Process for hydrotreatment and hydroisomerization of feedstocks obtained from a renewable source implementing a modified zeolite

Abstract

This invention describes a process for treatment of feedstocks obtained from a renewable source implementing a catalyst that comprises at least one hydro-dehydrogenating metal that is selected from the group that is formed by the metals of group VIB and group VIII of the periodic table and a substrate that comprises at least one zeolite that has at least one series of channels whose opening is defined by a ring with 8 oxygen atoms modified by a) at least one stage for introducing at least one alkaline cation that belongs to group IA or IIA of the periodic table, b) a stage for treating said zeolite in the presence of at least one molecular compound that contains at least one silicon atom, c) at least one stage of partial exchange of said alkaline cations by NH 4 + cations, and d) at least one heat treatment stage.

1 . Process for treatment of feedstocks obtained from a renewable source and comprising the following stages:
 a) Hydrotreatment of said feedstock in the presence of a fixed-bed catalyst that comprises a hydro-dehydrogenating function comprising at least one metal of group VIII and/or group VIB, taken by itself or in a mixture, and a substrate that is selected from the group that is formed by alumina, silica, silica-aluminas, magnesia, clays and mixtures of at least two of these minerals, whereby said hydrotreatment stage operates at a temperature of between 200 and 450° C., at a pressure of between 1 MPa and 10 MPa, at an hourly volumetric flow rate of between 0.1 h −1  and 10 I −1 , and in the presence of a total quantity of hydrogen mixed with the feedstock such that the hydrogen/feedstock ratio is between 70 and 1,000 Nm 3  of hydrogen/m 3  of feedstock,   b) Separation, starting from the effluent that is obtained from stage a), of hydrogen, gases, and at least one hydrocarbon base,   c) Hydroisomerization of at least a portion of said hydrocarbon base that is obtained from stage b) in the presence of a fixed-bed hydroisomerization catalyst, whereby said catalyst comprises at least one hydro-dehydrogenating metal that is selected from the group that is formed by the metals of group VIB and group VIII of the periodic table and a substrate that comprises a zeolite that comprises at least one series of channels whose opening is defined by a ring with 8 oxygen atoms, modified by a′) at least one stage for introducing at least one alkaline cation that belongs to group IA or IIA of the periodic table, b′) a stage for treatment of said zeolite in the presence of at least one molecular compound that contains at least one silicon atom, c′) at least one stage for partial exchange of said alkaline cations by NH 4   +  cations, and d′) at least one heat treatment stage, whereby said hydroisomerization stage is carried out at a temperature of between 150 and 500° C., at a pressure of between 1 MPa and 10 MPa, at an hourly volumetric flow rate of between 0.1 and 10 h −1 , and in the presence of a total quantity of hydrogen mixed with the feedstock such that the hydrogen/feedstock ratio is between 70 and 1,000 Nm 3 /m 3  of feedstock,   d) Separation, starting from the effluent that is obtained from stage c), of hydrogen, gases, and at least one gas oil base and one kerosene base.   
     
     
         2 . Process according to  claim 1 , in which the element of group VIII is selected from among platinum and palladium, taken by themselves or in a mixture. 
     
     
         3 . Process according to  claim 2 , in which said catalyst comprises, in % by weight relative to the total mass of the catalyst, a content of noble metal of between 0.01 and 10% by weight. 
     
     
         4 . Process according to  claim 1 , in which the catalyst comprises at least one metal of group VIB in combination with at least one non-noble metal of group VIII, whereby the metal content of group VIB encompasses, in oxide equivalent, between 5 and 40% by weight relative to the total mass of said catalyst, and the content of non-noble metal of group VIII encompasses, in oxide equivalent, between 0.5 and 10% by weight relative to the total mass of said catalyst. 
     
     
         5 . Process according to  claim 4 , in which the non-noble element of group VIII is selected from among iron, cobalt and nickel, taken by themselves or in a mixture. 
     
     
         6 . Process according to  claim 4 , in which the element of group VIB is selected from among tungsten and molybdenum. 
     
     
         7 . Process according to  claim 1 , in which the zeolite that is contained in the substrate of the catalyst that is used in stage c) of the process according to the invention is selected from among the zeolites Y, ZSM-48, ZBM-30, IZM-1 and COK-7, taken by themselves or in a mixture. 
     
     
         8 . Process according to  claim 7 , in which the initially used zeolite is the Y zeolite. 
     
     
         9 . Process according to  claim 1 , in which said alkaline cation that belongs to the groups IA and IIA introduced in stage a) is selected from among the cations Na+, Li+, K+, Rb+, Cs+, Ba2+ and Ca2+, and, preferably, said cation is the Na+ cation. 
     
     
         10 . Process according to  claim 1 , in which the molecular compound that contains at least one silicon atom that is used in the treatment stage b) is selected from among the compounds of formula Si-R4 and Si2-R6 where R is selected from among hydrogen, an alkyl, aryl or acyl group, an alkoxy group (O—R′), a hydroxyl group (—OH), or a halogen. 
     
     
         11 . Process according to  claim 1 , in which the content of alkaline cations remaining in the modified zeolite at the end of stage c) is such that the alkaline cation/aluminum molar ratio is between 0.2:1 and 0.01:1. 
     
     
         12 . Process according to  claim 11 , in which the content of alkaline cations remaining in the modified zeolite at the end of stage c) is such that the alkaline cation/aluminum molar ratio is between 0.2:1 and 0.015:1. 
     
     
         13 . Process according to  claim 11 , in which the content of alkaline cations remaining in the modified zeolite at the end of stage c) is such that the alkaline cation/aluminum molar ratio is between 0.15:1 and 0.02:1. 
     
     
         14 . Process according to  claim 1 , in which the feedstocks that are obtained from renewable sources are selected from among the oils and fats of plant or animal origin, or mixtures of such feedstocks, containing triglycerides and/or free fatty acids and/or esters and said vegetable oils that can be raw or refined, totally or partially, and obtained from the following plants: canola, sunflower, soybean, palm, palm-kernel, olive, coconut, jatropha, and the animal fats being selected from among lard or fats composed of waste from the food industry or obtained from catering industries.