Process For The Preparation Of An Olefin

PATENT
Process For The Preparation Of An Olefin
European Patent EP2024303
Inventors:
Chewter, Leslie Andrew (Badhuisweg 3, 1031 CM Amsterdam, NL)
Verhaak, Michiel Johannes Franciscus Maria (Badhuisweg 3, 1031 CM Amsterdam, NL)
Van Westrenen, Jeroen (Badhuisweg 3, 1031 CM Amsterdam, NL)
Application Number:
EP20070729189
Publication Date:
01/18/2012
Assignee:
Shell Internationale Research Maatschappij B.V.

Field of the invention
This invention relates to a process for the preparation of an olefin, such as ethene and/or propene.
 
Background of the invention
Processes for the preparation of olefins are known in the art.
 

WO2005016856A1 describes a process for converting a hydrocarbon feedstock to provide an effluent containing light olefins, the process comprising passing a hydrocarbon feedstock comprising a mixture of a first portion, containing one or more olefins of C4 or greater, and a second portion, containing at least one C1 to C6 aliphatic hetero compound selected from alcohols, ethers, carbonyl compounds and mixtures thereof, through a reactor containing a crystalline silicate catalyst to produce an effluent including propylene, the crystalline silicate being selected from at least one of an MFI-type crystalline silicate having a silicon/aluminium atomic ratio of at least 180 and an MEL-type crystalline silicate having a silicon/aluminium atomic ratio of from 150 to 800 which has been subjected to a steaming step.

US2003/0181777 describes a process wherein a conventional steam cracker C4-Raffinate-2, containing isobutane, 1-butene, n-butane, trans-2-butene and cis-2-butene, is contacted with a MTT type zeolite in the presence of a co-feed of methanol.
 
The process of

US2003/0181777 requires a continuous stream of olefins, as without olefins the therein described cracking process can not be carried out. That is, variations in the amount of olefins fed, will have a large influence on the process.

EP 485 145 A1 discloses a method for the very selective production of C4/C5 olefins from C3 and/or C4 olefins and methanol, formaldehyde or dimethylether, using a TON type zeolite catalyst, at a temperature greater than 200 C, and a molar ratio of olefin to oxygenate greater than 1:20.
 
At many refinery sites small waste streams containing C4 and C5 olefins are generated. Presently such olefins are blended into product fractions, converted into fuel components or sometimes even hydrogenated and used as fuel.
 
It would be desirable to be able to convert such "waste" olefins into valuable ethylene and propylene. Unfortunately such waste streams may not always be present as a continuous stream. The amounts in which such waste streams can be provided may vary widely in time and location. Processes such as those described in

US2003/0181777, however, require a continuous feed stream.
 
It would therefore be desirable to have a process which allows one to process "waste" olefins, even if such "waste" olefins are provided as non-continuous stream.
 
Summary of the invention
A process enabling one convert low value "waste" olefins into high value ethylene and propylene at one's convenience has now been found. Accordingly the present invention provides a process for the preparation of ethylene and/or propylene comprising reacting an oxygenate feed, wherein the oxygenate comprises at least one oxygen-bonded alkyl group, and an olefinic co-feed in a reactor in the presence of a zeolite catalyst, wherein the zeolite is a one-dimensional zeolite having 10-membered ring channels, to prepare an olefinic reaction mixture;  wherein the olefinic co-feed is partially obtained from an olefinic refinery stream and partially obtained from a olefinic recycle stream containing one or more olefins derived from the olefinic reaction mixture and wherein the ratio of mol oxygen-bonded alkyl groups in the oxygenate feed to mol olefin in the olefinic co-feed is more than 1:10.
 
Such a process allows one to convert low value "waste" olefins into high value ethylene and propylene at any point in time and independent of the amount of "waste" olefin supplied.
 
A further advantage is that the process is more environmentally friendly. The production of olefin in catalytic crackers or steam crackers produces environmentally unfriendly carbondioxide via the burning of fuel. When "waste" olefins, often produced in a first thermal or catalytic cracker are converted to ethylene and propylene in a second thermal or catalytic cracker, more such carbon dioxide is produced. By converting the waste olefins into ethylene and/propylene with the process according to the invention the amount of carbon dioxide generated per ton of product can be greatly reduced.
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