Optimized process for upgrading bio-oils of aromatic bases

Abstract

A process for preparing aromatic compounds from a liquid biofuel feedstock by introducing the feedstock into a hydroreforming stage in the presence of hydrogen and a hydroreforming catalyst that contains a transition metal of a group 3 to 12 element and an activated carbon, silicon carbide, silica, transition alumina, alumina-silica, zirconium oxide, cerium oxide, titanium oxide, or an aluminate of a transition metal substrate, to obtain a liquid effluent that contains an aqueous phase and an organic phase, a stage for hydrotreatment of the organic phase, a hydrocracking stage, recycling a fraction that boils higher than 160° C. in said hydrocracking stage, a separation into a fraction containing naphtha and a fraction that boils higher than 160° C., a stage for catalytic reforming of the fraction containing naphtha to obtain hydrogen and a reformate that contains aromatic compounds and a stage for separation of the aromatic compounds of the reformate.

1 . Process for the production of aromatic compounds starting from a liquid feedstock that comprises at least one bio-oil, said feedstock being introduced into at least the following stages:
 A first hydroreforming stage in the presence of hydrogen and a hydroreforming catalyst that comprises at least one transition metal that is selected from among the elements of groups 3 to 12 of the periodic table and at least one substrate that is selected from among activated carbons, silicon carbides, silicas, transition aluminas, alumina-silicas, zirconium oxide, cerium oxide, titanium oxide, and the aluminates of transition metals, taken by themselves or in a mixture, for obtaining at least one liquid effluent that comprises at least one aqueous phase and at least one organic phase,   A second stage for hydrotreatment of at least one portion of the organic phase of the effluent that is obtained from the first hydroreforming stage in the presence of hydrogen in at least one reactor that contains a hydrotreatment catalyst, operating at a temperature of between 250 and 400° C., at a pressure of between 2 MPa and 25 MPa, at an hourly volumetric flow rate of between 0.1 h −1  and 20 h −1 , and with a total amount of hydrogen mixed with the feedstock such that the hydrogen/hydrocarbon volumetric ratio is between 100 and 3,000 Nm 3 /m 3 ,   A third hydrocracking stage of at least one portion of the effluent that is obtained from the second hydrotreatment stage, in the presence of hydrogen, in at least one reactor that contains a hydrocracking catalyst, operating at a temperature of between 250 and 480° C., under a pressure of between 2 and 25 MPa, at a volumetric flow rate of between 0.1 and 20 h-1, and with an amount of hydrogen that is introduced such that the hydrogen to hydrocarbon volumetric ratio is between 80 and 5,000 Nm 3 /m 3 , in which at least one portion of the fraction that boils at a temperature that is higher than 160° C. that is separated at the end of said third hydrocracking stage is recycled in said third hydrocracking stage,   A separation of the effluent that is obtained at the end of the third hydrocracking stage into at least one fraction that contains naphtha and a fraction that boils at a temperature that is higher than 160° C.,   A fourth stage for catalytic reforming of the fraction containing naphtha that is obtained from the separation operating in the presence of a catalytic reforming catalyst, under a pressure of between 0.1 and 4 MPa, at a temperature of between 400 and 700° C., at a volumetric flow rate of between 0.1 and 10 h −1 , and with a hydrogen/hydrocarbon ratio of 0.1 to 10, making it possible to obtain hydrogen and a reformate that contains aromatic compounds,   and a stage for separation of the aromatic compounds of the reformate obtained at the end of the catalytic reforming stage.   
     
     
         2 . Process according to  claim 1 , in which said first hydroreforming stage is carried out at a temperature of between 250 and 450° C., and at an absolute pressure of between 3.4 and 27.6 MPa (500 and 4,000 psi), at a volumetric flow rate of between
 0.5 h −1  and 5 h −1  relative to the bio-oil and with an amount of hydrogen that is introduced such that the volumetric ratio of hydrogen to hydrocarbons is between 50 and 2,000 Nm 3 /m 3 . 
 
     
     
         3 . Process according to  claim 1 , in which said liquid feedstock comprising at least one bio-oil also contains other liquid feedstocks obtained from the biomass, with said liquid feedstocks being selected from among vegetable oils, alga or algal oils, fish oils, fats of vegetable or animal origin, and alcohols obtained from the fermenting of sugars of the biomass, or mixtures of such feedstocks, which may or may not be pretreated. 
     
     
         4 . Process according to  claim 1 , in which said liquid feedstock consists entirely of bio-oil. 
     
     
         5 . Process according to  claim 1 , in which the hydroreforming catalysts comprise Ni, Cu, NiCr, NiMo or NiMn on activated carbon or on alumina or nickel aluminate. 
     
     
         6 . Process according to  claim 1 , in which a stage for separation of at least one organic phase, at least one aqueous phase, and at least one gaseous phase can be carried out between said second hydrotreatment stage and said third hydrocracking stage. 
     
     
         7 . Process according to  claim 6 , in which said organic phase is fractionated in a fractionation zone into at least one light fraction that boils at a temperature of between 80 and 160° C. and into at least one heavy fraction that boils at a temperature that is higher than 160° C. 
     
     
         8 . Process according to  claim 7 , in which said heavy fraction that boils at a temperature that is higher than 160° C. is sent into said third hydrocracking stage and said light fraction is sent directly into the fourth catalytic reforming stage, mixed with the fraction that contains naphtha separated at the end of said third hydrocracking stage. 
     
     
         9 . Process according to  claim 1 , in which said hydrocracking catalyst comprises metals of groups 8 to 10 that are selected from among nickel and cobalt, combined with at least one metal of group 6, selected from among molybdenum and tungsten and a substrate that is selected from among alumina, silica, silica-aluminas, zeolites, magnesia, clays, and the mixtures of at least two of these minerals. 
     
     
         10 . Process according to  claim 9 , in which the substrate of said hydrocracking catalyst comprises at least one FAU-structural-type Y zeolite. 
     
     
         11 . Process according to  claim 1 , in which the entire fraction that boils at a temperature that is higher than 160° C., separated at the end of the third hydrocracking stage, is recycled in said third stage.