Increasing octane number of light naphtha using a germanium-zeolite catalyst

Abstract

This invention relates to a process for the increasing the octane number of a naphtha hydrocarbon feed having a predominantly paraffin content with a germanium-containing zeolite catalyst. The catalyst is a non-acidic germanium zeolite on which a noble metal, such as platinum, has been deposited. The zeolite structure may be of MTW, MWW, MEL, TON, MRE, FER, MFI, BEA, MOR, LTL or MTT. The zeolite is made non-acidic by being base-exchanged with an alkali metal or alkaline earth metal, such as cesium, potassium, sodium, rubidium, barium, calcium, magnesium and mixtures thereof, to reduce acidity. The catalyst is sulfur tolerant. The hydrocarbon feed may contain sulfur up to 1000 ppm. The present invention could be applicable to a feedstream which is predominantly naphthenes and paraffins.

1 . A process for increasing octane number of a hydrocarbon feed comprising:
 a) contacting at conditions for concurrently isomerizing n-paraffins to isoparaffins, further isomerizing isoparaffins to more highly branched isoparaffins, cracking n-paraffins to smaller n-isoparaffins, dehydrogenating both n-paraffins and iso-paraffins and dehydrocyclizing n-paraffins to aromatics a feed comprising naphtha having C 6 -C 8  alkanes with a catalyst comprising a non-acidic medium pore or large pore zeolite comprising silicon, germanium and, optionally, aluminum on which a noble metal has been deposited; and   b) recovering a hydrocarbon product.   
     
     
         2 . The process of  claim 1  wherein the zeolite is a medium pore zeolite. 
     
     
         3 . The process of  claim 2  wherein the average pore size is in the range from about 5 to about 7 angstroms. 
     
     
         4 . The process of  claim 1  wherein the zeolite has a Si/Al 2  atomic ratio of 40-500. 
     
     
         5 . The process of  claim 1  wherein the zeolite has a Si/Al 2  atomic ratio of 50-150. 
     
     
         6 . The process of  claim 1  wherein the germanium content of the zeolite is in the range from 1.0% to 10% by weight. 
     
     
         7 . The process of  claim 6  wherein the germanium content of the zeolite is from 3.5% to 6% by weight. 
     
     
         8 . The process of  claim 1  wherein the noble metal is present in the range of from 0.05% to 3%. 
     
     
         9 . The process of  claim 8  wherein the noble metal is present in the range of from 0.2% to 2%. 
     
     
         10 . The process of  claim 9  wherein the noble metal is present in the range of from 0.2% to 1.5%. 
     
     
         11 . The process of  claim 1  wherein the noble metal is platinum. 
     
     
         12 . The process of  claim 1  wherein the zeolite is non-acidic by base-exchange with an alkali metal or alkaline earth metal. 
     
     
         13 . The process of  claim 12  wherein the alkali metal is cesium present in a molar ratio to aluminum in the range from about 1 to about 2. 
     
     
         14 . The process of  claim 1  wherein the contact between the alkane and the catalyst is at a liquid hourly space velocity in the range between 0.1 and 100 h −1 . 
     
     
         15 . The process of  claim 1  wherein the contact between the alkane and the catalyst is at a temperature in the range between 200 and 600° C. 
     
     
         16 . The process of  claim 1  wherein the contact between the alkane and the catalyst is at a liquid hourly space velocity in the range between 0.1 and 100 h −1 , at a temperature in the range between 200 and 600° C. and at a pressure in the range between 1 and 315 psia. 
     
     
         17 . The process of  claim 1  wherein the zeolite has an MFI structure. 
     
     
         18 . The process of  claim 1  wherein the feed additionally contains sulfur up to 1000 ppm. 
     
     
         19 . The process of  claim 1  wherein the catalyst is supported or bound. 
     
     
         20 . The process of  claim 1  wherein the catalyst is of the formula:
   |Cs + 2Pt 0.37 |[Si 105 Ge 4 Al 2 O 222 ]-MFI 
 
     
     
         21 . The process of  claim 1  wherein the zeolite comprises additional elements of titanium, iron, gallium, boron or tin. 
     
     
         22 . The process of  claim 1  wherein the catalyst is Pt/CsGeZSM-5. 
     
     
         23 . The process of  claim 1  wherein the hydrocarbon feed comprises naphtha having at least 30% C 6 -C 8  alkanes. 
     
     
         24 . The process of  claim 1  wherein the hydrocarbon feed comprises naphtha having at least 40% C 6 -C 8  alkanes. 
     
     
         25 . The process of  claim 1  wherein the hydrocarbon feed comprises naphtha having at least 50% C 6 -C 8 alkanes. 
     
     
         26 . The process of  claim 1  wherein the feed additionally comprises higher and lower alkanes, isoparaffins, olefins, napthenes and aromatics. 
     
     
         27 . The process of  claim 1  wherein the feed additionally comprises pentane, nonane, decane and nonhydrocarbons which are catalytically nonreactive or inert. 
     
     
         28 . A process for increasing octane number of a hydrocarbon feed comprising:
 a) contacting a hydrocarbon feed having a C 6 -C 8  alkane content of at least 50% with a first catalyst at conditions to form a reformed product; and   b) contacting the reformed product with a second catalyst; and   c) recovering a hydrocarbon product,   wherein one catalyst comprises an acidic reforming catalyst comprising a Group VIII metal on an oxide support and   wherein the other catalyst is a non-acidic medium pore or large pore zeolite comprising silicon, germanium and, optionally, aluminum on which a noble metal has been deposited.   
     
     
         29 . The process of  claim 26  wherein the acidic reforming catalyst comprises platinum deposited on alumina or silica. 
     
     
         30 . The process of  claim 29  wherein the acid reforming catalyst additionally comprises rhenium, tin, cobalt, nickel, iridium, rhodium, ruthenium and combinations thereof. 
     
     
         31 . The process of  claim 30  wherein the acidic reforming catalyst comprises platinum and either rhenium or iridium deposited on alumina. 
     
     
         32 . The process of  claim 26  wherein the non-acidic medium pore or large pore zeolite comprising silicon, germanium and, optionally, aluminum on which a noble metal has been deposited comprises Pt/CsGeZSM-5. 
     
     
         33 . The process of  claim 26  wherein an acidic reforming catalyst comprising platinum deposited on alumina or silica is the first catalyst and wherein a non-acidic medium pore or large pore zeolite comprising silicon, germanium and, optionally, aluminum on which a noble metal has been deposited comprising Pt/CsGeZSM-5 is the second catalyst.