CA2321735A1

CA2321735A1 - Lignin based colloidal compositions

Info

Publication number: CA2321735A1
Application number: CA002321735A
Authority: CA
Inventors: Zhi-Zhong Liang
Original assignee: Individual
Current assignee: Polyphalt Inc
Priority date: 1998-02-23
Filing date: 1999-02-22
Publication date: 1999-08-26
Also published as: EP1058713A1; WO1999042526A1; AU2606299A

Abstract

A lignin based colloidal dispersion into lubricating oil or bitumen is prepared from black liquor residue. In one process, in the first step, the black liquor is converted from its aqueous colloidal system to an anhydrous colloidal dispersion in a re-refined lubricating oil medium in which a surfactant, such as DDBSA (dodecylbenzene sulfuric acid), is used to promote the colloidal dispersion. In second step, bitumen is mixed with the product obtained from said first step. In another process, bitumen first is treated with an inorganic acid, such as sulfuric acid, at elevated temperature. The alkaline black liquor is then added slowly to the acid-treated bitumen under agitation for de-watering at a controlled rate to form a stable, substantially anhydrous, colloidal dispersion in the bitumen.

Description

TITLE OF INVENTION
LIGNIN BASED COhLOIDAL COMPOSITIONS
FIELD OF INVENTION
The present invention relates to the processing of black liquor and the preparation of bitumen compositions containing black liquor.
Hi~ICKGROUND TO THE INVENTION
Black liquor is an aqueous alkaline pulping residue produced in Kraft pulping of wood chips in a pulp mill to provide wood fibers for paper-making. Black liquor generally contains about 55 to 65~ solids comprising lignin, sodium salts of poly-saccharinic acids, organic and inorganic sulfides and carbonates and many other compounds. The lignin in the black liquor is the main organic component and is present as a high mass colloid stabilized by ionized phenolic groups. Lignin is a phenylpropane polymer of amorphous structure comprising about 17 to about 30$ of wood. Lignin is so closely associated with the cellulosic fibres and hemi-cellulose that makes up the balance of woody material that lignin can be separated from wood only by chemical reaction at high temperature, such as that used in the Kraft pulping process, wherein wood chips are digested with an aqueous alkaline solution of sodium hydroxide and hydrogen sulfide, known as white liquor. Normally, the black liquor, after separation of the wood fibers, is processed to remove organic materials and to recover and regenerate pulping chemicals. Lignin can be recovered from wood-processing wastes only in limited quantities.
The lignin is a natural binder derivative of wood.
Alkali lignin from both softwoods and hardwoods are useful in many products. They are used as stabilizers for asphalt emulsions, modifiers and extenders for latex emulsions, compounding agents in vinyl plastics, soil conditioners, binders in printing inks, wood stains, protective colloids in soap emulsions, ,dispersing agents for clay, fire foam stabilizers, drilling mud additives, insecticide dispersants, absorbers in storage batteries and foundry sand binders. Alkali lignin can also be used as adhesives for plywood, molding powers and formed insulating resins and as a reinforcing agent for rubber.
Asphalt binders (or bitumen) are widely used in different applications, such as asphalt-aggregate blends for road paving, asphalt fiber reinforced membranes for roofing and asphalt-water emulsions in surface treating both for paving and roofing. Problems for straight-run asphalt in those applications axe the tendency to become brittle at low temperatures and to become soft at high temperatures, the tendency to flow under constant load at service temperatures and the tendency to phase separation during storage when mixed with other components.
Various approaches have been used for the purpose of improving asphalt compositions to address these problems. For instance, polymers have been utilized to improve the high and low temperature characteristics of asphalt compositions, as well as to improve their toughness and durability. Air blowing of straight-run asphalt has been used to improve stiffness and dimensional stability for hot applied roofing systems.
The asphalt may be treated with acid to improve its compatibility with the polymeric additives. Lignin or lignin based additives have been widely used to emulsify asphalt to achieve a stable dispersion of asphalt. in aqueous medium.
Black liquor is an aqueous colloidal system in which ample lignin is present. However, means have not been previously disclosed whereby a stable dispersion of lignin in asphalt can be achieved by combining black liquor with hot liquid asphalt. When the black liquor is added to the bitumen and dispersed with agitation into molten asphalt cement, de-watering of the black liquor occurs while lignin and other salts in the black liquor tend to form large, rigid aggregates which separate from the liquid asphalt and subsequently strongly resist dispersion in the asphalt.
It is one objective of the present invention to develop a process or processes whereby liquor-solid pulping residue (black liquor) can be converted from one in which water is the dispersing and plasticizing agent to one in which water is replaced by oil, achieving a dispersion in which a lignin based colloidal particulate phase is stably maintained. It is another objective to provide a lignin-oil dispersion which can be smoothly blended with liquid asphalt to produce a stable, homogeneous dispersion.
StIb~RY OF INVENTION
'The present invention relates to compositions and methods for combining black liquor with selected petroleum-derived products. More specifically, this invention provides two separate processes for preparing lignin-based colloidal dispersions in lubricating or other petroleum-based oils. The lignin-oil colloidal dispersions prepared by either of such processes may be blended with bitumen to produce novel bituminous composition. Two embodiments of such procedures are described herein. The black liquor used in the invention may be that resulting from cooking wood in an alkaline solution in the soda or sulfate (Kraft) paper-making process.
The asphalt employed in this invention can be any of the well known bituminous substances derived from petroleum, shale oil, coal tar and the like. Commonly, the asphalt is prepared by vacuum distillation of a topped crude oil. Preferably, the asphalt has a penetration at 25°C (as determined by ASTM D5) ranging for about 20 to about 400.
In a first embodiment of the invention, the 23-02-2000 ~' 6'a ~ F ioi 5i1~ il~6URSIEy ~ ~A 0 2 3 217 3 5 2 0 0 0 4~65831'i 63 ~~511 fi3-. T_068 4 P.05 OE CA 009900155 procedure ~rivolves essentially two steps . In zhe firs:.
step, the black liquor ~.s converted from its aqueou$
colloida3 system to an anhydrous colloidal dispersion in a lubricating oil med~.um in which a surfactant, wh~.oh nay be an anionic surfactant, such as DDBSA
(doderylbenzene sulfuric acid), is used to promote the provision of the anhydrous colloidal di.spersior~. The process may be effected under low shear conditions.
The anhydrous colloidal dispersion of l~.gain in oil may be m~.xed, in a secozid step, with asphalt bitumen, producing a unique combination, which is a novel bituminous composition.
In another e~c~bodiment of the u~.vent ion, the procedure again involves essentially two steps, rust, bitumen is treated with an inorganic acid, such a.a sulfuric acid, at elevated temperature to provide an acid-treated bitumen. The lalack alkaline liquor is then added slowly zo the ac~.d-created bitumen under agitation for de-watering the black liguor at a coritrolled race to form a stable, n.~bstantially anhydrous, colloidal dispersion of lignin iri the bitumen, also to provide a novrel b~turninous eo~pos~t~.on.
Accarcl~.ngly, in arLOtr~r septet of the present invention, there is provi~.ed a bituminous composit~.on comprising bitumen, and dewatered lignin-containing spent alkaline gulping liguor djspexsed thereir_. The dew~tered spent alkaline pulping liquor may be present in an amount up to about 5~ wt.% of the bitumtn, preferably about 5 to about 25 wt.% of the bitumen.
3o In such composition, the dewazered spent a7.kaline pulp~.ng liquor may comprise an anhydrous colloids?
d~apersic~ of lignin in a lubrs.cating oil. The dewatered spent alkaline pulping liquor may comprise a stable, substantially anhydrous, coilo~.dal dispersion: of lignin in the bitumen.
AMENDED SHEET

23-02-2000 56 ~ F r~S IM AICBIEtNEY3 Z- tf CA 0 2 3 217 3 5 2 0 0 4~ 6586 168 ~~ 1 1 e~~ T-068 P. 06!08 CA 009900155 DET74TLSt7 D~BCRIPTt~ 0>p 'T8S I~Y88T~0~
Referring firlst zo the first ealbod3me>at of the invention, a lubricat~.ng oil is mixed with black liguor at temperatures below the water boiling point. A
s surfactant, which may be pD88A tdodecylben2ene sul~uxic acid), is selected Lo be added to the m~.xture to facilitate the colloidal dispersion of black liquor in the lubr=cating oil while de-watering is gradually carried out at an elevated temperature. The dewatering many be effected by starting at an elevated temperature, which may be about 140° to about 180°C, preferably about 11Q° to about lsc~°c:. 'ttie resuhing cream-like pnr~~~
product ~.s miscible with hot liquid asphalt at any ratio to form a novel bituminous composition.
i5 The lubricaring oil used in the first embodiment of the invention may be a re-refined waste motor o~.l or other convenient petro7.eurn-based oil. Contaminants of waste motor oil, such as dirt, lead, arsenic and other hateful metals atsd checlu.cals, are raved frota the waste 2o motor ail to produce a clean base lubricating oil by the re-ref irfiz~g process .
The lubricating ail may be a selected fraction of refined m~.neral o~.l used for lubrication of moving surfaces. Such fraction may range in consistency from 25 thin l~.guid to grease-like substances . Usua~7.iy, lubricating oils contain sma~.3. amounts of additives to irnpaxt special propexties, such as vireo:ity index arid detergency.
The surf attest or disperh~.xsg agent used in the 3o process may typically be dodecylbenzene sulfuric acid t~SBA?, although ether anionic surfactants may be employed, ~f desired, such as f~.tty acid, linear alkyl sulfonates havi~ 10 or more carbon atoms in the chain.
DDBSA is benzene with dodecene, and the resulting 35 dodecylberme:~e ig aulfonated. DD$sA may be neutz'al~.zed with caustic sods from the alkaline black liquor or AMENDED SHEET

~ z3-02-2000 ji 6gm~Ff~-51M kIG$UR11E~' 1 ~A 02321735 20004~85851~~83bfl5i 1E~:3~ T-06B 4~ P 0%OE CA 009900155 other convenient source to promote the detergeacy of the lubricating oil and to reduce surface tension in the mixture .
however, a surfactant nead not always be necessary, at the lubr~c~xzing oil employed has a detergency high enough to ensure that a colloidal dispersion of the solid residue from the black lia_uor is achiEVed in the lubricating oil med~.um.
The lign~.n-oil dispersion produced by either of these pro~adures may be smoothly b;ended with bitumen to provide the desired lignin-asphalt composition. The spent pulping liquor, which may be bla:k liquor from a kraft pulp mill, may ~ present in an amount of about 25 to about 50 wt.% of the oo~aposizlon, preferably about 25 to 40 wt.% of the composition.
Referring now to the s~cond embodiment of the invention, the bitumen first is treated with a strong mineral acid, such as sulfuric acid, at elevated tetc~erature and then the alkaline black liguor ~.s added 2o to the treated b~.tumen at a controlled race under agitation to effect de-watering of the black ltguor to foxza a .cable. substantially anhydrous, colloidal dispersion in the bit~,rneri. The elevated te~erature may be about loci ° zo about 18Q ° C, preferably about 7.LO ~ to about 16o°C. The spent gulping liquor may bG present in an amouzit of about 5 tn ahnur 50 wt . % of tre compos~.tioa, preferably about 10 co about 3a wt.$
An inorgar~.c acid is contacted with, or added ta, the asphalt to form a.~ acid treated asphalt. In general, the acid addition shsfts Che asphalt etruecure from a~
sol to a gel, lowers the temperature susceptibility of the asphalt arid improves the stability of the additive dispersion in the treated aephalc. Sitzce black liquor is an aguECUS alkal~.ne system, ~t is critical that the acid not be added to the asphalt after add~.tion of or with the black liguor.
AMENDED SHEET

uE:;~c:xNw os : v:~ - ~_> . t) CA 0 2 3 217 3 5 2 0 0 0 - o s - 2 Zt~ss~s t i t~3i -~.a as ~ CA 009900155 ~3-02-2000 :3Bae~ F~oa-51411~B~IEY 4166851183 T-068 P.08/G8 6a Preferably, r.he acid a.s added slowly to the asphalt to avoid foaming, which may occur it all the acid were added ac one time. x'he inorganic acid content of the asphalt resulting from the acid treatment is not critical, but normally is in the range between about 0.2 and about 3.5 wt%, preferably between about a.5 and about 2.5 wc% of the asphalt. Although a wide variety of inorganic acids corn be used for treatment of the asphalt, the inorganic acid is preferably selected from cht group consisting of sulfuric acid, phosphoric acid.
poly-phosphoric acid, phosphorous pentoxide, hydrochloric acid, axed mixtures thereof. The sulfuric acid, phosphoric acid or poly~phosphoric acid are preferred inorgar~.c adds, with the sulfuric acid being part~.cularly preferred.
Following acid addition, the alkalizie black liquor is then added slowly to the acid-treated bitumeri at an elevated temperature, typically around 1~0°C, under agitation for a certain pe:iod of tscae to permit de-2 a was Bring of the bl ack 1 iquor to occur ~rhi le the sol ids are incorporated into the bitumen. The temperature of the final composition next is increased above the hoi3.sng point of Water, typically up to around lsooC
u.~til rasidual water is completely evaporated off to AMENDED SHEET

form a stable, substantially anhydrous, colloidal lignin dispersion in the bitumen.
EXAMPLES
Example 1:
This Example illustrates the first embodiment of the invention in which black liquor first dispersed in a lubricating oil and then in bitumen.
General Procedure:
Black liquor and DDBSA were mixed at room temperature in specific proportions under stirring for to 30 min to form a mixture. Re-refined waste lube oil was added into the mixture at room temperature to a desired concentration and stirred another about 20 min.
The resulting mixture was heated slowly to about 160° to 15 180°C for about 2 to 3 hours under stirring until water-free. During this step, the viscosity of the system exhibited complex phenomena because a raising of the temperature resulted in reduced viscosity while water loss resulted in increased viscosity. Accordingly, the 20 temperature and time for de-watering must be controlled.
Specific Experiments:
16 Kg of DDBSA was added to 266 g of black liquor (ca. 60~ solid content) and stirred at room temperature for 20 to 30 min. 184 g of reclaimed lube oil were added and stirred again at room temperature for 20 to 30 min.
The temperature of the mixture was slowly raised from room temperature to 170°C for 2 to 3 hours to de-water the composition. After de-watering and cooling, about 332 g sample was obtained. The sample was a black colored paste and water-free and was easily dispersed into asphalt at any ratio. This sample was designated as B-14, seen in Table 1.
Different black liquor/lube oil formulations have been prepared following the above procedure and the data are presented in the following Table 1:

+~ O N N G0 N
U

U ~ M O O t~
~T

M M M M

C

O , Q' C

a v H

CA S.a In l0 a0 ~ ~ W

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v a ~' er O O N ~-1 N

~ tf7 00 00 N N M ~-+

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Base asphalt (or bitumen) used in the present invention were selected from three different degrades:
AC-5 having an absolute viscosity of around 500 poises, I85/100 having a 25°C penetration range from 85 dmm to 100 dmm and I120/150 having a 25°C penetration range from 120 dmm to 150 dmm. The non-aqueous dispersing system of black liquor/lube-oil produced as described in the Table 1 was dispersed into hot liquid asphalt at about 160°C respectively to form a very fine dispersion mixture. The stability of these lignin based bituminous mixtures during hot storage at elevated temperature was evaluated using a conditioned tube test. The conditioning procedure consists of placing approximately 70g of the mixture in ~" aluminum tubes and storing such tubes in a vertical position at 165°C in an oven for 48 hrs. Following hot storage, a viscosity ratio was determined by comparing the viscosity of the mixture tested at 135°C from the bottom section of the sample and from the top section of the sample in the tube. A
ratio in the range of 0.80 to 1.20 is generally considered acceptable with respect to separation of the dispersed phase. The testing results on eight compositions are shown in the following Table 2. The results indicate that the lignin based solid dispersion in asphalt binder are quite stable.

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Example 2:
This Example illustrates the second embodiment of the invention in which bitumen first is acidified.
General Procedure:
Sulfuric acid (95 to 98~ HZSO4) was added into hot asphalt AC-5 at 100° to 110°C under stirring (800 to 1000 RPM) for 20 to 30 mins. to form an acid-modified asphalt, followed by addition of aqueous black liquor (c. a. 60$ solid content) into the acid-modified asphalt, according to the following procedure.
(1) While stirring at 800 to 1000 RPM, the acid was added into asphalt at 100° to 110°C for 20 to 30 min. and acid-modified asphalt was obtained.
(2) After 20 to 30 min., black liquor was added to the acid-modified asphalt at 105° to 115°C for 30 to 40 min., then maintained for 1 to 2 hours for de watering.
(3) The temperature was slowly increased to 170°C while stirring for 1 to 2 hours to effect further dewatering.
(4) The composition was allowed to cool and was sampled for stability.
Specific Experiments:
To 392 g of asphalt AC-5 were added 3.14 g of H2S04 (0.8$ AC-5) at 100° to 110°C under 800 to 1000 RPM
stirring for 20 min. The acidified asphalt was maintained at 100° to 110°C and black liquor 84 g (22$
AC-5) was added over about 30 min., and then the composition was maintained for 1 to 2 hrs at 105° to 115°C to dewater the black liquor. The temperature was raised to 170°C while stirring to effect further dewatering. The product was then cooled to provide 436 g of product (loss mass 43 g). The stability index determined on this sample (AC-B-18) was 0.94, shown in Table 3.

Results of dispersion and stability determinations are also shown below in the following Table 3. The results shown in Table 3 indicate that products of formulation containing 0.8 wt~ acid and 0 to 30 wt~, preferably 15 to 25 wt~ black liquor, based on the amount of asphalt, had good stability.

WO 99/4252b PCT/CA99/00155 x .G ~ u7lfld ODtn tn N u1 ~ u7 .~ T3 C~C1 a1 01O ~ M O C~-N
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SL~ARY OF TFIE DISCLOSURE
In summary of this disclosure, the present invention provides novel procedures for the stable dispersion of lignin components of black liquor in bitumen. Modifications are possible within the scope of the invention.

Claims

What I claim is:

1. A bituminous composition, comprising bitumen, and dewatered lignin-containing spent alkaline pulping liquor stably dispersed therein.

2. The bituminous composition of claim 1 wherein said dewatered spent alkaline pulping liquor is present in an amount up to about 50 wt% of the bitumen.

3. The bituminous composition of claim 2 wherein said dewatered spent alkaline pulping liquor is present in an amount of from about 5 to about 25 wt% of the bitumen.

4. The bituminous composition of claim 1 wherein said dewatered spent alkaline pulping liquor comprises an anhydrous colloidal dispersion of lignin in a lubricating oil.

5. The bituminous composition of claim 1 wherein said dewatered spent alkaline pulping liquor comprises a stable, substantially anhydrous, colloidal dispersion of lignin in the bitumen.

6. The bituminous composition of claim 1 wherein the spent alkaline pulping liquor is black liquor from a Kraft pulp mill.

7. A method of producing a composition, which comprises:
converting an aqueous colloidal dispersion of liquor in spent pulping liquor to an anhydrous colloidal dispersion of lignin in a lubricating oil.

8. The method of claim 7 wherein said converting step is effected by:
mixing a lubricating oil with the spent pulping liquor, and dewatering the mixture so formed at an elevated temperature to form a cream-like paste compatible with hot bitumen.

9. The method of claim 8 wherein said mixing step is effected in the presence of a surfactant to facilitate colloidal dispersion of the spent pulping liquor in the lubricating oil.

10. The method of claim 9 wherein said surfactant is an anionic surfactant.

11. The method of claim 10 wherein the anionic surfactant is a fatty acid linear alkyl sulfonate.

12. The method of claim 7 including blending the anhydrous colloidal dispersion of lignin in a lubricating oil with bitumen.

13. The method of claim 7 wherein said spent pulping liquor is black liquor from a Kraft pulp mill.

14. The method of claim 7 wherein the spent pulping liquor is present in an amount of about 10 to about 60 wt% of the composition.

15. The method of claim 14 wherein the black liquor is present in an amount of about 25 to 40 wt%.

16. A method of producing a bituminous composition, which comprises:
converting an aqueous colloidal dispersion of lignin in spent alkaline pulping liquor to an anhydrous colloidal dispersion of lignin in a lubricating oil, and mixing said anhydrous colloidal dispersion of lignin with bitumen.

17. The method of claim 16 wherein said spent alkaline pulping liquor is black liquor from a Kraft pulp mill.

18. The method of claim 16 which is effected by stressing at elevated temperature.

19. The method of claim 18 wherein said elevated temperature is about 100° to about 180°C.

20. The method of claim 19 wherein said temperature is about 110° to about 160°C

21. A method of producing a bituminous composition which comprises:
treating bitumen with an inorganic acid at an elevated temperature to provide acid-treated bitumen, slowly adding to the acid-treated bitumen a lignin-containing spent alkaline pulping liquor, while agitating the bitumen to effect controlled dewatering of the spent pulping liquor to form a stable, substantially anhydrous colloidal dispersion of lignin in the bitumen.

22. The method of claim 21 wherein said inorganic acid treatment of bitumen is effected to convert the bitumen structure from a sol to a gel, lower the temperature susceptibility of the asphalt and improve the stability of the additive dispersion in the treated bitumen.

23. The method of claim 22 wherein said inorganic acid is added slowly to the bitumen at an elevated temperature to avoid foaming to provide an inorganic acid content of said bitumen of about 0.2 to about 3.5 wt%.

24. The method of claim 23 wherein said inorganic acid content is from about 0.5 to about 2.5 wt% of the bitumen.

25. The method of claim 21 wherein said inorganic acid is sulfuric acid.

26. The method of claim 21 wherein said addition step is effected by:
initially slowly adding the spent alkaline pulping liquor to the acid-treated bitumen at substantially water boiling temperature while agitating the bitumen to effect an initial dewatering of the alkaline spent pulping liquor, and subsequently increasing the temperature of the bitumen above the water boiling point to effect a further dewatering of the bitumen to form the stable, substantially anhydrous, colloidal dispersion of lignin in the bitumen.

27. The method of claim 21 wherein said spent alkaline pulping liquor is black liquor from a Kraft pulp mill operation.

28. The method of claim 21 wherein said elevated temperature is about 100° to about 180°C.

29. The method of claim 28 wherein said temperature is about 110° to about 160°C.

30. The method of claim 21 wherein the spent pulping liquor is present in an amount of about 5 to about 50 wt% of the composition.

31. The method of claim 21 wherein the spent pulping liquor is present in an amount of about 10 to about 30 wt%.