Method and pulping composition for the selective delignification of lignocellulosic materials with an aqueous amine-alcohol mixture in the presence of a catalyst

• US 4,597,830 A
• Filed: 06/20/1983
• Issued: 07/01/1986
• Est. Priority Date: 06/20/1983
• Status: Expired due to Fees

• Current Assignee: University of Alabama (University of Alabama System)
• Original Assignee: University of Alabama (University of Alabama System)
• Inventors: April, Gary C., Nayak, Ramkrishna G.
• Primary Examiner(s): ALVO, MARC S
• Application Number:
  US06/505,972
• Time in Patent Office: 1,107 Days
• Field of Search: 162/72, 162/77, 162/32, 162/40, 8/676
• US Class Current: 162/32
• CPC Class Codes: D21C 3/20 with organic solvents or in solvent environment

Abstract

A pulping liquor for the delignification of lignocellulosic materials is disclosed which avoids the use of sodium hydroxide and so avoids degradation of substantial portions of the cellulose component, and simultaneously avoids the use of sulphide or other environmental pollutants. The cooking process employing this liquor can advantageously include recycling of the liquor to provide sustained delignification from the same original liquor provided, and distillation of spent liquor to recover the essential components thereof.

The liquor is comprised of alcohol, an amine and water, each present in amount of 1-12 parts by volume. The liquor is further used in the presence of a quinone and/or azine catalyst.

Claims

1. A pulping liquor for the delignification of lignocellulosic material consisting essentially of:

(A) a low molecular weight aliphatic alcohol selected from the group consisting of methanol, ethanol, butanol, pentanol and mixtures thereof;

(B) an aliphatic amine selected from the group consisting of ethylene diamine, propylene diamine, hexamethylene diamine, methylaniline, ethylamine and mixtures thereof; and

(C) water, wherein each of (A), (B), and (C) are present in amounts of 1-12 parts by volume, said liquor further comprising a catalyst selected from the group consisting of anthraquinone, benzoquinone, napthaquinone, phenazine, derivatives thereof and mixtures thereof present in amounts of grams of catalyst per milliliter of pulping liquor in a range of about 0.1;

4 to 0.001;

15.

2. The pulping liquor of claim 1, wherein said pulping liquor is particularly suited for the delignification of hardwood materials, wherein said components (A), (B) and (C) are present in a volume ratio of 1:

7.5;

11.5, respectively.

3. The pulping liquor of claim 1, wherein said pulping liquor is particularly suited for the delignification of softwood materials and said components (A), (B) and (C) are present in a volume ratio of 1:

5;

5, respectively.

4. The pulping liquor of claim 1, wherein said ratio is from about 0.015:

4 to 0.005;

12.

5. A process for the delignification of cellulosic materials, comprising:

cooking said cellulosic material with a pulping liquor consisting essentially of a low molecular weight aliphatic alcohol selected from the group consisting of methanol, ethanol, butanol, pentanol and mixtures thereof, an aliphatic amine selected from the group consisting of ethylene diamine, propylene diamine, hexamethylene diamine, methylaniline, ethylamine and mixtures thereof and water, wherein said alcohol, amine and water are each present in amounts of 1-12 parts by volume, said cooking further being conducted in the presence of a catalyst selected from the group consisting of anthraquinone, benzoquinone, napthaquinone, phenazine, derivatives thereof and mixtures thereof, said catalyst being present in amounts of grams of catalyst per milliliter of pulping liquor in a ratio of about 0.1;

4 to 0.001;

15, at a temperature of about 140°

-200°

C. for a period of about 50-360 minutes, wherein the ratio of grams of cellulosic material to milliliters of pulping liquor is about 1;

4 to 1;

15.

6. The process of claim 5, wherein said cellulosic material is comprised of softwood, said alcohol, amine and water are present in a ratio 1:

5;

5, respectively, and said temperature and time range between 170°

-190°

C. and 60-120 minutes, respectively.

7. The process of claim 5, wherein said material is comprised of hardwood, said alcohol, amine and water are present in amounts of 1:

7.5;

11.5 parts by volume, respectively, and said cooking temperature and time is between 160°

-175°

C. and 60-120 minutes, respectively.

8. The process of claim 5, wherein said ratio of grams of cellulosic material to milliliters of pulping liquor is about 1:

4 to 1;

12.

9. The process of claim 5, wherein said process further comprises recycling said liquor after said cooking for the delignification of additional cellulosic material.

10. The process of claim 9, wherein the alcohol and amine content of said liquor is recovered after repeated recycling by distillation.

11. The process of claim 5, wherein the alcohol and amine content of said liquor after cooking is recovered by distillation.