PROCESS FOR CONVERTING PLASTIC INTO WAXES BY CRACKING AND A MIXTURE OF HYDROCARBONS OBTAINED THEREBY

Abstract

The present invention relates to a process for converting plastic into waxes by cracking. The process comprises the steps of introducing the plastic within a reactor; allowing at least a portion of the plastic to be converted to waxes, the waxes being part of a pyrolysis gas formed within the reactor; and removing a product stream containing said waxes from the reactor. The invention also relates to a mixture of hydrocarbons obtainable by that process.

Claims

1. A process for converting plastic into waxes by cracking, the process comprising: introducing the plastic within a reactor; allowing at least a portion of the plastic to be converted to waxes, the waxes being part of the pyrolysis gas formed within the reactor; and removing a product stream containing said waxes from the reactor; wherein the pyrolysis gas has a residence time at a temperature above 370 C. of less than 60 seconds.

2. (canceled)

3. (canceled)

4. The process according to claim 1, wherein the reactor is operated at a pressure of 60 to 950 mbar.

5. The process according to claim 1, wherein the pyrolysis gas is diluted with a diluent, where the diluent is selected from the group consisting of nitrogen, hydrogen, steam, carbon dioxide, combustion gas and mixtures thereof.

6. The process according to claim 5, wherein the molar ratio of diluent to pyrolysis products in the pyrolysis gas is in the range of 0.7 to 40.

7. The process according to claim 1, wherein the conversion of at least a part of the plastic to waxes is conducted in the presence of a heat carrier, wherein the heat carrier comprises sand particles.

8.-11. (canceled)

12. The process according to claim 1, wherein the residence time of condensed material in the reactor is between 10 and 600 min.

13. The process according to claim 1, wherein the process is conducted continuously.

14. The process according to, claim 1 wherein the plastic is waste plastic.

15. (canceled)

16. A mixture of hydrocarbons, wherein the hydrocarbons exhibit a cumulative distribution of their number of carbon atoms such that 20d20 and 50d50; 50 mol % of the hydrocarbons are linear hydrocarbons; and the molar ratio of n-paraffins to alpha-olefins among the hydrocarbons is in the range of 0.1 to 10.

17.-20. (canceled)

21. The mixture according to claim 16, wherein the hydrocarbons exhibit a cumulative distribution of their number of carbon atoms such that 20d2040 and 50d5020.

22. The mixture according to claim 16, wherein the molar ratio of n-paraffins to alpha-olefins among the hydrocarbons is in the range of 0.5 to 2, and 70 mol % of the hydrocarbons are linear hydrocarbons.

23.-25. (canceled)

26. The mixture according to claim 16, having an iodine number in the range of 25 to 100.

27. The mixture according to claim 16, having a drop point of >40 C.

28. (canceled)

29. A wax obtained by the process according to claim 1, which is a mixture of hydrocarbons, wherein the hydrocarbons exhibit a cumulative distribution of their number of carbon atoms such that 20d20 and 50d50: 50 mol % of the hydrocarbons are linear hydrocarbons; and the molar ratio of n-paraffins to alpha-olefins among the hydrocarbons is in the range of 0.1 to 10.

30. (canceled)

31. A bituminous mixture, superficial wear coating, asphalt or sealing coating comprising the mixture according to claim 16.

32. A process for producing the mixture according to claim 16 by subjecting plastic to cracking, the process comprising: introducing the plastic within a reactor; allowing at least a portion of the plastic to be converted to waxes, at least part of the waxes being part of the pyrolysis gas formed within the reactor; and removing a product stream containing said waxes being part of the pyrolysis gas formed within the reactor from the reactor to obtain said mixture; wherein the pyrolysis gas has a residence time at a temperature above 370 C. of less than 60 seconds.

33. (canceled)

34. The process according to claim 1, wherein the pyrolysis gas has a residence time at a temperature above 370 C. of more than 5 seconds and less than 40 seconds.

35. The process according to claim 1, wherein the temperature at which at least a portion of the plastic is converted to waxes is in the range of 440 to 520 C.

36. The process according to claim 1, wherein the residence time of condensed material in the reactor is between 20 and 400 min.

37. The process according to claim 1, wherein the pyrolysis gas has a residence time at a temperature above 370 C. of more than 5 seconds and less than 40 seconds; the temperature at which at least a portion of the plastic is converted to waxes is in the range of 440 to 520 C.; the residence time of condensed material in the reactor is between 20 and 400 min.

Description

FIGURES

[0089] FIG. 1 schematically shows a first embodiment of the process of the present invention.

[0090] FIG. 2 schematically shows a second embodiment of the process of the present invention.

[0091] FIG. 3 shows the evolution of conversion (as %, y-axis) as function of reaction time (expressed in minutes, x-axis) at different temperatures: 425 C. (square-marked line), 450 C. (circle-marked line) and 465 C. (triangular-marked line).

[0092] FIG. 4 shows the cumulative selectivity (expressed as %, y-axis) of the different reaction products (listed in the x-axis) at different temperatures: 425 C. (white bars), 450 C. (black-white pattern fill bars) and 465 C. (black bars).

[0093] FIG. 5 shows the wax cumulative selectivity (expressed as %, y-axis) as function of the pyrolysis gas residence time (expressed in seconds, x-axis).

[0094] FIG. 6 shows the carbon number distribution of the waxes. The plot shows the weight percentage (wt %, y-axis) as function of carbon chain length (expressed as a number, x-axis) for different reaction temperatures: 425 C. (square-marked line), 450 C. (circle-marked line) and 465 C. (triangular-marked line).

[0095] FIG. 7 shows the conversion (expressed as %, y-axis) as function of reaction time (expressed in minutes) for different temperatures and inlet N.sub.2 flow rates: 450 C. and 150 mL/min N.sub.2 (empty-circle-marked line), 465 C. and 150 mL/min N.sub.2 (empty-triangular-marked line), 450 C. and 1 L/min N.sub.2 (full-circle-marked line), 465 C. and 1 L/min N.sub.2 (full-triangular-marked line), 465 C. and 2 L/min N.sub.2 (empty-rhombus-marked line), 465 C. and 4 L/min N.sub.2 (empty-square-marked line).

[0096] FIG. 8 shows the cumulative selectivity (expressed as %, y-axis) of the different reaction products (listed in the x-axis) at different temperatures and N.sub.2 flow rate. Legend: for each product, starting from left to the right the color of the bars refer to 450 C. and 150 mL/min, 450 C. and 1 L/min, 465 C. and 150 mL/min, 465 C. and 1 L/min, 465 C. and 2 L/min, 465 C. and 4 L/min.

[0097] FIG. 9 shows the waxes cumulative selectivity (expressed as %, y-axis) as function of the pyrolysis gas residence time (expressed in seconds, x-axis) for two reaction temperatures: 450 C. (circled-marked line) and 465 C. (square-marked line).

[0098] FIG. 10 shows the carbon number distribution of the waxes. The plot shows the weight percentage (wt %, y-axis) as function of carbon chain length (expressed as a number, x-axis) for different reaction temperatures and N.sub.2 inlet flow: 450 C. and 150 mL/min (circled-marked line), 465 C. and 150 mL/min (triangular-marked line), 450 C. and 1 L/min (x-marked line), 465 C. and 1 L/min (+-marked line), 465 C. and 2 L/min (rhombus-marked line), 465 C. and 4 L/min (square-marked line).

[0099] FIG. 11 shows the conversion (expressed as %, y-axis) as function of reaction time (expressed in minutes) for different type and flows of N.sub.2 inlet feed: 150 mL/min up (circle-marked line), 1 L/min up (rhombus-marked line), 1 L/min down (triangular-marked line) and 4 L/min up/down (1 L/min up and 3 L/min down, square-marked line).

[0100] FIG. 12 shows the cumulative selectivity (expressed as %, y-axis) of the different reaction products (listed in the x-axis) for different type and flows of N.sub.2 inlet feed. Legend: for each product, starting from left to the right the color of the bars refer to 150 mL/min up, 1 L/min up, 1 L/min down, 4 L/min up/down (1 L/min up and 3 L/min down).

[0101] FIG. 13 shows the waxes cumulative selectivity (expressed as %, y-axis) as function of the pyrolysis gas residence time (expressed in seconds, x-axis).

[0102] FIG. 14 shows the carbon number distribution of the waxes. The plot shows the weight percentage (wt %, y-axis) as function of carbon chain length (expressed as a number, x-axis)) for different type and flows of N.sub.2 inlet feed: 150 mL/min up (circle-marked line), 1 L/min up (rhombus-marked line), 1 L/min down (triangular-marked line) and 4 L/min up/down (1 L/min up and 3 L/min down, square-marked line).

[0103] The process of the invention will now be illustrated by way of example with reference to FIGS. 1 and 2.

[0104] In a first embodiment, schematically presented in FIG. 1, the pyrolysis of the raw material to produce waxes is realized under vacuum in an oxygen depleted atmosphere. The raw material 1 is pretreated by a combination of physico-chemical treatment 2 that separates an effluent stream 3 and the pretreated raw material 4. The pretreated raw material 4 is introduced with the help of the feeding device 5 in the pyrolysis reactor 10 through the line 6. The pyrolysis reactor is indirectly heated. Without limiting the scope, as example the reactor can be heated by the circulation of a hot stream 7 fed to a suitable heat transfer device 8 and recovered at the outlet as the stream 9. Optionally, a heat carrier stream 11 is introduced in the pyrolysis reactor. The pyrolysis gas 12 is recovered from the pyrolysis reactor and sent to a physic-chemical treatment 20. The residue 13 is recovered through the device 14 where it is treated in an adequate way to produce the stream 15. The residue contains the unconverted raw material, by product and optionally the heat carrier introduced in the pyrolysis reactor through the stream 11. In the physico-chemical treatment the pyrolysis gas is cleaned from dust and other detrimental components recovered in stream 21 and separated as a stream 22 that is sent to the treatment 25 where a incondensable stream 24 is separated from the condensate stream 23. The stream 24 is sent to a vacuum device 26. The effluent 27 from the vacuum device is sent to the combustion chamber 28 together with an adequate quantity of combustion air (29) to produce a hot stream 7. Optionally, an auxiliary fuel 30 is added to the combustion chamber 28. The condensate stream 23 is sent to the separation unit 31 where the waxes stream 32 is separated from the by-products 33.

[0105] In a second embodiment, the pyrolysis of the raw material to produce waxes realized under vacuum in the presence of a diluent gas is as an example schematically shown in FIG. 2. The pyrolysis of the raw material to produce waxes is realized under vacuum in an oxygen depleted atmosphere. The raw material 51 is pretreated by a combination of physico-chemical treatment 52 that separates an effluent stream 53 and the pretreated raw material 54. The pretreated raw material 54 is introduced with the help of the feeding device 55 in the pyrolysis reactor 60 through the line 56. The pyrolysis reactor is indirectly heated. Without limiting the scope, as example the reactor can be heated by the circulation of a hot stream 57 fed to a suitable heat transfer device 58 and recovered at the outlet as the stream 59. Optionally, a heat carrier stream 61 is introduced in the pyrolysis reactor. A gaseous diluent 66 is introduced at a controlled rate in the reactor 60. The pyrolysis gas in mixture with the diluent 62 is recovered from the pyrolysis reactor and sent to a physic-chemical treatment 70. The residue optionally in mixture with the heat carrier 63 is recovered through the device 64 where it is treated in an adequate way to produce the stream 65. The residue contains the unconverted raw material, by product and optionally the heat carrier introduced in the pyrolysis reactor through the stream 61. In the physico-chemical treatment the pyrolysis gas is cleaned from dust and other detrimental components recovered in stream 71 and separated as a stream 72 that is sent to the treatment 75 where an incondensable stream 74 is separated from the condensate stream 73. The stream 74 is sent to a vacuum device 76. The effluent 77 from the vacuum device is sent to the combustion chamber 78 together with an adequate quantity of combustion air (79) to produce a hot stream 57. Optionally, an auxiliary fuel 80 is added to the combustion chamber 78. The condensate stream 73 is sent to the separation unit 81 where the waxes stream 82 is separated from the by-products 83.

[0106] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

EXAMPLES

[0107] General Description of the Experimental Procedure

[0108] In each run in semi-batch mode, 30 g of plastic (20% polypropylene, 80% polyethylene) were loaded inside the reactor and a defined amount of heat carrier (SiO.sub.2, approximately 20 g) is stored in the heat carrier storage tank. The reactor was closed and heated from room temperature to 200 C. during 20 minutes, while simultaneously purging with a 150 mL/min nitrogen flow, which was introduced at the top of the reactor vessel. When the internal temperature reached the melting point of the plastic, stirring was started and slowly increased to 690 rpm. The temperature was held at 200 C. for 25-30 minutes. During this heating process, nitrogen coming out from the reactor was not collected. Meanwhile, the heat carrier storage tank containing the heat carrier was purged with nitrogen several times.

[0109] After this first pretreatment step, temperature was increased to the reaction temperature at a heating rate of 10 C./min, and the collection of gases and nitrogen in the corresponding gas sampling bag was started. When the internal temperature reached the reaction temperature, the heat carrier was introduced inside the reactor. Depending on the experiments, the nitrogen gas flow was set to 150 mL/min or adjusted to 1, 2 or 4 L/min, and the circulation of the gaseous products was commuted to another pair of glass traps and corresponding gas sampling bag. This was considered as the zero reaction time. Depending on the experiments, nitrogen can enter the reactor in two ways: at the top of the vessel or bubbled through the melted plastic.

[0110] During selected time periods, liquid and gaseous products were collected in a pair of glass traps and their associated gas sampling bag, respectively. At the end of the experiment the reactor was cooled to room temperature. During this cooling step, liquids and gases were also collected.

[0111] The reaction products were classified into 3 groups: i) gases, ii) liquid hydrocarbons and iii) residue (waxy compounds, ashes and coke accumulated on the heat carrier). Quantification of the gases was done by gas chromatography (GC) using nitrogen as the internal standard, while quantification of liquids and residue was done by weight. Glass traps (along with their corresponding caps) were weighed before and after the collection of liquids, while the reactor vessel was weighed before and after each run.

[0112] The simulated distillation (SIM-DIS) GC method allowed determination of the different fractions in the liquid samples (according to the selected cuts), the detailed hydrocarbon analysis (DHA) GC method allowed determination of the PIONAU components in the gasoline fraction of the last withdrawn sample (C5-C11: Boiling point <216.1 C.; what includes C5-C6 in the gas sample and C5-C11 in the liquid samples), and GCxGC allowed the determination of saturates, mono-, di- and tri-aromatics in the diesel fraction of the last withdrawn liquid samples (C12-C21; 216.1<BP<359 C.).

[0113] In all experimental cases, the residence time of the pyrolysis gas was calculated using a reactor volume of 300 mL, a raw plastic density of 0.94 g/mL, a bulk density of the silica of 1.1 g/mL. This leads to a gas hold-up of 250 mL.

[0114] In the examples, HCO refers to heavy cycle oil which is considered as hydrocarbon molecules with at least 22 carbon atoms (+C22). Waxes refer to hydrocarbon molecules with at least 20 carbon atoms (+C20). In general: [0115] Gasolines: contains C5s and C6s in gases+liquids with bp (boiling point) <150 C. (ca. C5-C9) [0116] Kerosene: liquids with boiling point 150<by <250 C. (ca. C10-C14) [0117] Diesel: liquids with boiling point 250<by <359 C. (ca. C15-C21) [0118] HCO: products with boiling point >359 C. (C22 and +) [0119] Waxes: products with boiling point >330 C. (C20 and +)

[0120] Determination of the different fractions is done by gas chromatography by the simulated distillation method and according to the ASTM-D-2887 standard.

[0121] General Description of the Analytical Methods

[0122] Measurement of the Number of Carbon Atoms

[0123] The number of carbon atoms and their distribution in a mixture of hydrocarbons is measured using the ASTM-D-2887 method. This method is a GC method for the simulated-distillation of complex hydrocarbon mixtures. The method allows separation of the hydrocarbon molecules in a complex mixture according to their boiling point. The boiling point is then related to the carbon number according to defined cut points. In the present invention, the relationship between boiling point and carbon number as defined in table 1 below is used.

TABLE-US-00001 TABLE 1 Carbon Boiling number point ( C.) 10 150.8-174.1 11 174.1-195.9 12 195.9-216.3 13 216.3-235.4 14 235.4-253.5 15 253.5-270.6 16 270.6-286.8 17 286.8-302 18 302-317 19 317-330 20 330-342.7 21 342.7-359 22 359-368.5 23 368.5-380 24 380-391.3 25 391.3-401 18 302-317 19 317-330 20 330-342.7 21 342.7-359 22 359-368.5 23 368.5-380 24 380-391.3 25 391.3-401 26 401-412.2 27 412.2-422 28 422-431.6 29 431.6-440.8 30 440.8-449.7 31 449.7-458 32 458-467 33 467-474 34 474-482 35 482-490 36 490-497.1 37 497.1-504.1 38 504.1-510.9 39 510.9-517.5 40 517.5-523.9 41 523.9-530.8 42 530.8-536.1 43 536.1-541.9 44 541.9-547.6 45 547.6-553.1 46 553.1-558.4 47 558.4-563.6 48 563.6-568.7 49 568.7-573.6 50 573.6-578.4 51 578.4-583 52 583-587.6 53 587.6-592 54 592-596.4 55-80 596.4-680 >70 >647.2 >80 >680

[0124] Those fractions having a boiling point below 105.8 C. are defined as hydrocarbons having a carbon number of less than 10. For determining the carbon chain length of the molecules in a given sample, the peaks obtained in the GC are integrated according to the boiling point cuts given in table 1 so that the obtained areas under the curves relate to the relative amount of hydrocarbons having the given carbon number for each boiling point range. Normalization of all peaks to 100% allows calculation of the distribution of the number of carbon atoms within the sample according to standard methods known to the person skilled in the art. The obtained distribution is a weight distribution related to the total weight of the sample.

[0125] Measurement of Linear and Branched Hydrocarbons

[0126] The amount of linear and branched hydrocarbons in the mixture of hydrocarbons according to the invention is determined according to the ASTM-D-6730 method. Measurements are carried out in a Varian 3900 chromatograph equipped with a FID detector and a 100 m capillary column. The GC is also equipped with a back-flush that only allowed a fraction of sample to enter the column. For determination of the composition of the mixture, the Varian DHA software (detailed hydrocarbon analysis) is used. The obtained peaks are integrated and then compared by the DHA software with its internal database to qualify and quantify the peaks. By this technique, the families of molecules which are quantified (paraffins, isoparaffins, olefins, naphtenes and aromatics) are those with boiling points below 216.1 C. For the present invention, it is assumed that the distribution that is observed in the gasolines having a boiling point below 216.1 C. is identical to that in the hydrocarbons having a higher boiling point.

[0127] Measurement of Unsaturated Hydrocarbons and Alpha-Olefins

[0128] The amount of alpha-olefins in the unsaturated hydrocarbons in the mixture according to the invention was determined using usual .sup.1H and .sup.13C NMR techniques. For example, in CDCl.sub.3 as solvent 1-alkenes show a peak at 5.82 ppm, 2-alkenes show a peak at 5.42 ppm and 2-methyl-1-alkenes show a peak at 4.69 ppm. Those unsaturated hydrocarbons which comprise both, alpha-double bonds and other double bonds can be distinguished by the GC method described above for the determination of the branched hydrocarbons. Alpha-olefins which comprise both, alpha-double bonds and other double bonds qualify as alpha-olefins in the context of the present invention.

[0129] n-paraffins (linear saturated hydrocarbons) can be distinguished from linear unsaturated hydrocarbons and branched (saturated or unsaturated) hydrocarbons by the same methods (GC and NMR).

[0130] Measurement of Iodine Number

[0131] The iodine number of the mixture of hydrocarbons according to the invention is measured by dissolving between 0.1 and 0.2 g of the sample in 10 ml of chloroform. 5 ml of Wijs solution comprising 0.1 M ICl are added to the solution and the mixture is allowed to react for 1 hour in the dark. The unreacted Wijs solution is then reacted with a potassium iodide solution at 100 g/l to convert unreacted ICl to I.sub.2. The amount of formed I.sub.2 is determined by titration using a thiosulfate solution. From the amount of thiosulfate required to react with the I.sub.2, the amount of unreacted Wijs solution is calculated indicating the number of unsaturated bonds in the hydrocarbons.

[0132] Measurement of Drop Point

[0133] The drop point of the mixture of hydrocarbons according to the invention is measured according to European standard EN1427 of March 2007.

Example 1

[0134] The experiment was carried out following the general procedure described above. Experiments were carried out using 80 wt. % HDPE and 20 wt. % PP as raw materials and 20 g of silica as heat carrier. Reaction temperature was varied from 425 to 465 C. and 0.15 L/min of N.sub.2 were introduced at the top of the reactor. Heat carrier to plastic weight ratio was equal to 20/30 by wt.

[0135] Experimental results are shown in FIGS. 3 to 6. As expected, FIG. 3 shows how increasing the temperature leads to higher conversion rates. On the other hand, FIG. 4 shows the surprising effect that increasing temperature results in increasing HCO and waxes yield. FIG. 5 shows the increase in selectivity for waxes with decreasing pyrolysis gas residence time. FIG. 6 further shows that waxes produced at high temperatures also have a different carbon chain distribution, shifted towards longer chain compounds.

[0136] The cumulative distribution of carbon atoms in the obtained mixtures of hydrocarbons depending on the reaction temperature is summarized in the following table 2.

TABLE-US-00002 TABLE 2 Temperature 425 C. 450 C. 465 C. d20 20 20 21 d50 22 23 24

[0137] A hydrocarbon mixture obtained in this example was further analyzed and the results of this analysis are summarized in the following table 3.

TABLE-US-00003 TABLE 3 C.sub.20-C.sub.30 C.sub.30-C.sub.40 C.sub.40+ Crude C.sub.20-C.sub.54 cut cut cut Melting point #45 C. 26 C. 57 C. 72 C. Iodine number 51 60 48 40 Congealing 70 C. > 15 C. TBD TBD TBD point Drop point 63.2 C. 26.2 C. 53.4 C. 75.4 C. C, H, O 79.9/12.7/0.7 84.8/14.85 85.3/14 85.6/14.1 1-olefins/ 60/27/10 68/20/5 60/29/6 52/38/7 2-olefins/ iso-olefins Aspect Pasty solid Pasty solid solid solid

Example 2

[0138] The experiment was carried out following the general procedure described above. Experiments were carried out using 80 wt. % HDPE and 20 wt. % PP as raw materials and 20 g of silica as heat carrier. Reaction temperature was set either to 450 C. or 465 C. and N.sub.2 flow varied from 0.15 L/min to 4 L/min. Heat carrier to plastic weight ratio was equal to 20/30 by wt.

[0139] Experimental results are shown in FIGS. 7 to 10. As expected, FIG. 7 shows how increasing the temperature from 450 to 465 C. leads to higher conversion rates. Moreover, as expected, reaction kinetic is quite independent from the N.sub.2 flow used. On the other hand, FIG. 8 shows the surprising effect that increasing nitrogen flow results in increasing HCO and waxes yield. FIG. 9 shows the increase in selectivity for waxes with decreasing pyrolysis gas residence time. FIG. 10 further shows that waxes produced using higher N.sub.2 flows also have a different carbon chain distribution, shifted towards longer chain compounds.

[0140] The cumulative distribution of carbon atoms in the obtained mixtures of hydrocarbons depending on the reaction temperature and the N.sub.2 flow are summarized in the following table 4.

TABLE-US-00004 TABLE 4 Temper- ature [ C.]/ N.sub.2 flow 450/ 465/ 450/ 465/ 465/ 465/ [ml/min] 150 150 1000 1000 2000 4000 d20 20 21 21 21 23 24 d50 23 24 24 25 30 32

Example 3

[0141] The experiment was carried out following the general procedure described above. Experiments were carried out using 80 wt. % HDPE and 20 wt. % PP as raw materials and 20 g of silica as heat carrier. Reaction temperature was set at 450 C. and N.sub.2 flow varied from 0.15 L/min to 4 L/min. Particularly N.sub.2 flow was set as following: [0142] The N.sub.2 inlet was positioned in the top of the reactor and did not come into contact with plastic melt under reaction conditions. This set-up was defined in the figure as up [0143] The N.sub.2 inlet was positioned in the bottom part of the reactor and came into contact with plastic melt under reaction conditions. This allowed a sort of stripping effect. This set-up was defined in the figure as down

[0144] Heat carrier to plastic weight ratio was equal to 20/30 by wt.

[0145] Experimental results are shown in FIGS. 10 to 13. FIG. 10 shows that increasing the flow results in higher conversion rates. Notably, contacting the N.sub.2 flow with the plastic melt by positioning the N.sub.2 inlet in the bottom of the reactor further increases the conversion rate. FIG. 11 shows the surprising effect that increasing nitrogen flow results in increasing HCO and waxes yield. Particularly, its effect is even more marked when N.sub.2 is allowed to come in contact with plastic melt under reaction conditions. FIG. 12 shows the increase in selectivity for waxes with decreasing pyrolysis gas residence time. FIG. 13 further shows that waxes produced also have a different carbon chain distribution, shifted towards longer chain compounds.

[0146] The cumulative distributions of carbon atoms in the obtained mixtures of hydrocarbons depending on the N.sub.2 flow are summarized in the following table 5.

TABLE-US-00005 TABLE 5 N.sub.2 flow [ml/min] 150 up 1000 up 1000 down 4000 up + down d20 20 21 22 24 d50 23 24 28 33

Example 4: Mass Balance According to the Invention

[0147] In this and the following examples, the post-consumer plastics are named from their main plastic component; on average, the considered post-consumer plastics contained 8% weight of additives.

[0148] A unit equipped with a double-wall rotating drum furnace of 1.4 m of internal diameter and 5 m internal length equipped with a gaseous product uptake line of 400 mm of diameter and 2 m long at a temperature above 370 C. was fed with 2500 kg/h of post-consumer mixed plastic waste of the following composition:

TABLE-US-00006 g/kg PE 415.2 PP 400.0 PS 20.0 PVC 20.0 Water 100.0 Food residue 20.0 Foreign solid 20.0 Air 4.8

[0149] The mixed plastic waste was first pretreated at 250 C. and atmospheric pressure to melt the plastic and remove most of the air, water, food residue and foreign solid as an effluent. This effluent contained also the gaseous product resulting from the decomposition of any component of the fed material. The pretreated material was introduced in the double-wall rotating drum furnace operating at 465 C. under 150 mbar absolute pressure as well as 4000 kg/h of a heat carrier constituted of fine sand supplied at 700 C. The gas hold-up in the furnace was estimated to 4 m.sup.3 and the condensed phase hold-up to 3.6 m.sup.3. The supplementary gas hold-up at a temperature equal or above 370 C. was estimated to 0.3 m.sup.3. The total gas flow produced flow produced at the outlet of the furnace was estimated to 9 kmol/h corresponding to 1903 kg/h.

[0150] The residence time of the gaseous products in the gas phase at or above 370 C. was calculated to 4.5 s. The calculated flows are given in the following table 6 with the numbering of FIG. 1.

TABLE-US-00007 TABLE 6 Average Molar 1 3 4 11 13 14 23 24 32 33 Mass kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h PE 1038 1038 PP 1000 1000 PS 50 50 PVC 50 50 Water 250 250 Organic impurities 50 50 50 Foreign solids 50 50 50 Gases 30 55 55 Gasoline 100 104 104 104 Kerosene 130 148 148 148 Diesel 180 327 327 327 Waxes 400 1269 1269 1269 Coke 64 Ashes 171 Heat carrier 4000 4000 Air 12 12 Total 2500 362 2138 4000 4235 1903 1848 55 579 1269

[0151] The heat duty of the reaction was estimated at 517 kW, the heat supplied by the heat carrier to 217 kW corresponding to 42% of the heat available by combustion of the coke and the heat supplied by the double-wall to 300 kW corresponding to 50% of the heat available by combustion of the gases. The heat transfer surface available in the furnace was estimated to 20 m.sup.2, the overall heat transfer coefficient was estimated to 80 W/m.sup.2K and the logarithmic difference of temperature between the hot gases used to heat up the furnace and the reaction medium reached 190 C.

[0152] The residence time of the condensed material in the furnace was estimated to 80 min. The waxes overall yield is calculated to 59% based on the plastic content (including the additives) of the mixed plastic waste. The waxes were mostly linear.

Example 5: Mass Balance According to the Invention

[0153] A unit equipped with a double-wall rotating drum furnace of 1.4 m of internal diameter and 5 m internal length equipped with a gaseous product uptake line of 400 mm of diameter and 5 m long at a temperature above 370 C. was fed with 2500 kg/h of post-consumer mixed plastic waste of the following composition:

TABLE-US-00008 g/kg PE 415.2 PP 400.0 PS 20.0 PVC 20.0 Water 100.0 Food residue 20.0 Foreign solid 20.0 Air 4.8

[0154] The mixed plastic waste was first pretreated at 250 C. and atmospheric pressure to melt the plastic and remove most of the air, water, food residue and foreign solid as an effluent. This effluent contained also the gaseous product resulting from the decomposition of any component of the fed material. The pretreated material was introduced in the double-wall rotating drum furnace operating at 465 C. under 355 mbar absolute pressure as well as 4000 kg/h of a heat carrier constituted of fine sand supplied at 700 C. and 560 kg/h of nitrogen at 25 C. The gas hold-up in the furnace was estimated to 6 m.sup.3 and the condensed phase hold-up to 1.7 m.sup.3. The supplementary gas hold-up at a temperature equal or above 370 C. was estimated to 0.3 m.sup.3. The total gas flow produced at the outlet of the furnace was estimated to 29 kmol/h corresponding to 2463 kg/h.

[0155] The residence time of the gaseous products in the gas phase at or above 370 C. was calculated to 4.9 s. The calculated flows are given in the following table 7 with the numbering of FIG. 2.

TABLE-US-00009 TABLE 7 Average Molar 51 53 64 61 63 62 66 73 74 32 33 Mass kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h PE 1038 1038 PP 1000 1000 PS 50 50 PVC 50 50 Water 250 250 Organic 50 50 50 impurities Foreign 50 50 50 solids Gases 30 55 55 Gasoline 100 104 104 104 Kerosene 130 148 148 148 Diesel 180 327 327 327 Waxes 400 1269 1269 1269 Coke 64 64 Ashes 171 Heat carrier 4000 4000 Nitrogen 560 560 560 Air 12 12 Total 2500 362 2138 4000 4235 2463 560 1848 615 579 1269

[0156] The heat duty of the reaction, including the preheating of the nitrogen was estimated at 585 kW, the heat supplied by the heat carrier to 261 kW corresponding to 50% of the heat available by combustion of the coke and the heat supplied by the double-wall to 324 kW corresponding to 53% of the heat available by combustion of the gases. The heat transfer surface available in the furnace was estimated to 20 m.sup.2, the overall heat transfer coefficient was estimated to 80 W/m.sup.2K and the logarithmic difference of temperature between the hot gases used to heat up the furnace and the reaction medium reach 205 C.

[0157] The residence time of the condensed material in the furnace was estimated to 132 min. The specific dilution ratio D/P is calculated to 6.3 mol/mol/bar. The waxes overall yield was calculated to 59% based on the plastic content (including the additives) of the mixed plastic waste. The waxes were mostly linear.

Example 6: Mass Balance According to the Invention

[0158] A unit equipped with a double-wall rotating drum furnace of 1.4 m of internal diameter and 5 m internal length equipped with a gaseous product uptake line of 400 mm of diameter and 5 m long at a temperature above 370 C. was fed with 1200 kg/h of post-consumer mixed plastic waste of the following composition:

TABLE-US-00010 g/kg PE 415.2 PP 400.0 PS 20.0 PVC 20.0 Water 100.0 Food residue 20.0 Foreign solid 20.0 Air 4.8

[0159] The mixed plastic waste was first pretreated at 250 C. and atmospheric pressure to melt the plastic and remove most of the air, water, food residue and foreign solid as an effluent. This effluent contained also the gaseous product resulting from the decomposition of any component of the fed material. The pretreated material was introduced in the double-wall rotating drum furnace operating at 465 C. under 120 mbar absolute pressure as well as 224 kg/h of nitrogen at 25 C. The gas hold-up in the furnace was estimated to 7 m3 and the condensed phase hold-up to 0.6 m.sup.3. The supplementary gas hold-up at a temperature equal or over 370 C. was estimated to 0.3 m.sup.3. The total gas flow produced at the outlet of the furnace was estimated to 12.3 kmol/h corresponding to 1137 kg/h.

[0160] The residence time of the gaseous products in the gas phase at or above 370 C. was calculated to 4.6 s. The calculated flows are given in the following table 8 with the numbering of FIG. 2.

TABLE-US-00011 TABLE 8 Average Molar 51 53 64 63 62 66 73 74 32 33 Mass kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h PE 498 498 PP 480 480 PS 24 24 PVC 24 24 Water 120 120 Organic 24 24 impurities Foreign 24 24 solids Gases 30 26 26 Gasoline 100 50 50 50 Kerosene 130 71 71 71 Diesel 180 157 157 157 Waxes 400 609 609 609 Coke 64 64 Ashes 171 Nitrogen 224 224 224 Air 6 6 Total 1200 174 1026 235 1137 224 887 250 278 609

[0161] The heat duty of the reaction, including the preheating of the nitrogen was estimated at 275 kW and the heat supplied by the double-wall to 275 kW corresponding to the heat available by combustion of the gases. The heat transfer surface available in the furnace was estimated to 20 m.sup.2, the overall heat transfer coefficient is estimated to 80 W/m.sup.2K and the logarithmic difference of temperature between the hot gases used to heat up the furnace and the reaction medium reached 174 C.

[0162] The residence time of the condensed material in the furnace was estimated to 161 min. The specific dilution ratio D/P was calculated to 15.4 mol/mol/bar. The waxes overall yield was calculated to 59% based on the plastic content (including the additives) of the mixed plastic waste. The waxes were mostly linear.

Reference Example 1: Mass Balance for Condition Outside the Invention

[0163] A unit equipped with a double-wall rotating drum furnace of 1.4 m of internal diameter and 8 m internal length equipped with a gaseous product uptake line of 400 mm of diameter and 2 m long at a temperature above 370 C. was fed with 2500 kg/h of post-consumer mixed plastic waste of the following composition:

TABLE-US-00012 g/kg PE 415.2 PP 400.0 PS 20.0 PVC 20.0 Water 100.0 Food residue 20.0 Foreign solid 20.0 Air 4.8

[0164] The mixed plastic waste was first pretreated at 250 C. and atmospheric pressure to melt the plastic and remove most of the air, water, food residue and foreign solid as an effluent. This effluent contained also the gaseous product resulting from the decomposition of any component of the fed material. The pretreated material was introduced in the double-wall rotating drum furnace operating at 450 C. under 1320 mbar absolute pressure. The gas hold-up in the furnace was estimated to 11.1 m.sup.3 and the condensed phase hold-up to 1.2 m.sup.3. The supplementary gas hold-up at a temperature equal or above 370 C. is estimated to 0.3 m.sup.3. The total gas flow produced at the outlet of the furnace was estimated to 15.1 kmol/h corresponding to 1902 kg/h.

[0165] The residence time of the gaseous products in the gas phase at or above 370 C. is calculated to 64.9 s. The calculated flows are given in the following table 9 with the numbering of the FIG. 1.

TABLE-US-00013 TABLE 9 Average Molar 1 3 4 13 14 23 24 32 33 Mass kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h PE 1038 1038 PP 1000 1000 PS 50 50 PVC 50 50 Water 250 250 Organic impurities 50 50 Foreign solids 50 50 Gases 30 140 140 Gasoline 100 322 322 322 Kerosene 130 385 385 385 Diesel 180 532 532 532 Waxes 400 523 523 523 Coke 64 Ashes 171 Air 12 12 Total 2500 362 2138 235 1902 1762 140 1239 523

[0166] The heat duty of the reaction was estimated at 668 kW, and the heat supplied by the double-wall to 668 kW corresponding to 43% of the heat available by combustion of the gases. The heat transfer surface available in the furnace was estimated to 32 m.sup.2, the overall heat transfer coefficient was estimated to 80 W/m.sup.2K and the logarithmic difference of temperature between the hot gases used to heat up the furnace and the reaction medium reach 263 C.

[0167] The residence time of the condensed material in the furnace was estimated to 300 min. The waxes overall yield was calculated to 24% based on the plastic content (including the additives) of the mixed plastic waste. The waxes were mostly linear.

Reference Example 2: Mass Balance for Condition Out of the Invention

[0168] A unit equipped with a double-wall rotating drum furnace of 1.4 m of internal diameter and 8 m internal length equipped with a gaseous product uptake line of 400 mm of diameter and 2 m long at a temperature above 370 C. was fed with 2500 kg/h of post-consumer mixed plastic waste of the following composition:

TABLE-US-00014 g/kg PE 415.2 PP 400.0 PS 20.0 PVC 20.0 Water 100.0 Food residue 20.0 Foreign solid 20.0 Air 4.8

[0169] The mixed plastic waste was first pretreated at 250 C. and atmospheric pressure to melt the plastic and remove most of the air, water, food residue and foreign solid as an effluent. This effluent contained also the gaseous product resulting from the decomposition of any component of the fed material. The pretreated material was introduced in the double-wall rotating drum furnace operating at 450 C. under 1400 mbar absolute pressure as well as 28 kg/h of nitrogen at 25 C. The gas hold-up in the furnace was estimated to 11.1 m.sup.3 and the condensed phase hold-up to 1.2 m.sup.3. The supplementary gas hold-up at a temperature equal or above 370 C. was estimated to 0.3 m.sup.3. The total gas flow produced at the outlet of the furnace was estimated to 16.1 kmol/h corresponding to 1929 kg/h.

[0170] The residence time of the gaseous products in the gas phase at or above 370 C. was calculated to 64.6 s. The calculated flows are given in the following table 10 with the numbering of FIG. 2.

TABLE-US-00015 TABLE 10 Average Molar 51 53 64 63 62 66 73 74 32 33 Mass kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h kg/h PE 1038 1038 PP 1000 1000 PS 50 50 PVC 50 50 Water 250 250 Organic 50 50 impurities Foreign 50 50 solids Gases 30 139 139 Gasoline 100 322 322 322 Kerosene 130 385 385 385 Diesel 180 532 532 532 Waxes 400 523 523 523 Coke 64 Ashes 171 Nitrogen 28 28 28 Air 12 12 Total 2500 362 2138 235 1929 28 1762 167 1239 523

[0171] The heat duty of the reaction was estimated at 670 kW, and the heat supplied by the double-wall to 670 kW corresponding to 43% of the heat available by combustion of the gases. The heat transfer surface available in the furnace was estimated to 32 m.sup.2, the overall heat transfer coefficient was estimated to 80 W/m.sup.2K and the logarithmic difference of temperature between the hot gases used to heat up the furnace and the reaction medium reach 265 C.

[0172] The residence time of the condensed material in the furnace was estimated to 300 min. The specific dilution ratio D/P was calculated to 0.05 mol/mol/bar. The waxes overall yield was calculated to 24% based on the plastic content (including the additives) of the mixed plastic waste. The waxes were mostly linear.

[0173] Waxes of the type obtained according to the process of the invention may, inter alia, be used as additives in bituminous coating compositions, and more generally in coating compositions on the basis (i) of mineral aggregates and (ii) of organic binders derived from petroleum (bitumen or mixtures of synthetic polymeric resins and oil) and/or from plants (in particular binders on the basis of resins and plant oils). Waxes of the invention are especially useful in bituminous mixtures and asphalt concretes, based on pure or modified bitumen (in particular through addition of polymers), as well as in coatings based on other organic binders, for example of the type of synthetic polymers and/or plant resins.

[0174] In a first aspect, the waxes according to the invention, when used in coatings on the basis of mineral aggregates and organic binders, can be employed to facilitate the use of the binder and/or the mixture of binder and aggregate; and/or to optimize the coating of the aggregates, and particularly in the heat: the presence of waxes according to the invention tends to decrease, typically by several tens of degrees Celsius, the temperature at which the compositions are sufficiently fluid to be used, which manifests itself especially in terms of reduced process costs.

[0175] According to another aspect, compatible with the previous and complementary thereto for certain applications of the type exemplified below, the waxes according to the invention may be used in a coating based on mineral aggregates and organic binders to increase hardening speed of the coating during its cooling. The waxes according to the invention indeed tend to have a setting speed higher than organic binders such as bitumen or clear binders mentioned above.

[0176] Thus, by way of illustration and not limitation, a wax of the invention may be advantageously used at least in the following applications: [0177] In so-called warm bituminous mixtures, obtained by coating aggregates with heated bitumen (pure or modified): for this application, the wax is advantageously mixed with the bitumen before the coating of the aggregates, whereby the bitumen can be mixed with aggregates at a much lower temperature than in the absence of wax (typically at a temperature of about 110-140 C. compared to 200 C. in the absence of resin, more precisely, 150-200 C.). [0178] In superficial wear coatings where the wax is typically mixed with a bitumen, a flux additive of the plant oil type, for example as described, inter alia, in EP 1845134. This fluxed binder is intended to be sprayed onto a road surface on which aggregates are then deposited. The presence of waxes allows in this context not only to reduce the temperature at which it is sprayed, but also to increase the speed of cohesion increase (setting) of the bitumen after its deposition and this despite the presence of fluxing agents. [0179] In poured asphalts, namely the compositions of the type of bituminous mixture mentioned above, but having a higher bitumen content (typically at least 10% by weight based on the total weight of the mix, against 4.5 to 5.5% by weight in conventional bituminous mixtures): the wax is typically mixed with the bituminous binder, whereby the bitumen can be mixed with the aggregates at a temperature of about 160 to 190 C., compared to a temperature above 200 C. (typically about 250 C.) in the absence of wax. The wax also imparts curing properties. [0180] In bituminous mixtures based on clear binders also called synthetic binders, i.e. based on binders on the basis of synthetic polymers and/or resins and oil of petroleum origin and/or of plant origin of the transparent type allows the aggregates they contain to be distinguished, in contrast to a bituminous mixtures: the presence of waxes in these binders allows, again, to reduce the temperature at which the coating is made and deposited. [0181] In sealing coatings, in particular for roofs, which comprise bitumen mixed with polymers: the presence of wax also here allows reducing the temperature at which the coatings are manufactured. It also allows an acceleration of the setting of the coating after deposition, which is particularly appreciable in the case of deposits on pitched roofs where the deposited composition tends to flow if it does not harden sufficiently rapidly.

[0182] Moreover, a wax of the invention may be used to improve the rheological properties of binders and more specifically, to increase the modulus of rigidity. A wax of the invention may, in this context, additionally provide lubricating properties.

[0183] On the other hand, at least in some cases, the presence of a wax according to the invention in a bituminous coating tends to improve the resistance to embrittlement of the coating in the face of solubilization by hydrocarbons. The waxes according to the invention are found in this context particularly suitable as additives in bituminous coatings that are intended to come into contact with gasoline or kerosene, such as bituminous coatings used in service stations.