Process for methacrylic acid and methacrylic acid ester production

Abstract

Provided herein are improved methods for producing methacrylic acid and methacrylate esters using combined or “integrated” processing steps including integrated hydrolysis, integrated cracking systems, and combinations thereof. In one embodiment, other aspects of an methacrylic acid and methacrylate ester production trains are integrated. Also provided are methods to purify crude methacrylic acid streams to form glacial methacrylic acid that is at least 95% pure.

What is claimed is:  
     
         1 . A process for the preparation of methacrylic acid and esters thereof, the process comprising: 
 (i) continuously feeding a first raw material comprising acetone cyanohydrin and a second raw material comprising sulfuric acid, oleum or mixtures thereof into a first hydrolysis system;    (ii) continuously feeding a third raw material comprising acetone cyanohydrin and a fourth raw material comprising sulfuric acid, oleum or mixtures thereof into a second hydrolysis system    (iii) continuously hydrolyzing said first raw material and said second raw material in said first hydrolysis system to form a first hydrolysis product comprising α-sulfatoisobutyramide and α-hydroxyisobutyramide;    (iv) continuously hydrolyzing said third raw material and said fourth raw material in said second hydrolysis system to form a second hydrolysis product comprising α-sulfatoisobutyramide and α-hydroxyisobutyramide;    (v) continuously feeding said first hydrolysis product and said second hydrolysis product to a cracking system;    (vi) continuously cracking said first hydrolysis product and said second hydrolysis product in said cracking system to form a cracking product comprising methacrylamide;    (vii) continuously feeding a first portion of said cracking product and water to an acid formation reactor, while continuously feeding a second portion of said cracking product and an alcohol to an ester formation reactor;    (viii) continuously reacting said first portion of said cracking product and said water in said acid formation reactor to form an acid formation product comprising methacrylic acid;    (ix) continuously reacting said second portion of said cracking product and said alcohol in said ester formation reactor to form an ester formation product comprising an ester of methacrylic acid;    with the proviso that, if said cracking system comprises two or more cracking reactors, in parallel, then a first portion of a cracking product from each of said cracking reactors and water is continuously fed to said acid formation reactor and a second portion of a cracking product from each of said cracking reactors and an alcohol is continuously fed to said ester formation reactor.    
     
     
         2 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 1  further comprising separating the acid formation product into a methacrylic acid product stream and a lower layer sulfur-bearing residue stream; distilling said methacrylic acid product stream in a first distillation column to produce a light ends overhead stream comprising acetone and water and a bottoms stream, and then distilling said bottoms stream in a second distillation column to form an overhead product stream comprising at least 95% methacrylic acid and a bottoms stream comprising heavy ends.  
     
     
         3 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 2  further comprising: providing MEHQ inhibitor to at least one of said first distillation column and said second distillation column; providing an O 2 -containing gas to said at least one of said first distillation column and said second distillation column; adjusting the addition rate of MEHQ to said at least one of said first distillation column and said second distillation column to maintain a ratio of MEHQ addition to a column feed between 1 kg MEHQ/10,000 kg column feed and 15 kg MEHQ/10,000 kg column feed; adjusting the addition rate of O 2 -containing gas to said at least one of said first distillation column and said second distillation column to maintain a molar ratio of O 2  to MEHQ between 1.0 mole O 2 /mole MEHQ and 11.5 moles O 2 /mole MEHQ.  
     
     
         4 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 2  further comprising: providing HQ inhibitor to at least one of said first distillation column and said second distillation column; providing an O 2 -containing gas to said at least one of said first distillation column and said second distillation column; adjusting the addition rate of HQ to said at least one of said first distillation column and said second distillation column to maintain a ratio of HQ addition to a column feed between 1 kg HQ/10,000 kg column feed and 10 kg HQ/10,000 kg column feed; adjusting the addition rate of O 2 -containing gas to said at least one of said first distillation column and said second distillation column to maintain a molar ratio of O 2  to HQ between 0.65 mole O 2 /mole MEHQ and 10 moles O 2 /mole MEHQ.  
     
     
         5 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 2  wherein said first distillation column is operated such that the pressure at the bottom of the column is 50 mm Hg to 80 mm Hg and the temperature at the bottom of the column is 70° C. to 110° C. and said second distillation column is operated such that the pressure at the bottom of the column is below 70 mm Hg and the temperature at the bottom of the column is below 110° C.  
     
     
         6 . A process for the preparation of methacrylic acid and esters thereof, the process comprising: 
 (i) continuously feeding a first raw material comprising acetone cyanohydrin and a second raw material comprising oleum into a hydrolysis system;    (ii) continuously hydrolyzing said first raw material and said second raw material in said hydrolysis system to form a hydrolysis product comprising α-sulfatoisobutyramide and α-hydroxyisobutyramide;    (iii) continuously feeding a first portion of said hydrolysis product to a first cracking system, while continuously feeding a second portion of said hydrolysis product to a second cracking system;    (iv) continuously cracking said first portion of said hydrolysis product in said first cracking system to form a first cracking product comprising methacrylamide;    (v) continuously cracking said second portion of said hydrolysis product in said second cracking system to form a second cracking product comprising methacrylamide;    (vi) continuously feeding said first cracking product and water to an acid formation reactor;    (vii) continuously feeding said second cracking product and an alcohol to an ester formation reactor;    (viii) continuously reacting said first cracking product and said water in said acid formation reactor to form an acid formation product comprising methacrylic acid;    (ix) continuously reacting said second cracking product and said alcohol in said ester formation reactor to form an ester formation product comprising an ester of methacrylic acid.    
     
     
         7 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 6  further comprising separating the acid formation product into a methacrylic acid product stream and a lower layer sulfur-bearing residue stream; distilling said methacrylic acid product stream in a first distillation column to produce a light ends overhead stream comprising acetone and water and a bottoms stream, and then distilling said bottoms stream in a second distillation column to form an overhead product stream comprising at least 95% methacrylic acid and a bottoms stream comprising heavy ends.  
     
     
         8 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 7  further comprising: providing MEHQ inhibitor to at least one of said first distillation column and said second distillation column; providing an O 2 -containing gas to said at least one of said first distillation column and said second distillation column; adjusting the addition rate of MEHQ to said at least one of said first distillation column and said second distillation column to maintain a ratio of MEHQ addition to a column feed between 1 kg MEHQ/10,000 kg column feed and 15 kg MEHQ/10,000 kg column feed; adjusting the addition rate of O 2 -containing gas to said at least one of said first distillation column and said second distillation column to maintain a molar ratio of O 2  to MEHQ between 1.0 mole O 2 /mole MEHQ and 11.5 moles O 2 /mole MEHQ.  
     
     
         9 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 7  further comprising: providing HQ inhibitor to at least one of said first distillation column and said second distillation column; providing an O 2 -containing gas to said at least one of said first distillation column and said second distillation column; adjusting the addition rate of HQ to said at least one of said first distillation column and said second distillation column to maintain a ratio of HQ addition to a column feed between 1 kg HQ/10,000 kg column feed and 10 kg HQ/10,000 kg column feed; adjusting the addition rate of O 2 -containing gas to said at least one of said first distillation column and said second distillation column to maintain a molar ratio of O 2  to HQ between 0.65 mole O 2 /mole HQ and 10 moles O 2 /mole HQ.  
     
     
         10 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 7  wherein said first distillation column is operated such that the pressure at the bottom of the column is 50 mm Hg to 80 mm Hg and the temperature at the bottom of the column is 70° C. to 110° C. and said second distillation column is operated such that the pressure at the bottom of the column is below 70 mm Hg and the temperature at the bottom of the column is below 110° C.  
     
     
         11 . A process for the preparation of methacrylic acid and esters thereof, the process comprising: 
 (i) continuously feeding a first raw material comprising acetone cyanohydrin and a second raw material comprising sulfuric acid, oleum or mixtures thereof into a hydrolysis system;    (ii) continuously hydrolyzing said first raw material and said second raw material in said hydrolysis system to form a hydrolysis product comprising α-sulfatoisobutyramide and α-hydroxyisobutyramide;    (iii) continuously feeding said hydrolysis product into a cracking system;    (iv) continuously cracking said hydrolysis product in said cracking system to form a cracking product comprising methacrylamide;    (v) continuously feeding a first portion of said cracking product and water to an acid formation reactor, while continuously feeding a second portion of said cracking product and an alcohol to an ester formation reactor;    (vi) continuously reacting said first portion of said cracking product and said water in said acid formation reactor to form an acid formation product comprising methacrylic acid;    (vii) continuously reacting said second portion of said cracking product and said alcohol in said ester formation reactor to form an ester formation product comprising an ester of methacrylic acid;    with the proviso that, if said cracking system comprises two or more cracking reactors, in parallel, then a first portion of a cracking product from each of said cracking reactors and water is continuously fed to said acid formation reactor and a second portion of a cracking product from each of said cracking reactors and an alcohol is continuously fed to said ester formation reactor.    
     
     
         12 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 11  further comprising separating the acid formation product into a methacrylic acid product stream and a lower layer sulfur-bearing residue stream; distilling said methacrylic acid product stream in a first distillation column to produce a light ends overhead stream comprising acetone and water and a bottoms stream, and then distilling said bottoms stream in a second distillation column to form an overhead product stream comprising at least 95% methacrylic acid and a bottoms stream comprising heavy ends.  
     
     
         13 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 12  further comprising: providing MEHQ inhibitor to at least one of said first distillation column and said second distillation column; providing an O 2 -containing gas to said at least one of said first distillation column and said second distillation column; adjusting the addition rate of MEHQ to said at least one of said first distillation column and said second distillation column to maintain a ratio of MEHQ addition to a column feed between 1 kg MEHQ/10,000 kg column feed and 15 kg MEHQ/10,000 kg column feed; adjusting the addition rate of O 2 -containing gas to said at least one of said first distillation column and said second distillation column to maintain a molar ratio of O 2  to MEHQ between 1.0 mole O 2 /mole MEHQ and 11.5 moles O 2 /mole MEHQ.  
     
     
         14 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 12  further comprising: providing HQ inhibitor to at least one of said first distillation column and said second distillation column; providing an O 2 -containing gas to said at least one of said first distillation column and said second distillation column; adjusting the addition rate of HQ to said at least one of said first distillation column and said second distillation column to maintain a ratio of HQ addition to a column feed between 1 kg HQ/10,000 kg column feed and 10 kg HQ/10,000 kg column feed; adjusting the addition rate of O 2 -containing gas to said at least one of said first distillation column and said second distillation column to maintain a molar ratio of O 2  to HQ between 0.65 mole O 2 /mole HQ and 10 moles O 2 /mole HQ.  
     
     
         15 . The process for the preparation of methacrylic acid and esters thereof as claimed in  claim 12  wherein said first distillation column is operated such that the pressure at the bottom of the column is 50 mm Hg to 80 mm Hg and the temperature at the bottom of the column is 70° C. to 110° C. and said second distillation column is operated such that the pressure at the bottom of the column is below 70 mm Hg and the temperature at the bottom of the column is below 110° C.  
     
     
         16 . A process for the preparation of methacrylic acid and esters thereof, the process comprising: 
 (i) continuously feeding a first raw material comprising acetone cyanohydrin and a second raw material comprising sulfuric acid, oleum, or mixtures thereof into a hydrolysis system;    (ii) feeding an inhibitor composition comprising a polymerization inhibitor and a solvent therefor into said hydrolysis system, said solvent comprising sulfuric acid, sulfur dioxide, methyl sulfone, tetramethylene sulfone or dimethyl sulfoxide;    (iii) continuously hydrolyzing said first raw material and said second raw material in said hydrolysis system to form a hydrolysis product comprising α-sulfatoisobutyramide and α-hydroxyisobutyramide;    (iv) continuously feeding a first portion of said hydrolysis product to a first cracking system, while continuously feeding a second portion of said hydrolysis product to a second cracking system;    (v) continuously cracking said first portion of said hydrolysis product in said first cracking system to form a first cracking product comprising methacrylamide;    (vi) continuously cracking said second portion of said hydrolysis product in said second cracking system to form a second cracking product comprising methacrylamide;    (viii) continuously feeding said first cracking product and water to an acid formation reactor;    (ix) continuously feeding said second cracking product and an alcohol to an ester formation reactor;    (x) continuously reacting said first cracking product and said water in said acid formation reactor to form an acid formation product comprising methacrylic acid;    (xi) continuously reacting said second cracking product and said alcohol in said ester formation reactor to form an ester formation product comprising n ester of methacrylic acid.