Method of recovering furfural from organic pulping liquor

• US 5,788,812 A
• Filed: 06/07/1995
• Issued: 08/04/1998
• Est. Priority Date: 11/05/1985
• Status: Expired due to Fees

• Current Assignee: Chih Fae Wu, Gopal C. Goyal, Jairo H. Lora, Malcolm Cronlund, Mikhail N. Raskin, Raphael Katzen, Richard C. Agar, Ron Leblanc, Stephen R. Winner
• Original Assignee: Chih Fae Wu, Gopal C. Goyal, Jairo H. Lora, Malcolm Cronlund, Mikhail N. Raskin, Raphael Katzen, Richard C. Agar, Ron Leblanc, Stephen R. Winner
• Inventors: Goyal, Gopal C., LeBlanc, Ron, Lora, Jairo H., Cronlund, Malcolm, Wu, Chih Fae, Agar, Richard C., Raskin, Mikhail N., Winner, Stephen R., Katzen, Raphael
• Primary Examiner(s): Alvo, Steven
• Application Number:
  US08/488,306
• Time in Patent Office: 1,154 Days
• Field of Search: 162/14, 162/16, 162/17, 162/29, 162/77, 162/40, 162/68, 162/37, 162/39, 549/485, 549/500, 549/489, 549/490, 530/507
• US Class Current: 162/16
• CPC Class Codes: C07D 307/50 Preparation from natural products
• CPC Class Codes: D21C 11/0007 Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for volatile compounds obtained by decomposition of spent liquors in order to regenerate them D21C11/125; compounds obtained by fractionating the liquors in order to regenerate them D21C11/0042
• CPC Class Codes: D21C 3/20 with organic solvents or in solvent environment

Abstract

This invention provides for the recovery of lignin and other by-products from the pulping of fibrous plant material. In accordance with this invention, solvents and filtrates are recovered and recycled for reuse. This results in significant solvent and energy savings. Filtrates from the bleaching and delignification of the pulp are recycled for reuse in pulping, separation, and recovery of lignin and other by-products which results in significant energy savings and mitigation if not the elimination of pollution typically associated with bleaching. This invention also relates to products derived from the process and apparatus for carrying out the process. Lignins of various molecular weights and by-products of the pulping process are also recovered. The lignins are precipitated in high yields and at a high rate from a black liquor produced by pulping wood at high temperature and pressures. As a by-product of this process a purified furfural product is recovered. This furfural may be recycled for use in the recovery of the low molecular weight lignin of this process.

Claims

1. A method for recovering furfural from black liquor produced when fibrous plant material is pulped in a water miscible organic solvent, said method comprising the steps of:

processing said black liquor to produce black liquor filtrates including said furfural;

removing a furfural-containing draw from said black liquor filtrates;

cooling said furfural-containing draw and producing a crude furfural layer and an alcohol rich layer;

separating said crude furfural layer from said alcohol rich layer;

extracting said crude furfural layer with a solvent and producing a furfural raffinate and an alcohol containing extract;

purifying said furfural raffinate; and

recovering furfural product from said purified furfural raffinate.

2. The method of claim 1 further comprising the steps of:

recovering alcohol from at least one of said alcohol rich layer and said alcohol containing extract; and

recycling said recovered alcohol and combining said recycled recovered alcohol with said water miscible organic solvent for use in pulping said fibrous plant materials.

3. The method of claim 1 wherein said furfural product comprises from about 95 to 99% furfural.

4. The method of claim 1 wherein all steps are practiced continuously.