Reactive distillation process and plant for obtaining acetic acid and alcohol from the hydrolysis of methyl acetate

Abstract

Forming acetic acid and methanol from the hydrolysis of methyl acetate by reactive distillation is disclosed. A feed containing water and methyl acetate contacts a catalyst in a reactive space to perform the hydrolysis to form methanol and acetic acid. The reactive space comprises at least a first rectification zone, a first stripping zone and a first reaction zone. A catalyst is provided in the first reaction zone. The column further comprises a product space with at least a second rectification zone and a second stripping zone. The second stripping zone shares at least a portion of the column sump with the first stripping zone. A first head product is discharged from a reactive space head portion and a bottom product is discharged from the column sump and a second head product is discharged from a product space head portion and an intermediate product is discharged from the product space.

1 . A method for obtaining acetic acid and methanol from the hydrolysis of methyl acetate by reactive distillation in a reactive distillation column ( 1 ) which is configured as a divided wall reactive distillation column ( 1 ) including a column head ( 36 ), a column body ( 37 ) and a column sump ( 38 ) with the column body ( 37 ) being arranged between the column head ( 36 ) and the column sump ( 38 ), the column further comprises a reactive space ( 19 ) and a product space ( 29 ), wherein the reactive space ( 19 ) comprises at least a first rectification zone ( 32 ) and a first reaction zone ( 33 ), whereby a catalyst is provided in the first reaction zone ( 33 ) and the first rectification zone ( 32 ) is arranged between the column head ( 36 ) and the first reaction zone ( 33 ), the column further comprises a first stripping zone ( 34 ), with the first stripping zone ( 34 ) being arranged between the column sump ( 38 ) and the first reaction zone ( 33 ), wherein the product space ( 29 ) comprises at least a second rectification zone ( 42 ) and a second stripping zone ( 44 ), whereby a feed containing water and methyl acetate enters the reactive space ( 19 ) and is brought into contact with the hydrolysis catalyst to be at least partially hydrolysed to acetic acid and methanol, characterised in that the second stripping zone ( 44 ) shares at least a portion of the column sump ( 38 ) with the first stripping zone ( 34 ) and a first head product is discharged from a reactive space head portion ( 45 ) and a bottom product is discharged from the column sump ( 38 ) and a second head product is discharged from a product space head portion ( 46 ) and an intermediate product is discharged from the product space ( 29 ). 
     
     
         2 . The method of  claim 1 , wherein the methanol and methyl acetate in the bottom product amount to less than 1%, preferably less than 0.5% particularly preferred less than 0.1%. 
     
     
         3 . The method of  claim 1 , wherein the second head product substantially consists of methanol and methyl acetate. 
     
     
         4 . The method of  claim 3 , wherein the impurities in the second head product amount to less than 1%, preferably less than 0.5% particularly preferred less than 0.1%. 
     
     
         5 . The method of  claim 1 , wherein a pre-reactor feed containing methyl acetate is firstly fed to a pre-reactor ( 2 ), in which the methyl acetate is brought into contact with a hydrolysis catalyst in the presence of water, by means of which the methyl acetate is partially cleaved into acetic acid and methanol and a pre-reactor product containing methyl acetate, acetic acid and methanol is discharged from the pre-reactor ( 2 ) and is fed as the first feed into the reactive distillation column. 
     
     
         6 . A methyl acetate hydrolysis plant for obtaining acetic acid and methanol through the hydrolysis of methyl acetate by reactive distillation includes a divided wall reactive distillation column ( 1 ) including a column head ( 36 ), a column body ( 37 ) and a column sump ( 38 ) and the column body ( 37 ) being arranged between the column head ( 36 ) and the column sump ( 38 ), the column further comprising a reactive space ( 19 ) and a product space ( 29 ), and a wall ( 5 ) arranged in parallel to the longitudinal axis ( 35 ) of the column, said wall ( 5 ) dividing the column into the reactive space ( 19 ) and the product space ( 29 ), wherein the reactive space ( 19 ) comprises at least a first rectification zone ( 32 ) and a first reaction zone ( 33 ) with a catalyst being provided in the first reaction zone ( 33 ), wherein the first rectification zone ( 32 ) is arranged between the column head ( 36 ) and the first reaction zone ( 33 ), the column further comprising a first stripping zone ( 34 ), with the first stripping zone ( 34 ) being arranged between the column sump ( 38 ) and the first reaction zone ( 33 ), wherein the product space ( 29 ) comprises at least a second rectification zone ( 42 ) and a second stripping zone ( 44 ), characterised in that the second stripping zone ( 44 ) shares at least a portion of the column sump ( 38 ) with the first stripping zone ( 34 ). 
     
     
         7 . The methyl acetate hydrolysis plant of  claim 6 , wherein a sump conduit ( 16 ) is provided for drawing off a bottom product from the column sump ( 38 ), said bottom product substantially consisting of acetic acid and water. 
     
     
         8 . The methyl acetate hydrolysis plant of  claim 6 , wherein a first head discharge conduit ( 18 ) is provided for drawing off a first head product from a reactive space column head portion ( 45 ) and a second head discharge conduit ( 28 ) is provided for drawing off a second head product from the product space column head portion ( 46 ), said second head product consisting substantially of methanol and methyl acetate. 
     
     
         9 . The methyl acetate hydrolysis plant of  claim 8 , wherein a first condenser ( 30 ) is foreseen for condensing a portion or all of said first head product and a second condenser ( 31 ) is foreseen for condensing a portion or all of said second head product. 
     
     
         10 . The methyl acetate hydrolysis plant of  claim 9 , wherein a first reflux conduit ( 24 ) is provided for recycling a portion of said first head product to the reactive space ( 19 ) and a second reflux conduit ( 24 ) is provided for recycling a portion of said second head product to the product space ( 29 ). 
     
     
         11 . The methyl acetate hydrolysis plant of  claim 6 , wherein a first feed conduit ( 14 ) for a first feed containing water and a second feed conduit ( 15 ) for a second feed containing methyl acetate are provided to enter the column ( 1 ) on the reactive space ( 19 ) thereof. 
     
     
         12 . The methyl acetate hydrolysis plant of  claim 6 , wherein a pre-reactor feed conduit ( 3 ) for a pre-reactor feed containing methyl acetate and water to a pre-reactor ( 2 ) is provided, the pre-reactor ( 2 ) containing a hydrolysis catalyst, by means of which the methyl acetate is partially cleavable into acetic acid and methanol and a pre-reactor product containing methyl acetate, acetic acid and methanol from the pre-reactor is provided to be fed to the second feed conduit ( 15 ) to the divided wall reactive distillation column ( 1 ). 
     
     
         13 . Use of a structured packing or trays in the reaction zone of a methyl acetate hydrolysis plant of  claim 6  which can comprise a hydrolysis catalyst provided on the surfaces of a structured packing, which can form a structured catalyst packing. 
     
     
         14 . Use of a structured packing according to  claim 13 , whereby the structured catalyst packing comprises at least one retaining device. 
     
     
         15 . Use of a structured packing according to  claim 14 , wherein the retaining device comprises at least one of a bag for solid catalyst material or a flow channel.