Chemistry of hydrocarbon compounds – Adding hydrogen to unsaturated bond of hydrocarbon – i.e.,... – Hydrocarbon is contaminant in desired hydrocarbon
Reexamination Certificate
1999-08-30
2002-08-20
Griffin, Steven P. (Department: 1754)
Chemistry of hydrocarbon compounds
Adding hydrogen to unsaturated bond of hydrocarbon, i.e.,...
Hydrocarbon is contaminant in desired hydrocarbon
C585S259000, C585S258000, C502S339000, C502S330000, C502S331000, C502S345000, C502S347000
Reexamination Certificate
active
06437206
ABSTRACT:
The present invention relates to noble metal-containing catalysts on an alumina support and processes for the selective hydrogenation of unsaturated compounds in hydrocarbon streams containing said compounds with the use of these catalysts.
In refineries and petrochemical plants, hydrocarbon streams are produced, stored and processed on a large scale. These hydrocarbon streams frequently contain unsaturated compounds, the presence of which is known to give rise to problems, in particular during processing and/or storage, or which are not the desired product, and which therefore are undesired components of the corresponding hydrocarbon streams. General overviews of such problems in steamcrackers and conventional solutions are given, for example, by H.-M. Allmann, Ch. Herion and P. Polanek in their lecture “Selective Hydrogenations and Purifications in the Steamcracker Downstream Treatment” at the DGMK Conference “Selective Hydrogenation and Dehydrogenation” on Nov. 11 and 12, 1993 in Kassel, Germany, the manuscript of which has also appeared in Conference Report 9305 of DGMK Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e. V., Hamburg, pages 1-30, (ISSN 0938-068X, ISBN 3-928164-61-9), and M. L. Derrien in: L. Cerveny (Editor), Stud. Surf. Sci. Catal., Vol. 27, pages 613-666, Elsevier, Amsterdam 1986.
Usually, the by-product acetylene is undesired in C2 streams of steamcrackers, the by-products propyne and allene are undesired in C3 streams and the by-products 1- and 2-butyne, 1,2-butadiene and vinylacetylene are undesired in C4 streams if 1,3-butadiene is to be obtained as the desired product and further processed, and said by-products and 1,3-butadiene itself where 1-butene, 2-butene (in the cis and/or the trans form) or isobutene are the desired products. In the processing of C5+ streams (CS+: hydrocarbons having at least 5 carbon atoms, pyrolysis gasoline), di- and polyenes, such as pentadiene and cyclopentadiene, alkynes and/or aromatics having unsaturated substituents, such as phenylacetylene and styrene, are undesired in the production and processing of aromatics or carburetor fuel.
In hydrocarbon streams originating from an FCC cracker or reformer instead of a steamcracker, analogous problems occur. A general overview of such problems, especially in the case of C4 and C5+ streams from FCC crackers, is given, for example, by J. P. Boitiaux, C. J. Cameron, J. Cosyns, F. Eschard and P. Sarrazin in their lecture “Selective Hydrogenation Catalysts and Processes: Bench to Industrial Scale” at the DGMK Conference “Selective Hydrogenation and Dehydrogenation” on Nov. 11 and 12, 1993, in Kassel, Germany, the manuscript of which has also appeared in Conference Report 9305 of the DGMK Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e. V., Hamburg, pages 49-57, (ISSN 0938-068X, ISBN 3-928164-61-9).
In general, unsaturated compounds having triple bonds (alkynes) and/or diunsaturated compounds (dienes) and/or other diunsaturated or polyunsaturated compounds (polyenes, allenes, alkynenes) and/or aromatic compounds having one or more unsaturated substituents (phenylalkenes and phenylalkynes) therefore have to be removed from hydrocarbon streams in order to obtain desired products, such as ethylene, propylene, 1-butene, isobutene, 1,3-butadiene, aromatics or carburetor fuel in the required quality. However, not every unsaturated compound is always an undesired component which has to be removed from the hydrocarbon stream in question. For example, 1,3-butadiene, as indicated above, is an undesired by-product or the desired product depending on the application.
The removal of undesired unsaturated compounds from hydrocarbon streams containing them is frequently carried out by selective hydrogenation of some or all of the undesired unsaturated compounds in the corresponding hydrocarbon stream, preferably by selective hydrogenation to give more highly saturated compounds which present no problems and, in a particularly preferred manner, to give components of the hydrocarbon stream which constitute the desired products. For example, acetylene is hydrogenated to ethylene in C2 streams, propyne and allene to propylene in C3 streams, butyne to butenes, vinylacetylene to 1,3-butadiene and/or 1,3-butadiene to butenes in C4 streams and phenylacetylene and styrene to ethylbenzene, cyclopentadiene to cyclopentene and pentadiene to pentene in C5+ streams.
Typically, such compounds have to be removed to residual contents of a few ppm by weight. (Over)hydrogenation to give compounds which are more highly saturated than the desired product and/or the parallel hydrogenation of a desired product containing one or more multiple bonds to give the corresponding more highly or completely saturated compound should however as far as possible be avoided owing to the associated loss of value. The selectivity of the hydrogenation of the undesired unsaturated compounds must therefore be as high as possible. In addition, a sufficiently high activity of the catalyst and a long time-on-stream are generally desirable. At the same time, the catalyst should as far as possible not give rise to any other undesired secondary reactions; for example, catalysis of the isomerization of 1-butene to 2-butene, with the exception of special cases, should as far as possible be avoided. Usually, supported noble metal catalysts in which noble metal is deposited on a catalyst support are used. A frequently used noble metal is palladium and the support is generally a porous inorganic oxide, for example silica, an aluminosilicate, titanium dioxide, zirconium dioxide, zinc aluminate, zinc titanate and/or mixtures of such supports, but alumina or silica is generally used. Furthermore, promoters or other additives may be present. Processes for the selective hydrogenation of unsaturated compounds in hydrocarbon streams containing them are known both in the form of liquid-phase hydrogenation or mixed gas/liquid-phase hydrogenation, by the trickle-bed or liquid-phase procedure, and in the form of pure gas-phase hydrogenation, various process engineering measures for improving the selectivity having been published.
For example, EP-A 87980 describes such a process in a fixed-bed reactor, in which the hydrogen for the hydrogenation is fed in at two or more points along the reactor, with the result that a higher selectivity is achieved. EP-A 523482 discloses carrying out such a process in two reaction zones connected in series, with the result that the undesired overhydrogenation to n-butane is substantially suppressed and the total selectivity also increases. EP-A 81041 states that the addition of carbon monoxide reduces the hydrogenation and isomerization activity of the palladium used as catalyst metal and thus increases the selectivity. JP-A 01-110594 describes the addition of further electron donor compounds, either by doping the catalyst, for example with alkali metals, or by addition to the reaction mixture, for example of alcohols, ethers or nitrogen-containing compounds.
The use of promoters or dopants in addition to the catalyst metal actually having hydrogenation activity is also known. Thus, J. P. Boitiaux, J. Cosyns, M. Derrien and G. Léger in Hydrocarbon Processing, 3 1985, 51-59, describe the use of bimetallic catalysts, in particular those which contain metals of group VIII (current IUPAC nomenclature: groups 8, 9 and 10), especially palladium, and metals of group IB (current IUPAC nomenclature: group 11) of the Periodic Table of Elements. EP-A 564328 and EP-A 564329 describe the use of catalysts which contain metals of group VIII, especially palladium, and metals of group IIIA (current IUPAC nomenclature: group 3), specially indium or gallium, and their use. EP-A 89252 discloses a process for the preparation of a supported catalyst containing palladium and gold and the use of said catalyst. US-A 5,475,173 discloses a catalyst containing palladium, silver and alkali metal fluoride. EP-A 722776 discloses a catalyst which is particularly resistant to contamination with sul
Hesse Michael
Meyer Gerald
Müller Hans-Joachim
Schwab Ekkehard
Trübenbach Peter
BASF - Aktiengesellschaft
Griffin Steven P.
Ildebrando Christina
Keil & Weinkauf
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