Process for hydrotreatment and hydroisomerization of feedstocks obtained from a renewable source implementing a zeolite that is modified by a basic treatment

Abstract

This invention describes a process for treatment of feedstocks obtained from a renewable source implementing—in one hydroisomerization stage—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 dealuminified Y zeolite that has an initial overall atomic ratio of silicon to aluminum of between 2.5 and 20, a fraction by weight of an initial extra-network aluminum atom that is greater than 10%, relative to the total mass of aluminum that is present in the zeolite, an initial mesopore volume that is measured by nitrogen porosimetry that is greater than 0.07 ml·g −1 , and an initial crystalline parameter a o of the unit cell mesh of between 24.38 Å and 24.30 Å, whereby said zeolite is modified by a) a basic treatment stage that consists of the mixing of said dealuminified Y zeolite with a basic aqueous solution, and at least one heat treatment stage c).

1 . A 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 selected from 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 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  of hydrogen/m 3  of feedstock,   b) Separation, from the effluent obtained from stage a), of hydrogen, gases, and at least one hydrocarbon base,   c) Hydroisomerization of at least a portion of said hydrocarbon base obtained from stage b) in the presence of a fixed-bed hydroisomerization catalyst, wherein said catalyst comprises at least one hydro-dehydrogenating metal selected from metals of group VIB and group VIII of the periodic table and a substrate comprising at least one dealuminified Y zeolite having an initial overall atomic ratio of silicon to aluminum of between 2.5 and 20, an initial extra lattice aluminum atom fraction by weight that is greater than 10%, relative to the total mass of the aluminum present in the zeolite, an initial meospore volume measured by nitrogen porosimetry greater than 0.07 ml·g −1 , and an initial crystalline parameter a0 of the unit cell that is between 24.38 Å and 24.30 Å, whereby said zeolite is modified by a′) a basic treatment stage comprising mixing said dealuminified Y zeolite with a basic aqueous solution, comprising basic compounds selected from alkaline bases and strong non-alkaline bases, and at least one heat treatment stage c′) implemented at a temperature of between 200 and 700° C., wherein 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, from the effluent obtained from stage c), of hydrogen, gases, and at least one gas oil base and one kerosene base.   
     
     
         2 . A process according to  claim 1 , that catalyst in the hydroisomerization stage c) comprises noble metals selected from platinum and palladium, taken by themselves or in a mixture. 
     
     
         3 . A process according to  claim 2 , in which the content of noble metal of said catalyst that is used in the hydroisomerization stage c) is between 0.01 and 10% by weight relative to the total mass of said catalyst. 
     
     
         4 . A process according to  claim 1 , in which said catalyst that is used in the hydroisomerization stage c) 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 non-noble metal content of group VIII encompasses, in oxide equivalent, between 0.5 and 10% by weight relative to the total mass of said catalyst. 
     
     
         5 . A process according to  claim 1 , in which the initial dealuminified Y zeolite has, before being modified, an initial overall atomic ratio of silicon to aluminum of between 2.7 and 10.0. 
     
     
         6 . A process according to  claim 1 , in which the initial dealuminified Y zeolite, before being modified, has a fraction by weight of initial extra-network aluminum atoms that is greater than 30% by weight relative to the total mass of aluminum that is present in the zeolite. 
     
     
         7 . A process according to  claim 1 , in which the alkaline bases in the basic aqueous solution of stage a′) are selected from among alkaline carbonates and alkaline hydroxides, and the non-alkaline bases are selected from among quaternary ammonium compounds, taken by themselves or in a mixture. 
     
     
         8 . A process according to  claim 7 , in which the aqueous solution is a sodium carbonate or sodium hydroxide solution. 
     
     
         9 . A process according to  claim 1 , in which in the case where the basic treatment stage a′) comprises mixing of said initial dealuminified Y zeolite with a basic aqueous solution of compounds that are selected from among alkaline bases, and the process for modification of said zeolite comprises a stage b′) of at least one partial or total exchange of said alkaline cations belonging to groups IA and IIA of the periodic table, introduced during stage a), by NH 4   +  cations. 
     
     
         10 . A process according to  claim 1  wherein, the basic treatment stage a′) comprises mixing said initial dealuminified Y zeolite with a basic aqueous solution of compounds selected from quaternary ammonium compounds, taken by themselves or in a mixture and the process for modification of said initial dealuminified Y zeolite does not comprise a stage b′) of at least one intermediate partial or total exchange. 
     
     
         11 . A process according to  claim 1 , in which the feedstocks that are obtained from renewable sources are selected from oils and fats of plant or animal origin, or mixtures of such feedstocks, containing triglycerides and/or free fatty acids and/or esters, said vegetable oils be raw, or refined, and are totally or partially obtained from the following plants: canola, sunflower, soybean, palm, palm-kernel, olive, coconut, jatropha, and the animal fats are selected from among lard or fats composed of waste from the food industry or obtained from catering industries.