Waste tire-derived asphalt modifier
Products from waste tire pyrolysis are prepared using an initial step of i) at least partially pyrolyzing, separately from such asphaltic binder, whole rubber articles or size-reduced rubber particles to provide one or more pyrolyzed rubber fractions including a pyrolyzed oil fraction having a selected minimum initial boiling point or flash point, and ii) removing some or all polycyclic aromatic hydrocarbon (PAH) compounds from such pyrolyzed oil fraction to provide a reduced-PAH and preferably translucent pyrolyzed oil fraction that may be combined with an asphaltic binder to provide a modified asphalt composition.
1 . A pyrolysis oil having reduced polynuclear aromatic hydrocarbon (PAH) content, and made by:
i) at least partially pyrolyzing whole rubber particles or size-reduced rubber particles to provide one or more pyrolyzed rubber fractions including a pyrolyzed oil fraction having a selected minimum initial boiling point or flash point,
ii) removing at least some PAH compounds from such pyrolyzed oil fraction having a selected minimum initial boiling point or flash point by one or more of:
a) fractionally distilling the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point over a temperature range that removes a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leaves behind at least some PAH compounds;
b) solvent extracting the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point using one or more solvents that remove a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leave behind at least some PAH compounds;
c) centrifuging the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point to separate a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction from a fraction containing concentrated PAH compounds; or
d) wiped film evaporating the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point to remove a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leave behind at least some PAH compounds,
to provide a reduced-PAH pyrolyzed oil fraction having a total PAH content less than about 100 ppm by weight.
2 . A composition according to claim 1 , wherein at least some of the PAH compounds are removed by fractionally distilling the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point.
3 . A composition according to claim 2 , wherein fractionally distilling removes a pyrolyzed oil fraction with an initial boiling point of at least about 300° C.
4 . A composition according to claim 2 , wherein fractionally distilling removes a pyrolyzed oil fraction with boiling points up to about 400° C.
5 . A composition according to claim 2 , wherein fractionally distilling removes a pyrolyzed oil fraction with an initial boiling point of at least about 550° C.
6 . A composition according to claim 2 , wherein fractionally distilling removes a pyrolyzed oil fraction with boiling points up to at least about 650° C.
7 . A composition according to claim 2 , wherein fractionally distilling removes a pyrolyzed oil fraction with boiling points between about 300° C. and about 400° C.
8 . A composition according to claim 2 , wherein fractionally distilling removes a pyrolyzed oil fraction with boiling points between about 550° C. and about 650° C.
9 . A composition according to claim 2 , wherein fractionally distilling leaves behind a black oil residue containing carbon black and concentrated PAH compounds and removes an amber-colored oil fraction containing reduced PAH compounds.
10 . A composition according to claim 1 , wherein at least some of the PAH compounds are removed by solvent extracting.
11 . A composition according to claim 1 , wherein at least some of the PAH compounds are removed by centrifuging.
12 . A composition according to claim 1 , wherein at least some of the PAH compounds are removed by wiped film evaporating.
13 . A composition according to claim 1 , wherein the total PAH content in the reduced-PAH pyrolyzed oil fraction is less than about 50 ppm by weight.
14 . A composition according to claim 1 , wherein the total PAH content in the reduced-PAH pyrolyzed oil fraction is less than about 20 ppm by weight.
15 . A composition according to claim 1 , wherein the reduced-PAH pyrolyzed oil fraction contains less than about 10 ppm by weight total concentration of benzo(a)pyrene, benzo(e)pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene and dibenzo(a,h)anthracene.
16 . A composition according to claim 1 , wherein the reduced-PAH pyrolyzed oil fraction contains less than about 5 wt. % carbon black solids.
17 . A composition according to claim 1 , wherein the reduced-PAH pyrolyzed oil fraction contains less than about 0.5 wt. % carbon black solids.
18 . A composition according to claim 1 , wherein the reduced-PAH pyrolyzed oil fraction is translucent.
19 . A composition according to claim 1 , wherein the reduced-PAH pyrolyzed oil fraction has an open cup flash point of at least 50° C.
20 . A method for making pyrolysis oil having reduced polynuclear aromatic hydrocarbon (PAH) content, the method comprising the steps of:
i) at least partially pyrolyzing whole rubber particles or size-reduced rubber particles to provide one or more pyrolyzed rubber fractions including a pyrolyzed oil fraction having a selected minimum initial boiling point or flash point,
ii) removing at least some PAH compounds from such pyrolyzed oil fraction having a selected minimum initial boiling point or flash point by one or more of:
a) fractionally distilling the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point over a temperature range that removes a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leaves behind at least some PAH compounds;
b) solvent extracting the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point using one or more solvents that remove a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leave behind at least some PAH compounds;
c) centrifuging the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point to separate a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction from a fraction containing concentrated PAH compounds; or
d) wiped film evaporating the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point to remove a desired initial boiling point or desired minimum flash point pyrolyzed oil fraction and leave behind at least some PAH compounds;
to provide a reduced-PAH pyrolyzed oil fraction having a total PAH content less than about 100 ppm by weight.
21 . A method according to claim 19 , wherein at least some of the PAH compounds are removed by fractionally distilling the pyrolyzed oil fraction having a selected minimum initial boiling point or flash point.
22 . A method according to claim 19 , wherein fractionally distilling removes a pyrolyzed oil fraction with boiling points between about 300° C. and about 400° C.
23 . A method according to claim 19 , wherein fractionally distilling removes a pyrolyzed oil fraction with boiling points between about 550° C. and about 650° C.
24 . A method according to claim 19 , wherein the reduced-PAH pyrolyzed oil fraction contains less than about 10 ppm by weight total concentration of benzo(a)pyrene, benzo(e)pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene and dibenzo(a,h)anthracene.