CA1083063A - Synthetic asphalt and its production - Google Patents

Abstract

ABSTRACT

Novel bituminous binding and coating agents suitable for, e.g., road surfacing and similar applications, are made by reacting elemental sulfur with a hydrocarbon feedstock at temperatures of from 180°C up to no more than 20°C below the boiling point of the feedstock, until all the sulfur has reacted. The hydrocarbon feedstock is preferably at least one selected from feedstocks comprising aromatic extracts, precipitated and other asphalts (e.g. straight run and vacuum bottom), catalytic cycle oil, deasphalted aromatic hydrocarbons and heavy vacuum pipestill side streams, and the like.
Preferably, the reaction temperature is as low as is economically possible - e.g. 180 to 320°C.
The novel products have advantageous properties compared to conventional bituminous or asphaltic products.

Description

3~1~i3 The present invention relates to a method of Making bituminous or asphaltic materials suitable for use as bind;ng and/or coating agents~ and also to novel bituminous or asphaltic materials made by the methodO
It is known from prior art that bituminous materials with characteristics of penetration and softening that are acceptable to allow their use as ~inding agents for asphalts can be obtained by 'blowing with air at 200-230C9 the normal temperature of oxidation, aromatic type extracts~ but this technique is not ~evoid of drawbacks, since the products obtained do not always have a sufficient degree of hardness and moreover, even in favourable cases, uneconomically long blowing times are required) for instance exceeding 10 hoursO
Techniques'are also known (vide for instance British Patent NoO 19327,535 ~
of the British Petroleum Company Limited), in which blowing with air is carried ~ ' -out on original mixtures containing to begin with, together with a small percentage of sulphur in elementary form, bitumen, copolymeric resins and aromatic extracts, but in this case, too, the cost of production is very high, both through the use of synthetic components and through the methods of operationO
There are also known'(vide British patent 956,313 of the British Petroleum Company Limi.ted), propane precipitated asphalt ("PPA") sulphurising operations~
but these are said to be carried out to eliminate the waxes and to increase the ~.
conten~ of asphaltenes, but without specifying the type of products obtained, and there are like.wise known'(British patent 1,031,631 of the British Petroleum COQ Ltdo) bituminous compositions made by mixing PPA, previously and separately sulphurised9 wi~h aromatic extracts and residues'from vacuum distilling operationsO
It.is an object of the present invention to avoid the drawbacks of the ' prior art methodsO
The presen~ invention provides'a method of making a bituminous or asphaltic ma~erial suitable for use as a binding and/or coating agent, comprising ,

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chem;cally reacting a hydrocarbon feedstock with at ]east 5% by weight, kafled on the weight of feedstock, of elemental sulphur, at a temperature in the range of from 180C to no more than 20C below the initial boiling point of the feedstock at the reaction pressure, wherein the hydrocarbon feedstock is selected from (a) hydrocarbon feedstocks comprising aromatic extracts; (b) hydrocarbon feedstocks comprising DU~SO1 e~traCts~(c) hydrocarbon feedstocks comprising cycle oils from hydrocarbon cracking processes; (d) hydrocarbon feedstocks comprising vacuum distillates; (e) hydrocarbon feedstocks comprising vacuum distillates of deasphalted residues; (f) hydrocarbon feedstocks comprising asphalts; (g) hydrocarbon feedstocks comprising residues from distillation of petroleum fractions under reduced pressurei and (h) feedstocks comprising a mixture or blend of at least two of feedstocks (a) to (g), the reaction being performed for a period of time until the evolution of any H2S ceases and the reaction mixture is substantially free of unreacted elemental sulphur, and recovering a bituminous or asphaltic material of increased chemically combined sulphur contentg relative to the hydrocarbon feedstock, having a penetration of .

no more than 2000 dmm at 25 C, according to ASTM test D5~
The feedstock may comprise a precipitated asphalt, e.gO PPA, and/or it may ~comprise a mi~ture or blend of an aromatic extract and precipitated asphalt; the latter~may form up to 65 wto% of the feedstockO
The feedstock may alternatively or additionally comprise up to 50 wt.%, e,g, 20-50 wto% of heavy cycle oil and at least one material selected from precipitated asphalts and distillation residues, Alternatively~ or in addition~ the feedstock may comprise up to 60 wto%
(e,g, 20 to 60 wt,%) of a third side stream from a vacuum pipestillg and at least one material 9elected from precipitated asphalts and distillation residues, The feedstock may comprise, alternatively or additionally, up to 40 wt,%
(e,gO 20 to 40 wt,%) of light cycle oil and at least one material selected from -precipitated asphalts and distillation residuesO The distillation residue may be a vacuum distillation residuum, -~
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Dependiny on the type of feed3tock and the desired type and properties of the product, the amount of sulphur may vary within wide ranges, and may be employed in amounts up to, e.g., 30% by weight based on the weight of feedstock.
The invention also comprises novel bituminous or asphaltic materials ~ade by the above-described method. Such novel materials may comprise from 20 to 30% of chemically combined sulphur in the form of polysulphides and have a penetration of no more than 2000 dmm at 25C.
The temperature at which the reaction which sulphur is performed depends on the feedstock and the nature of the desired product. Generally speaking, the lower the reaction temperature, the greater will be the incorporation of sulphur in the feedstock, while the higher the reaction temperature, the more predominant will be reactions in which the sulphur dehydrogenates the feedstock and increases the asphalticity of the product, sulphur being converted to hydrogen sulphide.
Simple experiments will enable those skilled in the art to select the temperature(s) best suited to obtain desired products from particular feedstocks. Some guidance on the nature of the reactions will be found in an article entitle "Reactions and Technological Properties o~ Sulphur - Treated Asphalts" published in "Industrial and Engineerin~ Chemistry,' Product Research and Development, Vol. II, pages 214-219, June 1972 and in an English-language article`entitled "Heavy Hydrocarbons and Sulphur Reactions and Reaction Products" published in "La Chimica e l'Industria", Vol. 55, ~, : , No. 5, May 1973, pages 425-431. When the feedstocks comprise aromatic extracts, the preferred reaction temperatures are 180 to 300C, depending on the extract, and for feedstocks comprising cycle oils, reaction temparatures will preferably ;~ ~ ~4~

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be around 240 to 270C. The actual temperature range will be governed by any other materials in the feedstocks.
An important benefit of the invention is that relatively low-value refinery products can be upgraded to higher premium material useful for binding and coating surfaces and solids, e.g. for road surfacing. ~he reaction can conveniently be performed at, or in the vicinity of a petroleum refinery since elemental sulphur is usually available as a by-product of oil refining.

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, -The preferred hydrocarbon feedstocks are those containing saturatedJ
aromatic3 asphaltic moieties, substituted or not, and their der;vatives~
Fxamples of these are aromatic extracts obta;ned during the manufacture of lubricating oils9 and heavy high vacuum distillates from, e~gO Middle East crudes, boiling in the range 370 to 570C at atmospheric pressure, and vacuum distillates of deasphalted residua (eOgO of Middle East crudes) boiling at 480C or higher (equivalent temperature at atmospheric pressure)O
Some common hydrocarbon feedstocks can be reacted with 5 to 25 wto% of sulphur to give useful binding and coating materials~ For example, an aromatic extract of the following broad type can be so reacted:
Specific Gravity 0,96 to 0099 Vlscosity at 210 F (SSU)200 to 300 Flash Point ( F) 480 to 580 Sulphur (wto%) 3 to 4 Aromatic Content (wt,%)60 to 80 Distillation : IBP ( F)500 to 550 50~ (F)700 to 850 : If a relatively harder product is required, such an aromatic material .:
can be blended with up to 65 wt,% o propane precipitated asphalt, 20 to 30% ~:
of the sulphur is fixed in the product as polysulphides, The remalnder ~:
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escapes as H2S during the reaction, preferably performed at 180 to 235C, and may be passed eo a Claus Kiln unit to recover sulphur or recirculated at least ~ : :
in part through the liquid reactants, ~:
Table I gives some typical characteristics of aro~atic extracts obtained by phenol extraction of, e,g, llght Arabian stocks~

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.' Ch~recteriseic Extract 1 Extract 2 Specific Gravity (15C) OD98 ~ loOl 0096 ~ 0~99 Viscosity (SSU @ 210 F) 110 - 140 200 ~ 270 Flash Point (Open cup F) 480 560 Conradson Carbon wto% 405 5 Pour Point (F) 110 110 An~line Point (F) 130 190 Sulphur (wto%) 4 ~ 5 3 _ 4 Aromatic Contents (%) 75 ~ 84 65 ~ 75 Distillation at cOlO~m.HgO
I.BP ( F) 435 550 20 volO % (F) 570 ~40 50 vol. % (F) 610 300 Table Il gives some typical characteristics of an asphalt precipitated by . .
a C3-C6 paraffinic hydrocarbon,' eOg, propane~
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TABLE II : .
Charecteri5tic ~ A=l__ Specific Gravity (15C)1 oO60 ~ 1.080 Softening Point (C) 68 ~ 70 Penetration (dmm) 10 - 5 .
Viscos;ty at 130 C ( Engler) 241 ~ 251 -Viscosity a~ 150C (F) 79 ~ 87 Sulphur (wt,%) 5~1 - 505 Table IIlgives characteristics for so~e heavy hydrocarbon feeds~ocks which can be used in the practice of the invention:

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~ABL
3rd D:istillate Vacuum Distillate Fract;on from of Light Deasphalted CharacteristicVacuum Pipestill Arabian Crude Oil , . . . ..
Viscosity @ 210 ~ ~SSU) 76 0 - 184 Sulphur (wto%) 2.33 401 Flash point9 Cleveland Open Cup (C) 296 324 300 Aromatic Content % 53 78 59 Penetration (dmm) - 400 - .
The origin of the feedstocks is substantially immaterial, and the invention can be performed with feedstocks derived from Middle Eastern, African, Arabian -- -and naphthenic crudesO ~
The reaction time between the sulphur and hydrocarbon feedstock will be a : :
function of reaction temperature, composition, the feed and the ratio of parameters that define the penetration and softening points of the product, as will be apparent from the fol:lowing tables IV, V and VI ~. .
: TABLE IV
Mixture comprising 80 wto% Extract 2 -~ 20 wto% PPA
Reaction Time (hrs) ~180 10 60 :

260 4,30 70 300 ~ 3,30 67 The amount of sulphur was the same in each run (about 12% of the weight of hydrocarbon feed mixture)O It is apparent that a given ring and ball temperature is attained after a shorter time with more elevated reaction temperaturesO

TABLE V
Reaction temperature : 250CJ
Reactants : cO 12% S (based on hydrocarbons) -~ extract 2 ~ PPA
Wto% PPA in Hydrocarbon Mixture_ ~ - R~

58 4 ~ 15 3~30 It will be seen that a given penetration is achieved more rapidly as the proportion of PPA is increased, and that after relatively long reaction timas (11-12 hours) the penetration becomes relatively reducedO
TABLE VI
Reactants : c.12~ S I (70 wto~ extract 2 ~ 30 wt ~ PPA) Reaction temperature : 250 C . .

An increased reaction time reduces the penetration index and increases the ring and ball temperature, iOeO the ratio of penetration to R ~ B
decrea`ses0 The influence of the amount of sulphur ln a reaction mixture is typified in Table VII, wherein the hydrocarbon feedstock was a mixture of 80% extract 2 and 20% PPA, and the reaction temperature was 220Co TABLE V:[I
% Su~ r ~ 're~e~ ~ x) C

1~l0 The invention will now be further illustrated by way of some non~
l;mitative examples thereofO

~:~ ' -.A 1 kg~ charge of aro.m~tic extract 2 mixed'with PPA in a weight ratio of 4:1 was placed'in a 2 litre container'with 200 g. of elemental sulphurO ~' -The mixture was heated to 60 C and thereafter mechanically stirred while its ..
temperature was rapidly ~aised to 160 G, and thereafter.more slow~ly raised, with continued'stirring, to 1O0-220 C0 Relatively large amounts of H2S were .
liberated, and the temperature was not allowed to rise above 220C to avoid excessive production of H2So The reaction was monitored'for H2S evolution .
with lead acetate paper'and was regarded as substantially complete after 7 ~: .
hoursO The product was then'cooled, and its tested properties'wereo Penetration : 65 dmm @ 25C
Softening Point : 111C .
: Fraass Breaking Point o -3b~C ~:
'Exam~le B . -:
A mixture of 300 gO of aromatic ~xtract 1, 200 g of a vacuum distillate ' ~' '' residue from Arabian crudes'and 15 gO of sulphur were heated ln a 1 litre cont:iner'first to 60C~ and then~ with stirring, to 200C, which temperature was a~curat:ly maintained'for 5 hours. The reaction w:s then'stopped, and the following product properties'were found:
; Penetration ~ 102 dmm at 25C ~:
Softening Point : 63C . -: Fr:ass Breaklng Point : -30 C

. ~, ;' _ g _ " ' D~3 The invention will now be further described w:itll reference to the drawings, illustrating the character:istics of prnduct.s according to the i.nvention, and wherein:
Figure 1 shows gr~phically, relationships between the Fraass 'breaking point (C) on the ordinate as a function of the penetration (dmm) on the abscissa for different products;
Figure 2 is a graph of the Fraass breaking point (C) on the ordinate ' versus ring and ball softening temperature (C) on the abscissa for the products of Figure l;
Figure 3 is a graph of penetration (dmm) on the ordinate as a function of softening point expressed in C (R ~ B) on the abscissa for the Figure 1 products; ~ :
Figure 4 is a graph like figure 2 for products obtained by reacting a ch~rge '-' of 50% extract 2 + 50% PPA with 5 to 15æ sulphur, based on the charge, and ..
Figure 5 is a graph like figure 2 for products obtained by reacting 50% '~ .
extract 1 ~ 50% PPA + 5 to 25% sulphur, based on the chargeO '~.
In all the figures9 there are illustrated, for comparison, the corresponding pro~erties of known'bituminous products, particularly Middle East asphalts, high penetratlon (HP~ grades of asphalt and blown'asphaltO -From figures 1, 2 and 3, in which the curves A, B, C and D relate the products obtained by reacting, in accordance with the invention, mixtures of aromatic extracts with 20, 30, 50 and 65% PPA and various amounts of sulphur (5 : .
to 20 wto% based on hydrocarbons) respectively, the higher amounts of sulphur ~giving the products of lower penetration and higher softening pointO
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It will be noted'that the values of Fraass temperatures for products formed from feedstocks comprising atomatic extracts are lower than those' for~conventional asphalts (curve E) with equal penètration tFigure 1) and less than those'of blown'asphalts (curve F) and HP grades (curve G) having equal softening points (Figure 2)o- The values of penetration ~are higher for given'softening points for compositions of the invention .
(curves~A, B9 C and D~ than for blown'asphalts (curve G) and HP
grade (curve G) as is seen from figure 30 .

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, 0~3 In figure 4, curve A represents the character:istics of Fraa~s point (ordinate) C versus ring and ball softening temperature ( C) for a composition formed by reacting 50% aromatic extract 1 ~ 50% PPA with 5 to 25% sulphur, compared with the same characteristics for conventional products F and G It will be seen that curve A ls about the same or above the values for F and Go In figure 5, curve B ;s for the same range of products of the invention as curve A of figure 4, the characteristics shown being the penetration ~dmm) on the ordinate versus softening point (C) on the abscissaO It will be seen'that the penetration for a given softening point is at least equal to that of conventional products F and G, while from figure 4, the Eraass temperatures are for a given softening point about the same as, or higher than, those for the :
conventional products F, G.
The variations possible in the properties of compositions according to the invention are further illustrated by reference to Table VIII wherein the products were obtained'by the reaction of aromatic extract 2("E2") + PPA and 15 to 25% sulphurO ~ ~ -~BL~ VIII
Ductility Flash Marshall Flow ' Hydrocarbon Penetration cms at Point Wto Loss Feedstock ~ 25C C at 165C ~ mms 20% E2 + 20% PPA 65 204 280 - 848 4~3 80% E2 + 20% PPA 57 2.6 - 0002 - - .
50% E2 + 50% PPA 57 301 295 65% E2 + 35% PPA 31 2 305 0~01 1016 701 70% E2 + 30% PPA 32 l o 9 ~ ~ ~ ~
In Table IX, the same types of hydrocarbon feedstocks treated with 5 to 25 ~ ~ -wto% sulphur were employed and other properties of the products are shownO In :'. :, , general, a higher'proportion of sulphur was employed when the proportion of : ~ -extract 2 was high in the hydrocarbon feedstockO The high~r'proport;on of the sulphur reacted~ the harder was the final product, ;n general, the higher the ~jH ratio and the higher the sulphur content and molecular weightO :

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TABLE IX
Hydrocar'bonSofteningFraass C/H Mol Feedstock PointC Pt C Ratio ~ SWeight ~ _ ~ O
80% E2 + 20% PPA - - 6070 lol 812 80% E2 + 20% PPA 65 ~40 7016 3~37 962 80% E2 + 20% PPA 75 ~39 7028 3086 995 .
80% E2 + 20% PPA 111 ~35 7040 4006 1015 70% E2 ~ 30% PPA 121 ~30 7028 4008 1083 70% E2 + 30% PPA 142 ~ 7038 5009 1110 50% E2 ~ 50% PPA - - 7~53 2003 902 50% E2 + 50% PPA 171 -29 7068 5051 1193 -35% E2 ~ 65% PPA - - 7069 2031 917 35% E2 ~ 65% PPA 97 -18 8001 7~31 1204 In Table X which follows, the properties'of products obtained'by reacting other'hydrocarbon feedstocks with sulphur are given: ' '"
TA_LE X
: Eydrocarbon Feedstock Penetration Softening Fraass Point b~ 2~ L r~ (dmm) 'Point (c)' C
(80% PPA + 12% Cycle Oil*) ~ 5% S 56 49 -8 (70% PPA ~ 20% Cycle Oil* + 10%
'.
Vacuum Bottoms) + 10% S 115 43 -15 (65% Vacuum Residue + 35% Cycle ' Oil*) + 25% S 20 121 - ' * cycle oil from catalytic cracklng havlng a viscosity of 4~45 cS at 50 C, 201 wto% sulphur and an~aromatics content of 25%o : Any type of cycle oil can be employed'in the inYention~ Typical inspections are~

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:' TABLE X L
Light Cycle Oil Heavy_~cle Oil Specific Gravity 00900 00920 00920 - 00930 Viscosity at 100 F (cS) 2.8 - 3.2 4 - 5 Sulphur Content 200 - 208 3 - 305 Distillation (C) FBP 330 _ 350 350 _ 370 The reaction with cycle oils is preferably effected at 180 to 280C, e.g.
230 to 280C most preferably 230 to 240C, but the optimum temperature will be ' governed by the amount and nature of other hydrocarbons present in the hydrocarbon feedstockO Cycle oils and PPA or vacuum bottoms will generally react with sulphur to give excellent products at lower'temperatures'than the foregoing - eOgO in the range of 180 - 250C.
It will be seen from the foregoing that by the reaction of elementary sulphur with low value hydrocarbon feedstocks, at the lowest economical temperatures~ (bearing in mind the necessity of avoiding dehydrogenation beyond the required amount and oE avoiding excessive reaction times)~ it is possible to obtain novel'high grade bituminous products which are superior to conventional bituminous materialsO The novel products are suitable for use as binding ;
agents and in road surfacing, and have a lower Fraass breaking point than ' otherwise comparable conventional blown asphalts, and a higher penetration ':
index'and lower Fraass point than otherwise comparable conventional bituminous ' . : .
productsO " ' ' :
The invention has hereinabove been described'with particular reference to ' ::'.
specific embodiments, but it is understood that the invention can be practlced in any way falling within the scope of the appended claims. `-` - 13 -, .,. - - . ~ ................... , ,., .. .... , , ~ ~ . . . :
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Claims (14)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of making a bituminous or asphaltic material suitable for use as a binding and/or coating agent, comprising chemically reacting a hydrocarbon feedstock with at least 5% by weight, based on the weight of feedstocks of elemental sulphur, at a temperature in the range of from 180°C to no more than 20°C below the initial boiling point of the feedstock at the reaction pressure, wherein the hydrocarbon feedstock is selected from (a) hydrocarbon feedstocks comprising aromatic extracts; (b) hydrocarbon feedstocks comprising Duosol extracts; (c) hydrocarbon feedstocks comprising cycle oils from hydrocarbon cracking processes; (d) hydrocarbon feedstocks comprising vacuum distillates;
(e) hydrocarbon feedstocks comprising vacuum distillates of deasphalted residues, (f) hydrocarbon feedstocks comprising asphalts; (g) hydrocarbon feedstocks comprising residues from distillation of petroleum fractions under reduced pressure, and (h) feedstocks comprising a mixture or blend of at least two of feedstocks (a) to (g), the reaction being performed for a period of time until the evolution of any H2S ceases and the reaction mixture is substantially free of unreacted elemental sulphur, and recovering a bituminous or asphaltic material of increased chemically combined sulphur content, relative to the hydrocarbon feedstock, having a penetration of no more than 2000 dmm at 25°C, according to ASTM test D5.

2. The method of claim 1 wherein the hydrocarbon feedstock comprises a precipitated asphalt.

3. The method of claim 1 wherein the hydrocarbon feedstock comprises a mixture or blend of an aromatic extract and precipitated asphalt.

4. The method of claim 3 wherein the precipitated asphalt forms up to 65 wt.% of the feedstock.

5. The method of claim 3 wherein the precipitated asphalt is a propane precipitated asphalt.

6. The method of claim 1 in which the hydrocarbon feedstock comprises up to 50 wt.% heavy cycle oil and at least one material selected from precipitated asphalts and distillation residues.

7. The method of claim 6 wherein the hydrocarbon feedstock comprises from 20 to 50 wt.% heavy cycle oil.

8. The method of claim 1 wherein the hydrocarbon feedstock comprises up to 60 wt.% of a third side stream from a vacuum pipestill and at least one material selected from precipitated asphalts and distillation residues.

9. The method of claim 8 wherein the hydrocarbon feedstock comprises from 20 to 60 wt.% of the third side stream from a vacuum pipestill.

10. The method of claim 1 wherein the hydrocarbon feedstock comprises up to 40 wt.% light cycle oil and at least one material selected from precipitated asphalts and distillation residues.

11. The method of claim 10 wherein the hydrocarbon feedstock comprises from 20 to 40 wt.% of light cycle oil.

12. The method of any one of claims 6, 8 and 10 in which the distillation residue is a vacuum distillation residue.

13. The method of any one of claims 1, 3 and 6 in which up to 30% by weight of sulphur, based on the hydro-carbon feedstock, is reacted with the hydrocarbon feedstock.

14. A novel bituminous or asphaltic material comprising from 20 to 30% of chemically combined sulphur in the form of polysulphides and having a penetration of no more than 2000 dmm at 25°C according to ASTM test D5.