Title of Invention

PROCESS FOR THE PREPARATION OF AN ISOBUTANE / ISOHEXANE CONTAINING PRODUCT

Abstract

The present invention relates to a process for the preparation of an isobutane/isohexane containing product such as herein described comprising passing an isopentane feed to a disproportion stage and disproportionating the isopentane feed in the presence of olefinic and/or higher branched paraffinic hydrocarbons by contact with an acid catalyst having an acidity of Ho>8 at a tempature of between 0C and 150°C and withdrawing an isobutane/isohexane containing product. PRICE: THIRTY RUPEES

Full Text

The present invention concerns the preparation of isobutane and isohexane containing products. More paruicu-lar, the invention relates to. a process for the preparation of the those products by disproportionation of an isopent-ane feedstock in the presence of olefinic or branched-chain paraffinic hydrocarbons and an acid catalyst. Disproportionation of saturated hydrocarbons is a well-known reaction step in the isomerization of normal hydrocarbons to isoparaffins during petroleum refi.-i.ng, Isoparaff-ins have a higher octane number than normal paraffins, and are, therefore, preferred components in high octane gasoline products. During disproportionation reactions, a"hydrocarbon feedstock is converted to a hydrocarbon product. of higher and lower rnolecuiar weight: . Disproportionation of lower paraffinic hycrocarbons to isoparaffinic hydrocarbons is mentioned in U.S. Pateno No. 3,666,269. At the disclosed process, paraffinic hydro¬carbon feed is contacted with a solid acidic caralyst comprising a platinum-group metal on a crystalline aluminc-silicate. The product obtained thereby contains isoparaf-fin-hydrocarbons with one more and one less carbon atom.s per molecule than the hydrocarbon feed. Production of isopentane by disproportionation of Cg alkanes with a catalyst comprising a Group VIII metal and a Group VIB metal is, furthermore, disclosed in U.S. Patent Nos. 3,766,292 and 5,766,2 92. It is also known to use A1C1-, on an aluminum SUD-port or alkyl fluoride and BP3 as promotexs in the dis¬proportionation of saturated hydrocarbons. The general object of this invention is to provide a product being rich in isobutane and isohexane by catalyt¬ic disproportionation of isopentane feed. As mentioned by way of introduction, isoparaffins including isopentane are presently preferred components in high octane gasoline products. However, recent requirements to lower vapour pressure of gasoline, makes it necessary to substitute isoparaffins having a high vapour pressure with componenr.s of lower vapour pressure ir gasoline. Since isopentane may be disproporLionated to iso-hexanes with a lower vapour pressure ana to isobutane, which is a preferred feedstock in aikylation processes for the producnion of high octane alkylate gasoline and MTBE, it is desirable to substitute iscpencane in gasoline. It has now been found that disproportionation of isopentane is catalyzed by a strong and, and the reaction is further promoted by the preseiacs of oiefins or higher paiaflins, which crack to oJefins ny influence of a strong acid. Accordingly, the present inven-cicn relates to process for the preparati-on of an isobutane,/isohexene containing product, which process comprises passing an isopentane feed to a disproportion stage, and dispropor-tionating the isopentane feed in the presence of rlefinic and/or branched higher paraffinic hydrocarbons by contact with an acid catalyst having an acidity of Ho>8 at a tem¬perature of between O^C axod 1SC°C to obtain the isobutan^^-/-isohexane containing product. High yield of desired isobutane and ischexanes 1= obtained with acids having an acidity of sulphuric acid or higher. The acid may be a Erensted or a Lewis acid. Presently, preferred acids are selected from the group of fluormated sulphonic acids most preferred is trifluoromethanesulphonic acid. An attractive featuxe of the invention is utiliz¬ation of higher branched-chain paraffins in the dispropor-tionation process. These paraffins are b-yproducts being formed during e.g. pxoduction of alkylate gasoline. The . carbon number of the paraffins will typically be in the range of between C10 to C30, which by contact with the acid used in the disproportionation step crack to olefinic hydrocarbons. Olefinic hydrocarbons promote the isopentane dis¬proportionation presumably by protonation of the olefins to carbenium ions and reaction of the carbenium ions with isopentane to form an iso-C10-carbenium ion, which finally is converted to isobutane and isohexanes. The isopentane disproportionation rate is, thereby, proportional with the olefin content in the reaction stage. High concentrations of olefins, however, result in the formation of higher molecular weight paraffinic hydrocarbon byproducts. Thus, a preferred concentration range of olefinic and/or higher branch-chain paraffinic hydrocarbons in the process is between 0.1% and 50% by volume of the isopentane feed in the disproportionation stage. Accordingly, the present invention provides a process for the preparation of an isobutane/isohexane containing product such as herein described comprising passing an isopentane feed to a disproportion stage and disproportionating the isopentane feed in the presence of known olefinic and/or higher branched parafifinic hydrocarbons by contact with an acid catalyst having an acidity of Ho>8 at a temperature of between 0C and 150C and withdrawing an isobutane/isohexane containing product therefrom. Examples In the Examples, a 6 meter \T reactor tube packed with silica (Merck 100, 0.2 - 0.5 mm particle size) was used. The reactor tube was thermostated in a bath, and 6 ml trifluoromethanesulphonic acid were introduced into the reactor. A feed stream as specified in Table 1 below, was passed on at a flow rate of 5 ml/min. and at a temperature of between 0°C and 40°C through the packed reactor. Further process parameters and results obtained thereby are summarized in Table 1. WE CLAIM: 1. A process for the preparation of an isobutane/isohexane containing product such as herein described comprising passing an isopentane feed to a disproportion stage and disproportionating the isopentane feed in the presence of known olefiric and/or higher branched paraffinic hydrocarbons by contact with an acid catalyst having an acidity of Ho>8 at a temperature of between 0°C and 150°C and withdrawing an isobutane/isohexane containing product therefrom. 2. The process as claimed in claim 1, wherein the olefmic hydrocarbons are selected from Cs-Cg olefinic hydrocarbons. 3. The process as claimed in claim 1. wherein the higher branched paraflFmic hydrocarbons are selected from C10-C30 branched paraffinic hydrocarbons. 4. The process as claimed in claim 1, wherein the olefinic and/or higher branched paraffinic hydrocarbons constitute between 0.1 and 50% by volume of the isopentane feed in the disproportionation stage. 5. The process as claimed in claim 1, wherein the acid catalyst comprises a fluorinated sulphonic acid. 6. The process as claimed in claim 5, wherein the fluorinated sulphonic acid is trifluoromethanesulphonic acid. 7. A process for the preparation of an isobutane/isohexane containing product substantially as herein described and exemplified.

Documents:

1680-mas-1995 abstract.pdf

1680-mas-1995 claims.pdf

1680-mas-1995 correspondence-others.pdf

1680-mas-1995 correspondence-po.pdf

1680-mas-1995 description (complete).pdf

1680-mas-1995 form-1.pdf

1680-mas-1995 form-26.pdf

1680-mas-1995 form-4.pdf

1680-mas-1995 others.pdf

1680-mas-1995 petition.pdf