ALKALI-ENHANCED HYDROTHERMAL PURIFICATION OF PLASTIC PYROLYSIS OILS

Abstract

A method is disclosed for preparing fuel components from waste pyrolysis oil. Exemplary embodiments include providing a waste pyrolysis oil having plastic pyrolysis oil and/or tyre pyrolysis oil, and impurities; purifying the waste pyrolysis oil by hydrothermal treatment with water or alkaline water; separating the hydrothermally treated waste pyrolysis oil from an aqueous phase; preparing a hydroprocessing feed from the hydrothermally treated waste pyrolysis oil; hydroprocessing the hydroprocessing feed catalytically with hydrogen to cause hydrogenation; and recovering a hydrocarbon fraction boiling in a liquid fuel range.

Claims

1. A method for preparing fuel components from waste pyrolysis oil (WPO), the method comprising: a) providing a waste pyrolysis oil, containing as a major part, plastic pyrolysis oil (PPO) and/or tyre pyrolysis oil (TPO), the waste pyrolysis oil including as the major part hydrocarbons, and including impurities formed as: chlorine compounds, containing at least 20 mg/kg chlorine of the WPO and/or up to 3500 mg/kg; nitrogen compounds, containing at least 50 mg/kg nitrogen of the WPO and/or up to 10,000 mg/kg; sulphur compounds, containing at least 10 mg/kg sulphur of the WPO and/or up to 15,000 mg/kg; b) purifying the waste pyrolysis oil by subjecting it to a hydrothermal treatment with water or with water having a pH above 7 at 150-450° C., where an oil to water ratio is selected to be at least one or more of from 9:1 to 1:9 (weight/weight), and/or from 4:1 to 1:1; c) separating the hydrothermally treated waste pyrolysis oil from an aqueous phase; d) preparing a hydroprocessing feed consisting essentially of the hydrothermally treated waste pyrolysis oil; or consisting essentially of a mixture of the hydrothermally treated waste pyrolysis oil and one or more feed(s) selected from a list consisting of oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon and hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon; e) hydroprocessing the hydroprocessing feed catalytically with hydrogen to cause hydrogenation, and/or one or more of hydrodeoxygenation (HDO), hydrodesulfurisation (HDS), hydrodenitrification (HDN), hydrodechlorination (HDCl), hydrodearomatization (HDAr), and hydroisomerisation (HI), at a temperature between 200 and 450° C. and at a pressure between 1 MPa and 25 MPa; and f) recovering from a hydroprocessed product at least one hydrocarbon fraction boiling in a liquid fuel range.

2. The method according to claim 1, wherein the WPO comprises: impurities formed as silicon compounds, containing at least 20 mg/kg silicon of the WPO and/or up to 2000 mg/kg, and/or impurities formed as bromine compounds, containing at least 10 mg/kg bromine of the WPO and/or up to 2000 mg/kg.

3. The method according to claim 1, wherein the further comprises: impurities formed as silicon compounds, containing at least 20 mg/kg silicon of the WPO and/or up to 2000 mg/kg, wherein in step b) the hydrothermal treatment is conducted so as to cause at least a 50% reduction of silicon compounds of the WPO; or at least a 50% reduction of chlorine compounds of the WPO; or at least a 50% reduction of silicon compounds of the WPO, and at least a 50% reduction of chlorine compounds of the WPO, and/or where silicon in the hydrothermally treated WPO are below 20 mg/kg, and/or where oxygen in the hydrothermally treated WPO are is above 20 mg/kg.

4. The method according to claim 1, wherein in step b) water having a pH above 7 contains one or more cations selected from a list consisting of: alkali metals, Li, Na, K, Rb, Cs, alkaline earth metals, and/or Mg, Ca, Sr, Ba.

5. The method according to claim 1, wherein the hydroprocessing feed consists essentially of: a mixture of the hydrothermally treated waste pyrolysis oil and one or more feed(s) selected from a list consisting of oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon and hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon.

6. The method according to claim 1, wherein the hydroprocessing feed consists essentially of: a mixture of the hydrothermally treated waste pyrolysis oil, oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon, and hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon.

7. The method according to claim 1, wherein the hydroprocessing feed consists essentially of a mixture of: 1-100 wt % of hydrothermally treated waste pyrolysis oil, 0-40 wt % of the oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon; and 0-99 wt % of hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon.

8. The method according to claim 1, wherein the hydroprocessing feed consists essentially of a mixture of: 1-10 wt % of the hydrothermally treated waste pyrolysis oil; 1-40 wt % of the oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon; and 50-98 wt % of the hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon.

9. The method according to claim 1, wherein in step d) at least 80 wt % of the hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon are recycled product obtained from step f).

10. The method according to claim 1, wherein in step d) the hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon also have less than 1 wt % olefins.

11. The method according to claim 1, wherein in step f) the at least one hydrocarbon fraction boiling in the liquid fuel range is diesel and/or gasoline and/or naphtha.

12. The method according to claim 1, wherein in step e) the hydroprocessing is conducted in a fixed bed reactor.

13. The method according to claim 1, wherein the hydroprocessing reaction conditions comprise: a temperature in a range from 270 to 390° C., a pressure in a range from 2 MPa to 8 MPa, a WHSV in a range from 0.1-10 h.sup.−1, and a H.sub.2 flow of 50-2000 nl H.sub.2/l feed.

14. The method according to claim 13, wherein the reaction conditions comprise: a presence of a hydrodeoxygenation catalyst, and/or NiMo on an alumina support.

15. The method according to claim 1, wherein the hydroprocessing reaction conditions comprise: conditions suitable for isomerisation, which reaction conditions include a temperature in a range from 250 to 450° C., a pressure in a range from 1 MPa to 6 MPa, a WHSV in a range from 0.1 to 10 h.sup.−1, and a H.sub.2 flow of 50 to 2000 nl H.sub.2/l feed, in a presence of an isomerisation catalyst, and/or a catalyst containing a Group VIII metal and a molecular sieve, and/or on an alumina and/or silica support.

16. The method according to claim 2, wherein the further comprises: impurities formed as silicon compounds, containing at least 20 mg/kg silicon of the WPO and/or up to 2000 mg/kg, wherein in step b) the hydrothermal treatment is conducted so as to cause at least a 50% reduction of silicon compounds of the WPO; or at least a 50% reduction of chlorine compounds of the WPO; or at least a 50% reduction of silicon compounds of the WPO, and at least a 50% reduction of chlorine compounds of the WPO, and/or where silicon in the hydrothermally treated WPO are below 20 mg/kg, and/or where oxygen in the hydrothermally treated WPO is above 20 mg/kg.

17. The method according to claim 16, wherein in step b) water having a pH above 7 contains one or more cations selected from a list consisting of: alkali metals, Li, Na, K, Rb, Cs, alkaline earth metals, and/or Mg, Ca, Sr, Ba.

18. The method according to claim 17, wherein the hydroprocessing feed consists essentially of: a mixture of the hydrothermally treated waste pyrolysis oil and one or more feed(s) selected from a list consisting of oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon and hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon.

19. The method according to claim 18, wherein the hydroprocessing feed consists essentially of: a mixture of the hydrothermally treated waste pyrolysis oil, oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon, and hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon.

20. The method according to claim 19, wherein the hydroprocessing feed consists essentially of a mixture of: 1-100 wt % of hydrothermally treated waste pyrolysis oil, 0-40 wt % of the oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon; and 0-99 wt % of hydrocarbons having less than 50 mg/kg chlorine and less than 1 mg/kg silicon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0040] In describing the embodiments of the invention, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.

[0041] When describing the embodiments of the present invention, the combinations and permutations of all possible embodiments have not been explicitly described. Nevertheless, the mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage. The present invention envisages all possible combinations and permutations of the described embodiments.

[0042] The terms “comprising”, “comprise” and comprises herein are intended by the inventors to be optionally substitutable with the terms “consisting of”, “consist of” and “consists of”, respectively, in every instance.

[0043] According to the method of the invention, the WPO comprises as a major part PPO and/or TPO that comprises hydrocarbons as their major part. The major part constitutes for example at least 75 wt % PPO and/or TPO in the WPO, such as at least 80 wt %, e.g. at least 85 wt %, at least 90 wt %, at least 95 wt %, or at least 98 wt %. The hydrocarbons constitute for example at least 75 wt % of the WPO, such as at least 80 wt %, e.g. at least 85 wt %, at least 90 wt %, at least 95 wt %, or at least 98 wt % of the WPO.

[0044] The impurities in the WPO in the form of chlorine compounds constitute at least 20 mg/kg chlorine of the WPO, such as at least 50 mg/kg, e.g. at least 100 mg/kg, at least 200 mg/kg, at least 300 mg/kg, at least 400 mg/kg, at least 500 mg/kg, at least 1000 mg/kg, at least 1500 mg/kg, at least 2000 mg/kg, at least 2500 mg/kg, at least 3000 mg/kg, and up to 3500 mg/kg.

[0045] The impurities in the WPO in the form of nitrogen compounds constitute at least 50 mg/kg nitrogen of the WPO, e.g. at least 100 mg/kg, at least 200 mg/kg, at least 300 mg/kg, at least 400 mg/kg, at least 500 mg/kg, at least 1000 mg/kg, at least 2000 mg/kg, at least 3000 mg/kg, at least 5000 mg/kg, at least 7000 mg/kg, and up to 10,000 mg/kg.

[0046] The impurities in the WPO in the form of sulphur compounds constitute at least 10 mg/kg sulphur of the WPO, such as at least 20 mg/kg, e.g. at least 50 mg/kg, at least 100 mg/kg, at least 200 mg/kg, at least 300 mg/kg, at least 400 mg/kg, at least 500 mg/kg, at least 1000 mg/kg, at least 2000 mg/kg, at least 3000 mg/kg, at least 5000 mg/kg, at least 7000 mg/kg, at least 10,000 mg/kg, and up to 15,000 mg/kg.

[0047] During the hydrothermal treatment, the pH in the water may be adjusted to above 7 be adding any convenient base, such as NaOH, KOH, LiOH, Ca(OH).sub.2, Mg(OH).sub.2, Ba(OH).sub.2, preferably NaOH.

[0048] During the hydrothermal treatment, the temperature is from 150 to 450° C., such as from 175 to 425° C., e.g. from 200 to 400° C., from 225 to 375° C., from 250 to 350° C., from 275 to 325° C., or from 250 to 300° C.

[0049] During the hydrothermal treatment, the oil to water ratio (weight/weight) is from 9:1 to 1:9, such as from 4:1 to 1:1, e.g. 2:1.

[0050] In a first embodiment of the method of the invention, the WPO may further comprise impurities in the form of silicon compounds, comprising at least 20 mg/kg silicon of the WPO, such as at least 30 mg/kg, at least 40 mg/kg, at least 50 mg/kg, at least 60 mg/kg, at least 70 mg/kg, at least 80 mg/kg, at least 90 mg/kg, at least 100 mg/kg, at least 150 mg/kg, at least 200 mg/kg, at least 300 mg/kg, at least 400 mg/kg, at least 500 mg/kg, at least 600 mg/kg, at least 700 mg/kg, at least 800 mg/kg, at least 900 mg/kg, at least 100 mg/kg, at least 1500 mg/kg, and up to 2000 mg/kg; and/or impurities in the form of bromine compounds, comprising at least 10 mg/kg bromine of the WPO, such as at least 20 mg/kg, at least 30 mg/kg, at least 40 mg/kg, at least 50 mg/kg, at least 60 mg/kg, at least 70 mg/kg, at least 80 mg/kg, at least 90 mg/kg, at least 100 mg/kg, at least 150 mg/kg, at least 200 mg/kg, at least 300 mg/kg, at least 400 mg/kg, at least 500 mg/kg, at least 600 mg/kg, at least 700 mg/kg, at least 800 mg/kg, at least 900 mg/kg, at least 1000 mg/kg, at least 1500 mg/kg, and up to 2000 mg/kg.

[0051] In any of the embodiments of the invention, the WPO may further comprise impurities in the form of silicon compounds, comprising at least 20 mg/kg silicon and up to 2000 mg/kg, and the hydrothermal treatment in step b) may be conducted so as to cause at least a 50% reduction of silicon compounds of the waste pyrolysis oil and/or at least a 50% reduction of chlorine compounds, optionally whereby the silicon in the hydrothermally treated waste pyrolysis oil are below 20 mg/kg, and/or whereby the oxygen in the hydrothermally treated waste pyrolysis oil are above 20 mg/kg.

[0052] In any of the embodiments of the invention, the water used in step b) having a pH above 7 may contain one or more cations selected from the list consisting of: alkali metals, such as Li, Na, K, Rb, Cs, and alkaline earth metals, such as Mg, Ca, Sr, and Ba.

[0053] In any of the embodiments of the invention, the hydroprocessing feed may consist essentially of a mixture of the hydrothermally treated waste pyrolysis oil and one or more of the list consisting of: oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon and hydrocarbons having less than 5 mg/kg chlorine and less than 1 mg/kg silicon.

[0054] In any of the embodiments of the invention, the hydroprocessing feed may consist essentially of a mixture of the hydrothermally treated waste pyrolysis oil, oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon, and hydrocarbons having less than 5 mg/kg chlorine and less than 1 mg/kg silicon.

[0055] In any of the embodiments of the invention, the hydroprocessing feed may consist essentially of a mixture of: [0056] 1-100 wt % of the hydrothermally treated waste pyrolysis oil, such as 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95 wt %; [0057] 0-40 wt % of the oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon, such as 1-30 wt %, e.g. 5-25 wt %, or 10-20 wt %; and [0058] 0-99 wt % of the hydrocarbons, such as 2, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 90, or 95 wt %, having less than 5 mg/kg chlorine and less than 1 mg/kg silicon.

[0059] In any of the embodiments of the invention, the hydroprocessing feed may consist essentially of a mixture of: [0060] 1-10 wt % of the hydrothermally treated waste pyrolysis oil, such as 2, 3, 4, 5, 6, 7, 8, 9, or 10 wt %; [0061] 1-40 wt % of the oxygen-containing biological oils having less than 50 mg/kg chlorine and less than 1 mg/kg silicon, such as 5-30 wt %, e.g. 10-25 wt %, or 15-20 wt %; and [0062] 50-98 wt % of the hydrocarbons, such as 55-95 wt %, e.g. 60-90 wt %, or 70-80 wt %, having less than 5 mg/kg chlorine and less than 1 mg/kg silicon.

[0063] In any of the embodiments of the invention, in step d) at least 80 wt % of the hydrocarbons having less than 5 mg/kg chlorine and less than 1 mg/kg silicon, such as at least 85 wt %, e.g. at least 90 wt % or at least 95 wt %, may be recycled product obtained from step f).

[0064] In any of the embodiments of the invention, in step d) the hydrocarbons having less than 5 mg/kg chlorine and less than 1 mg/kg silicon may further also have less than 1 wt % olefins.

[0065] In any of the embodiments of the invention, in step f) the at least one hydrocarbon fraction boiling in the liquid fuel range may be diesel and/or gasoline and/or naphtha.

[0066] In any of the embodiments of the invention, in step e) the hydroprocessing may be conducted in a fixed bed reactor.

[0067] In any of the embodiments of the invention, the hydroprocessing reaction conditions may comprise a temperature in the range from 270 to 390° C., such as 280° C., 290° C., 300° C., 310° C., 320° C., 330° C., 340° C., 350° C., 360° C., 370° C., or 380° C., depending of the nature of the hydrocarbon and the biological oil in the mixture, a pressure in the range from 2 to 8 MPa, and a WHSV in the range from 0.1-10 h.sup.−1, preferably from 0.5 to 5 h.sup.−1, and a H.sub.2 flow of 50 to 2000 nl H.sub.2/l feed, preferably from 100 to 900 nl H.sub.2/l feed, in the presence of a hydrodeoxygenation catalyst, such as NiMo on an alumina support.

[0068] In any of the embodiments of the invention, the hydroprocessing reaction conditions may comprise conditions suitable for isomerisation, which reaction conditions comprise a temperature in the range from 250 to 450° C., such as 300 to 400° C., a pressure in the range from 1 to 6 MPa, such as 2 to 5 MPa, and a WHSV in the range from 0.1 to 10 h.sup.−1, preferably from 0.5 to 5 h.sup.−1, more preferably from 0.5 to 3 h.sup.−1, and a H.sub.2 flow of from 50 to 2000 nl H.sub.2/l feed, preferably from 100 to 900 nl H.sub.2/l feed, more preferably from 100 to 800 nl H.sub.2/l feed, in the presence of an isomerisation catalyst, such as a catalyst comprising a Group VIII metal and a molecular sieve, optionally on an alumina and/or silica support.

EXAMPLES

Example 1

[0069] High Temperature NaOH Treatment of Waste Plastic Pyrolysis Oil Naphtha Fraction

[0070] The following experiment was carried out in a 1-litre batch autoclave reactor. A distilled naphtha fraction (5-95 wt % distillation range 85-174° C.) derived from waste plastic pyrolysis oil (340 g) and the 2 wt % aqueous NaOH (227 g) were weighed together into the reactor vessel. After sealing and pressure testing, the reactor that was stirred at 500 rpm was heated to the desired reaction temperature of 240° C., which was then maintained for 30 min. The reactor was subsequently cooled down to room temperature before recovery of products. The contents were decanted from the reactor vessel into centrifugation tubes, and the liquids were centrifuged at 20° C. and 4300 rpm for 30 minutes. After the centrifugation, the purified pyrolysis oil was recovered as a separate layer, and analysed for its Cl, Br, S, and N content. Cl, Br, and S content was determined using X-ray fluorescence spectroscopy, and N content was determined according to standard ASTM D 5762. The results, which are presented in Table 1, show that the content of both CI and Br is reduced by more than 90%.

TABLE-US-00001 TABLE 1 Impurity content of waste plastic pyrolysis oil naphtha fraction before and after 30 min treatment with 2 wt-% aqueous sodium hydroxide at 240° C. Original Purified waste waste plastic plastic pyrolysis pyrolysis oil naphtha oil naphtha Decrease fraction fraction (%) N (mg/kg) 500 25 95 Cl (mg/kg) 590 36 94 Br (mg/kg) 213  7 97 S (mg/kg)  89 80 10

Example 2

[0071] High Temperature NaOH Treatment of Waste Plastic Pyrolysis Oil Naphtha Fraction

[0072] The following experiment was carried out in a 1-litre batch autoclave reactor. A distilled naphtha fraction (5-95 wt % distillation range 85-174° C.) derived from waste plastic pyrolysis oil (340 g) (obtained commercially from Ecomation) and the 2 wt % aqueous NaOH (227 g) were weighed together into the reactor vessel. After sealing and pressure testing, the reactor that was stirred at 500 rpm was heated to the desired reaction temperature of 240° C., which was then maintained for 30 min. The reactor was subsequently cooled down to room temperature before recovery of products. The contents were decanted from the reactor vessel into centrifugation tubes, and the liquids were centrifuged at 20° C. and 4300 rpm for 30 minutes. After the centrifugation, the purified pyrolysis oil was recovered as a separate layer, and analysed for its Cl, Br, S, N and Si content. Cl, Br, and S content was determined using X-ray fluorescence spectroscopy, and N content was determined according to standard ASTMD5762. The silicon content was analysed using inductively coupled plasma mass spectrometry. The results, which are presented in Table 2, clearly show that the content of Cl, Br and Si decreased by more than 90%.

TABLE-US-00002 TABLE 2 Impurity content of waste plastic pyrolysis oil naphtha fraction before and after 30 min treatment with 2 wt-% aqueous sodium hydroxide at 240° C. Original Purified waste waste plastic plastic pyrolysis pyrolysis oil naphtha oil naphtha Decrease fraction fraction (%) N (mg/kg 500 65 87 Cl (mg/kg) 590 28 95 Br (mg/kg) 213  7 97 S (mg/kg)  89 87  2 Si (mg/kg) 230  2 99

Example 3

[0073] Solvent Extraction of Waste Plastic Pyrolysis Oil Middle Distillate Fraction

[0074] In this example, impurities were removed from a waste plastic pyrolysis oil middle distillate fraction (5-95 wt % distillation range 172-342° C.) using solvent extraction with N-methyl-2-pyrrolidone (NMP). The waste plastic pyrolysis oil (100 g) was first mixed with NMP containing 2 wt % water (196 g NMP, 4 g water) in a glass separation funnel at ambient temperature. After mixing, the raffinate and extract were allowed to separate. The raffinate, which in this case represents the purified waste plastic pyrolysis oil, was subjected to the same extraction treatment two more times (3 extraction steps in total). After the third extraction step, the raffinate was washed with water at ambient temperature in a glass separation funnel using a water-to-oil ratio of 2:1 (w/w). The water-washed raffinate, i.e. the purified pyrolysis oil middle distillate fraction, was analysed for its Cl, Br, S and N content. Cl, Br and S content was determined using X-ray fluorescence spectroscopy, and N content was determined according to standard ASTM D 5762. The results in Table 3 show CI and Br content were both reduced by more than 90% as a result of the solvent extraction treatment.

TABLE-US-00003 TABLE 3 Impurity content of waste plastic pyrolysis oil middle distillate fraction before and after solvent extraction with N-methyl-2-pyrrolidone and water washing. Original Purified waste waste plastic plastic pyrolysis pyrolysis oil middle oil middle distillate distillate Decrease fraction fraction (%) N (mg/kg) 810 24 97 Cl (mg/kg) 590 40 93 Br (mg/kg) 325 14 96 S (mg/kg) 695 35 95