Production of levulinic acid from carbohydrate-containing materials

A continuous process for producing levulinic acid from a carbohydrate-containing material using a first reactor having an entrance and an exit and a second reactor having an entrance and an exit said process comprising,

• continuously supplying a sample containing said carbohydrate-containing material to said first reactor through said entrance to said first reactor,
• hydrolyzing said carbohydrate containing material in said first reactor at between 210.degree. C. and 230.degree. C. for between 13 seconds and 25 seconds in the presence of a mineral acid comprising between 1% and 5% by weight of said sample to produce hydroxymethylfurfural and other reaction intermediates,
• continuously removing an intermediate sample containing said hydroxymethylfurfural and other reaction intermediates from said first reactor through said exit of said first reactor in such a manner that substantially no axial mixing occurs in said first reactor,
• continuously supplying the intermediate sample that has been removed from said first reactor to said second reactor through said entrance to said second reactor,
• hydrolyzing said hydroxymethylfurfural and other reaction intermediates in said intermediate sample in said second reactor at between 195.degree. C. and 215.degree. C. for between 15 minutes and 30 minutes in the presence of a mineral acid comprising between 3% and 7.5% by weight of said intermediate sample to produce levulinic acid, and
• continuously removing levulinic acid from said second reactor through said exit of said second reactor, wherein the yield of levulinic acid removed from said second reactor comprises at least 60% of the theoretical yield.