Process and catalyst for selective hydrogenation of dienes and acetylenes

Abstract

A process for the selective hydrogenation of dienes and acetylenes in a mixed hydrocarbon stream from a pyrolysis steam cracker in which a front end a one step acetylene hydrogenation is carried out using catalyst comprising (A) 1 to 30 wt. % based on the total weight of the catalyst of a catalytic component of nickel only or nickel and one or more elements selected from the group consisting of copper, rhenium, palladium, zinc, gold, silver, magnesium, molybdenum, calcium and bismuth deposited on (B) a support having the a BET surface area of from 1 to about 100 m 2 /gram, total nitrogen pore volume of from 0.2 to about 0.9 cc/gram and an average pore diameter of from about 110 to 450 Å under conditions of temperature and pressure to selectively hydrogenate acetylenes and dienes. The process hydrogenates the dienes and acetylenes to olefins without loss of ethylene and propylene in the light and heavy products which eliminates the need for further processing of the heavier stream. In addition the amount of polymerization in the lower part of the distillation column reactor is reduced.

1 . A process for the selective hydrogenation of acetylenes and dienes in a mixed hydrocarbon stream containing C 1  to C 8  hydrocarbons comprising contacting a mixed hydrocarbon stream containing C 1  to C 8  hydrocarbons, including ethylene, acetylenes and dienes and hydrogen with a catalyst comprising (A) 1 to 30 wt. % based on the total weight of the catalyst of a catalytic component of nickel only or nickel and one or more elements selected from the group consisting of copper, rhenium, palladium, zinc, gold, silver, magnesium, molybdenum, calcium and bismuth deposited on (B) a support having the a BET surface area of from 1 to about 100 m 2 /gram, total nitrogen pore volume of from 0.2 to about 0.9 cc/gram and an average pore diameter of from about 110 to 450 Å under conditions of temperature and pressure to selectively hydrogenate acetylenes and dienes.  
   
   
       2 . The process according to  claim 1  wherein said catalytic component is Ni.  
   
   
       3 . The process according to  claim 1  wherein said catalytic component is nickel and one or more elements selected from the group consisting of copper, rhenium, palladium, zinc, gold, silver, magnesium, molybdenum, calcium and bismuth.  
   
   
       4 . The process according to  claim 1  wherein said support is selected from the group consisting of alumina, silica, zirconia, talcite, silica alumina, and charcoal.  
   
   
       5 . The process according to  claim 4  wherein said support is alumina.  
   
   
       6 . The process according to  claim 5  wherein said alumina has been calcined at a temperature in the range of 700 to 1200° C.  
   
   
       7 . The process according to  claim 6  wherein said catalyst has at least 30% of the pores larger the 100 Å diameter and a total pore volume from about 0.2 cc/g to about 0.9 cc/g and ABD from about 035 to about 0.75 g/cc.  
   
   
       8 . The process according to  claim 7  wherein at least 50% of the pores are larger than 100 Å diameter.  
   
   
       9 . The process according to  claim 1  wherein said mixed hydrocarbon stream is from a pyrolysis plant.  
   
   
       10 . A process for the selective hydrogenation of acetylenes and dienes in a mixed hydrocarbon stream containing C 1  up to C 8  hydrocarbons comprising the steps of: 
 (a) feeding a stream containing hydrogen, ethylene, propylene, acetylenes, butenes and dienes to a distillation column reactor between two beds of selective hydrogenation catalyst;    (b) feeding hydrogen below the lowest of the two beds of selective hydrogenation catalyst;    (c) concurrently in said distillation column reactor, 
 (i) reacting at least a portion of said acetylenes and dienes with hydrogen to produce mono olefins, and  
 (ii) separating the mixed hydrocarbon stream into a lower boiling stream and a higher boiling stream by fractional distillation;  
   (d) removing the lower boiling stream from the distillation column reactor as overheads; and    (e) removing the higher boiling stream from the distillation column reactor as bottoms.    
   
   
       11 . The process according to  claim 10  wherein said lower boiling stream contains the C 4  and lighter components and the higher boiling stream contains the C 5  and heavier components.  
   
   
       12 . The process according to  claim 10  wherein said lower boiling stream contains the C 3  and lighter components and the higher boiling stream contains the C 4  and heavier components.  
   
   
       13 . The process according to  claim 10  wherein the selective hydrogenation catalyst comprises nickel only or nickel and one or more elements selected from the group consisting of copper, rhenium, palladium, zinc, gold, silver, magnesium, molybdenum, calcium and bismuth deposited on a support having the a BET surface area of from 1 to about 100 m 2 /gram, total nitrogen pore volume of from 0.2 to about 0.9 cc/gram and an average pore diameter of from about 110 to 450 Å.  
   
   
       14 . The process according to  claim 13  wherein the support is selected from the group consisting of alumina, silica, zirconia, talcite, silica alumina and charcoal.  
   
   
       15 . The process according to  claim 14  wherein the catalyst has a concentration on the catalyst from 1 to 30 wt. % based on the total weight of the catalyst.  
   
   
       16 . The process according to  claim 10  wherein a portion of the overheads is condensed and returned to the distillation column reactor as reflux.  
   
   
       17 . The process according to  claim 16  wherein the pressure within the distillation column reactor is about 170 psig, the average catalyst bed temperature is about 210° F. and the reflux ratio is about 5:1.  
   
   
       18 . The process according to  claim 10  wherein the mixed hydrocarbon stream comprises the vapor product stream from the quench system of a hydrocarbon steam cracker comprising hydrogen, methane, C 2 -C 6  olefins and paraffins, C 2 -C 6  acetylenes and dienes, benzene, toluene, xylenes, and other C 6 + components.  
   
   
       19 . A catalyst comprising (A) 1 to 30 wt. % based on the total weight of the catalyst of a catalytic component of nickel only or nickel and one or more elements selected from the group consisting of copper, rhenium, palladium, zinc, gold, silver, magnesium, molybdenum, calcium and bismuth deposited on (B) a support having the a BET surface area of from 1 to about 100 m 2 /gram, total nitrogen pore volume of from 0.2 to about 0.9 cc/gram and an average pore diameter of from about 110 to 450 Å.  
   
   
       20 . The catalyst according to  claim 19  wherein the support is selected from the group consisting of alumina, silica, zirconia, talcite, silica alumina and charcoal.  
   
   
       21 . The catalyst according to  claim 20  wherein said catalyst has at least 30% of the pores larger than 100 Å diameter and a total pore volume from about 0.2 cc/g to about 0.9 cc/g and ABD from about 035 to about 0.75 g/cc.  
   
   
       22 . The catalyst according to  claim 19  wherein said catalytic component is Ni.  
   
   
       23 . The catalyst according to  claim 19  wherein said catalytic component is nickel and one or more elements selected from the group consisting of copper, rhenium, palladium zinc, gold, silver, magnesium, molybdenum, calcium and bismuth.  
   
   
       24 . The catalyst according to  claim 20  wherein said support is alumina.  
   
   
       25 . The catalyst according to  claim 24  wherein said alumina has been calcined at a temperature in the range of 700 to 1200° C.  
   
   
       26 . The catalyst according to  claim 21  wherein at least 50% of the pores are larger than 100 Å diameter.