Process for skeletal isomerisation of linear olefins using a pretreated molecular sieve and a catalyst containing a pretreated sieve

Abstract

The invention concerns a process for skeletal isomerisation of linear olefins using a catalyst containing at least one pre-treated molecular sieve selected from the group formed by SAPO-31, SAPO-11, Theta-1, EU-1, omega zeolite, mordenite, Nu-10, Nu-86, Nu-87, ferrierite, ZSM-12 and ZSM-23. The pre-treatment process consists in bringing the molecular sieve, which has a pore size of 0.4 to 0.8 nm, into contact with at least one hydrocarbon molecule containing 4 to 20 carbon atoms, at a space velocity of 0.1-45 h −1 , a temperature of 300-550° C. and at a pressure of 0.1-1 MPa, for 0.5-48 h, to deposit coke in the pores. The process is of particular application to one-dimensional sieves. It is preferably carried out outside the reaction zone. The invention also concerns a catalyst containing a pre-treated sieve, the sieve being selected from SAPO-31, SAPO-11, Theta-1, EU-1, omega zeolite, mordenite, ferrierite, Nu-10, Nu-86 and Nu-87.

1 . A process for skeletal isomerisation of a feed containing linear, olefinic hydrocarbons containing 4 to 20 carbon atoms using a catalyst containing at least one molecular sieve with a pore size in the range 0.4 nm to 0.8 nm, characterized in that prior to commencing the process, said sieve is brought into contact with at least one hydrocarbon molecule containing 4 to 20 carbon atoms at a space velocity of 0.1-45 h −1 , a temperature of 300-550° C., and at a pressure of 0.1-1 MPa for 0.5-48 h, to deposit coke in said pores in said sieve.  
     
     
         2 . A process according to  claim 1 , in which the hydrocarbon molecule contains 4 to 12 carbon atoms.  
     
     
         3 . A process according to  claim 1  or  claim 2 , in which the hydrocarbon molecule is selected from the group formed by monoolefins, polyolefins and alkanes.  
     
     
         4 . A process according to any one of the preceding claims, in which the hydrocarbon molecule is diluted in an inert gas.  
     
     
         5 . A process according to any one of the preceding claims, in which the temperature is in the range 400° C. to 535°C., the pressure is in the range 0.1 MPa to 0.5 MPa, the space velocity is in the range 0.5 h −1  to 25 h −1  and the duration is in the range 0.5 h to 24 h.  
     
     
         6 . A process according to  claim 1 , in which the sieve has a pore size in the range 0.4 nm to 0.7 nm.  
     
     
         7 . A process according to any one of the preceding claims, in which the sieve includes a one-dimensional microporous network.  
     
     
         8 . A process according to any one of the preceding claims, in which the molecular sieve is selected from the group formed by ferrierite, SAPO-31, SAPO-11, Theta-1, EU-1, ZSM-12, ZSM-23, omega zeolite, mordenite, Nu-10, Nu-86 and Nu-87.  
     
     
         9 . A process according to any one of the preceding claims, in which the sieve is pre-treated before forming it in a matrix.  
     
     
         10 . A process according to any one of the preceding claims, in which the sieve is pre-treated after forming it in a matrix.  
     
     
         11 . A process according to any one of the preceding claims, in which the sieve is pre-treated outside the reaction zone.  
     
     
         12 . A process according to any one of the preceding claims, in which the feed is brought into contact with the catalyst at a temperature of 150-500° C., a pressure of 0.01-1 MPa, and at a space velocity of 0.1-10 h −1 .  
     
     
         13 . A process according to any one of the preceding claims, applied to olefinic C 4  feed.  
     
     
         14 . A process according to any one of  claims 1  to  12 , applied to an olefinic C 5  feed.  
     
     
         15 . A catalyst containing at least one molecular sieve selected from the group formed by ferrierite, SAPO-31, SAPO-11, Theta-1, EU-1, omega zeolite, mordenite, Nu-10, Nu-86 and Nu-87, said sieve having been brought into contact with at least one hydrocarbon molecule containing 4 to 20 carbon atoms at a space velocity of 0.1-45 h −1 , a temperature of 300-550° C. and at a pressure of 0.1-1 MPa, for 0.5-48 h, to deposit coke in the pores of said sieve.  
     
     
         16 . A catalyst according to  claim 13 , in which the sieve is brought into contact with at least one hydrocarbon molecule selected from the group constituted by monoolofins, polyolefins and alkanes, containing 4 to 12 carbon atoms, at a temperature of 400-535° C. and at a pressure of 0.1-0.5 MPa, in the absence of hydrogen.  
     
     
         17 . A catalyst according to  claim 15  or  claim 16 , in which the sieve is pre-treated before forming it in a matrix.  
     
     
         18 . A catalyst according to  claim 15  or  claim 16 , in which the sieve is pre-treated after forming it in a matrix.