Process for the epoxidation of an olefin with improved energy balance

Abstract

The invention relates to a process for the epoxidation of an olefin comprising (a) reacting the olefin with hydrogen peroxide in the presence of methanol as solvent in at least two reaction stages to obtain a mixture (M-a) comprising olefin oxide, unreacted olefin, methanol and water, wherein between at least two reaction stages, olefin oxide is separated by distillation; (b) separating unreacted olefin from the mixture (M-a) by distillation to obtain a mixture (M-bi) comprising at least 80 wt.-% of olefin and a mixture (M-bii) comprising methanol, water and at least 7 wt.-% of olefin oxide; (c) separating olefin oxide from the mixture (M-bii) in at least one distillation stage to obtain a mixture (M-ci) comprising at least 99 wt.-% of oletin oxide and a mixture (M-cii) comprising water and at least 55 wt.-% of methanol; (d) separating methanol from the mixture (M-cii) in at least one distillation stage to obtain a mixture (M-di) comprising at least 85 wt.-% of methanol and up to 10 wt.-% of water, and a mixture (M-dii) comprising at least 90 wt.-% of water; wherein a vapor top stream (Td) obtained from at least one distillation column used in (d), said vapor top stream (Td) comprising at least 85 wt.-% methanol, is used to operate at least partially at least one vaporizer used in at least one distillation column used in at least one of stages (a), (b) and (c).

1 . A process for the epoxidation of an olefin comprising 
 (a) reacting the olefin with hydrogen peroxide in the presence of methanol as solvent in at least two reaction stages to obtain a mixture (M-a) comprising olefin oxide, unreacted olefin, methanol and water, wherein between at least two reaction stages, olefin oxide is separated by distillation:    (b) separating unreacted olefin from the mixture (M-a) by distillation to obtain a mixture (M-bi) comprising at least 80 wt.-% of olefin and a mixture (M-bii) comprising methanol, water and at least 7 wt.-% of olefin oxide;    (c) separating olefin oxide from the mixture (M-bii) in at least one distillation stage to obtain a mixture (M-ci) comprising at least 99 wt.-% of olefin oxide and a mixture (M-cii) comprising water and at least 55 wt.-% of methanol;    (d) separating methanol from the mixture (M-cii) in at least one distillation stage to obtain a mixture (M-di) comprising at least 85 wt.-% of methanol and up to 10 wt.-% of water, and a mixture (M-dii) comprising at least 90 wt.-% of water;    wherein a vapor top stream (Td) obtained from at least one distillation column used in (d), said vapor top stream (Td) comprising at least 85 wt.-% methanol, is used to operate at least partially at least one vaporizer used in at least one distillation column used in at least one of stages (a), (b) and (c).    
   
   
       2 . The process as claimed in  claim 1 , wherein from 5 to 60 wt.-% of (Td) are used to operate at least partially a vaporizer used in (a), from 1 to 20 wt.-% of (Td) are used to operate at least partially a vaporizer used in (b), and from 1 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (c).  
   
   
       3 . The process as claimed in  claim 1 , wherein the olefin is propene and the olefin oxide is propylene oxide.  
   
   
       4 . The process as claimed in  claim 3 , wherein in (a), the mixture (M-a) additionally comprises propane, wherein in (b), unreacted propene is separated from the mixture (M-a) by distillation to obtain the mixture (M-bi) comprising the unreacted propene and propane, said process additionally comprising 
 (x) separating the propene from the mixture (M-bi) by distillation to obtain a mixture (M-x) comprising at least 90 wt.-% of propene,    and wherein the vapor top stream (Td) is used to operate at least partially at least one vaporizer used in at least one distillation column used in at least one of stages (a), (b), (c) and (x).    
   
   
       5 . The process as claimed in  claim 4 , wherein from 5 to 60 wt.-% of (Td) are used to operate at least partially a vaporizer used in (a), from 1 to 20 wt.-% of (Td) are used to operate at least partially a vaporizer used in (b), from 1 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (c), and from 1 to 20 wt.-% of (Td) are used to operate at least partially a vaporizer used in (x).  
   
   
       6 . The process as claimed in  claim 3 , wherein in (c), the mixture (M-cii) additionally comprises at least one compound having a boiling temperature lower than methanol and lower than water at a given pressure, said process comprising 
 (y) separating the at least one compound having a boiling point lower than methanol and lower than water from the mixture (M-cii) by distillation to obtain a mixture (M-y) comprising from 40 to 80 wt.-% of methanol and from 10 to 55 wt.-% of water;    (d) separating methanol from the mixture (M-y) in at least one distillation stage to obtain a mixture (M-di) comprising at least 85 wt.-% of methanol and up to 10 wt.-% of water, and a mixture (M-dii) comprising at least 90 wt.-% of water,    and wherein the vapor top stream (Td) is used to operate at least partially at least one vaporizer used in at least one distillation column used in at least one of stages (a), (b), (c) and (y).    
   
   
       7 . The process as claimed in  claim 6 , wherein from 5 to 60 wt.-% of (Td) are used to operate at least partially a vaporizer used in (a), from 1 to 20 wt.-% of (Td) are used to operate at least partially a vaporizer used in (b), from 1 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (c), and from 5 to 60 wt.-% of (Td) are used to operate at least partially a vaporizer used in (y).  
   
   
       8 . The process as claimed in  claim 3 , wherein in (c), the mixture (M-cii) additionally comprises at least one compound having a boiling temperature lower than methanol and lower than water at a given pressure, said process comprising 
 (d) separating methanol from the mixture (M-cii) in at least one distillation stage to obtain a mixture (M-di) comprising at least 85 wt.-% of methanol, up to 10 wt.-% of water and the at least one compound having a boiling temperature lower than methanol and lower than water, and a mixture (M-dii) comprising at least 90 wt.-% of water,    (z) separating the compound having a boiling point lower than methanol and lower than water from the mixture (M-di) by distillation to obtain a mixture (M-z) comprising from 85 to 99.5 wt.-% of methanol and from 0.5 to 10 wt.-% of water;    and wherein the vapor top stream (Td) is used to operate at least partially at least one vaporizer used in at least one distillation column used in at least one of steps (a), (b), (c) and (z).    
   
   
       9 . The process as claimed in  claim 8  wherein from 5 to 60 wt.-% of (Td) are used to operate at least partially a vaporizer used in (a), from 1 to 20 wt.-% of (Td) are used to operate at least partially a vaporizer used in (b), from 1 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (c), and from 5 to 60 wt.-% of (Td) are used to operate at least partially a vaporizer used in (z).  
   
   
       10 . The process as claimed in  claim 1 , wherein in (c), the olefin oxide is separated in two distillation columns, and wherein from 0 to 20 wt.-% of (Td) is used to at least partially operate a vaporizer of the first distillation column from which a mixture comprising at least 98 wt.-% of olefin oxide is obtained, said mixture being introduced into the second distillation column, and from 1 to 30 wt.-%. of (Td) are used to at least partially operate a vaporizer of the second distillation column from which an olefin oxide stream comprising at least 99.8 wt.-% olefin oxide is obtained.  
   
   
       11 . The process as claimed in  claim 1 , additionally comprising 
 (e) evaporating the mixture (M-dii).    
   
   
       12 . The process as claimed in  claim 11 , wherein from 5 to 60 wt.-% of (Td) are used to operate at least partially a vaporizer used in (a), from 1 to 20 wt.-% of (Td) are used to operate at least partially a vaporizer used in (b), from 1 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (c), and from 1 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (e).  
   
   
       13 . The process as claimed in  claim 1 , wherein from 1 to 50 wt.-% of (Td) are used to at least partially operate at least one control heat exchanger used in the process.  
   
   
       14 . The process as claimed in  claim 1 , wherein the feed of at least one distillation column used in stages (a), (b), (c), and (d) is heated with the bottom stream of this distillation column.  
   
   
       15 . The process as claimed in  claim 1 , wherein the top stream obtained from at least one distillation column used in stages (a), (b), and (c) is condensed in two stages, wherein in the first stage, the condenser is cooled with water having an inlet temperature of from 15 to 40° C. and in the second stage, the condenser is cooled with water having an inlet temperature of from 5 to 20° C., wherein the inlet temperature of the water used in the second stage is lower than the inlet temperature of the water used in the first stage.  
   
   
       16 . The process as claimed in  claim 15 , wherein in (c), the olefin oxide is separated in two distillation columns, and wherein from 0 to 20 wt.-% of (Td) are used to at least partially operate a vaporizer of the first distillation column from which a mixture comprising at least 98 wt.-% of olefin oxide is obtained, said mixture being introduced into the second distillation column, and from 1 to 30 wt.-% of (Td) are used to at least partially operate a vaporizer of the second distillation column from which an olefin oxide stream comprising at least 99.8 wt.-% olefin oxide is obtained, said olefin oxide stream comprising at least 99.8 wt.-% olefin oxide being condensed in two stages, wherein in the first stage, the condenser is cooled with water having an inlet temperature of from 15 to 40° C. and in the second stage, the condenser is cooled with water having an inlet temperature of from 5 to 20° C., wherein the inlet temperature of the water used in the second stage is lower than the inlet temperature of the water used in the first stage.  
   
   
       17 . The process as claimed in  claim 1 , wherein in (d), methanol is separated from the mixture (M-cii) in a two pressure distillation process, where in a first distillation column, distillation is carried out at a top pressure which is different from the top pressure of a second distillation column and wherein the condenser used to condense the top stream of the first or second distillation column is used simultaneously as the vaporizer of the second or first distillation column.  
   
   
       18 . The process as claimed in  claim 17 , wherein the top pressure of the first distillation column is from 2 to 8 bar and the top pressure of the second distillation column is from 8 to 15 bar.  
   
   
       19 . The process as claimed in  claim 1 , wherein in (d), 
 (i) the mixture (M-cii) is introduced into a first distillation column (K1) from which the vapor top stream (Td) is obtained, the distillation in (K1) being carried out at a top pressure of from 2.5 to 6 bar; and    (ii) the bottoms stream obtained from (K1) is introduced into a second distillation column (K2), the distillation in (K2) being carried out at a top pressure of from 9 to 13 bar,    wherein prior to introducing into (K2), the bottoms stream obtained from (K1) is heated to a temperature from 110 to 180° C. with the bottoms stream obtained from (K2), and wherein the condenser used to condense the top stream obtained from (K2) is simultaneously used as vaporizer of (K1).    
   
   
       20 . The process as claimed in  claim 19 , wherein (K2) is a dividing wall column.  
   
   
       21 . The process as claimed in  claim 1 , wherein the olefin separated in (c) is reintroduced into (a).  
   
   
       22 . The process as claimed in  claim 1 , wherein the methanol separated in (d) is reintroduced into (a).  
   
   
       23 . A process for the epoxidation of propene, comprising 
 (a) reacting the propene with hydrogen peroxide in the presence of methanol as solvent in at least two reaction stages to obtain a mixture (M-a) comprising propylene oxide, unreacted propene, propane, methanol and water, wherein between at least two reaction stages, propylene oxide is separated by distillation;    (b) separating unreacted propene from the mixture (M-a) by distillation to obtain a mixture (M-bi) comprising propane and at least 80 wt.-% of propene, and a mixture (M-bii) comprising methanol, water and at least 7 wt.-% of propylene oxide;    (x) separating propene from the mixture (M-bi) by distillation to obtain a mixture (M-x) comprising at least 95 wt.-% of propene, and re-introducing (M-x) into (a);    (c) separating the propylene oxide from the mixture (M-bii) in at least one distillation stage to obtain a mixture (M-ci) comprising at least 99 wt.-% of propylene oxide and a mixture (M-cii) comprising water, at least one compound having a boiling temperature lower than methanol and lower than water at a given pressure, and at least 60 wt.-% of methanol;    (y) separating the at least one compound having a boiling point lower than methanol and lower than water from the mixture (M-cii) by distillation to obtain a mixture (M-y) comprising from 40 to 80 wt.-% of methanol and from 10 to 55 wt.-% of water;    (d) separating methanol from the mixture (M-y) in at least one distillation stage to obtain a mixture (M-di) comprising at least 85 wt.-% of methanol and up to 10 wt.-% of water, and a mixture (M-dii) comprising at least 90 wt.-% of water, and re-introducing (M-di) into (a);    (e) evaporating the mixture (M-dii),    wherein a vapor top stream (Td) obtained from at least one distillation column used in (d), said vapor top stream (Td) comprising at least 85 wt.-% methanol, and wherein from 15 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (a), from 2 to 15 wt.-% of (Td) are used to operate at least partially a vaporizer used in (b), from 1 to 10 wt.-% of (Td) are used to operate at least partially a vaporizer used in (x), from 1 to 40 wt.-% of (Td) are used to operate at least partially a vaporizer used in (c), from 15 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (y), and from 10 to 40 wt.-% of (Td) are used to operate at least partially a vaporizer used in (e).    
   
   
       24 . The process as claimed in  claim 23 , wherein in (c), the propylene oxide is separated in two distillation columns, and wherein from 0 to 20 wt.-% of (Tf) is used to at least partially operate a vaporizer of the first distillation column from which a mixture comprising at least 98 wt.-% of propylene oxide is obtained, said mixture being introduced into the second distillation column, and from 1 to 30 wt.-% of (Tf) are used to at least partially operate a vaporizer of the second distillation column from which an propylene oxide stream comprising at least 99.8 wt.-% propylene oxide is obtained.  
   
   
       25 . The process as claimed in  claim 23 , additionally comprising at least one further integration method selected from the group consisting of 
 (I) using 1 to 40 wt.-% of (Td) to at least partially operate at least one control heat exchanger used in the process;    (II) heating the feed of at least one distillation column used in stages (a), (b), (x), (c), (y), (d) and (e) with the bottom stream of this distillation column; and    (III) condensing the top stream obtained from at least one distillation column used in stages (a), (b), (x), (c), (y), and (e) in two stages, wherein in the first stage, the condenser is cooled with water having an inlet temperature of from 15 to 40° C. and in the second stage, the condenser is cooled with water having an inlet temperature of from 5 to 20° C., wherein the inlet temperature of the water used in the second stage is lower than the inlet temperature of the water used in the first stage.    
   
   
       26 . The process as claimed in  claim 23 , wherein in (d), 
 (i) the mixture (M-y) is introduced into a first distillation column (K1) from which the vapor top stream (Td) is obtained, the distillation in (K1) being carried out at a top pressure of from 2.5 to 6 bar; and    (ii) the bottoms stream obtained from (K1) is introduced into a second distillation column (K2), the distillation in (K2) being carried out at a top pressure of from 9 to 13 bar,    wherein prior to introducing into (K2), then bottoms stream obtained from (K1) is heated to a temperature from 120 to 180° C. with the bottoms stream obtained from (K2), and wherein the condenser used to condense the top stream obtained from (K2) is simultaneously used as vaporizer of (K1).    
   
   
       27 . The process as claimed in  claim 26 , wherein (K2) is a dividing wall column.  
   
   
       28 . A process for the epoxidation of propene, comprising 
 (a) reacting the propene with hydrogen peroxide in the presence of methanol as solvent in at least two reaction stages to obtain a mixture (M-a) comprising propylene oxide, unreacted propene, propane, methanol and water, wherein between at least two reaction stages, propylene oxide is separated by distillation in a divided wall column, wherein separated methanol is recycled into (a);    (b) separating unreacted propene from the mixture (M-a) by distillation to obtain a mixture (M-bi) comprising propane and at least 80 wt.-% of propene, and a mixture (M-bii) comprising methanol, water and at least 7 wt.-% of propylene oxide;    (x) separating propene from the mixture (M-bi) by distillation to obtain a mixture (M-x) comprising at least 95 wt.-% of propene, and re-introducing (M-x) into (a);    (c) separating the propylene oxide from the mixture (M-bii) in two distillation columns, wherein from the first distillation column, a first mixture comprising at least 99 wt.-% of propylene oxide and a mixture (M-cii) comprising water, at least one compound having a boiling temperature lower than methanol and lower than water at a given pressure, and at least 60 wt.-% of methanol, are obtained, said first mixture being introduced into the second distillation column from which a mixture (M-ci) comprising at least 99.8 wt.-% propylene oxide is obtained;    (y) separating the at least one compound having a boiling point lower than methanol and lower than water from the mixture (M-cii) by distillation to obtain a mixture (M-y) comprising from 40 to 80 wt.-% of methanol and from 10 to 65 wt.-% of water;    (d) separating methanol from the mixture (M-y) wherein 
 (i) the mixture (M-y) is introduced into a first distillation column (K1) from which the vapor top stream (Td) is obtained, the distillation in (K1) being carried out at a top pressure of from 2.5 to 6 bar; and  
 (ii) the bottoms stream obtained from (K1) is introduced into a second distillation column (K2), the distillation in (K2) being carried out at a top pressure of from 9 to 13 bar, (K2) being a dividing wall column,  
 and wherein, prior to introducing into (K2), the bottoms stream obtained from (K1) is heated to a temperature from 130 to 175° C. with the bottoms stream obtained from (K2), and wherein the condenser used to condense the top stream obtained from (K2) is simultaneously used as vaporizer of (K1), and wherein (Td) and the top stream obtained from (K2) are reintroduced into (a);  
   (e) evaporating the mixture (M-dii),    wherein a vapor top stream (Td) obtained from at least one distillation column used in (d), said vapor top stream (Td) comprising at least 85 wt.-% methanol, is used to operate at least partially at least one vaporizer used in at least one-distillation column used in at least one of stages (a), (b), (c), (e), (x) and (y).    
   
   
       29 . The process as claimed in  claim 28 , wherein from 15 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (a), from 2 to 15 wt.-% of (Td) are used to operate at least partially a vaporizer used in (b), from 2 to 10 wt.-% of (Td) are used to operate at least partially a vaporizer used in (x), from 0 to 156 wt.-% of (Td) are used to operate at least partially a vaporizer used in the first distillation column in (c), from 1 to 25 wt.-% of (Td) are used to operate at least partially a vaporizer used in the second distillation column in (c), from 15 to 50 wt.-% of (Td) are used to operate at least partially a vaporizer used in (y), and from 10 to 40 wt.-% of (Td) are used to operate at least partially a vaporizer used in (e).  
   
   
       30 . The process as claimed in  claim 29 , additionally comprising at least one further integration method selected from the group consisting of 
 (I) using 1 to 40 wt.-% of (Td) to at least partially operate at least one control heat exchanger used in the process;    (II) heating the feed of at least one distillation column used in stages (a), (b), (x), (c), (y), (d) and (e) with the bottom stream of this distillation column; and    (III) condensing the top stream obtained from at least one distillation column used in stages (a), (b), (x), (c), (y), and (e) in two stages, wherein in the first stage, the condenser is cooled with water having an inlet temperature of from 15 to 40° C. and in the second stage, the condenser is cooled with water having an inlet temperature of from 5 to 20° C., wherein the inlet temperature of the water used in the second stage is lower than the inlet temperature of the water used in the first stage.    
   
   
       31 . A process for the epoxidation of propene, comprising 
 (a) reacting the propene with hydrogen peroxide in the presence of methanol as solvent in at least two reaction stages to obtain a mixture (M-a) comprising propylene oxide, unreacted propene, propane, methanol and water, wherein between at least two reaction stages, propylene oxide is separated by distillation;    (b) separating unreacted propene from the mixture (M-a) by distillation to obtain a mixture (M-bi) comprising propane and at least 80 wt.-% of propene, and a mixture (M-bii) comprising methanol, water and at least 7 wt.-% of propylene oxide;    (x) separating propene from the mixture (M-bi) by distillation to obtain a mixture (M-x) comprising at least 95 wt.-% of propene, and re-introducing (M-x) into (a); (c) separating the propylene oxide from the mixture (M-bii) in two distillation columns, wherein from the first distillation column, a first mixture comprising at least 99 wt.-% of propylene oxide and a mixture (M-cii) comprising water, at least one compound having a boiling temperature lower than methanol and lower than water at a given pressure and at least 60 wt.-% of methanol, are obtained, said first mixture being introduced into the second distillation column from which a mixture (M-ci) comprising at least 99.8 wt.-% propylene oxide is obtained;    (y) separating the at least one compound having a boiling point lower than methanol and lower than water from the mixture (M-cii) by distillation to obtain a mixture (M-y) comprising from 40 to 80 wt.-% of methanol and from 10 to 55 wt.-% of water;    (d) separating methanol from the mixture (M-y) wherein 
 (i) the mixture (M-y) is introduced into a first distillation column (K1) from which the vapor top stream (Td) is obtained, the distillation in (K1) being carried out at a top pressure of from 2.5 to 6 bar; and  
 (ii) the bottoms stream obtained from (K1) is introduced into a second distillation column (K2), the distillation in (K2) being carried out at a top pressure of from 9 to 13 bar, (K2) being a dividing wall column,  
 and wherein, prior to introducing into (K2), the bottoms stream obtained from (K1) is heated to a temperature from 140 to 170° C. with the bottoms stream obtained from (K2), and wherein the condenser used to condense the top stream obtained from (K2) is simultaneously used as vaporizer of (K1), and wherein (Td) and the top stream obtained from (K2) are reintroduced into (a);  
   (e) evaporating the mixture (M-dii),    wherein a vapor top stream (Td) obtained from at least one distillation column used in (d), said vapor top stream (Td) comprising at least 85 wt.-% methanol, wherein from 20 to 40 wt.-% of (Td) are used to operate at least partially a vaporizer used in (a), from 3 to 10 wt.-% of (Td) are used to operate at least partially a vaporizer used in (b), from 3 to 10 wt.-% of (Td) are used to operate at least partially a vaporizer used in (x), from 0 to 10 wt.-% of (Td) are used to operate at least partially a vaporizer used in the first distillation column in (c), from 2 to 20 wt.-% of (Td) are used to operate at least partially a vaporizer used in the second distillation column in (c), from 20 to 40 wt.-% of (Td) are used to operate at least partially a vaporizer used in (y), from 15 to 35 wt.-% of (Td) are used to operate at least partially a vaporizer used in (e), and from 3 to 30 wt.-% of (Td) are used to at least partially operate at least one control heat exchanger used in the process, said process further comprising at least one further integration method selected from the group consisting of 
 (II) heating the feed of the distillation column used in stage (a) with the bottoms stream of this column and the feed of at least one distillation column used in stage (d) with the bottoms stream of this column;  
 (III) condensing the top stream obtained from at least one distillation column used in stages (a), (b), (x), (c), (y), and (e) in two stages, wherein in the first stage, the condenser is cooled with water having an inlet temperature of from 15 to 40° C. and in the second stage, the condenser is cooled with water having an inlet temperature of from 5 to 20° C., wherein the inlet temperature of the water used in the second stage is lower than the inlet temperature of the water used in the first stage.