Process for manufacturing high purity methacrylic acid

Abstract

A process is provided herein for the high yield production of high purity glacial methacrylic acid (“HPMAA”) that is substantially pure, specifically 99% pure or greater with a water content of 0.05% or less. This improved process comprises providing a crude MAA stream and purifying the crude methacrylic acid stream in a series of successive distillation steps

1 - 7 . (canceled)  
   
   
       8 . (canceled)  
   
   
       9 . An apparatus for the preparation of high purity methacrylic acid, said apparatus comprising: 
 (i) a first distillation column, said first distillation column having a top, a bottom, an upper section adjacent said top, a lower section adjacent said bottom and a center section intermediate said upper section and said lower section;    (ii) a second distillation column, said second distillation column having a top, a bottom, an upper section adjacent said top, a lower section adjacent said bottom and a center section intermediate said upper section and said lower section;    (iii) a third distillation column, said third distillation column having a top, a bottom, an upper section adjacent said top, a lower section adjacent said bottom and a center section intermediate said upper section and said lower section;    (iv) a first inlet line connected to said upper section of said first distillation column;    (v) a first outlet line connected to said top of said first distillation column;    (vi) a second outlet line connecting said bottom of said first distillation column and said center section of said second distillation column;    (vii) a third outlet line connecting said top of said second distillation column with said upper section of said second distillation column and said upper section of said third distillation column;    (viii) a fourth outlet line connected to said bottom of said second distillation column;    (ix) a fifth outlet line connected to said top of said third distillation column;    (x) a sixth outlet line connected to said lower section of said third distillation column;    (xi) a seventh outlet line connecting said bottom of said third distillation column to said center section of said second distillation column.    
   
   
       10 . (canceled)  
   
   
       11 . An apparatus for the preparation of high purity methacrylic acid, said apparatus comprising at least one distillation column and its ancillaries, said at least one distillation column and its ancillaries being designed to operate at less than atmospheric pressure, said at least one distillation column comprising perforated plate trays, said at least one distillation column and its ancillaries being constructed, at least in part, of a corrosion resistant material selected from the group consisting of 300 series stainless steel, 904L stainless steel, 6-moly stainless steel, Hastelloy®, tantalum, zirconium and covered base metal.  
   
   
       12 . The apparatus according to  claim 11 , wherein said at least one distillation column has a bottom and is designed to operate in the range of from 50 mmHg to 80 mmHg, allowing said bottom to be operated at a temperature from 70° C. to 100° C.  
   
   
       13 . The apparatus according to  claim 11 , wherein said at least one distillation column has a bottom and is designed to operate in the range of from 60 mmHg to 100 mmHg, allowing said bottom to be operated at a temperature from 75° C. to 115° C.  
   
   
       14 . A process for preparation of high purity methacrylic acid using at least two distillation columns which are fluidly connected to one another in series and which comprise a last distillation column positioned furthest downstream in the series, said process comprising: 
 withdrawing a product sidestream from a center portion of the last distillation column in the series, said product sidestream comprising a lower level of heavy ands and undesirable impurities than a product stream would have if withdrawn from a lower section of the last distillation column.    
   
   
       15 . A process for preparation of high purity methacrylic acid using at least two distillation columns which are fluidly connected to one another in series and which comprise a last distillation column having a bottom and a side and which is positioned furthest downstream in the series, wherein a product stream, comprising methacrylic acid and a level of heavy ands and undesirable impurities, is withdrawn from the last distillation column, said process comprising: 
 reducing the level of heavy ands and undesirable impurities in said product stream by withdrawing said product stream from the side, rather than the bottom, of the last distillation column.    
   
   
       16 . The process according to  claim 15 , wherein the side of the last distillation column comprises a center section and a lower section of the last distillation column.