A METHOD OF CONVERTING WASTE PLASTIC FEEDSTOCK INTO FUELS AND CHEMICALS

Abstract

The present invention relates to a method for converting plastics into valuable fuels and chemicals. Particularly, the present disclosure provides a method for converting polycarbonate (PC), polystyrene (PS), polypropylene (PP) and low-density polyethylene (LDPE) plastics into phenols, alkyl benzene, aliphatic hydrocarbons, linear aliphatic hydrocarbons, respectively. These plastics were liquefied at sub- and supercritical conditions using water as a solvent.

Specification

Description:1.
A method of converting waste plastic feedstock into fuels and chemicals, comprising the steps of:
a)
mixing waste plastic feedstock with water in a reactor;
b)
pressurizing the reactor with nitrogen gas;
c)
heating the reaction mixture of step (a) at a temperature of 250 ºC to 490 ºC till completion of reaction;
d)
cooling the reactor and collecting the gases and kerogen separately;
e)
washing the reactor walls and the magnetic stirrer with a suitable solvent to extract residual kerogen;
f)
filtering the kerogen obtained from steps (d) and (e) to separate hydrochar from liquid phase;
g)
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h)
separating the oil phase of step (g) into crude oil and the solvent.
2.
The method as claimed in claim 1, wherein the method is hydrothermal liquefaction method.
3.
The method as claimed in claim 1, wherein in step (a), the waste plastic feedstock comprises granules of polycarbonate, polystyrene, polypropylene, and low-density polyethylene plastics.
4.
The method as claimed in claim 3, wherein the plastic granules are in size of 1 mm to 5 mm.
5.
The method as claimed in claim 1, wherein in step (a), the water is Milli Q water.
6.
The method as claimed in claim 1, wherein the plastic and water are taken in a ratio of 1:9 to 13:9.
7.
The method as claimed in claim 6, wherein the ratio of plastic and water is 1:9, 1:3, or 1:1.
8.
The method as claimed in claim 1, wherein the reactor has a solid plastic loading of 10wt% to 60wt%.
41
9.
The method as claimed in claim 1, wherein the solvent is selected from dichloromethane, acetone, hexane, heptane, or ethyl acetate.
10.
The method as claimed in claim 1, wherein in step (c), the reaction mixture is heated at a temperature of 290 ºC to 450 ºC.
11.
The method as claimed in claim 1, wherein in step (f), the separation of kerogen from hydrochar is carried out by vacuum filtration apparatus.
12.
The method as claimed in claim 1, wherein in step (g), the separation of the liquid phase is carried out by density difference via separating funnel.
13.
The method as claimed in claim 1, wherein in step (h), the oil phase is separated via rotary evaporator at a temperature of 40 ºC to 50 ºC.
14.
The method as claimed in claim 1, wherein the method further comprises the addition of a catalyst.
15.
The method as claimed in claim 14, wherein the catalyst is selected from the group consisting of potassium hydroxide, sulfuric acid, sodium hydroxide, alumina, or nickel-based alumina catalyst (Ni/Al2O3).
16.
A method for converting waste plastic feedstock into phenol, comprising the steps of:
a.
mixing waste plastic feedstock comprising plastic granules of polycarbonate with water in the presence of a catalyst in a reactor;
b.
pressurizing the reactor with nitrogen gas;
c.
heating the reaction mixture of step (a) at a temperature of 280 ºC to 370 ºC till completion of reaction;
d.
cooling the reactor and collecting the gases and kerogen separately;
e.
washing the reactor walls and the magnetic stirrer with a dichloromethane to extract residual kerogen;
f.
filtering the kerogen obtained from steps (d) and (e) to separate into hydrochar and liquid phase;
g.
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h.
separating the oil phase of step (g) into crude oil and dichloromethane;
42
wherein the crude oil comprises bisphenol-A which cleaves into phenol and alkyl phenols, and other chemicals.
17.
The method as claimed in claim 16, wherein in step (c), the reaction mixture is heated at a temperature of 290 ºC.
18.
The method as claimed in claim 16, wherein the catalyst is potassium hydroxide.
19.
A method for converting waste plastic feedstock into alkyl benzene and styrene, comprising the steps of:
a.
mixing waste plastic feedstock comprising plastic granules of polystyrene with water in the presence of a catalyst in a reactor;
b.
pressurizing the reactor with nitrogen gas;
c.
heating the reaction mixture of step (a) at a temperature of 350 ºC to 410 ºC till completion of reaction;
d.
cooling the reactor and collecting the gases and kerogen separately;
e.
washing the reactor walls and the magnetic stirrer with a dichloromethane to extract residual kerogen;
f.
filtering the kerogen obtained from steps (d) and (e) to separate into hydrochar and liquid phase;
g.
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h.
separating the oil phase of step (g) into crude oil and dichloromethane;
wherein the crude oil comprises alkyl benzene, styrene, dimers, and other chemicals.
20.
The method as claimed in claim 19, wherein in step (c), the reaction mixture is heated at a temperature of 410 ºC.
21.
The method as claimed in claim 19, wherein the catalyst is sulfuric acid.
22.
The method as claimed in claim 16 or 19 wherein the reactor has a solid plastic loading of 10wt% to 60wt%.
23.
The method as claimed in claim 22, wherein the solid plastic loading is 20wt% to 50wt%.
43
24.
The method as claimed in claim 16, wherein the solid plastic loading is 40wt%.
25.
The method as claimed in claim 19, wherein the solid plastic loading is 50wt%.
26.
The method as claimed in claim 16 or 19, wherein the catalyst is in an amount of 2wt% to 12wt%.
27.
The method as claimed in claim 26, wherein the catalyst is in amount of 5wt%.
28.
A method for converting waste plastic feedstock into aliphatic hydrocarbons, comprising the steps of:
a.
mixing waste plastic feedstock comprising plastic granules of polypropylene with water in a reactor;
b.
pressurizing the reactor with nitrogen gas;
c.
heating the reaction mixture of step (a) at a temperature of 400 ºC to 450 ºC till completion of reaction;
d.
cooling the reactor and collecting the gases and kerogen separately;
e.
washing the reactor walls and the magnetic stirrer with a dichloromethane to extract residual kerogen;
f.
filtering the kerogen obtained from steps (d) and (e) to separate into hydrochar and liquid phase;
g.
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h.
separating the oil phase of step (g) into crude oil and dichloromethane;
wherein the crude oil comprises aliphatic hydrocarbons which are linear and cyclic, and other chemicals.
29.
A method for converting waste plastic feedstock into linear aliphatic hydrocarbons, comprising the steps of:
a.
mixing waste plastic feedstock comprising plastic granules of low-density polyethylene with water in a reactor;
b.
pressurizing the reactor with nitrogen gas;
44
c.
heating the reaction mixture of step (a) at a temperature of 400 ºC to 450 ºC till completion of reaction;
d.
cooling the reactor and collecting the gases and kerogen separately;
e.
washing the reactor walls and the magnetic stirrer with a dichloromethane to extract residual kerogen;
f.
filtering the kerogen obtained from steps (d) and (e) to separate into hydrochar and liquid phase;
g.
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h.
separating the oil phase of step (g) into crude oil and dichloromethane;
wherein the crude oil comprises linear aliphatic hydrocarbons and other chemicals.
30.
The method as claimed in claim 28 or 29, wherein the reactor has a solid plastic loading of 10wt%.
31.
The method as claimed in claim 28 or 29, wherein in step (c), the reaction mixture is heated at a temperature of 450 ºC.
References
1 O. Lai, 8 Shocking Plastic Pollution Statistics to Know About, https://earth.org/plastic-pollution-statistics/, (accessed 27 March 2023).
2 S. Saikrishnan, D. Jubinville, C. Tzoganakis and T. H. Mekonnen, Thermo-mechanical degradation of polypropylene (PP) and low-density polyethylene (LDPE) blends exposed to simulated recycling, Polym. Degrad. Stab., 2020, 182, 109390.
3 A. A. Peterson, F. Vogel, R. P. Lachance, M. Fröling, M. J. Antal and J. W. Tester, Thermochemical biofuel production in hydrothermal media: A review of sub- and supercritical water technologies, Energy Environ. Sci., 2008, 1, 32-65.
4 D. R. Vardon, B. K. Sharma, J. Scott, G. Yu, Z. Wang, L. Schideman, Y. Zhang and T. J. Strathmann, Chemical properties of biocrude oil from the hydrothermal liquefaction of Spirulina algae, swine manure, and digested anaerobic sludge, Bioresour. Technol., 2011, 102, 8295-8303.
5 M. S. Seshasayee and P. E. Savage, Oil from plastic via hydrothermal liquefaction: Production and characterization, Appl. Energy, 2020, 278, 115673. , Claims:1.
A method of converting waste plastic feedstock into fuels and chemicals, comprising the steps of:
a)
mixing waste plastic feedstock with water in a reactor;
b)
pressurizing the reactor with nitrogen gas;
c)
heating the reaction mixture of step (a) at a temperature of 250 ºC to 490 ºC till completion of reaction;
d)
cooling the reactor and collecting the gases and kerogen separately;
e)
washing the reactor walls and the magnetic stirrer with a suitable solvent to extract residual kerogen;
f)
filtering the kerogen obtained from steps (d) and (e) to separate hydrochar from liquid phase;
g)
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h)
separating the oil phase of step (g) into crude oil and the solvent.
2.
The method as claimed in claim 1, wherein the method is hydrothermal liquefaction method.
3.
The method as claimed in claim 1, wherein in step (a), the waste plastic feedstock comprises granules of polycarbonate, polystyrene, polypropylene, and low-density polyethylene plastics.
4.
The method as claimed in claim 3, wherein the plastic granules are in size of 1 mm to 5 mm.
5.
The method as claimed in claim 1, wherein in step (a), the water is Milli Q water.
6.
The method as claimed in claim 1, wherein the plastic and water are taken in a ratio of 1:9 to 13:9.
7.
The method as claimed in claim 6, wherein the ratio of plastic and water is 1:9, 1:3, or 1:1.
8.
The method as claimed in claim 1, wherein the reactor has a solid plastic loading of 10wt% to 60wt%.
41
9.
The method as claimed in claim 1, wherein the solvent is selected from dichloromethane, acetone, hexane, heptane, or ethyl acetate.
10.
The method as claimed in claim 1, wherein in step (c), the reaction mixture is heated at a temperature of 290 ºC to 450 ºC.
11.
The method as claimed in claim 1, wherein in step (f), the separation of kerogen from hydrochar is carried out by vacuum filtration apparatus.
12.
The method as claimed in claim 1, wherein in step (g), the separation of the liquid phase is carried out by density difference via separating funnel.
13.
The method as claimed in claim 1, wherein in step (h), the oil phase is separated via rotary evaporator at a temperature of 40 ºC to 50 ºC.
14.
The method as claimed in claim 1, wherein the method further comprises the addition of a catalyst.
15.
The method as claimed in claim 14, wherein the catalyst is selected from the group consisting of potassium hydroxide, sulfuric acid, sodium hydroxide, alumina, or nickel-based alumina catalyst (Ni/Al2O3).
16.
A method for converting waste plastic feedstock into phenol, comprising the steps of:
a.
mixing waste plastic feedstock comprising plastic granules of polycarbonate with water in the presence of a catalyst in a reactor;
b.
pressurizing the reactor with nitrogen gas;
c.
heating the reaction mixture of step (a) at a temperature of 280 ºC to 370 ºC till completion of reaction;
d.
cooling the reactor and collecting the gases and kerogen separately;
e.
washing the reactor walls and the magnetic stirrer with a dichloromethane to extract residual kerogen;
f.
filtering the kerogen obtained from steps (d) and (e) to separate into hydrochar and liquid phase;
g.
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h.
separating the oil phase of step (g) into crude oil and dichloromethane;
42
wherein the crude oil comprises bisphenol-A which cleaves into phenol and alkyl phenols, and other chemicals.
17.
The method as claimed in claim 16, wherein in step (c), the reaction mixture is heated at a temperature of 290 ºC.
18.
The method as claimed in claim 16, wherein the catalyst is potassium hydroxide.
19.
A method for converting waste plastic feedstock into alkyl benzene and styrene, comprising the steps of:
a.
mixing waste plastic feedstock comprising plastic granules of polystyrene with water in the presence of a catalyst in a reactor;
b.
pressurizing the reactor with nitrogen gas;
c.
heating the reaction mixture of step (a) at a temperature of 350 ºC to 410 ºC till completion of reaction;
d.
cooling the reactor and collecting the gases and kerogen separately;
e.
washing the reactor walls and the magnetic stirrer with a dichloromethane to extract residual kerogen;
f.
filtering the kerogen obtained from steps (d) and (e) to separate into hydrochar and liquid phase;
g.
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h.
separating the oil phase of step (g) into crude oil and dichloromethane;
wherein the crude oil comprises alkyl benzene, styrene, dimers, and other chemicals.
20.
The method as claimed in claim 19, wherein in step (c), the reaction mixture is heated at a temperature of 410 ºC.
21.
The method as claimed in claim 19, wherein the catalyst is sulfuric acid.
22.
The method as claimed in claim 16 or 19 wherein the reactor has a solid plastic loading of 10wt% to 60wt%.
23.
The method as claimed in claim 22, wherein the solid plastic loading is 20wt% to 50wt%.
43
24.
The method as claimed in claim 16, wherein the solid plastic loading is 40wt%.
25.
The method as claimed in claim 19, wherein the solid plastic loading is 50wt%.
26.
The method as claimed in claim 16 or 19, wherein the catalyst is in an amount of 2wt% to 12wt%.
27.
The method as claimed in claim 26, wherein the catalyst is in amount of 5wt%.
28.
A method for converting waste plastic feedstock into aliphatic hydrocarbons, comprising the steps of:
a.
mixing waste plastic feedstock comprising plastic granules of polypropylene with water in a reactor;
b.
pressurizing the reactor with nitrogen gas;
c.
heating the reaction mixture of step (a) at a temperature of 400 ºC to 450 ºC till completion of reaction;
d.
cooling the reactor and collecting the gases and kerogen separately;
e.
washing the reactor walls and the magnetic stirrer with a dichloromethane to extract residual kerogen;
f.
filtering the kerogen obtained from steps (d) and (e) to separate into hydrochar and liquid phase;
g.
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h.
separating the oil phase of step (g) into crude oil and dichloromethane;
wherein the crude oil comprises aliphatic hydrocarbons which are linear and cyclic, and other chemicals.
29.
A method for converting waste plastic feedstock into linear aliphatic hydrocarbons, comprising the steps of:
a.
mixing waste plastic feedstock comprising plastic granules of low-density polyethylene with water in a reactor;
b.
pressurizing the reactor with nitrogen gas;
44
c.
heating the reaction mixture of step (a) at a temperature of 400 ºC to 450 ºC till completion of reaction;
d.
cooling the reactor and collecting the gases and kerogen separately;
e.
washing the reactor walls and the magnetic stirrer with a dichloromethane to extract residual kerogen;
f.
filtering the kerogen obtained from steps (d) and (e) to separate into hydrochar and liquid phase;
g.
separating the liquid phase of step (f) into an oil phase and an aqueous phase;
h.
separating the oil phase of step (g) into crude oil and dichloromethane;
wherein the crude oil comprises linear aliphatic hydrocarbons and other chemicals.
30.
The method as claimed in claim 28 or 29, wherein the reactor has a solid plastic loading of 10wt%.
31.
The method as claimed in claim 28 or 29, wherein in step (c), the reaction mixture is heated at a temperature of 450 ºC.

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