Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
1999-12-06
2003-02-11
Parsa, Jafar (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C502S056000
Reexamination Certificate
active
06518441
ABSTRACT:
The present invention relates to a process for oxidizing an organic compound having at least one C—C double bond or a mixture of two or more thereof by reacting the organic compound having at least one C—C double bond or the mixture of two or more thereof with a hydroperoxide in the presence of a zeolite catalyst, regenerating this catalyst, and reusing the catalyst for the above-mentioned reaction following its regeneration.
Processes for oxidizing an organic compound having at least one C—C double bond, especially olefins, preferably propylene, using a hydroperoxide are known.
U.S. Pat. No. 5,374,747 discloses such an epoxidation process using a titanium-containing molecular sieve having a structure which is isomorphous to zeolite &bgr;, and the preparation of such a molecular sieve.
U.S. Pat. No. 5,384,418 discloses an integrated process for preparing epoxides by reacting a hydroperoxide with an ethylenically unsaturated compound in the presence of a titanium silicalite.
Other processes for preparing epoxides in the presence of zeolite catalysts are disclosed, inter alia, in U.S. Pat. No. 5,463,090 and EP-A-0 230 949, the first of which produces the hydrogen peroxide used for oxidizing from an anthraquinone process, whereas the latter discloses the epoxidation of propylene with hydrogen peroxide in the presence of titanium silicalites defined therein.
According to U.S. Pat. No. 5,599,955, propylene, which is most commonly used for such oxidations, can be obtained starting from synthesis gas. U.S. Pat. No. 5,599,956 discloses a process for preparing propylene oxide, wherein the propylene is obtained by steam cracking, catalytic cracking or catalytic dehydrogenation.
It is known that in these catalytic reactions organic deposits are formed after some time, which result in partial or complete deactivation of the catalysts, especially when using catalysts having micropores, for example zeolite catalysts such as titanium silicalite or titanium-containing zeolite &bgr;.
These organic deposits can be mostly removed by calcining the catalyst or washing with solvent (M. G. Clerici, G. Bellussi, U. Romano, J. Catal., 129 (1991), 159-167; JP-A-03 114 536).
EP-A-0 743 094 discloses a process for regenerating a Ti-containing molecular sieve by heating the molecular sieve at from more than 150° C. to less than 400° C. This reference also discloses that it is possible to use the catalyst regenerated in this manner for reacting organic compounds, for example for the hydroxylation of aromatic compounds, the ammoxidation of ketones, the oxidation of saturated hydrocarbons to obtain alcohols and ketones, and for olefin epoxidation. DE-A-44 25 672 discloses an oxidation catalyst based on titanium or vanadium silicates having a zeolite structure and a process for preparing epoxides from olefins, hydrogen and oxygen using the catalyst described therein. It is also stated that the catalyst described therein may be regenerated.
Above-discussed U.S. Pat. No. 5,599,955 also mentions the possible regeneration of the catalyst used in connection with the process described therein, but no details of the regeneration procedure are given.
As can be seen from the above, there is extensive prior art relating to integrated processes for preparing epoxides, but the problem of practicable regeneration of the deactivated catalyst and the useful integration of such a step into the overall process remains unsolved. This step and its integration into the overall process are, however, critical for the economic viability of such a process. It is in principle possible to conduct regenerations as disclosed in EP-A-0 743 094; these are, however, economically unviable because of the low temperatures used therein and the resulting long regeneration period.
It is an object of the present invention to provide a process for oxidizing an organic compound having at least one C—C double bond, regenerating the catalyst used in this process and reusing the regenerated catalyst for further reaction in the process.
We have found that this object is achieved by the process of the invention.
The present invention accordingly provides a process for oxidizing an organic compound having at least one C—C double bond or a mixture of two or more thereof, which comprises the following steps:
(I) preparing a hydroperoxide,
(II) reacting an organic compound having at least one C—C double bond or a mixture of two or more thereof with the hydroperoxide prepared in step (I) in the presence of a zeolite catalyst,
(III) regenerating the at least partially deactivated zeolite catalyst used in step (II), and
(IV) conducting the reaction of step (II) using a zeolite catalyst comprising the catalyst regenerated in step (III).
Step (I)
This step relates to the preparation of a hydroperoxide. For the purposes of the present invention, hydroperoxide refers to hydrogen peroxide as well as organic compounds of the formula R—O—OH, where R is alkyl, cycloalkyl, aralkyl or aryl.
In the process of the invention, preference is given to using hydrogen peroxide.
Processes for preparing the hydroperoxides are known and will herein only be recited briefly for the synthesis of hydrogen peroxide.
Hydrogen peroxide is preferably synthesized via an anthraquinone process or directly from hydrogen and oxygen over noble metal catalysts.
In the anthraquinone process, a mixture is prepared which is referred to as working solution hereinafter. This mixture comprises a solution of a 2-alkylanthraquinone, preferably 2-ethyl-, 2-butyl-, 2-hexyl-, 2-hexenyl-, particularly preferably 2-ethylanthraquinone, in a solvent mixture comprising a quinone solvent and a hydroquinone solvent. The quinone solvent is generally selected from the group consisting of aromatic and alkylaromatic solvents, preferably benzene, toluene, xylenes or higher alkylaromatics having 6 to 20, preferably 9 to 11, carbon atoms or mixtures of two or more thereof, such mixtures being preferred.
The hydroquinone solvent is generally selected from the group consisting of alkyl phosphates, alkyl phosphonates, nonyl alcohols, alkylcyclohexanol esters, N,N-dialkylcarbonylamides, tetraalkylurethanes or N-alkyl-2-pyrrolidone and mixtures of two or more thereof, tetrabutylurea being preferred.
The working solution is hydrogenated with hydrogen at from about 20 to 100° C., preferably at from about 40 to 70° C., over a commercially available catalyst containing at least one transition metal, preferably from 0.5 to 20% by weight Pd on carbon, more preferably from 2 to 15% by weight Pd on carbon. The catalyst can be arranged in the form of a suspension or a fixed bed.
The resulting hydroquinone-containing solution is oxidized with oxygen, preferably with air, more preferably with an oxygen- and nitrogen-containing mixture in which the oxygen is present in deficiency, based on the total mixture, in a suitable apparatus, for example a bubble column. The oxidation is carried out at a reaction temperature of from about 20 to about 100° C., preferably from about 35 to about 60° C., until the hydrogen peroxide content of the solution is constant and the conversion of the hydroquinone into quinone is complete.
The resulting hydrogen peroxide mixture is subsequently extracted with a solvent which is not miscible with the solvent mixture, preferably with water, methanol, a monohydric alcohol having from 2 to 6 carbon atoms or a mixture of two or more thereof, more preferably with water. The resulting hydrogen peroxide mixture may then be used directly in the reaction of step (II) of the process of the invention. Such a work-up procedure is disclosed, inter alia, in EP-B-0 549 013, which suggests using a mixture of water and an alcohol, preferably methanol.
Furthermore, the hydrogen peroxide preferably used for oxidation in the present invention may also be prepared directly from the elements. Processes for preparing hydrogen peroxide from the elements oxygen and hydrogen are well known, as can be seen from DE-A-196 42 770 and the prior art cited therein. In the process of the invention, hydrogen peroxide is preferably prepared fro
Bassler Peter
Böttcher Arnd
Eller Karsten
Fischer Martin
Grosch Georg Heinrich
BASF - Aktiengesellschaft
Parsa Jafar
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