Selective Conversion of Paraffinic Naphtha to Propane in the Presence of Hydrogen

Abstract

The invention relates to Process of catalytic conversion by hydrocracking of paraffinic and naphthenic hydrocarbons from a naphtha feedstock to propane, the process comprising the steps of providing a naphtha feedstock containing one or more paraffin comprising 4 to 10 carbon atoms and no olefins; and contacting said naphtha feedstock with a catalyst composition in the presence of hydrogen in a reaction zone under hydrocracking conditions; wherein the catalyst composition consists of one or more zeolite catalysts comprising acid 10-membered ring channels containing no added metals.

1 .- 15 . (canceled) 
     
     
         16 . A process of catalytic conversion by hydrocracking of paraffinic and naphthenic hydrocarbons from a naphtha feedstock to propane, the process comprising the following steps:
 a. providing a naphtha feedstock containing one or more paraffins comprising 4 to 10 carbon atoms, wherein the one or more paraffins have an olefin content of less than 1 wt % relating to the total weight of said naphtha feedstock; and   b. submitting said naphtha feedstock to a hydrocracking step by contacting said naphtha feedstock with a catalyst composition in the presence of hydrogen in a reaction zone under hydrocracking conditions;   characterized in that the catalyst composition comprises one or more zeolite catalysts comprising an acid 10-membered ring channels and in that said catalyst composition contains no added noble metal and no added transition metals.   
     
     
         17 . The process according to  claim 16 , characterized in that the naphtha feedstock comprises at least 10 wt % of naphthenes as based on the total weight of the naphtha feedstock. 
     
     
         18 . The process according to  claim 16 , characterized in that the one or more zeolite catalysts have a Si/Al molar ratio ranging from 10 to 100. 
     
     
         19 . The process according to  claim 16 , characterized in that the hydrocracking conditions of the hydrocracking step comprise:
 a. the naphtha feedstock being contacted with the catalyst composition at a temperature ranging from 200 to 600° C., and/or   b. the naphtha feedstock being contacted with the catalyst composition at a pressure ranging from 1 to 10 MPa.   
     
     
         20 . The process according to  claim 16 , characterized in that the catalyst composition contains less than 1000 wt ppm of noble metal and less than 1 wt % of transition metals as based on the total weight of the catalyst composition. 
     
     
         21 . The process according to  claim 16 , characterized in that hydrocracking conditions of the hydrocracking step comprise the naphtha feedstock being contacted with the catalyst composition at a WHSV (feed) of at least 0.1 h −1 , preferably is ranging from 0.1 h −1  to 10.0 h −1 . 
     
     
         22 . The process according to  claim 16 , characterized in that, in the hydrocracking step, hydrogen is provided to the naphtha feedstock at a molar ratio Hz/Naphtha ranging from 1000:1 to 1:1. 
     
     
         23 . The process according to  claim 16 , characterized in that the catalyst composition comprises at least 60 wt % of one or more zeolite catalysts comprising an acid 10-membered ring channels. 
     
     
         24 . The process according to  claim 16 , characterized in that the catalyst composition comprises one or more zeolite catalysts comprising an acid 10-membered ring channels selected from the list comprising ZSM-5, silicalite-1, ZSM-11, silicalite-2, SSZ-46, MCM-68, CIT-1, SSZ-33, ZSM-8, Ferrierite, FU-9, ZSM-35, ZSM-23, ZSM-22, Theta-1, NU-10, ZSM-50, EU-1, ZSM-57, SAPO-11 or ZSM-48. 
     
     
         25 . The process according to  claim 16  characterized in that the one or more zeolite catalysts comprising an acid 10-membered ring channels comprise or are zeolite catalysts of the MFI-type. 
     
     
         26 . The process according to  claim 16  characterized in that the catalyst composition comprises a binder selected from silica, alpha-alumina, gamma-alumina, clays, alumina phosphates, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, iron, bronze and stainless steel, glass, and carbon, preferably the binder is alumina. 
     
     
         27 . The process according to  claim 16  characterized in that the propane produced in the hydrocracking is recovered and is further submitted to a step of dehydrogenation) into propylene, wherein the step of dehydrogenation into propylene is performed at a temperature ranging from 500 to 800° C. and a partial pressure of propylene below one atmosphere. 
     
     
         28 . The process according to  claim 27  characterized in that it further comprises a step of collecting hydrogen produced in the step of dehydrogenation into propylene, and a step of recycling said hydrogen back to the hydrocracking reaction zone in order to perform the hydrocracking step. 
     
     
         29 . The use of one or more zeolite catalysts comprising acid 10-membered ring channels in a process according to  claim 16  of catalytic conversion by hydrocracking of paraffinic and naphthenic hydrocarbons from a naphtha feedstock to propane characterized in that the zeolite catalysts are metal-free that is to said that it contains no added noble metal and no added transition metals. 
     
     
         30 . The process according to  claim 16  characterized in that the process comprises a separation step performed on the effluent of the hydrocracking step in order to recover propane; with preference the separation step comprises recovering the C4 paraffins fraction from the effluent of step b) and a step of recycling back the C4 paraffins fraction to the hydrocraking reaction zone, and/or the separation step comprises recovering the C5+ fraction from the effluent of step b) and a step of valorization of said C5+ fraction as gasoline.