Silicon Removal from Depolymerized Oil

Abstract

The present invention relates to an improved method for removing silicon from depolymerized oil, and more specifically, to a method for producing pyrolysis oil, comprising the following steps: adding alumina in the form of granules to an organosilicon-containing waste plastic to form a mixture, feeding the mixture into a pyrolysis reactor, pyrolyzing the mixture in the reactor, recovering at least pyrolysis gas and solid residue from the reactor to provide an oil product, and condensing the pyrolysis gas, wherein the solid residue contains alumina reacted with silicon. The invention relates to a method comprising.

Description

【Technical Field】 【0001】 The present invention relates to an improved method for removing silicon from depolymerized oil, and more specifically, to the in-situ reduction of the silicon content during the pyrolysis of waste plastics, and to the use of alumina for the in-situ reduction of the silicon content during the pyrolysis of waste plastics. 【Background Art】 【0002】 Purifying liquefied waste plastic (LWP), also called depolymerized oil, to obtain more valuable (pure) substances has been studied for several years. 【0003】 LWP is usually produced by pyrolysis or hydrothermal liquefaction (HTL) of waste plastics. Depending on the raw material of the waste plastics, the impurity levels of LWP vary. 【0004】 Raw materials for chemical recycling of plastics usually consist of mixed plastic waste. This mixed plastic waste is generated, for example, from plastics separately collected from households where a clean plastic fraction has been removed for mechanical recycling, or from plastics separated from municipal solid waste (MSW). However, it is economically impossible to separate the waste almost 100%. Therefore, the waste plastic raw material (waste plastic feed) for producing LWP usually contains materials other than plastics. These materials, including biomass, can also cause impurities in LWP. 【0005】 In particular, consumer waste including waste packaging often contains compositions other than hydrocarbons. Silicon is one of the non-hydrocarbon elements commonly contained in plastic waste from various sources, such as silicone. Therefore, plastic waste used for chemical recycling often contains a large amount of silicon impurities. Other typical impurity components are chlorine, nitrogen, sulfur, and oxygen. 【0006】 Whether the LWP is simply subjected to a general purification process (e.g., fractional distillation) or then subjected to a petrochemical conversion process, the LWP feed needs to meet the impurity levels of these processes in order to avoid equipment deterioration such as catalyst poisoning. In this regard, since silicon impurities can cause catalyst deactivation in, for example, a hydrogenation process, techniques for reducing the silicon content in LWP have been studied. 【0007】 Patent Document 1 discloses passing LWP (i.e., depolymerized oil) over an absorbent in the presence of hydrogen at a temperature of 80°C to 360°C. 【0008】 However, further improvement is desired regarding the removal of silicon from LWP products. 【Prior Art Documents】 【Patent Documents】 【0009】 【Patent Document 1】 International Publication No. 2021 / 80899 【Summary of the Invention】 【0010】 The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for reducing the silicon content in LWP obtained by a pyrolysis process. 【0011】 The present invention is based on the finding that by using alumina as a reactant, the silicon content in LWP can be reduced in-situ during pyrolysis. That is, in addition to the prior art, there is no need to provide a dedicated step for removing silicon from the already produced LWP. Rather, the amount of silicon in LWP has already decreased at the pyrolysis stage. 【0012】 The problem underlying the present invention is solved by the subject matter recited in the independent claims. Further advantageous developments are recited in the dependent claims. 【0013】 Briefly, the present invention relates to one or more of the following items: 1. A method for producing pyrolysis oil, comprising the following steps: Adding alumina in the form of granules to the organosilicon-containing waste plastic to form a mixture; Feeding the mixture into a pyrolysis reactor; Pyrolyzing the mixture in the reactor; Recovering at least pyrolysis gas and solid residue from the reactor and condensing the pyrolysis gas to provide an oil product, wherein the solid residue contains alumina reacted with silicon. Including. 【0014】 2. The method according to item 1, wherein the alumina is added in an amount of 0.2 to 40.0 wt.-%, preferably 0.5 to 35.0 wt.-%, 1.0 to 30.0 wt.-%, 1.5 to 25.0%, 2.0 to 20.0 wt.-%, 2.5 to 15.0 wt.-%, 3.0 to 13.0 wt.-%, 4.0 to 12.0 wt.-%, 5.0 to 11.0 wt.-%, 5.5 to 10.0 wt.-%, or 6.0 to 9.0 wt.-%. 【0015】 3. The method according to item 1 or 2, wherein the addition of the alumina to form the mixture is carried out at a high temperature. 【0016】 4. The method according to any one of the preceding items, wherein the addition of the alumina to form the mixture is carried out at a temperature in the range of 50°C to 280°C, preferably 60°C to 270°C, 80°C to 260°C, 100°C to 250°C, 110°C to 250°C, 120°C to 250°C, 130°C to 240°C, 140°C to 230°C, or 150°C to 220°C. 【0017】 5. The method according to any one of the preceding items, wherein the addition of the alumina to form the mixture includes melting the waste plastic. 【0018】 6. The addition of the alumina to form the mixture includes melting the waste plastic, and the addition of the alumina is carried out before and / or during and / or after melting the waste plastic, preferably at least before melting, according to any one of the preceding items. 【0019】 7. The method according to any one of the preceding items, wherein the waste plastic mainly comprises a thermoplastic compound. 【0020】 8. The method according to any one of the preceding items, wherein the addition of the alumina to form the mixture is carried out in an extruder, preferably a melt extruder. 【0021】 9. The method according to any one of the preceding items, wherein the addition of the alumina to form the mixture is carried out by blending the alumina with the waste plastic, preferably solid waste plastic, without external heating. 【0022】 10. The method according to any one of the preceding items, wherein the alumina has an average particle size in the range of 50 nm to 10 mm, preferably in the range of 10 μm to 2.0 mm, 50 μm to 1.8 mm, or 100 μm to 1.5 mm. 【0023】 11. The method according to any one of the preceding items, wherein the alumina is activated alumina. 【0024】 12. The method according to any one of the preceding items, wherein the alumina has an open pore structure. 【0025】 13. The method according to any one of the preceding items, wherein the alumina has a pore size in the range of 30 angstroms to 10000 angstroms, preferably in the range of 40 angstroms to 1000 angstroms, 50 angstroms to 500 angstroms, 55 angstroms to 300 angstroms, or 60 angstroms to 200 angstroms. 【0026】 14. The alumina has a BET specific surface area in the range of 50 m 2 / g to 500 m 2 / g, preferably more than 50 m 2 / g, more preferably more than 100 m 2 / g, or more than 150 m 2 / g or more, for example 150 - 300 m 2 / g, and is the method according to any one of the preceding items. 【0027】 15. The method according to any one of the preceding items, further comprising post - treating the oil product recovered from the pyrolysis reactor. 【0028】 16. The post - treatment includes subjecting the oil product to heat treatment with an aqueous solution of a basic substance, preferably an aqueous solution of a metal hydroxide, more preferably an aqueous solution of sodium hydroxide, and then to phase separation (liquid - liquid separation) to provide a further purified oil product, as described in item 15. 【0029】 17. The method according to item 16, wherein the aqueous solution contains at least 50 wt.-% water, preferably at least 70 wt.-% water, more preferably at least 85 wt.-% water, at least 90 wt.-% water, or at least 95 wt.-% water. 【0030】 18. The method according to item 16 or 17, wherein the aqueous solution contains at least 0.3 wt.-%, more preferably at least 0.5 wt.-%, at least 1.0 wt.-%, or at least 1.5 wt.-% of a basic substance, for example, 0.5 wt.-% - 10.0 wt.-%, 1.0 wt.-% - 6.0 wt.-%, or 1.5 wt.-% - 4.0 wt.-%. 【0031】 19. The method according to any one of items 16 to 18, wherein the aqueous solution contains at least 0.5 wt.-%, preferably at least 1.0 wt.-%, or at least 1.5 wt.-% of a metal hydroxide or an alkali metal hydroxide, for example 0.5 wt.-% - 10.0 wt.-%, 1.0 wt.-% - 6.0 wt.-%, or 1.5 - 4.0 wt.-%. 【0032】 20. The method according to any one of items 16 to 19, wherein the heat treatment is carried out at a temperature of 150 °C or higher, preferably 190 °C or higher. 【0033】 21. The method according to any one of items 16 to 20, wherein the heat treatment is carried out at a temperature of 200 °C or higher, such as 210 °C or higher, 220 °C or higher, 240 °C or higher, or 260 °C or higher. 【0034】 22. The method according to any one of items 16 to 21, wherein the heat treatment is carried out at a temperature of 450 °C or lower, preferably 400 °C or lower, 350 °C or lower, 320 °C or lower, or 300 °C or lower. 【0035】 23. The method according to any one of items 16 to 22, wherein the heat treatment is carried out at a temperature in the range of 200 °C to 350 °C, preferably 220 °C to 330 °C, 240 °C to 320 °C, or 260 °C to 300 °C. 【0036】 24. The method according to any one of items 15 to 23, wherein the post-treatment includes subjecting the oil product to a hydrogenation treatment to provide a hydrogenated oil product. 【0037】 25. The method according to any one of the preceding items, wherein the pyrolysis is carried out in two or more stages. 【0038】 26. The method according to item 25, wherein the first pyrolysis step is carried out in the absence of a pyrolysis catalyst, and at least one of the subsequent pyrolysis steps is carried out in the presence of a pyrolysis catalyst. 【0039】 27. The method according to any one of the preceding items, wherein the Group II metal oxide or Group II metal hydroxide (Group II metal oxide / hydroxide) is added to the step of adding alumina for forming a mixture and / or directly to the pyrolysis reactor. 【0040】 28. The method according to item 27, wherein the Group II metal is magnesium or calcium. 【0041】 29. The method according to item 27 or 28, wherein the Group II metal oxide / hydroxide is at least one selected from the group consisting of calcium oxide and calcium hydroxide. 【0042】 30. The method according to any one of items 27 to 29, wherein the Group II metal oxide / hydroxide is added in an amount in the range of 0.2 to 40.0 wt.-%, preferably 0.5 to 35.0 wt.-%, 1.0 to 30.0 wt.-%, 1.5 to 25.0 wt.-%, 2.0 to 20.0 wt.-%, 2.5 to 15.0 wt.-%, 3.0 to 13.0 wt.-%, 4.0 to 12.0 wt.-%, 5.0 to 11.0 wt.-%, 5.0 to 10.0 wt.-% or 5.5 to 9.0 wt.-%. 【0043】 31. The method according to any one of the preceding items, wherein alumina is added in an amount such that the silicon content (by weight) in the oil product recovered from the pyrolysis reactor is at least 15% less than the silicon content in the oil product recovered from the pyrolysis reactor when no alumina is added. 【0044】 32. The method according to any one of the preceding items, wherein the alumina is acidic alumina or basic alumina, preferably acidic alumina. 【0045】 33. The method according to any one of the preceding items, wherein the pyrolysis is carried out at a temperature in the range of 250°C to 850°C. 【0046】 34. The method according to any one of the preceding items, further comprising heating the organosilicon-containing waste plastic and / or mixture to a high temperature and liquefying at least a part of the organosilicon compound contained therein. 【0047】 35. The method according to any one of the preceding items, wherein the temperature is 175°C or higher, preferably 180°C or higher, 185°C or higher, 190°C or higher, 200°C or higher, or 210°C or higher. 【0048】 36. The method according to item 34, wherein the temperature is 280 °C or lower, preferably 270 °C or lower, 265 °C or lower, 260 °C or lower, 255 °C or lower, or 250 °C or lower. 【0049】 37. The method according to any one of items 34 to 36, wherein the temperature is in the range of 175 °C to 280 °C, for example, 180 °C to 270 °C, 185 °C to 265 °C, 190 °C to 260 °C, 200 °C to 255 °C, or 210 °C to 250 °C. 【0050】 38. The method according to any one of items 34 to 37, wherein the liquefaction is carried out before adding alumina, during adding alumina, and / or after adding alumina. 【0051】 39. The method according to any one of items 34 to 38, wherein the liquefaction is carried out at least in the step of adding alumina to form a mixture. 【0052】 40. The method according to any one of items 34 to 39, wherein the liquefaction is carried out at least in the step of adding alumina to form a mixture. 【0053】 41. The method according to any one of items 34 to 40, wherein the liquefaction is carried out by an extruder. 【0054】 42. The method according to any one of items 34 to 41, wherein the liquefaction is carried out in a melt extruder. 【0055】 43. The method according to item 41 or 42, wherein the extruder has a gas discharge port. 【0056】 44. The method according to any one of the preceding items, wherein the alumina is acidic alumina. 【0057】 45. The method according to any one of the preceding items, wherein alumina is added in an amount of 0.2 to 12.0 wt.-%, preferably 0.5 to 10.0 wt.-%, 1.0 to 10.0 wt.-%, 1.5 to 10.0 wt.-%, 2.0 to 10.0 wt.-%, 2.5 to 10.0 wt.-%, 3.0 to 10.0 wt.-%, 4.0 to 10.0 wt.-%, 5.0 to 10.0 wt.-%, 5.5 to 10.0 wt.-% or 6.0 to 10.0 wt.-%. 【0058】 46. The method according to any one of the preceding items, wherein forming the mixture by adding the alumina is carried out at a temperature in the range of 150°C to 280°C, preferably 160°C to 280°C, 170°C to 280°C, 175°C to 280°C, 180°C to 270°C, 185°C to 265°C, 190°C to 260°C, 200°C to 255°C, or 210°C to 250°C. 【0059】 47. Use of alumina in the form of granules for reducing in-situ the amount of organosilicon in the waste plastic pyrolysis process. 【0060】 48. Use according to item 47 in the waste plastic pyrolysis process (method) defined by any one of items 1 to 46. 【0061】 49. A method for producing pyrolysis oil, comprising the following steps: Adding alumina in the form of granules to the organosilicon-containing waste plastic to form a mixture; Feeding the mixture to a pyrolysis reactor; Pyrolyzing the mixture in the reactor; Recovering at least pyrolysis gas and solid residue from the reactor and condensing the pyrolysis gas to provide an oil product, wherein the solid residue contains alumina reacted with silicon. Use according to item 47 or 48 in a method comprising the above steps. 【0062】 50. The use according to any one of items 47 to 49, wherein alumina is added in an amount of 0.2 to 40.0 wt.-%, preferably 0.5 to 35.0 wt.-%, 1.0 to 30.0 wt.-%, 1.5 to 25.0%, 2.0 to 20.0 wt.-%, 2.5 to 15.0 wt.-%, 3.0 to 13.0 wt.-%, 4.0 to 12.0 wt.-%, 5.0 to 11.0 wt.-%, 5.5 to 10.0 wt.-%, or 6.0 to 9.0 wt.-%. 【0063】 51. The use according to any one of items 47 to 50, wherein the addition of the alumina to form the mixture is carried out at a high temperature. 【0064】 52. The use according to any one of items 47 to 51, wherein the addition of the alumina to form the mixture is carried out at a temperature in the range of 50°C to 280°C, preferably 60°C to 270°C, 80°C to 260°C, 100°C to 250°C, 110°C to 250°C, 120°C to 250°C, 130°C to 240°C, 140°C to 230°C, or 150°C to 220°C. 【0065】 53. The use according to any one of items 47 to 52, wherein the addition of the alumina to form the mixture includes melting the waste plastic. 【0066】 54. The use according to any one of items 47 to 53, wherein the addition of the alumina to form the mixture includes melting the waste plastic, and the addition of the alumina is carried out before and / or during and / or after melting the waste plastic, preferably at least before melting. 【0067】 55. The use according to any one of items 47 to 54, wherein the waste plastic mainly contains a thermoplastic compound. 【0068】 56. The use according to any one of items 47 to 55, wherein the addition of the alumina to form the mixture is carried out in an extruder, preferably a melt extruder. 【0069】 57. Use according to any one of items 47 to 56, wherein said addition of said alumina to form a mixture is carried out by blending alumina with waste plastic, preferably solid waste plastic, without external heating. 【0070】 58. Use according to any one of items 47 to 57, wherein the alumina has an average particle size in the range of 50 nm to 10 mm. 【0071】 59. Use according to any one of items 47 to 58, wherein the alumina has an average particle size in the range of 10 μm to 2.0 mm, preferably in the range of 50 μm to 1.8 mm, or in the range of 100 μm to 1.5 mm. 【0072】 60. Use according to any one of items 47 to 58, wherein the alumina has an open pore structure. 【0073】 61. Use according to any one of items 47 to 60, wherein the alumina is added to the waste plastic before the thermal decomposition reaction (before the waste plastic enters the thermal decomposition reactor). 【0074】 62. Use according to any one of items 47 to 61, wherein the alumina has pores with a size in the range of 30 angstroms to 10000 angstroms, preferably in the range of 40 angstroms to 1000 angstroms, 50 angstroms to 500 angstroms, 55 angstroms to 300 angstroms, or 60 angstroms to 200 angstroms. 【0075】 63. The alumina is 50 m 2 / g to 500 m 2 / g, preferably more than 50 m 2 / g, more than 100 m 2 / g, or 150 m 2 / g or more, for example in the range of 100 to 300 m 2 / g, or in the range of 150 to 300 m 2 / g, and has a BET specific surface area as described in any one of items 47 to 62. 【0076】 64. Use according to any one of items 47 to 63, wherein the pyrolysis is carried out in two or more steps. 【0077】 65. Use according to any one of items 47 to 64, wherein the first pyrolysis step is carried out in the absence of a pyrolysis catalyst and at least one of the subsequent pyrolysis steps is carried out in the presence of a pyrolysis catalyst. 【0078】 66. Use according to any one of items 47 to 65, wherein a Group II metal oxide or a Group II metal hydroxide (Group II metal oxide / hydroxide) is added to the pyrolysis reactor. 【0079】 67. Use according to item 66, wherein the Group II metal is magnesium or calcium. 【0080】 68. Use according to item 65 or 66, wherein the Group II metal oxide / hydroxide is at least one selected from the group consisting of calcium oxide and calcium hydroxide. 【0081】 69. Use according to any one of items 65 to 68, wherein the Group II metal oxide / hydroxide is added in an amount in the range of 0.2 to 40.0 wt.-%, preferably in the range of 0.5 to 35.0 wt.-%, 1.0 to 30.0 wt.-%, 1.5 to 25.0 wt.-%, 2.0 to 20.0 wt.-%, 2.5 to 15.0 wt.-%, 3.0 to 13.0 wt.-%, 4.0 to 12.0 wt.-%, 5.0 to 11.0 wt.-%, 5.0 to 10.0 wt.-% or 5.5 to 9.0 wt.-%. 【0082】 70. Use according to any one of items 47 to 69, wherein alumina is added in an amount such that the silicon content (by weight) in the oil product recovered from the pyrolysis reactor is reduced by at least 15% compared to the silicon content in the oil product recovered from the pyrolysis reactor when no alumina is added. 【0083】 71. Use according to any one of items 47 to 70, wherein the alumina is acidic alumina or basic alumina, preferably acidic alumina. 【0084】 72. Use according to any one of items 47 to 71, wherein the alumina is activated alumina. 【0085】 73. Use according to any one of items 47 to 72, wherein the thermal decomposition is carried out at a temperature in the range of 250 °C to 850 °C. 【0086】 74. Use according to any one of items 47 to 73, further comprising heating the organosilicon-containing waste plastic and / or mixture to a high temperature and liquefying at least a part of the organosilicon compound contained therein. 【0087】 75. Use according to item 74, wherein the temperature is 175 °C or higher, preferably 180 °C or higher, 185 °C or higher, 190 °C or higher, 200 °C or higher, or 210 °C or higher. 【0088】 76. Use according to item 74 or 75, wherein the temperature is 280 °C or lower, preferably 270 °C or lower, 265 °C or lower, 260 °C or lower, 255 °C or lower, or 250 °C or lower. 【0089】 77. Use according to any one of items 74 to 76, wherein the temperature is in the range of 175 °C to 280 °C, for example, 180 °C to 270 °C, 185 °C to 265 °C, 190 °C to 260 °C, 200 °C to 255 °C, or 210 °C to 250 °C. 【0090】 78. Use according to any one of items 74 to 77, wherein the liquefaction is carried out before adding the alumina, during adding the alumina, and / or after adding the alumina. 【0091】 79. Use according to any one of items 74 to 78, wherein the liquefaction is carried out at least in the step of adding the alumina to form a mixture. 【0092】 80. The liquefaction is the use according to any one of items 74 to 79, which is carried out in the step of adding alumina to form a mixture. 【0093】 81. The liquefaction is the use according to any one of items 74 to 80, which is carried out by an extruder. 【0094】 82. The liquefaction is the use according to any one of items 74 to 81, which is carried out in a melt extruder. 【0095】 83. The use according to item 81 or 82, wherein the extruder has a gas outlet. 【0096】 84. The use according to any one of items 47 to 83, wherein the alumina is acidic alumina. 【0097】 85. The use according to any one of items 47 to 84, wherein the alumina is added in an amount of 0.2 to 12.0 wt.-%, preferably 0.5 to 10.0 wt.-%, 1.0 to 10.0 wt.-%, 1.5 to 10.0 wt.-%, 2.0 to 10.0 wt.-%, 2.5 to 10.0 wt.-%, 3.0 to 10.0 wt.-%, 4.0 to 10.0 wt.-%, 5.0 to 10.0 wt.-%, 5.5 to 10.0 wt.-% or 6.0 to 10.0 wt.-%. 【0098】 86. The use according to any one of items 47 to 85, wherein the step of adding the alumina to form a mixture is carried out at a temperature in the range of 150°C to 280°C, preferably in the range of 160°C to 280°C, 170°C to 280°C, 175°C to 280°C, 180°C to 270°C, 185°C to 265°C, 190°C to 260°C, 200°C to 255°C, or 210°C to 250°C. 【DETAILED DESCRIPTION OF THE INVENTION】 【0099】 The present invention relates to an improved method for reducing the silicon content in depolymerized oil. 【0100】 The silicon impurity content should be reduced before the LWP is subjected to further processing. The present invention focuses on a method for in-situ removal of silicon during the pyrolysis process (i.e., during the depolymerization of waste plastics). The present invention particularly relates to the use of alumina in the form of granules (also referred to as granular alumina or alumina granules), which is added to the waste plastics before pyrolysis and reacts with the silicon compounds generated from the organosilicon in the waste plastics during pyrolysis. Thus, the silicon that has undergone a reaction with alumina remains in the solid residue of the pyrolysis reaction, while the gas product (gas effluent) has its silicon content minimized and is then condensed to provide depolymerized oil (liquefied waste plastic; LWP). 【0101】 In the context of the present invention, liquefied waste plastic (LWP) means the product stream from a pyrolysis process that includes at least depolymerizing waste plastics. Thus, LWP is the material obtained by depolymerizing waste plastics. LWP is also referred to as waste polymer-based oil or depolymerized oil. 【0102】 The waste plastics can be from any source, such as (recycled or recovered) consumer plastics, (recycled or recovered) industrial plastics, (recycled or recovered) end-of-life tires (ELT), etc. In particular, the term waste plastics refers to organic polymer materials that are no longer suitable for use or are discarded for other reasons. More specifically, waste plastics are end-of-life tires, recycled consumer plastics (consumer plastics refer to any organic polymer material included in consumer goods. In the context of the present invention, the terms waste plastics or "polymers" generally do not include purely inorganic materials (sometimes called inorganic polymers). The polymers in waste plastics can be of natural and / or synthetic origin and can be based on renewable and / or fossil raw materials. 【0103】 The liquefaction process (pyrolysis) is carried out at a high temperature, preferably under non-oxidizing conditions. The liquefaction process may be carried out under high pressure. The liquefaction process may be carried out in the presence of a catalyst. The liquefaction process provides a gas effluent and a solid residue, and the gas effluent is condensed to obtain an oil product. The oil product may be employed as such as pyrolysis oil (LWP; i.e., as a product of the process), or may be subjected to fractionation (or separation) to provide fractions (or separated liquids), and may also be subjected to other post-treatments, particularly further purification. In this specification, fractionation refers to fractional distillation and / or flash evaporation. 【0104】 In addition to liquid (NTP) hydrocarbons, i.e., hydrocarbons that are liquid at normal temperature and pressure (NTP; 20 °C, absolute pressure 101.325 kPa), typical oil products from the pyrolysis process include gaseous (NTP) hydrocarbons, and hydrocarbons that are wax-like or solid at NTP but become liquid when heated, for example, to 80 °C. 【0105】 In the context of the present disclosure, the depolymerization of waste plastics means that the polymer backbone of the waste plastics is decomposed or degraded by pyrolysis to such an extent as to yield polymer and / or oligomer species of a lower molecular weight compared to the starting waste plastics, but still contains at least liquid (NTP) hydrocarbons. The depolymerization of waste plastics also optionally includes cleaving covalently bonded heteroatoms such as O, S, N from heteroatom-containing compounds present. 【0106】 At the start, the waste plastics to be subjected to pyrolysis, or each waste plastic species in the mixed waste plastics, are usually in a solid state and typically have a melting point in the range of 100 °C or higher as measured by DSC, as described by Larsen et al. ("Determining the PE fraction in recycled PP", Polymer testing, Vol. 96, April 2021, 107058). However, the waste plastics, or each waste plastic species, may be melted before and / or during depolymerization. 【0107】 Solid waste plastics can contain various additional components such as fillers, pigments, printing inks, flame retardants, stabilizers, antioxidants, plasticizers, lubricants, labels, metals, paper, cardboard, cellulose-based fibers, glass fibers, and further additives containing dirt such as sand, reinforcing materials, etc. Further, if necessary, some of the additional components can be removed from the solid waste plastics, from the molten waste plastics, and / or from the liquefied waste plastics using generally known methods. 【0108】 Preferably, the (solid) waste plastics to be subjected to pyrolysis have an oxygen content of 15 wt.-% or less, preferably 10 wt.-% or less, more preferably 5 wt.-% or less, based on the total weight of the (solid) waste plastics. The oxygen content may be 0 wt.-%, and preferably may be in the range of 0 wt.-% to 15 wt.-% or 0 wt.-% to 10 wt.-%. The oxygen content (wt.-%) can be determined by difference using the formula of 100 wt.-% (CHN content + ash content). Here, the CHN content means the combined content of carbon, hydrogen, and nitrogen determined in accordance with ASTM D5291, and the ash content means the ash content determined in accordance with ASTM D482 / EN15403. 【0109】 In the present disclosure, when referring to a standard, it shall mean the latest revised version available as of January 31, 2022. Further, unless otherwise stated, all embodiments of the present invention (such as all preferred values and / or ranges within the embodiments, etc.) can be combined with each other to provide new (preferred) embodiments, unless explicitly specified otherwise or such combinations result in contradictions. 【0110】 In the present invention, "granules" or "granulated" includes everything such as powders, granules, aggregates, etc., and is not limited to a specific shape. 【0111】 The "pyrolysis reactor" refers to the pyrolysis zone of the apparatus for performing the pyrolysis reaction. That is, the "pyrolysis reactor" is the place where the actual pyrolysis reaction takes place. 【0112】 "Solid residue" means a substance that does not transfer to the gas phase during the pyrolysis reaction. Usually, such solid residues include tar and inorganic impurities that do not evaporate. In the present invention, the solid residue contains alumina reacted with silicon. This means that the silicon content is higher than that at the time of addition of alumina (that is, higher than that of granular alumina). The reaction may be a physical reaction (such as adsorption) and / or a chemical reaction, or may include these. Preferably, silicon chemically reacts with alumina and preferably binds to the alumina surface (accessible surface including penetration into open pores). Although the mechanism is not completely clear, when silicon is added to the pyrolysis reactor, it mainly reacts with alumina on its surface to form a layered structure, and this layered structure is presumed to be formed of a Si - Al - oxide type material. 【0113】 Most of the organic silicon contained in waste plastics is in the form of polysiloxane, and it is assumed to form volatile oligomeric siloxanes during pyrolysis and thus transfer to petroleum products. On the other hand, inorganic silicon, for example, silicon in the form of silica, is non - reactive (non - volatile) under pyrolysis conditions and thus ends up in the solid residue in any case. 【0114】 The method of the present invention is characterized in that granular alumina is mixed with waste plastics, and this mixture is subjected to pyrolysis in a pyrolysis reactor, whereby silicon in the waste plastics reacts with alumina and transfers to the solid residue. 【0115】 Specifically, the present invention relates to a method for producing pyrolysis oil, the method comprising the steps of adding alumina in the form of granules to an organosilicon-containing waste plastic to form a mixture, feeding the mixture to a pyrolysis reactor, pyrolyzing the mixture in the reactor, and recovering at least pyrolysis gas and solid residue from the reactor and condensing the pyrolysis gas to provide an oil product, wherein the solid residue comprises alumina reacted with silicon. 【0116】 Thus, the mixture is prepared before the mixture enters the pyrolysis reactor (i.e., the pyrolysis reaction zone). For example, the mixture can be prepared in advance or in a supply unit such as an extruder. The step of adding alumina to form the mixture may also be referred to as a mixing step. 【0117】 Alumina is preferably added in an amount of 0.2 to 40.0 wt.-% (more preferably 0.5 to 35.0 wt.-%, 1.0 to 30.0 wt.-%, 1.5 to 25.0%, 2.0 to 20.0 wt.-%, 2.5 to 15.0 wt.-%, 3.0 to 13.0 wt.-%, 4.0 to 12.0 wt.-%, 5.0 to 11.0 wt.-%, 5.5 to 10.0 wt.-%, or 6.0 to 9.0 wt.-%) based on 100 wt.-% of the pyrolysis feed. The inventors have found that adding alumina in an amount of 0.2 to 12.0 wt.-%, for example 0.5 to 10.0 wt.-%, 1.0 to 10.0 wt.-%, 1.5 to 10.0 wt.-%, 2.0 to 10.0 wt.-%, 2.5 to 10.0 wt.-%, 3.0 to 10.0 wt.-%, 4.0 to 10.0 wt.-%, 5.0 to 10.0 wt.-%, 5.5 to 10.0 wt.-%, or 6.0 to 10.0 wt.-% is particularly preferred from the viewpoint of the balance between silicon removal efficiency and alumina use efficiency. "Based on 100 wt.-% of the pyrolysis feed" means the total amount of waste plastic (including all impurities and contaminants such as biomass), alumina and other feeds (excluding pyrolysis catalysts if present). That is, as pointed out above, the waste plastic may be derived from municipal waste and may contain biomass even after sorting. 【0118】 The step of adding alumina to form a mixture (i.e., the mixing step) may be carried out at a high temperature. In this regard, "high temperature" means that external heating is applied to the mixing device (the components to be mixed are heated). 【0119】 For example, the mixing step can be carried out at a temperature in the range of 50°C to 280°C, preferably in the range of 60°C to 270°C, 80°C to 260°C, 100°C to 250°C, 110°C to 250°C, 120°C to 250°C, 130°C to 240°C, 140°C to 230°C, or 150°C to 220°C. By employing a high temperature in the mixing step, the treatment can be facilitated and a more intimate mixture can be prepared. In some embodiments, it may be beneficial to limit the temperature in the mixing stage to 180°C or lower, for example, in the range of 50°C to 180°C, in order to minimize the generation of hydrochloric acid in the mixing stage. In the context of the present invention, the "temperature" at which the mixing step is carried out refers to the temperature of the mixed materials (not the temperature of the heating medium). 【0120】 In particular, adding alumina to form the mixture may include (at least partially) melting the waste plastic. When the waste plastic is melted, a more intimate mixture can be prepared. Further, the melted material is easier to handle. The addition of alumina can be carried out before and / or during and / or after the melting of the waste plastic, but preferably, it is preferably carried out at least before melting. 【0121】 To (at least partially) melt the waste plastic, the presence of a thermoplastic compound is required. Thus, the waste plastic in the present invention preferably mainly contains a thermoplastic compound. The term "mainly contains" means that at least 50 wt.-% (preferably at least 60 wt.-%, at least 70 wt.-%, at least 80 wt.-%, at least 90 wt.-%) of the waste plastic, based on the whole waste plastic, is formed of the thermoplastic compound. 【0122】 In one embodiment, the mixing step is carried out in an extruder, preferably a melt extruder. Since the extruder is often used as a supply unit for supplying waste plastic to the pyrolysis reactor, the addition of alumina at this stage can be easily achieved, and at the same time, intimate mixing can be achieved. In particular, by using a melt extruder, the mixture of the material, homogenized alumina and waste plastic can be obtained, and the pyrolysis process can be improved. Further, the melt-extruded material can be directly supplied to the pyrolysis reactor, for example, or pelletized and supplied to the pyrolysis reactor, which facilitates handling. 【0123】 Alternatively, or in addition thereto, the mixing step can be carried out without external heating such as at room temperature. In this case, since there is no need to pay attention to high temperature and / or cooling effects in the mixing step, handling becomes easier. 【0124】 In another embodiment, in addition to the use of an additive for silicon removal before the pyrolysis step, the present invention can utilize a liquefaction step to further remove the silicon component contained in the waste plastic. Surprisingly, by heating the organosilicon-containing waste plastic to a certain temperature before pyrolysis, i.e., before feeding the mixture into the pyrolysis reactor (before, during, and / or after the addition of alumina), the amount of silicon-containing compounds in the oil product (i.e., obtained from the condensation of pyrolysis gas) is further reduced. The reason for this effect has not been fully elucidated, but it is presumed that heating removes a part of the organosilicon compounds (most of which are presumed to be siloxane compounds) into the gas phase. Based on this understanding, this heating step is also referred to as the "degassing" or "devolatilisation" step. Therefore, the heating temperature is preferably high enough to sufficiently convert the organosilicon compounds contained in the waste plastic to be degassed (optionally in the mixture). Specifically, preferably 175 °C or higher, for example 180 °C or higher, 185 °C or higher, 190 °C or higher. In particular, it may be 200 °C or higher, 210 °C or higher. Also, the temperature is preferably not too low to avoid (or minimize) product loss. The temperature is preferably in the range of 175 °C to 280 °C, for example 180 °C to 270 °C, 185 °C to 265 °C, 190 °C to 260 °C, 200 °C to 255 °C, or 210 °C to 250 °C. 【0125】 Heating and degassing (devolatilisation) can preferably be carried out in a course where alumina addition can be performed, because they bring a synergistic effect with the use of high temperature in the homogenization of waste plastics together. In this case, the alumina addition (mixing) temperature preferably corresponds to the above-mentioned heating (devolatilisation) temperature. Nevertheless, it is also possible to carry out heating (devolatilisation) as a dedicated step (process) before and / or after alumina addition / mixing (in addition to, or instead of, during alumina addition / mixing). 【0126】 Pyrolysis may be carried out by a batch method or a continuous method, but preferably by a continuous method. 【0127】 Alumina (alumina particles) preferably has an average particle size in the range of 50 nm to 10 mm, more preferably in the range of 10 μm to 2.0 mm, 50 μm to 1.8 mm, or 100 μm to 1.5 mm. The average particle size can be measured, for example, by laser diffraction method (ISO 13320), optical microscopy method, or electron microscopy method (ISO 13322). The specific surface area and pore size (pore diameter) of alumina can be determined, for example, by gas adsorption measurement based on ISO 9277 or ISO 15901-2. In the case of aggregates, the particle size refers to the size of the aggregates, not the primary particle size. Alumina (alumina particles) can have a porosity in the range of, for example, 20 to 85%. 【0128】 Alumina (alumina particles) preferably has an open pore structure. The inventors have found that since silicon mainly reacts with the alumina surface, an open pore structure (having a highly accessible alumina surface) is preferred. Preferably, alumina has a pore size in the range of 30 Å to 10000 Å, preferably 40 Å to 1000 Å, 50 Å to 500 Å, 55 Å to 300 Å, or 60 Å to 200 Å. 【0129】 Alumina (alumina particles) has a BET specific surface area in the range of 50 m 2 / g to 500 m 2 / g, preferably more than 50 m 2 / g, more than 100 m 2 / g, or more than 150 m 2 / g, for example, in the range of 100 to 300 m 2 / g, or in the range of 150 to 300 m 2 / g, etc. 【0130】 The method of the present invention may further include post-treating the oil product recovered from the pyrolysis reactor. The oil product produced by the method of the present invention will likely be of sufficiently high purity to be added to the value chain (e.g., used in a crude oil refining process), but it is preferred to post-treat the oil product to improve its purity or usability. Post-treatment includes, in particular, purification steps such as fractional distillation or extraction, and / or upgrading steps such as hydrotreatment. That said, known petrochemical processes can be used for post-treatment, and in particular, the oil product can be used as a co-feed for petrochemical processes. 【0131】 In one embodiment, the post-treatment includes heat-treating the oil product with an aqueous solution of a basic substance, preferably an aqueous solution of a metal hydroxide, more preferably an aqueous solution of sodium hydroxide, and then performing liquid-liquid separation to provide a further purified oil product. Such treatment is suitable for very efficiently removing impurities, particularly chlorine-containing impurities, from the oil product. The aqueous solution preferably contains at least 50 wt.-% water, more preferably at least 70 wt.-% water, more preferably at least 85 wt.-% water, at least 90 wt.-% water, or at least 95 wt.-% water. The aqueous solution preferably contains at least 0.3 wt.-%, more preferably at least 0.5 wt.-%, at least 1.0 wt.-%, or at least 1.5 wt.-%, for example 0.5 wt.-% to 10.0 wt.-%, 1.0 wt.-% to 6.0 wt.-%, or 1.5 wt.-% to 4.0 wt.-% of the basic substance. For example, the aqueous solution contains at least 0.5 wt.-%, preferably at least 1.0 wt.-%, or at least 1.5 wt.-%, for example from 0.5 wt.-% to 10.0 wt.-%, from 1.0 wt.-% to 6.0 wt.-%, or from 1.5 wt.-% to 4.0 wt.-% of the metal hydroxide or alkali metal hydroxide. The heat treatment can be carried out at a temperature of 150 °C or higher, preferably 190 °C or higher, 200 °C or higher, for example 210 °C or higher, 220 °C or higher, 240 °C or higher, or 260 °C or higher. In order to keep the heating effort within a normal range and avoid excessive side reactions, the heat treatment is preferably carried out at a temperature of 450 °C or lower, more preferably 400 °C or lower, 350 °C or lower, 320 °C or lower, or 300 °C or lower. In particular, the heat treatment can be carried out at a temperature in the range of 200 °C to 350 °C, preferably 220 °C to 330 °C, 240 °C to 320 °C, or 260 °C to 300 °C. 【0132】 The post-treatment may include hydrotreating the oil product to provide a hydrotreated oil product. The hydrotreating can be used, in particular, for the removal of heteroatoms and / or olefin saturation. Hydrotreating is particularly preferred in the present invention because organosilicon may act as a catalyst deactivator. Thus, the method of the present invention can protect the hydrotreating catalyst from degradation and extend its life. 【0133】 The pyrolysis step in the method of the present invention can be further carried out in a second step (as a two-step process). In this embodiment, both the reactor type and the reaction temperature can be varied. Usually, the first step is to decompose the solid residue removed in the first reactor. The second step then involves treating the pyrolysis gas by contacting it with a catalyst, optionally, to decompose long chains (carbon chains). For example, a mixture of waste plastic and alumina is fed to the first step, where the solid residue is removed, while the product stream (e.g., oil or gas) is sent to the second step (and optionally subsequent steps). The first step is to decompose the waste plastic into (long-chain) compounds, and the second step is mainly to decompose the (long-chain) compounds of the already decomposed material. By adopting such a two-step process, the product distribution is improved. In particular, the viscosity of the oil product decreases, making it easier to handle and store. 【0134】 The decomposition in the second step is preferably a selective decomposition step. Thus, the second pyrolysis step (more preferably, a subsequent pyrolysis step) is preferably carried out in the presence of a catalyst. In the first pyrolysis step, the catalyst is not very beneficial, so it can preferably be omitted. Thus, it is preferred to carry out the first pyrolysis step in the absence of a pyrolysis catalyst and at least one of the subsequent pyrolysis steps in the presence of a pyrolysis catalyst. It is particularly preferred to carry out at least the last pyrolysis step in the presence of a catalyst. Solid catalysts are preferred, for example, acidic solid catalysts such as acidic FCC catalysts, acidic zeolite catalysts or acidic silica-alumina catalysts such as ZSM-5 or H-USY zeolite. 【0135】 To further improve the product distribution, particularly to reduce the chlorine content of the oil product, it is preferred that a Group II metal oxide or a Group II metal hydroxide (hereinafter sometimes collectively referred to as a Group II metal oxide / hydroxide) be added to the step of adding alumina to form a mixture and / or be added directly to the pyrolysis reactor. The Group II metal oxide / hydroxide is suitable for reducing chlorine impurities in situ during pyrolysis, and the inventors have further found that the presence of an additional Group II metal oxide / hydroxide further reduces the silicon content of the oil product. From the perspective of process efficiency, alumina and the Group II metal oxide / hydroxide are preferably added simultaneously and / or sequentially in the same process, for example, first adding alumina and then adding the Group II metal oxide / hydroxide. 【0136】 The Group II metal of the Group II metal oxide / hydroxide is preferably at least one selected from the group consisting of calcium and magnesium. Specifically, the Group II metal oxide / hydroxide is preferably at least one selected from the group consisting of calcium oxide and calcium hydroxide. The Group II metal oxide / hydroxide is preferably added in an amount in the range of 0.2 wt.-% to 40.0 wt.-%, more preferably 0.5 wt.-% to 35.0 wt.-%, 1.0 wt.-% to 30.0 wt.-%, 1.5 wt.-% to 25.0 wt.-%, 2.0 wt.-% to 20.0 wt.-%, 2.5 wt.-% to 15.0 wt.-%, 3.0 wt.-% to 13.0 wt.-%, 4.0 wt.-% to 12.0 wt.-%, 5.0 wt.-% to 11.0 wt.-%, 5.0 wt.-% to 10.0 wt.-%, or 5.5 wt.-% to 9.0 wt.-%. The amount of the Group II metal oxide / hydroxide is calculated with respect to the Group II metal oxide. That is, when a Group II metal hydroxide (e.g., Ca(OH)2) is added, the Group II metal oxide (e.g., CaO) equivalent is calculated assuming that the Group II metal-containing compound exists as the Group II metal oxide (e.g., CaO), that is, based on the content of the Group II metal (e.g., Ca). 【0137】 Alumina is preferably added in an amount such that the silicon content (by weight) in the oil product recovered from the pyrolysis reactor is reduced by at least 15% compared to the silicon content in the oil product recovered from the pyrolysis reactor without the addition of alumina. The amount of silicon can be determined based on ASTM D5185. In this regard, the oil product means the oil product immediately after pyrolysis (i.e., the condensed product), from which only the gaseous (NTP) product is removed and no further workup or post-treatment is applied. Further, the term "when no alumina is added" means performing the reaction without the addition of alumina under the same conditions. The adjustment of the silicon content reduction can preferably be achieved by feedback control or feedforward control, for example, feedforward control using the aggregated values for known waste plastic compositions. 【0138】 Alumina may be any of acidic alumina, neutral alumina, and basic alumina, preferably neutral alumina or acidic alumina, and more preferably acidic alumina. When alumina is of the acidic type, when placed in water, it tends to give a pH of 6 or 6 or less (e.g., less than 6) to the water. When alumina is of the basic type, when placed in water, it tends to give a pH of 8 or 8 or more (e.g., higher than 8) to the water. When alumina is referred to as neutral, it tends to give a pH between 6 and 8 to the water. Alumina can be of acidic, neutral, and basic types, and each has been shown to be able to provide the chemisorption ability of alumina with respect to Si for indicating Si removal efficiency. However, the inventors have surprisingly shown that acidic type alumina has improved silicon removal efficiency compared to basic and neutral equivalents, and thus have found that the acidic type is most preferred. Without being bound by a particular theory, alumina provides active sites that can be further optimized by pH to provide conditions suitable for chemisorption interaction between alumina and silicon, thereby performing the intended silicon removal function. 【0139】 Furthermore, in order to improve reactivity, the alumina is preferably activated alumina, and more preferably acidic activated alumina. Activated alumina is a highly porous form of aluminum oxide, for example, used in the chemical field as a desiccant. Its surface area is high, usually greater than 100 m 2 / g, and often even exceeds 200 m 2 / g. Activated alumina is produced by dehydrating and deoxidizing aluminum hydroxide so that a highly porous material is formed. Activated alumina may have an open pore structure, particularly tunnel-shaped pores. Activated alumina may contain or be composed of γ-alumina (Al2O3). 【0140】 The temperature of the pyrolysis step is not particularly limited, and a normal range can be adopted. When a plurality of pyrolysis steps are adopted, it is preferable to adjust the temperature according to the presence or absence of a catalyst. 【0141】 Thermal non-catalytic pyrolysis uses a temperature in the range preferably from 300 °C to 850 °C, for example from 400 °C to 800 °C. This process is usually carried out under atmospheric pressure, under non-oxidizing conditions, especially in the absence of air. Non-oxidizing conditions can be achieved, for example, by purging the liquefaction device with an inert gas such as nitrogen. 【0142】 Thermal catalytic pyrolysis uses a temperature in the range preferably from 250 °C to 500 °C, for example from 300 °C to 450 °C. This process is usually carried out under atmospheric pressure, usually under non-oxidizing conditions, especially in the absence of air. This process typically uses a solid catalyst, preferably an acidic solid catalyst, such as an acidic FCC catalyst, an acidic zeolite catalyst or an acidic silica-alumina catalyst, such as ZSM-5 or H-USY zeolite. Non-oxidizing conditions can be achieved, for example, by purging the liquefaction device with an inert gas such as nitrogen. 【0143】 The waste plastic may be mixed waste plastic or sorted waste plastic. Since the present invention is particularly suitable for waste plastics highly contaminated, it is possible to reduce the dependence on the quality of the sorted waste plastic, and thus, lower quality sorted waste plastic can be used. Waste plastics, especially untreated mixed waste plastics, can contain a large amount of silicon from various sources. The waste plastic can contain a silicon content in the range of, for example, 300 to 50000 ppm, for example 300 to 20000 ppm, or 500 to 10000 ppm. The silicon content can be measured by conventional methods such as ICP-MS (Inductively Coupled Plasma Mass Spectrometry) or XRF (X-ray Fluorescence). 【0144】 The present invention further relates to the use of alumina granules for the in-situ reduction of the amount of organosilicon in the waste plastic pyrolysis process. In this regard, in-situ reduction means that organosilicon species (which may originally exist and may also be generated during the pyrolysis reaction) are removed and accumulated in the solid residue, and the content in the product stream (gas / oil product) is reduced while performing pyrolysis. In this use, alumina is preferably added before starting the pyrolysis reaction (for example, before feeding the waste plastic into the reaction zone). The embodiments shown for the method of the present invention can be similarly applied to the process of the present invention. 【0145】 The present invention provides a pyrolysis oil having a reduced organosilicon content and an efficient method for achieving this. 【Examples】 【0146】 Hereinafter, the present invention will be described with reference to non-limiting examples. The examples represent preferred embodiments of the present invention. In particular, it should be understood that the numerical values and ranges described in the examples can be combined with other ranges and values disclosed in the specification to provide the scope of implementing the present invention. 【0147】 Comparative Example 1 For pyrolysis, PVC at 1 wt.-% (relative to the final waste plastic mixture) was added to the selected waste plastic (industrial grade DKR310 commonly used in Germany), and further %) was added, and 0.5 wt.-% of PDMS (polydimethylsiloxane; 0.5 wt.-% was further added) was used to mimic an organosilicon-containing waste plastic material with a high organosilicon content. 【0148】 Pyrolysis was carried out without a catalyst at a temperature (pyrolysis temperature inside the reactor) of 380 °C. The generated gas was condensed and recovered to provide oil products. The oil products were analyzed. The Si content in the oil was analyzed based on ASTM D5185, and the procedure was adjusted as necessary for the measurement of pyrolysis oil. The results are shown in Table 1. 【0149】 Example 1 20 wt.-% of activated acidic alumina powder (BET SSA 155 m 2 / g, pore diameter 58 Å, average particle size 150 mesh, corresponding to 105 μm) was further added by mixing without external heating (giving a mixture containing 20 wt.-% alumina and 80 wt.-% mixed waste plastics). Example 1 was repeated under the same conditions except for this. The oil products were analyzed. The results are shown in Table 1. 【0150】 Comparative Example 2 Comparative Example 1 was repeated under the same conditions except that DKR350 (industrial grade) sorted waste plastics (originally with a high Si content) were used without the addition of PVC or PDMS. The oil products were analyzed. The results are shown in Table 1. 【0151】 Examples 2 - 4 Comparative Example 2 was repeated under the same conditions except that the amount of alumina specified in Example 1 was changed. Specifically, 3 wt.-% (Example 2) and 7 wt.-% (Example 3) were added into a twin-screw melt extruder at a temperature of 165 °C. In Example 4, 7 wt.-% of alumina was added and 6.7 wt.-% of CaO was further added. The oil products were analyzed. The results are shown in Table 1. 【0152】 【Table 1】 【0153】 The results show that a significant reduction in the silicon content in the oil products can be achieved simply by adding alumina to the pyrolysis raw materials. 【0154】 Examples 5 to 8 Example 3 (addition of 7 wt.-% alumina) was repeated under the same conditions except that various types of alumina were used. 【0155】 In Example 5, activated acidic alumina (pH of the stirred dispersion aqueous solution: 4.5 ± 0.5, 150-mesh powder, specific surface area 155 m 2 / g, pore diameter 58 Å) was used. In Example 6, activated basic alumina (pH of the stirred dispersion aqueous solution: 9.5 ± 0.5, 150-mesh powder, specific surface area 205 m 2 / g, pore diameter 58 Å) was used. In Example 7, activated neutral alumina (pH of the stirred dispersion aqueous solution: 7.0 ± 0.5, 40 - 160 μm powder, specific surface area 20 m 2 / g, pore diameter 58 Å) was used. 【0156】 Example 8 was carried out under the conditions of Example 5 (acidic alumina) on a pilot plant scale (Examples 5 to 7 were carried out on a laboratory scale). 【0157】 The silicon content in the obtained oil product was measured and is shown in Table 2 below. Further, a graph showing the results of Comparative Example 2 (without alumina) and Examples 2, 5 to 7, 8 (7 wt.-% alumina each) is shown in FIG. 1. 【0158】 【Table 2】 【0159】 Experiments 1 to 3 In order to quantify the effect on silicon removal by heating (liquefying) waste plastics), experimental tests were carried out without the addition of alumina. Therefore, the possibility of the influence due to the reaction with the alumina mixed in at high temperature during heating was excluded for better comparison. 【0160】 The experiments were conducted using the same mixed waste plastic raw material (DSD 350), subjecting it to melt extrusion at various temperatures, and then subjecting it to laboratory-scale pyrolysis under the same conditions. The results are shown in Table 3 below. Experiment 1 was conducted twice, and the obtained silicon contents were averaged. Experiments 2 and 3 were conducted only once. It was confirmed that heating (liquefying) at a high temperature prior to pyrolysis can significantly reduce the silicon content in the resulting oil product. 【0161】 【Table 3】

Claims

[Claim 1] A method for producing pyrolysis oil, comprising the following steps: The process involves adding alumina in granular form to organosilicon-containing waste plastic in order to form a mixture. A step of supplying the mixture to a pyrolysis reactor, A step of thermally decomposing the mixture in the reactor, and A step of recovering at least pyrolysis gas and solid residue from the reactor and condensing the pyrolysis gas in order to provide an oil product, wherein the solid residue includes alumina reacted with silicon. A method that includes this. [Claim 2] The method according to claim 1, wherein the alumina is added in an amount of 0.2 to 40.0 wt. -%, preferably 0.5 to 35.0 wt. -%, 1.0 to 30.0 wt. -%, 1.5 to 25.0 wt. -%, 2.0 to 20.0 wt. -%, 2.5 to 15.0 wt. -%, 3.0 to 13.0 wt. -%, 4.0 to 12.0 wt. -%, 5.0 to 11.0 wt. -%, 5.5 to 10.0 wt. -%, or 6.0 to 9.0 wt. -%. [Claim 3] The method according to claim 1 or 2, wherein the addition of alumina to form the mixture is carried out at a temperature in the range of 50°C to 280°C, preferably in the range of 60°C to 270°C, 80°C to 260°C, 100°C to 250°C, 110°C to 250°C, 120°C to 250°C, 130°C to 240°C, 140°C to 230°C, or 150°C to 220°C. [Claim 4] The method according to claim 1, wherein the addition of alumina to form the mixture includes melting waste plastic. [Claim 5] The method according to claim 1, wherein the addition of alumina to form the mixture is carried out in an extruder, preferably a melt extruder. [Claim 6] The method according to claim 1, wherein the alumina has an open structure. [Claim 7] The alumina is 50 m 2 / g to 500m 2 / g, preferably 50m 2 More than / g, 100m 2 More than / g, or 150m 2 / g or more, for example, 100-300m 2 Range of / g, or 150-300m 2 The method according to claim 1, having a BET specific surface area in the range of / g. [Claim 8] The method according to claim 1, wherein the thermal decomposition is carried out in two or more stages. [Claim 9] The method according to claim 1, wherein the first pyrolysis step is carried out in the absence of a pyrolysis catalyst, and at least one of the subsequent pyrolysis steps is carried out in the presence of a pyrolysis catalyst. [Claim 10] The method according to claim 1, wherein a group II metal oxide or group II metal hydroxide (group II metal oxide / hydroxide) is added to the alumina addition step for forming a mixture, and / or directly to the pyrolysis reactor, wherein the group II metal is preferably magnesium or calcium. [Claim 11] The method according to claim 10, wherein the group II metal oxide / hydroxide is at least one selected from the group consisting of calcium oxide and calcium hydroxide. [Claim 12] The method according to claim 10 or 11, wherein the group II metal oxide / hydroxide is added in an amount in the range of 0.2 to 40.0 wt. -%, preferably in the range of 0.5 to 35.0 wt. -%, 1.0 to 30.0 wt. -%, 1.5 to 25.0 wt. -%, 2.0 to 20.0 wt. -%, 2.5 to 15.0 wt. -%, 3.0 to 13.0 wt. -%, 4.0 to 12.0 wt. -%, 5.0 to 11.0 wt. -%, 5.0 to 10.0 wt. -%, or 5.5 to 9.0 wt. -%. [Claim 13] The method according to claim 1, further comprising heating organosilicon-containing waste plastics and / or mixtures to a high temperature and defoliating at least a portion of the organosilicon compounds contained therein, wherein the heating is performed at a temperature in the range of 175°C to 280°C, for example, 180°C to 270°C, 185°C to 265°C, 190°C to 260°C, 200°C to 255°C, or 210°C to 250°C, before supplying the mixture to the pyrolysis reactor. [Claim 14] The method according to claim 1, wherein the alumina is acidic alumina, preferably activated acidic alumina. [Claim 15] The use of granular alumina to reduce the amount of organosilicon in-situ during the thermal decomposition process of waste plastics.

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