unsaturated and saturated hydrocarbons with 2 to 20, preferably 3 to 10 carbon atoms, are preferred for the present invention. In particular, hydrocarbons such as, for example, propylene, propane, isobutane, isobutylene, 1-butene, 2-butene, cis-2-butene, trans-2-butene, 1,3-butadiene, pentene, pentane, 1-hexene, hexane, hexadiene, cyclohexene, benzene, are preferred.
The oxygen used in the present invention may be in a very wide variety of forms. Suitable forms of oxygen include those such as, for example, molecular oxygen, air and nitrogen oxide. Molecular oxygen is preferred.
Suitable mixtures of at least two elements for the epoxidation catalysts of the present invention include preferably binary mixtures of the metals selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Fe, Co, Ni, Sn, Pb, Sb, Bi and Se.
It may be advantageous to add conventional promoters or moderators to the element mixture, such as alkaline earth and/or alkali metal ions such as, for example, the hydroxides, carbonates, nitrates, chlorides of one or more alkaline earth and/or alkali metals and/or silver. These are described in EP-A1-0 933 130 on page 4, lines 39 et. seq., which is believed to correspond to U.S. Pat. No. 6,087,299, the disclosure of which is herein incorporated by reference.
The different elements and promoters in the mixtures can be in the range from 0 to 100% by weight of the total weight of the active ingredients, preferably from 0.01 to 99.99%, even more preferably in the range from 0.1 to 99.9% with the sum of all elements in the mixture totalling 100% by weight. The preferred range for the promoters is from 0.001 to 35% by weight of the total weight of the active ingredients. Preferred mixtures of elements to be used in the present invention include mixtures comprising: CoFe, CoRe, CoCo, CoNi, NiCr, Co—Fe, Co—Re, Co—Cr, Co—Ni, Ni—Cr, Sb—Fe, Co—Fe—Ag, Co—Pb—Ag, Ni—Pb—Ag, Ni—Co—Ag, Co—Fe—Sr—Ag, Co—Pb—Sr—Ag, Co—Pb—Fe—Ag, Co—Cs—Fe—Ag, Co—Cs—Pb—Ag, Co—Ba—Bi—Ag, Ni—Pb—Fe—Ag, Ni—Cs—Fe—Ag, Ni—Cs—Pb—Ag, Ni—Ba-Fe—Ag, Ni—Ba—Pb—Ag, Ni—Co—Sr—Ag, Ni—Co—Fe—Ag, Eu—Er—Pb—W, Mo—Pb—Sr—Ag, Fe—Pb—Sr—Ag, Fe—Pb—Sr—Re, Fe—Mo—Sr—Ag, Cr—Sr—Re—Ag, Cr—Fe—Re—Ag, Cr—Fe—Sr—Ag, Cr—Fe—Pb—Ag, Cr—Fe—Mo—Pb, Co—Fe—Sr—Ag, Co—Cr—Re—Ag, Co—Cr—Pb—Re, Co—Cr—Pb—Sr, Co—Cr—Mo—Ag, Co—Cr—Fe—Sr, Co—Cr—Fe—Pb, Co—Cr—Fe—Mo, Co—K—Pb—Ag, Co—Nd—Pb—Ag, Co—Fe—Pb—Ag, Co—Fe—K—Ag, Co—Cs—Pb—Ag, Co—Cs—Fe—Ag and SbFe.
Suitable supports for the element mixtures which are used to form the epoxidation catalysts for the present invention are compounds with BET surface areas of from <200
Jansen Ursula
Wegner Andreas
Bayer Aktiengesellschaft
Brown N. Denise
Gil Joseph C.
Mrozinski, Jr. John E.
Solola Taofiz A
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