Method for producing tetrafluoropropene

Abstract

A method for preparing tetrafluoropropene utilising three reactors is described. Each reactor comprises a catalytic bed containing a catalyst or a preliminary catalyst. The method comprises the implementation, separately in each of the reactors, of catalytic reactions or reactions regenerating the catalyst, the quantity of catalyst or preliminary catalyst in the catalytic bed of one of the reactors representing between 90% and 110% of the quantity of catalyst or preliminary catalyst contained in the catalytic bed of one of the other two reactors. A facility configured to implement the method is also described.

What is claimed is: 
     
         1 . A plant for the manufacture of tetrafluoropropene comprising three reactors for reaction in the gas phase each comprising a catalytic bed containing a catalyst or a preliminary catalyst, the three reactors for reaction in the gas phase each being configured in order to be fed by:
 a device for feeding with a reaction stream comprising a compound B and hydrofluoric acid; and/or   a device for feeding with a preliminary reaction stream comprising a compound A and hydrofluoric acid; and/or   a device for feeding with a regeneration stream configured in order to feed the reactor with a regeneration stream comprising an oxidizing agent; and   optionally, a device for feeding with a waiting stream configured in order to feed the reactor with an inert gaseous stream comprising an inert gas;   wherein the amount of catalyst or of preliminary catalyst in the catalytic bed of one of the reactors represents between 90% and 110% of the amount of catalyst or of preliminary catalyst present in the catalytic bed of one of the other two reactors.   
     
     
         2 . The plant as claimed in  claim 1 , wherein the amount of catalyst or of preliminary catalyst present in the catalytic bed of each reactor is between 90% and 110% of the amount of catalyst or of preliminary catalyst present in the catalytic bed of the other two reactors considered independently of one another. 
     
     
         3 . The plant as claimed in  claim 1 , wherein the amount of catalyst or of preliminary catalyst present in the catalytic bed of each reactor is identical in the three reactors. 
     
     
         4 . The plant as claimed in  claim 1 , wherein the tetrafluoropropene comprises 2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene. 
     
     
         5 . The plant as claimed in  claim 1 , comprising:
 a first reactor, a second reactor and a third reactor;   a first device for collecting a stream of products resulting from the first reactor connected at the outlet of the latter;   a second device for collecting a stream of products resulting from the second reactor connected at the outlet of the latter;   a third device for collecting a stream of products resulting from the third reactor connected at the outlet of the latter;   a first intermediate collecting device connected to any one of the devices for collecting stream of products resulting from the first, second and/or third reactor and joined to the device for feeding with preliminary reaction stream;   a second intermediate collecting device connected to any one of the devices for collecting stream of products resulting from the first, second and/or third reactor and joined to the separation unit;   a separation unit fed by the second intermediate collecting device;   a first collecting pipe and a second collecting pipe which are connected at the outlet of the separation unit, the first collecting pipe being configured in order to transport a stream comprising hydrochloric acid and tetrafluoropropene and the second collecting pipe being configured in order to transport a stream comprising hydrofluoric acid and compound B;   a device for feeding with a reaction stream configured in order to feed the first reactor, the second reactor and the third reactor, this device being itself fed by a device for feeding with hydrofluoric acid and optionally by the second collecting pipe;   a device for feeding with a preliminary reaction stream configured in order to feed the first reactor, the second reactor and the third reactor, this device being itself fed by a device for feeding with hydrofluoric acid and optionally by the first intermediate collecting device;   a device for feeding with a regeneration stream configured in order to feed the first reactor, the second reactor and the third reactor;   a device for collecting a stream of gas resulting from the regeneration of the first reactor, of the second reactor and of the third reactor.   
     
     
         6 . The plant as claimed in  claim 1 , comprising:
 a first reactor, a second reactor and a third reactor;   a first device for collecting a stream of products resulting from the first reactor connected at the outlet of the latter;   a second device for collecting a stream of products resulting from the second reactor connected at the outlet of the latter;   a third device for collecting a stream of products resulting from the third reactor connected at the outlet of the latter;   a third intermediate collecting device connected to any one of the devices for collecting a stream of products resulting from the first, second and/or third reactor and joined to the device for feeding with a reaction stream;   a second intermediate collecting device connected to any one of the devices for collecting the stream of products resulting from the first, second and/or third reactor and joined to the separation unit;   a separation unit fed by the second intermediate collecting device;   a first collecting pipe and a second collecting pipe which are connected at the outlet of the separation unit, the first collecting pipe being configured in order to transport a stream comprising hydrochloric acid and tetrafluoropropene and the second collecting pipe being configured in order to transport a stream comprising hydrofluoric acid and compound B;   a device for feeding with a reaction stream configured in order to feed the first reactor, the second reactor and the third reactor, this device being itself fed by a device for feeding with hydrofluoric acid, and by the third intermediate collecting device and optionally by the second collecting pipe;   a device for feeding with a preliminary reaction stream configured in order to feed the first reactor, the second reactor and the third reactor, this device being itself fed by a device for feeding with hydrofluoric acid and optionally by the second collecting pipe;   a device for feeding with a regeneration stream configured in order to feed the first reactor, the second reactor and the third reactor;   a device for collecting a stream of gas resulting from the regeneration of the first reactor, of the second reactor and of the third reactor.   
     
     
         7 . The plant as claimed in  claim 1 , wherein the reactors are made of steel and have an interior surface covered with an alloy comprising more than 30% by weight of nickel or with a fluoropolymer-type coating.