PROCESS FOR PURIFYING PYROLIZED PLASTIC WASTE

Abstract

The present invention relates to a process for purifying a pyrolyzed plastic waste, the process comprising the steps of providing the pyrolyzed plastic waste, wherein the pyrolyzed plastic waste is a liquid or a wax at 20° C. and 1 atm, contacting the pyrolyzed plastic waste with activated carbon yielding a pretreated 5 plastic waste and hydrogenating the pretreated plastic waste using hydrogen and a metal-based catalyst yielding a hydrogenated plastic waste suitable for steam cracking.

Claims

1. A process for purifying a pyrolyzed plastic waste, the process comprising the steps of: a) providing the pyrolyzed plastic waste, wherein the pyrolyzed plastic waste is a liquid or a wax at 20° C. and 1 atm; b) contacting the pyrolyzed plastic waste with activated carbon yielding a pretreated plastic waste, wherein step b) is carried out in a first vessel; c) hydrogenating the pretreated plastic waste using hydrogen and a metal-based catalyst yielding a hydrogenated plastic waste, wherein step c) is carried out in a second vessel.

2. The process according to claim 1, wherein the plastic waste comprises a waste comprising polyolefin, polyvinylchloride, polystyrene or a mixture thereof.

3. The process according to claim 1, wherein the metal-based catalyst comprises at least one metal and a carrier.

4. The process according to claim 3, wherein the carrier comprises a compound selected from a list consisting of silica, carbon and/or metal oxide and mixtures thereof.

5. The process according to claim 3, wherein the carrier comprises alumina.

6. The process according to claim 3, wherein the metal of the metal-based catalyst comprises a metal selected from a group 6 metal and/or a list of group 9-11 metals.

7. The process according to claim 6, wherein the metal of the metal-based catalyst comprises a metal selected from a list of group 10 metals.

8. The process according to claim 7, wherein the metal of the metal-based catalyst comprises palladium.

9. The process according to claim 3, wherein the metal-based catalyst comprises the metal in an amount of between 0.1 and 10 wt. %.

10. The process according to claim 1, wherein the metal-based catalyst is pre-activated.

11. The process according to claim 10, wherein the metal-based catalyst is pre-activated in the presence of hydrogen.

12. The process according to claim 1, wherein the step c) of hydrogenating is carried out at a temperature of from 200 to 400° C.

13. The process according to claim 1, wherein the step c) of hydrogenating is carried out at a Weight Hourly Space Velocity (WHSV) of from 0.1 to 100.0 1/h with respect to the amount of the pretreated plastic waste.

14. The process according to claim 1, wherein the hydrogen for conducting the hydrogenating step c) of the pretreated plastic waste is provided as gas with a pressure up to 100 bar.

15. The process according to claim 1, wherein the step b) is carried out with a Weight Hourly Space Velocity (WHSV) of from 0.1 to 50.0 1/h with respect to the amount of the pyrolyzed plastic waste.

Description

EXAMPLES

[0054] For the analysis of the pyrolyzed plastic waste a GC-MS (gas chromatography-mass spectrometry) and a GC-AED (gas chromatography-atomic emission detector) have been used.

[0055] The GC-MS analysis was performed on Agilent GC 6890 with MSD 5975B inert XL. The GC column was Agilent DB1 (60 m×0.25 mm i.d., film thickness 1.0 μm). The temperature of the column was held at 40° C. for 3 min and raised to 320° C. (5° C./min) and be held for 10 min. The injector was maintained at 350° C. with split ratio of 30:1. Injection volume of liquid sample was 1 μL. The carrier gas was helium and was set at a constant flow rate of 1 mL/min.

[0056] The GC-AED analysis was performed on Agilent GC-7890A with JAS AED. The GC column was Agilent DB1 (60 m×0.25 mm i.d., film thickness 1.0 μm). The temperature of the column was held at 40° C. for 3 min and raised to 320° C. (5° C./min) and be held for 10 min. The injector was maintained at 350° C. with split ratio of 10:1. Injection volume of liquid sample was 1 μL. The carrier gas was helium and was set at a constant flow rate of 1 mL/min. The reagent gases were O2, H2 and 10% CH4/90% N2 for oxygen.

[0057] A first set of experiments was conducted in a laboratory batch hydrogenation reactor.

Example 1

[0058] 3 g of a commercially available activated carbon from CarboTech AC GmbH with a surface area of 550 m.sup.2/g were added to 60 ml of pyrolysis oil, obtained from pyrolysis of non-recyclable, post-consumer mixed polyolefin waste with polyethylene, polypropylene and polystyrene as main constituents. The solution was then stirred for 1 h at room temperature.

Example 2

[0059] A Palladium-Alumina catalyst with 5 wt. % Pd was pre-activated for 1 hour under 30 bar of hydrogen at 250° C. The solution of example 1 (˜40 ml) was then added to an autoclave reactor upon 0.9 g of the preactivated catalyst. 30 bar of hydrogen was added and the solution was heated up to 300° C. under stirring. A constant supply of 30 bar hydrogen was provided.

TABLE-US-00001 TABLE 1 Activated Volume Catalyst Carbon solution Temp. Time WHSV Examples [g] [g] [ml] [° C.] [h] [1/h] H.sub.2 feed 1 0 3 60 25 1 18 none 2 0.9 0 40 300 1 40 continuous N.B.: a continuous H.sub.2 feed indicates a constant H.sub.2 feeding to the reactor (H.sub.2 valve to the reactor open)

[0060] The liquid was subsequently analysed via GC-MS and also GC-AED. The tables 2 and 3 present the hydrogenation on chemicals.

TABLE-US-00002 TABLE 2 3-methylhexa-2.4-diene 3-methylhexane Retention time Retention time Examples (min) Area % (min) Area % Original 19.68 0.09 12.70 0 2 19.68 0.03 12.70 0.03

TABLE-US-00003 TABLE 3 toluene methylcyclohexane Retention time Retention time Examples (min) Area % (min) Area % Original 19.25 0.77 17.90 0.07 2 19.25 0.56 17.90 0.14

[0061] The analysis of the identified impurities (N, S, Cl and O) and the effect of the precontact with activated carbon is presented in the table 4 below.

TABLE-US-00004 TABLE 4 Total N Total S Total Cl Total O Examples [ppm] [ppm] [ppm] [ppm] Original 912 0.7 531.3 1630.4 1 877.5 0.3 400.5 1531.2 2 521.8 0.0 58.8 1190.0

[0062] A further set of experiments was conducted in a laboratory batch hydrogenation reactor to analyze the several parameters such as amount of catalyst, reaction time, temperature of reaction, hydrogen feed.

Examples 3-7

[0063] A Palladium-Alumina catalyst with 5 wt. % Pd was pre-activated for 1 hour under 30 bar of hydrogen at 250° C. The solution of example 1 was then added to an autoclave reactor upon the preactivated catalyst. Hydrogen was added and the solution was heated under stirring. The examples 3 to 7 are recorded in table 5.

TABLE-US-00005 TABLE 5 Volume Catalyst solution Temp. Time WHSV Examples [g] [ml] [° C.] [h] [1/h] H.sub.2 feed 3 0.5 50 250 1 90 discontinuous 4 0.9 50 250 1 50 discontinuous 5 0.9 50 300 1 50 discontinuous 6 0.9 50 300 2.5 20 discontinuous 7 0.9 50 300 4 12.5 continuous N.B.: in table 5, the discontinuous H.sub.2 feed corresponds to one filling of the reactor with hydrogen (H.sub.2 valve to the reactor closed). A continuous H.sub.2 feed indicates a constant H.sub.2 feeding to the reactor (H.sub.2 valve to the reactor open).

[0064] The liquids of the examples 3 to 7 were subsequently analysed via GS-MS and also GC-AED. The tables 6 to 8 present the hydrogenation on chemicals.

TABLE-US-00006 TABLE 6 3-methylhexa-2.4-diene 3-methylhexane Retention time Retention time Examples (min) Area % (min) Area % Original 19.68 0.09 12.70 0.13 3 19.68 0.1 12.70 0.26 4 19.68 0.08 12.70 0.37 5 19.68 0.05 12.70 0.40 6 19.68 0.06 12.70 0.40 7 19.68 0.04 12.70 0.51

TABLE-US-00007 TABLE 7 heptene heptane Retention time Retention time Examples [min] Area % [min] Area % Original 16.24 0.48 16.73 0.38 3 16.24 0.12 16.73 0.51 4 16.24 0.03 16.73 0.78 5 16.24 0.02 16.73 0.82 6 16.24 0.17 16.73 0.64 7 16.24 0.04 16.73 0.90

TABLE-US-00008 TABLE 8 toluene methylcyclohexane Retention time Retention time Examples [min] Area % [min] Area % Original 19.25 0.77 17.90 0.07 3 19.25 0.7 17.90 0.09 4 19.25 0.62 17.90 0.12 5 19.25 0.69 17.90 0.11 6 19.25 0.71 17.90 0.11 7 19.25 0.63 17.90 0.16

[0065] The analysis of the identified impurities (N, S, Cl and O) is presented in the table 9 below.

TABLE-US-00009 TABLE 9 Total N Total S Total Cl Total O Examples [ppm] [ppm] [ppm] [ppm] Original 912 0.7 531.3 1630.4 3 1072.0 0.4 257.6 1586.0 4 1160.4 0.0 184.7 1457.6 5 756.1 0.0 122.4 1290.6 6 671.2 0.0 66.8 1116.6 7 647.4 0.0 83.2 1360.5

[0066] The term “Original” in the tables above refer to the non-treated pyrolysis oil.