Process for producing furfural
First Claim
1. A process for making furfural, comprising the steps of:
- (a) passing a suspension of a comminuted pentosan-containing raw material in dilute sulfuric acid continuously through a flow reactor and mixing said suspension in said reactor with high-pressure steam to heat said suspension to a temperature between 170° and
230°
C. for a residence time sufficient to hydrolyze and dehydrate pentosan in said raw material to furfural, thereby forming a reacted suspension containing furfural which is discharged from said flow reactor;
(b) cooling the reacted suspension discharged from said reactor in a heat exchanger to a temperature between 140° and
200°
C.;
(c) thereafter passing the reacted suspension, cooled in said heat exchanger, through a valve into an expansion evaporator maintained at a pressure of at most 760 Torr to separate a residual suspension phase containing furfural from a water/furfural mixed vapor phase; and
(d) recovering furfural from the vapor phase by distillation, either directly or after liquefaction.
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Accused Products
Abstract
A feed suspension of pentosan-containing organic raw materials in dilute sulfuric acid is passed with low residence time through a flow reactor heated by high-pressure steam to 170°-230° C. and then through a cooler in which it is cooled to 140°-200° C. before the suspension is admitted to a flash evaporating unit from which a furfural-rich vapor phase is separated from the residual suspension. Process water is recovered from the residual suspension and recycled for the preparation of the feed suspension. From the vapor phase, furfural is recovered by distillation, either directly or after liquefaction. In the latter case, partial condensation in a primary condenser can be used to increase the furfural concentration in the final condenser, the condensate of the primary condenser being recycled for the preparation of the feed suspension.
44 Citations
8 Claims
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1. A process for making furfural, comprising the steps of:
-
(a) passing a suspension of a comminuted pentosan-containing raw material in dilute sulfuric acid continuously through a flow reactor and mixing said suspension in said reactor with high-pressure steam to heat said suspension to a temperature between 170° and
230°
C. for a residence time sufficient to hydrolyze and dehydrate pentosan in said raw material to furfural, thereby forming a reacted suspension containing furfural which is discharged from said flow reactor;(b) cooling the reacted suspension discharged from said reactor in a heat exchanger to a temperature between 140° and
200°
C.;(c) thereafter passing the reacted suspension, cooled in said heat exchanger, through a valve into an expansion evaporator maintained at a pressure of at most 760 Torr to separate a residual suspension phase containing furfural from a water/furfural mixed vapor phase; and (d) recovering furfural from the vapor phase by distillation, either directly or after liquefaction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification