Process for the hydroconversion of heavy oils

Abstract

A process for the conversion of heavy oils comprising sending the heavy oil to hydrotreatment, of the high severity type, in the presence of high concentrations of a suitable hydrogenation catalyst dispersed in slurry phase, effected in a suitable solid accumulation reactor capable of operating stably in the presence of solids deriving from and generated by the feedstock charged, wherein the hydrogen or mixtures thereof is fed at suitable flow-rates and suitably distributed, obtaining the conversion products in vapour phase directly in the reactor.

1 . A process for the hydroconversion of heavy oils, selected from crude oils, heavy crude oils, bitumens from tar sands, distillation residues, heavy distillation cuts, deasphalted distillation residues, vegetable oils, oils deriving from coke and oil shales, oils obtained from the thermodecomposition of waste products, polymers, biomasses, effected in a suitable solid accumulation reactor with a specific hydrogenation catalyst in slurry phase and with the introduction of hydrogen or a mixture of hydrogen and H 2 S,
 comprising sending the heavy oil to a hydroconversion step with a high severity index, producing a quantity of products insoluble in tetrahydrofuran (THF 1 ) of at least 3 kg per ton of feedstock converted, and with a high concentration of a catalyst based on molybdenum in slurry phase, the quantity of molybdenum being at least 5 kg per m 3  referring to the reaction medium, effected in a reactor of the bubbling tower type, operating with an accumulation of solids in the reaction medium of at least 50 kg/m 3  consisting of coke and metallic sulphides deriving from the feedstock, wherein the hydrogen introduced is in a weight ratio of at least 0.3 with respect to the feedstock, obtaining the conversion products in vapour phase directly in the reactor.   
     
     
         2 . The process according to  claim 1 , wherein the non-converted heavy oil remains constantly in the reaction medium. 
     
     
         3 . The process according to  claim 1 , wherein the hydrogenation catalyst remains continuously in the reaction medium. 
     
     
         4 . The process according to  claim 1 , wherein the solids deriving from and generated by the heavy oils to be converted are removed exclusively by flushing. 
     
     
         5 . The process according to  claim 1 , wherein the catalyst is charged into the reactor at the start-up of the hydrogenation reaction, in proportion to the volume of the reactor, and continuously maintained inside the reaction medium. 
     
     
         6 . The process according to  claim 4 , wherein the catalyst present in the flushing is integrated in the reactor in continuous or batchwise. 
     
     
         7 . The process according to  claim 1 , wherein the hydrogenation catalyst based on molybdenum is a decomposable precursor or a preformed compound of the same. 
     
     
         8 . The process according to  claim 1  or  7 , wherein the catalyst additionally contains one or more transition metals. 
     
     
         9 . The process according to  claim 1 , wherein the quantity charged into the reactor of the transition metal contained in the catalyst, expressed as a concentration of molybdenum, is at least 8 kg per m 3  referring to the reaction medium. 
     
     
         10 . The process according to  claim 1 , wherein the reactor operates with an accumulation level of solids of at least 100 kg per m 3  referring to the reaction medium. 
     
     
         11 . The process according to  claim 1 , wherein the hydrotreatment step is carried out at a temperature ranging from 400 to 480° C. and a pressure ranging from 100 to 200 atmospheres. 
     
     
         12 . The process according to  claim 1 , wherein the feedstock flow-rate necessary for keeping the volume of reaction liquid constant ranges from 50 to 300 kg/h per m 3  of reaction volume.