Process for Limiting Self-Heating of Activated Catalysts

Abstract

The invention provides a process for limiting self-heating of activated particle catalysts wherein the catalyst particles are placed in motion inside a hot gas flow that passes through them and a liquid composition containing one or several film forming polymer(s) is pulverized onto the particles in motion until a protective layer is obtained on the surface of said particles containing said film forming polymer and having an average thickness of less than or equal to 20 μm. The invention also provides the use of this process to reduce the quantities of toxic gases that may be emitted by the activated catalysts, as well as an activated catalyst for the hydroconversion of hydrocarbons covered with a continuous protective layer that are obtained by this process.

1 . A process for limiting self-heating of activated catalyst particles, comprising:
 placing activated catalyst particles in motion in a fluidized bed within a hot gas flow passing continuously through the activated catalyst particles, wherein the gas has a temperature greater than 25° C.; and   spraying onto the activated catalyst particles in motion a liquid composition comprising a solution or a dispersion of one or more film forming polymer(s) in a solvent, wherein the liquid composition contains 0.5% to 50% by weight of film-forming polymer(s) with respect to the total weight of the composition, wherein, upon evaporation of the solvent from the liquid composition, a protective layer containing said film-forming polymer(s) is formed on the surface of the activated catalyst particles, and wherein the protective layer has an average thickness lower than or equal to 20 μm;   thereby limiting self-heating of the activated catalyst particles.   
     
     
         2 . The process according to  claim 1 , wherein the liquid composition contains from 0.5 to 25% by weight, with respect to the total weight of the composition. 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . The process according to  claim 1 , wherein the hot gas has a temperature ranging from 30 to 150° C. 
     
     
         6 . The process according to  claim 1 , wherein the gas flows at a rate ranging from 5 to 100 m 3  per hour per kilogram of catalyst. 
     
     
         7 . The process according to  claim 1 , wherein the one or more film-forming polymer(s) forming the protective layer comprises from 50 to 100% by weight of the protective layer. 
     
     
         8 . The process according to  claim 1 , wherein the one or more film-forming polymer(s) is (are) selected from the group consisting of:
 vinyl alcohol homo- and copolymer;   polyvinyl alcohols and copolymers made up of vinyl alcohol and olefin(s) monomers   ethylene and vinyl alcohol monomers (EVOH copolymers)-;   partially hydrolyzed vinyl alcohol homo- and copolymers containing non-hydrolyzed vinyl acetate units-;   polyethylene glycols-;   collagen;   polyethylene terephtalates (PET)-;   polyethylene naphtalates (PEN)-;   polyamides;   polysaccharides;   polyvinyl chlorides (PVC)-;   polyvinylidene chlorides (PVDC)-;   polyacrylonitriles (PAN)-;   polyacrylate resins;   copolymers of which at least one of the monomers is of the acrylate type; and   mixtures thereof.   
     
     
         9 . The process according to  claim 1 , wherein the film forming polymer is selected from the group consisting of polyvinyl alcohols, copolymers made up of vinyl alcohol and olefin(s) monomers. 
     
     
         10 . The process according to  claim 1 , wherein the average thickness of the protective layer is less than or equal to 10 μm. 
     
     
         11 . The process according to  claim 1 , wherein the total amount of film-forming polymer used is within a range between 0.1 to 6% by weight with respect to the total weight of the initial activated catalyst particles. 
     
     
         12 . The process according to  claim 1 , wherein the process further results in reducing emission of toxic gases by the activated catalyst particles. 
     
     
         13 . An activated hydrocarbon hydroconversion catalyst obtained by a process as defined in  claim 1 , comprising activated catalyst particles which are each covered on their surface by a continuous protective layer having an average thickness ranging from 0.1 to 20 μm and comprising from 50 to 100% by weight of one or several film forming polymer(s) chosen among:
 vinyl alcohol homo- and copolymers; 
 partially hydrolyzed vinyl alcohol homo- and copolymers; 
 polyethylene glycols-; 
 collagen-; 
 polyethylene terephtalates (PET)-; 
 polyethylene naphtalates (PEN)-; 
 polyamides-; 
 polysaccharides; 
 polyvinyl chlorides (PVC)-; 
 polyvinylidene chlorides (PVDC)-; 
 polyacrylonitriles (PAN)-; 
 polyacrylates resins-; 
 copolymers of which at least one of the monomers is of the acrylate type-; and 
 mixtures thereof; 
 
       wherein the total amount of film forming polymer represents from 0.1 to 0.4% by weight with respect to the total weight of the initial catalyst. 
     
     
         14 - 18 . (canceled) 
     
     
         19 . The process according to  claim 1 , wherein the liquid composition contains from 1 to 10% by weight of film forming polymer, with respect to the total weight of the composition. 
     
     
         20 . The process according to  claim 1 , wherein the hot gas has a temperature ranging from 50 to 100° C.