CA1216105A - Pulping process - Google Patents
Pulping processInfo
- Publication number
- CA1216105A CA1216105A CA000451494A CA451494A CA1216105A CA 1216105 A CA1216105 A CA 1216105A CA 000451494 A CA000451494 A CA 000451494A CA 451494 A CA451494 A CA 451494A CA 1216105 A CA1216105 A CA 1216105A
- Authority
- CA
- Canada
- Prior art keywords
- liquor
- anthraquinone
- alkaline
- pulping
- cyclic ketone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/22—Other features of pulping processes
- D21C3/222—Use of compounds accelerating the pulping processes
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- Paper (AREA)
Abstract
Abstract Pulping Process A process for the delignification of lignocellulosic material comprising treating the cellulosic material in a closed reaction vessel with an alkaline pulping liquor containing from 0.001% to 10.0% by weight based on the cellulosic material of a cyclic ketone selected from the group consisting of anthraquinone and anthraquinone substi-tuted with one or more alkyl radicals containing 1 - 4 carbon atoms, said treatment taking place at a maximum temperature in the range of from 150° to 200°C for a period of 0.5 to 480 minutes, the improvement comprising adding said cyclic ketone as a solution in sulphuric acid or neutralized sulphuric acid.
Description
Pulping Process 1. C-I-L 668 This invention relates to a process for the delignifi-cation of lignocellulosic material such as wood, straw, buggies, etc.
The processing of lignocellulosic material to produce cellulose suitable for the manufacture of paper products involves the removal of lignin and other non-cellulosic components such as gums. Reagents that attack lignin without affecting appreciably the cellulose component are preferred for this purpose. In the sulfite or raft process lignocell-ulosic material is cooked with a mixture of sodium hydroxide and sodium sulfide. In the soda process the cooking is carried out with sodium hydroxide alone. In Canadian Patent No. 895,756 issued on March 21, 1972 to HUE. Worsted and ME'.
Paddock there is described a two stage soda-oxygen pulping process comprising a first stage sodium hydroxide digestion, followed by defiberization of the product of the sodium hydroxide digestion, and a second stage digestion with sodium hydroxide in the presence of excess oxygen. This process produces pulp in yield comparable to the yield of a conventional raft process. Although these processes are effective in the removal of lignin from lignocellulosic material such as wood, the cellulose component of the material is at-tacked also to a certain degree, resulting in a lowering of yields and degradation of the product.
One alternative delignification system is the so-called neutral sulfite semi-chemical pulping process (NSSC) wherein
The processing of lignocellulosic material to produce cellulose suitable for the manufacture of paper products involves the removal of lignin and other non-cellulosic components such as gums. Reagents that attack lignin without affecting appreciably the cellulose component are preferred for this purpose. In the sulfite or raft process lignocell-ulosic material is cooked with a mixture of sodium hydroxide and sodium sulfide. In the soda process the cooking is carried out with sodium hydroxide alone. In Canadian Patent No. 895,756 issued on March 21, 1972 to HUE. Worsted and ME'.
Paddock there is described a two stage soda-oxygen pulping process comprising a first stage sodium hydroxide digestion, followed by defiberization of the product of the sodium hydroxide digestion, and a second stage digestion with sodium hydroxide in the presence of excess oxygen. This process produces pulp in yield comparable to the yield of a conventional raft process. Although these processes are effective in the removal of lignin from lignocellulosic material such as wood, the cellulose component of the material is at-tacked also to a certain degree, resulting in a lowering of yields and degradation of the product.
One alternative delignification system is the so-called neutral sulfite semi-chemical pulping process (NSSC) wherein
2. C-I-L 56 the pulping agent is generally sodium sulfite in a system buffered to slightly alkaline of pi 7 to reduce corrosion and increase yields. Common buffers are sodium carbonate and 7 sodium bicarbonate. The SKYE process is usually used with hardwood species. Yet another delignification process is the well-established sulfite delignification process which involves a bisulphite solution containing an excess of Selfware dioxide.
In our Canadian Patent No. 1,073,161 there are described processes for the delignification of lignocellulosic material in high yield by digestion of the material with an alkaline pulping liquor in the presence of certain cyclic kittens as pulping additives. The processes of Canadian l; Patent No. 1,073,161 provide a pulp in higher yields at an increased rate of delignification when compared with similar processes without said cyclic kitten being present as a pulping additive. Thus, the use of said cyclic kittens as pulping additives has been found to be of value in, for example, the raft, polysulphide, soda, NSSC, NS-AQ (so-called neutral sulphite-anthraquinone or semi-alkaline sulfite) and AS
(alkaline sulfite) processes in respect of particular wood species.
Cyclic kittens of particular use in the above processes are anthraquinone and anthraquinone substituted with one or more alkyd radicals of 1 - 4 carbon atoms. The most useful of the alkyd substituted anthraquinones in the above processes is 2-methyl anthraquinone.
Anthraquinone may be prepared by the Friedel-Crafts reaction of phthalic android with Bunsen to produce ortho bouncily benzoic acid which upon heating in concentrated sulfuric acid cyclists to produce anthraquinone in solution.
Dilution with water and cooling of this solution effects precipitation of solid anthraquinone which is then separated, I washed and dried for use. Alkyd substituted anthraqulnones
In our Canadian Patent No. 1,073,161 there are described processes for the delignification of lignocellulosic material in high yield by digestion of the material with an alkaline pulping liquor in the presence of certain cyclic kittens as pulping additives. The processes of Canadian l; Patent No. 1,073,161 provide a pulp in higher yields at an increased rate of delignification when compared with similar processes without said cyclic kitten being present as a pulping additive. Thus, the use of said cyclic kittens as pulping additives has been found to be of value in, for example, the raft, polysulphide, soda, NSSC, NS-AQ (so-called neutral sulphite-anthraquinone or semi-alkaline sulfite) and AS
(alkaline sulfite) processes in respect of particular wood species.
Cyclic kittens of particular use in the above processes are anthraquinone and anthraquinone substituted with one or more alkyd radicals of 1 - 4 carbon atoms. The most useful of the alkyd substituted anthraquinones in the above processes is 2-methyl anthraquinone.
Anthraquinone may be prepared by the Friedel-Crafts reaction of phthalic android with Bunsen to produce ortho bouncily benzoic acid which upon heating in concentrated sulfuric acid cyclists to produce anthraquinone in solution.
Dilution with water and cooling of this solution effects precipitation of solid anthraquinone which is then separated, I washed and dried for use. Alkyd substituted anthraqulnones
3 C-I-L 668 may be similarly prepared from the appropriate alkyd substituted phthalic android and benzenes.
The cyclic kittens are added to the reaction vessel 5 directly or indirectly either as a dry powder or, preferably, as an aqueous dispersion prepared by the wetting and milling of the dry material. When anthraquinone per so is prepared by chemical synthesis it is generally recovered and dried to a handle able powder. Canadian Patent No. 1,136,808, issued lo 7 December, 1982, describes the use of cyclic kittens employed in the form of a dispersion in a liquid dispersing agent having a specific density similar to the cyclic kitten in processes for pulp production from lignocellulosic materials. The steps of drying, writing and dispersing anthraquinone for use as a pulping additive has been found to add as much as 40% to the cost of anthraquinone.
It has now been found that a true solution of anthrax quinine in sulfuric acid can be used directly as a pulping additive in the delignification of lignocellulosic material;
thus dispensing with the necessity of recovering the anthrax quinine from a sulfuric acid reaction medium and subsequently drying, writing and milling it for use in the form of a dispersion.
Accordingly, the invention provides an improved process for the delignification of lignocellulosic material comprising treating the cellulosic material in a closed reaction vessel with an alkaline pulping liquor containing from 0.001% to 10.0% by weight based on the cellulosic material of a cyclic kitten selected from the group consisting of anthraquinone and anthraquinone substituted with one or more alkyd radicals containing 1 - 4 carbon atoms, said treatment taking place at a maximum temperature in the range of from 150 to 200C for a period of 0.5 to 480 minutes, the improvement comprising adding said cyclic kitten as a solution in sulfuric acid or neutralized sulfuric acid.
The cyclic kittens are added to the reaction vessel 5 directly or indirectly either as a dry powder or, preferably, as an aqueous dispersion prepared by the wetting and milling of the dry material. When anthraquinone per so is prepared by chemical synthesis it is generally recovered and dried to a handle able powder. Canadian Patent No. 1,136,808, issued lo 7 December, 1982, describes the use of cyclic kittens employed in the form of a dispersion in a liquid dispersing agent having a specific density similar to the cyclic kitten in processes for pulp production from lignocellulosic materials. The steps of drying, writing and dispersing anthraquinone for use as a pulping additive has been found to add as much as 40% to the cost of anthraquinone.
It has now been found that a true solution of anthrax quinine in sulfuric acid can be used directly as a pulping additive in the delignification of lignocellulosic material;
thus dispensing with the necessity of recovering the anthrax quinine from a sulfuric acid reaction medium and subsequently drying, writing and milling it for use in the form of a dispersion.
Accordingly, the invention provides an improved process for the delignification of lignocellulosic material comprising treating the cellulosic material in a closed reaction vessel with an alkaline pulping liquor containing from 0.001% to 10.0% by weight based on the cellulosic material of a cyclic kitten selected from the group consisting of anthraquinone and anthraquinone substituted with one or more alkyd radicals containing 1 - 4 carbon atoms, said treatment taking place at a maximum temperature in the range of from 150 to 200C for a period of 0.5 to 480 minutes, the improvement comprising adding said cyclic kitten as a solution in sulfuric acid or neutralized sulfuric acid.
4. C-I-L 668 The preferred alkyd substituted anthraquinone is 2-methyl anthraquinone.
The invention has been found to be of use in the soda,
The invention has been found to be of use in the soda,
5 raft, chemi-mechanical, neutral sulfite semi-chemical, neutral sulfite anthraquinone, alkaline sulfite anthraquinone, and other variants of alkaline chemical pulping processes.
While the term "neutral" as used in the names of several of the above processes is generally regarded as a 10 misnomer, the term as used in this specification means that at some time during the total pulping process the pi of the pulping liquor will be neither strongly acid nor strongly alkaline but will be at or near pi 7. Accordingly, by the term "alkaline pulping" as used in this specification and the claims is meant any pulping process in which the pi at any time during the process is seven or greater.
It has thus been found that the highly acidic solution of anthraquinone compound in sulfuric acid can be used in alkaline pulping processes wherein the effect of anthraquinone and alkyd substituted anthraquinones as pulping additives is fully realized.
The concentration of the anthraquinone compound in sulfuric acid can extend up to the saturation level. At room temperature anthraquinone is soluble to about 20% by weight in 98% sulfuric acid.
The amount of anthraquinone compound in solution added to the pulping system is such as to provide 0.001% to 10.0%
by weight based on the cellulosic material of anthraquinone compound in the closed reaction vessel. Thus, the pulping additive may be added to the reaction vessel directly or via appropriate process streams leading to the reaction vessel.
Also, it is within the scope of the invention for the anthraquinone sulfuric acid solution to be neutralized, if desired, external of -the reaction vessel or said appropriate process streams.
It will be readily appreciated that the amount of 5. L 668 sulfite added either in the form of sulfuric acid or neutralized sulfite ion is small relative to the amounts of other chemical pul~inq ingredients in the reaction vessel and thus only minor pi adjustments, if any, are needed in consequence of the addition of the anthraquinone pulping additive in the form according to the invention.
When the solution of anthraquinone compound in sulfuric acid is used according to the invention in the raft and lug alkaline sulfite processes such as chemi-mechanical, NSSC, NSAQ and ASK processes, the alkaline sulfite resulting from the neutralization of the sulfuric acid by alkaline liquor constitutes a useful source of Selfware. On the other hand, when the anthraquinone compound in sulfuric acid solution is used in the soda process, the amount of Selfware in the form of sulfite is not significant as compared to the sources of Selfware present in wood and other process chemicals.
The lignocellulosic material produced by the process as herein before defined may be used without further treatment or ? subjected to conventional bleaching steps required to produce the desired product.
When the lignocellulosic material employed is wood, it is first converted into the form of chips. This step is not required when the lignocellulosic material is of fibrous form.
'I; Ire lignocellulosic material may be refined as required between steps before or after the above process to achieve the necessary degree of defiberisation for the desired product.
The process of this invention can be used to dellgnify either coniferous or deciduous species of wood. By coniferous is meant species such as pine, spruce and balsam fir. By deciduous is meant species such as birch, aspen, eastern cottonwood, maple, beech and oak.
The alkaline pulping liquor ideally suitable for use in the first step of the process of the invention is the soda I liquor. However, other conventional alkaline pulping liquors can be used, e.g. the raft or polysulphide liquor, in which
While the term "neutral" as used in the names of several of the above processes is generally regarded as a 10 misnomer, the term as used in this specification means that at some time during the total pulping process the pi of the pulping liquor will be neither strongly acid nor strongly alkaline but will be at or near pi 7. Accordingly, by the term "alkaline pulping" as used in this specification and the claims is meant any pulping process in which the pi at any time during the process is seven or greater.
It has thus been found that the highly acidic solution of anthraquinone compound in sulfuric acid can be used in alkaline pulping processes wherein the effect of anthraquinone and alkyd substituted anthraquinones as pulping additives is fully realized.
The concentration of the anthraquinone compound in sulfuric acid can extend up to the saturation level. At room temperature anthraquinone is soluble to about 20% by weight in 98% sulfuric acid.
The amount of anthraquinone compound in solution added to the pulping system is such as to provide 0.001% to 10.0%
by weight based on the cellulosic material of anthraquinone compound in the closed reaction vessel. Thus, the pulping additive may be added to the reaction vessel directly or via appropriate process streams leading to the reaction vessel.
Also, it is within the scope of the invention for the anthraquinone sulfuric acid solution to be neutralized, if desired, external of -the reaction vessel or said appropriate process streams.
It will be readily appreciated that the amount of 5. L 668 sulfite added either in the form of sulfuric acid or neutralized sulfite ion is small relative to the amounts of other chemical pul~inq ingredients in the reaction vessel and thus only minor pi adjustments, if any, are needed in consequence of the addition of the anthraquinone pulping additive in the form according to the invention.
When the solution of anthraquinone compound in sulfuric acid is used according to the invention in the raft and lug alkaline sulfite processes such as chemi-mechanical, NSSC, NSAQ and ASK processes, the alkaline sulfite resulting from the neutralization of the sulfuric acid by alkaline liquor constitutes a useful source of Selfware. On the other hand, when the anthraquinone compound in sulfuric acid solution is used in the soda process, the amount of Selfware in the form of sulfite is not significant as compared to the sources of Selfware present in wood and other process chemicals.
The lignocellulosic material produced by the process as herein before defined may be used without further treatment or ? subjected to conventional bleaching steps required to produce the desired product.
When the lignocellulosic material employed is wood, it is first converted into the form of chips. This step is not required when the lignocellulosic material is of fibrous form.
'I; Ire lignocellulosic material may be refined as required between steps before or after the above process to achieve the necessary degree of defiberisation for the desired product.
The process of this invention can be used to dellgnify either coniferous or deciduous species of wood. By coniferous is meant species such as pine, spruce and balsam fir. By deciduous is meant species such as birch, aspen, eastern cottonwood, maple, beech and oak.
The alkaline pulping liquor ideally suitable for use in the first step of the process of the invention is the soda I liquor. However, other conventional alkaline pulping liquors can be used, e.g. the raft or polysulphide liquor, in which
6. C-I-L 668 case environmental effects are still present but, due to the presence of the additives of the invention, the pulping action is accelerated and yields are increased.
The soda liquor contains from 8% to 20~ by weight of alkali metal base expressed as percent effective alkali, based on the weight of the lignocellulosic material, and normally also contains alkali metal carbonate. Digestion with this liquor in the presence of the anthraquinones according to the invention results in certain cases, in the cooking time being lessened by a factor of four.
The raft or sulfite liquor contains from 8% to 15~ by weight of alkali metal base expressed as percent effective alkali (TAIPEI T-1203 S-61) and from 5% to 40% by weight of alkali metal sulfide expressed as percent sulphidity (TAIPEI T-1203 OOZE), based on lignocellulosic material.
This pulping liquor will normally contain alkali metal sulfite and alkali metal carbonate. The pulping liquor may contain excess Selfware, i.e. polysulphides. The presence of polysulphides results in an improved yield and an amount of 1.0% to 5.0%, preferably 2.0% thereof (expressed as Selfware) in the liquor is therefore a definite advantage.
Effective alkali is the sum of all alkali hydroxide in solution expressed as NATO including that formed by hydrolysis of the alkali sulfide, also expressed as NATO.
Sulphidity is the total sulfide, expressed as NATO, calculated as a percentage of total titratable alkali, including that formed by hydrolysis of the sulfide, also expressed as No 2 ' Since treatment of the process is carried out in a closed reaction vessel at a temperature in the range of from 150C. to 200C. in the presence of water, the reaction will take place under swooper atmospheric pressure.
After the treatment with pulping liquor the resulting pulp yield will be about 40% to about 70%, by weight, based
The soda liquor contains from 8% to 20~ by weight of alkali metal base expressed as percent effective alkali, based on the weight of the lignocellulosic material, and normally also contains alkali metal carbonate. Digestion with this liquor in the presence of the anthraquinones according to the invention results in certain cases, in the cooking time being lessened by a factor of four.
The raft or sulfite liquor contains from 8% to 15~ by weight of alkali metal base expressed as percent effective alkali (TAIPEI T-1203 S-61) and from 5% to 40% by weight of alkali metal sulfide expressed as percent sulphidity (TAIPEI T-1203 OOZE), based on lignocellulosic material.
This pulping liquor will normally contain alkali metal sulfite and alkali metal carbonate. The pulping liquor may contain excess Selfware, i.e. polysulphides. The presence of polysulphides results in an improved yield and an amount of 1.0% to 5.0%, preferably 2.0% thereof (expressed as Selfware) in the liquor is therefore a definite advantage.
Effective alkali is the sum of all alkali hydroxide in solution expressed as NATO including that formed by hydrolysis of the alkali sulfide, also expressed as NATO.
Sulphidity is the total sulfide, expressed as NATO, calculated as a percentage of total titratable alkali, including that formed by hydrolysis of the sulfide, also expressed as No 2 ' Since treatment of the process is carried out in a closed reaction vessel at a temperature in the range of from 150C. to 200C. in the presence of water, the reaction will take place under swooper atmospheric pressure.
After the treatment with pulping liquor the resulting pulp yield will be about 40% to about 70%, by weight, based
7. C-I-L 668 on the lignocellulosic material. The kappa number of the material at completion of the first step will lie in the range 10 to 150 for coniferous woods and in the range 5 to 100 for deciduous woods.
The material resulting from the process according to the invention may be bleached by any conventional bleaching process. A conventional sequence comprising chlorination, alkaline extraction, chlorine dioxide treatment, alkaline extraction, chlorine dioxide treatment (C-E-D-E-D) when applied to the material resulting from the process, will provide a product having a brightness of approximately 85 -90 units (Elrepho). The material resulting from the process may be bleached by the sequence oxygen chlorination alkaline extraction, chlorine dioxide treatment (OKAYED) or any other conventional sequence. When applied to the material resulting from step (4), the sequence O-C-E-D will provide a product having a brightness of approximately 85 90 units (Elrepho). Other sequences known to the man skilled in the art may also be employed.
Among the alkyd derivatives which may be mentioned of use in the practice of the invention are anthraquinones substituted with one or two alkyd groups containing from 1 to 4, preferably 1 or 2 carbon atoms.
The invention is illustrated by the following Examples but its scope is not limited to the embodiments shown therein.
In the Examples the brightness, kappa number, permangan-ate number and viscosity determination were carried out by the following methods:
Brightness CPPA Method Eel Kappa number TAIPEI Method T-236 M-60 Permanganate number TAIPEI Method T-214 M-50 using 25 ml. of 0.lN KMnO4 Viscosity TAPPI-Method T-230 SUE.
In all the following Examples, pulping was carried out
The material resulting from the process according to the invention may be bleached by any conventional bleaching process. A conventional sequence comprising chlorination, alkaline extraction, chlorine dioxide treatment, alkaline extraction, chlorine dioxide treatment (C-E-D-E-D) when applied to the material resulting from the process, will provide a product having a brightness of approximately 85 -90 units (Elrepho). The material resulting from the process may be bleached by the sequence oxygen chlorination alkaline extraction, chlorine dioxide treatment (OKAYED) or any other conventional sequence. When applied to the material resulting from step (4), the sequence O-C-E-D will provide a product having a brightness of approximately 85 90 units (Elrepho). Other sequences known to the man skilled in the art may also be employed.
Among the alkyd derivatives which may be mentioned of use in the practice of the invention are anthraquinones substituted with one or two alkyd groups containing from 1 to 4, preferably 1 or 2 carbon atoms.
The invention is illustrated by the following Examples but its scope is not limited to the embodiments shown therein.
In the Examples the brightness, kappa number, permangan-ate number and viscosity determination were carried out by the following methods:
Brightness CPPA Method Eel Kappa number TAIPEI Method T-236 M-60 Permanganate number TAIPEI Method T-214 M-50 using 25 ml. of 0.lN KMnO4 Viscosity TAPPI-Method T-230 SUE.
In all the following Examples, pulping was carried out
8. C-I-L 668 in stainless steel pressure vessels of an assembly of eight such vessels (hereinafter called the micro digester assembly) each of which is itself horizontally rotatable. Samples of 75 grams were pulped eight at a time in the micro digester assembly. the chips were dried to approximately 90~
consistency, divided into appropriate portions in consider-anion of the number and size of the pulping runs to be carried out and stored at 4C. Exact amounts of chips of accurately known consistency were weighed out and soaked 24 hours in water prior to pulping. Soaked chips were placed inside the pressure vessel and optionally pre-steamed for 10 minutes. Pulping liquor and dilution water were then added in the amounts required to give the desired effective alkali and to obtain a liquor to wood ratio of 3.7:1.
Indirect electrical heating was used in both types of vessels.
In the case of the micro digester assembly water under pressure was employed as a heat transfer medium. Heating was controlled to linearly raise the temperature to a preset maximum in a given time and to maintain it within +2C of said maximum to the end of the cooking period.
After completion of the cooking, the pressure was released and the pulp together with the used cooking liquor was transferred to a mixer such as a Cowls dissolver, diluted to 2% consistency and stirred for 5 minutes to simulate the blow down of pulp that occurs in commercial scale digesters. The pulp was then washed twice by dilution to 2%
consistency with water and filtered and pressed to 25%
consistency. The pulp was then crumbled in a Hubert mixer, weighed and samples were taken for yield, kappa number and viscosity measurements.
consistency, divided into appropriate portions in consider-anion of the number and size of the pulping runs to be carried out and stored at 4C. Exact amounts of chips of accurately known consistency were weighed out and soaked 24 hours in water prior to pulping. Soaked chips were placed inside the pressure vessel and optionally pre-steamed for 10 minutes. Pulping liquor and dilution water were then added in the amounts required to give the desired effective alkali and to obtain a liquor to wood ratio of 3.7:1.
Indirect electrical heating was used in both types of vessels.
In the case of the micro digester assembly water under pressure was employed as a heat transfer medium. Heating was controlled to linearly raise the temperature to a preset maximum in a given time and to maintain it within +2C of said maximum to the end of the cooking period.
After completion of the cooking, the pressure was released and the pulp together with the used cooking liquor was transferred to a mixer such as a Cowls dissolver, diluted to 2% consistency and stirred for 5 minutes to simulate the blow down of pulp that occurs in commercial scale digesters. The pulp was then washed twice by dilution to 2%
consistency with water and filtered and pressed to 25%
consistency. The pulp was then crumbled in a Hubert mixer, weighed and samples were taken for yield, kappa number and viscosity measurements.
9. C-I-L 668 Example 1 Black spruce chips (75g OLD.) were cooked in a raft liquor at Tax = 170C, Time to Tax = 60 min., Told = 55 min., Lit. to wood = 3.7:1, ETA. = 14.9 and sulfidity = 10% in the presence and absence of 0.1% (on wood) anthraquinone dissolved in 50% wt. by wt. 96% sulfuric acid. Cooking with pulping liquor was carried out using the digester and procedure described immediately above. The results are shown in accompanying Table I.
Example 2 The procedure of Example 1 was repeated except that the sulfidity level was 15%. The results are shown in accompany yin Table I.
Example 3 The procedure of Example 1 was repeated except that southern pine chips were used and the sulfidity level was 5%. The results are shown in accompanying Table I.
Table I
- A Dissolved in 96% H2SO
Example Wood Sulfidity (% on pulp - 4 Kappa No. Species (%) based on 100% A) No.
1 Black Spurs 0 53.7 0.1 37.9 25 2 Black Spurs 0 46.7 0.1 33.4 3 Southern Pine 0 87.2 0.1 48.9.
Example 2 The procedure of Example 1 was repeated except that the sulfidity level was 15%. The results are shown in accompany yin Table I.
Example 3 The procedure of Example 1 was repeated except that southern pine chips were used and the sulfidity level was 5%. The results are shown in accompanying Table I.
Table I
- A Dissolved in 96% H2SO
Example Wood Sulfidity (% on pulp - 4 Kappa No. Species (%) based on 100% A) No.
1 Black Spurs 0 53.7 0.1 37.9 25 2 Black Spurs 0 46.7 0.1 33.4 3 Southern Pine 0 87.2 0.1 48.9.
Claims (8)
1. A process for the delignification of lignocellulosic material comprising treating the cellulosic material in a closed reaction vessel with an alkaline pulping liquor containing from 0.001% to 10.0% by weight based on the cellulosic material of a cyclic ketone selected from the group consisting of anthraquinone and anthraquinone substi-tuted with one or more alkyl radicals containing 1 - 4 carbon atoms, said treatment taking place at a maximum temperature in the range of from 150° to 200°C for a period of 0.5 to 480 minutes, the improvement comprising adding said cyclic ketone as a solution in sulphuric acid or neutralized sulphuric acid.
2. A process as claimed in Claim 1 wherein said cyclic ketone is anthraquinone.
3. A process as claimed in Claim 1 wherein said cyclic ketone is 2-methyl anthraquinone.
4. A process as claimed in any one of Claims 1, 2 and 3 wherein the alkaline pulping liquor is a soda liquor.
5. A process as claimed in any one of Claims 1, 2 and 3 wherein the alkaline pulping liquor is a kraft, or polysulphide liquor.
6. A process as claimed in any one of Claims 1, 2 and 3 wherein the alkaline pulping liquor is a neutral sulphite semi-chemical liquor.
7. A process as claimed in any one of Claims 1, 2 and 3 wherein the alkaline pulping liquor is a semi-alkaline sulphite liquor.
8. A process as claimed in any one of Claims 1, 2 and 3 wherein the alkaline pulping liquor is an alkaline sulphite liquor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000451494A CA1216105A (en) | 1984-04-06 | 1984-04-06 | Pulping process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000451494A CA1216105A (en) | 1984-04-06 | 1984-04-06 | Pulping process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1216105A true CA1216105A (en) | 1987-01-06 |
Family
ID=4127601
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000451494A Expired CA1216105A (en) | 1984-04-06 | 1984-04-06 | Pulping process |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1216105A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0287960A3 (en) * | 1987-04-21 | 1991-04-17 | SciTech Services, Inc. | A process for the production of a hemicellulose hydrolysate and special pulp |
| US5139617A (en) * | 1987-04-21 | 1992-08-18 | Suomen Sokeri Oy | Process for the production of a hemicellulose hydrolysate and special high alpha cellulose pulp |
-
1984
- 1984-04-06 CA CA000451494A patent/CA1216105A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0287960A3 (en) * | 1987-04-21 | 1991-04-17 | SciTech Services, Inc. | A process for the production of a hemicellulose hydrolysate and special pulp |
| US5139617A (en) * | 1987-04-21 | 1992-08-18 | Suomen Sokeri Oy | Process for the production of a hemicellulose hydrolysate and special high alpha cellulose pulp |
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