Patent Application
20240384184
This application claims priority to Korean Patent Application No. 10-2023-0064316 filed May 18, 2023, and Korean Patent Application No. 10-2023-0103369 filed Aug. 8, 2023, the disclosures of each of which are hereby incorporated by reference in their entireties.
The following disclosure relates to a method of refining waste plastic pyrolysis oil using waste tire pyrolysis oil and a molybdenum-based hydrotreating catalyst, and a continuous operation method thereof.
Waste plastics, which are produced using petroleum as a feedstock, are difficult to recycle and are mostly disposed of as garbage. These wastes take a long time to degrade in nature, which causes contamination of the soil and serious environmental pollution. As plastic decomposes by exposure to sunlight and heat, the plastic waste releases greenhouse gases such as methane and ethylene. Incineration of plastic waste releases significant amounts of greenhouse gases (GHG), such as carbon dioxide, nitrous oxide and/or methane, into the environment. Carbon dioxide is the primary greenhouse gas contributing to climate change.
As a method for recycling waste plastics, there is a method for pyrolyzing waste plastics and converting the pyrolyzed waste plastics into usable oil, and the obtained oil is called waste plastic pyrolysis oil.
However, pyrolysis oil obtained by pyrolyzing waste plastics cannot be directly used as a high-value-added fuel such as gasoline or diesel oil because it has a higher content of impurities such as chlorine, nitrogen, and metals than oil produced from crude oil by a general method, and therefore, pyrolysis oil needs to go through a refining process.
As such, as a refining method for removing impurities such as chlorine, nitrogen, and metals contained in waste plastic pyrolysis oil, a method of performing dechlorination/denitrification by reacting waste plastic pyrolysis oil with hydrogen in the presence of a hydrotreating catalyst, a method of removing chlorine contained in waste plastic pyrolysis oil by adsorption using a chlorine adsorbent, or the like is known.
As a hydrotreating catalyst, a molybdenum-based catalyst is generally used, and the molybdenum-based catalyst reacts with sulfur to form an active site. Therefore, in a crude oil refining process, reaction activity may be maintained by injecting dimethyl disulfide (DMDS) during a start-up process to activate (sulfidize) the catalyst, or catalytic activity may be maintained naturally through hydrogen sulfide produced in a process of processing the sulfur component contained in crude oil.
However, since a content of sulfur impurities in waste plastic pyrolysis oil is significantly lower than that in oil derived from crude oil, the catalytic activity is reduced over time during hydrotreating using the molybdenum-based catalyst in the refining process.
Some embodiments of the present disclosure are directed to providing a method of refining waste plastic pyrolysis oil that may produce refined oil having a significantly reduced content of impurities such as chlorine, nitrogen, oxygen, and/or metals.
Some embodiments of the present disclosure are directed to providing a continuous operation method of a device of refining waste plastic pyrolysis oil that may realize a long-term operation of the refining device by continuously supplying sulfur from waste tire pyrolysis oil and maintaining activity of a molybdenum-based sulfide hydrotreating catalyst.
In some embodiments, a method of refining waste plastic pyrolysis oil comprises: (S1) mixing waste plastic pyrolysis oil and waste tire pyrolysis oil to produce a mixed oil; (S2) hydrotreating the mixed oil with a reaction gas comprising hydrogen gas (H2) in the presence of a molybdenum-based hydrotreating catalyst to form a product; and (S3) removing a by-product of the hydrotreating from the product of step (S2) to obtain refined oil.
In some embodiments, the mixed oil may comprise 300 ppm or more of sulfur.
In some embodiments, the waste tire pyrolysis oil may be comprised in an amount of less than 100 parts by weight with respect to 100 parts by weight of the waste plastic pyrolysis oil.
In some embodiments, the reaction gas in step (S2) may comprise hydrogen sulfide gas (H2S).
In some embodiments, the hydrogen sulfide gas (H2S) may be separated from the by-product of the hydrotreating removed in step (S3) and then re-supplied to step (S2).
In some embodiments, the molybdenum-based hydrotreating catalyst may be a catalyst in which a molybdenum-based metal, or a metal comprising one or two or more selected from nickel, cobalt, and tungsten and a molybdenum-based metal, are supported on a support.
In some embodiments, the molybdenum-based hydrotreating catalyst may comprise a molybdenum-based sulfide hydrotreating catalyst.
In some embodiments, Step (S2) may be performed at a pressure of 200 bar or less.
In some embodiments, Step (S2) may be performed at a temperature of 300° C. or higher and lower than 450° C.
In some embodiments, Step (S2) may be performed at a liquid hourly space velocity (LHSV) of 0.1 to 10 h−1.
In some embodiments, the mixed oil may further comprise a sulfur source.
In some embodiments, the sulfur source may comprise sulfur-containing oil.
In some embodiments, the sulfur-containing oil may be comprised in an amount of 100 parts by weight or less with respect to 100 parts by weight of the waste plastic pyrolysis oil.
In some embodiments, the sulfur source may comprise one or two or more sulfur-containing organic compounds selected from a disulfide-based compound, a sulfide-based compound, a sulfonate-based compound, and/or a sulfate-based compound.
In some embodiments, a continuous operation method of a device of refining waste plastic pyrolysis oil comprises: (S1) mixing waste plastic pyrolysis oil and waste tire pyrolysis oil to produce a mixed oil; (S2) hydrotreating the mixed oil with a reaction gas comprising hydrogen gas (H2) and hydrogen sulfide gas (H2S) at a pressure of 200 bar or less in the presence of a molybdenum-based sulfide hydrotreating catalyst; and (S3) removing a by-product of the hydrotreating from a product of step (S2) to obtain refined oil, wherein the hydrogen sulfide gas (H2S) in step (S2) is separated from the by-product of the hydrotreating in step (S3), and the separated hydrogen sulfide gas (H2S) is re-supplied.
In some embodiments, the mixed oil may comprise 300 ppm or more of sulfur.
In some embodiments, the waste tire pyrolysis oil may be comprised in an amount of less than 100 parts by weight with respect to 100 parts by weight of the waste plastic pyrolysis oil.
In some embodiments, the mixed oil may further comprise a sulfur source.
In some embodiments, the sulfur-containing oil may be comprised in an amount of 100 parts by weight or less with respect to 100 parts by weight of the waste plastic pyrolysis oil.
In some embodiments, the sulfur source may comprise one or two or more sulfur-containing organic compounds selected from a disulfide-based compound, a sulfide-based compound, a sulfonate-based compound, and/or a sulfate-based compound.
Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.
The advantages and features of the present disclosure and methods for accomplishing them will become apparent from embodiments described herein in detail with reference to the accompanying drawings. The drawings described in the present specification are provided by way of example so that the spirit of the present disclosure can be sufficiently transferred to those skilled in the art. Therefore, the present disclosure is not limited to the drawings suggested, and may be implemented in other forms. In addition, the drawings may be exaggerated in order to convey the spirit of the present disclosure.
Unless otherwise defined, all of the technical terms and scientific terms used in the present specification have the same meanings as commonly understood by those skilled in the art to which the present disclosure pertains.
Unless the context clearly indicates otherwise, the singular forms of the terms used in the present specification may be interpreted as including the plural forms. As used herein, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly states otherwise.
For the purposes of this specification, unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, dimensions, physical characteristics, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
A numerical range used in the present specification includes upper and lower limits and all values within these limits, increments logically derived from a form and span of a defined range, all double limited values, and all possible combinations of the upper and lower limits in the numerical range defined in different forms. Unless otherwise specifically defined in the present specification, values out of the numerical range that may occur due to experimental errors or rounded values also fall within the defined numerical range. For example, a range of “1 to 10” is intended to include any and all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10, that is, all subranges beginning with a minimum value equal to or greater than 1 and ending with a maximum value equal to or less than 10, and all subranges in between, e.g., 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1.
The expression “comprise(s)” described in the present specification is intended to be an open-ended transitional phrase having an equivalent meaning to “include(s)”, “contain(s)”, “have (has)”, or “are (is) characterized by”, and does not exclude elements, materials, or steps, all of which are not further recited herein.
Unless otherwise defined, a unit of “ppm” used in the present specification refers to “mass ppm”.
A method of refining waste plastic pyrolysis oil according to the present disclosure may solve the problem of deactivation of a molybdenum-based hydrotreating catalyst due to a low content of sulfur in waste plastic pyrolysis oil as hydrotreating is performed. Since pyrolysis oil recovered from waste tires is rich in sulfur, when the pyrolysis oil is used in a refining process of waste plastic pyrolysis oil, the activity of the molybdenum-based hydrotreating catalyst may be maintained even when the refining is performed for a long time. Also, the pyrolysis oil has an effect of reducing the environmental load according to recycling of waste resources.
Hereinafter, a method of refining waste plastic pyrolysis oil and a continuous operation method thereof will be described in detail.
In some embodiments, there is provided a method of refining waste plastic pyrolysis oil, the method comprising: (S1) mixing waste plastic pyrolysis oil and waste tire pyrolysis oil to produce a mixed oil; (S2) hydrotreating the mixed oil with a reaction gas comprising hydrogen gas (H2) in the presence of a molybdenum-based hydrotreating catalyst; and (S3) removing a by-product of the hydrotreating from a product in step (S2) to obtain refined oil.
In some embodiments, the waste plastic pyrolysis oil refers to a mixture of hydrocarbon oils produced by pyrolyzing waste plastics. In some embodiments, the waste plastics may comprise solid or liquid wastes related to synthetic polymer compounds such as waste synthetic resins, waste synthetic fibers, waste synthetic rubber, and/or waste vinyl. In some embodiments, the waste plastic pyrolysis oil may comprise impurities such as at least one of a chlorine compound, a nitrogen compound, and/or a metal compound, in addition to the hydrocarbon oils. Alternatively or additionally, in some embodiments the waste plastic pyrolysis oil may comprise impurities in the form of compounds in which chlorine, nitrogen, and/or a metal is bonded to hydrocarbons, and may comprise hydrocarbons in the form of olefins.
In some embodiments, the waste plastic pyrolysis oil may comprise 300 ppm or more of nitrogen and 30 ppm or more of chlorine, or may comprise 20 vol % or more (based on 1 atm and 25° C.) of olefins and 1 vol % or more (based on 1 atm and 25° C.) of conjugated diolefins, but a content of the impurities is merely a specific example that may be comprised in the waste plastic pyrolysis oil, and a composition of the waste plastic pyrolysis oil is not limited thereto.
In some embodiments, the mixed oil is produced by mixing the waste plastic pyrolysis oil and the waste tire pyrolysis oil in step (S1), such that deactivation of the molybdenum-based hydrotreating catalyst due to lack of sulfur and a high-temperature operation during the refining process may be suppressed, and the catalytic activity may be maintained.
Since the waste tire pyrolysis oil obtained by pyrolyzing waste tires comprises not only hydrocarbons but also a high content of sulfur, the waste tire pyrolysis oil may advantageously serve as a source of sulfur in the refining process of waste plastic pyrolysis oil. Also, the use of the waste tire pyrolysis oil in the refining process of waste plastic pyrolysis oil is advantageous in terms of reducing the environmental load due to recycling of waste tires and maintaining the catalytic activity for a long period of time.
In some embodiments, the waste tire pyrolysis oil may comprise 500 ppm or more of sulfur. When the sulfur component is comprised in an amount of less than 500 ppm, a content of the sulfur component supplied is small, such that the effect of preventing deactivation of the molybdenum-based hydrotreating catalyst may be insufficient. In some embodiments, the sulfur component may be comprised in an amount of 1,000 ppm or more, or 3,000 ppm or more, and without limitation, 200,000 ppm or less.
In some embodiments, the mixed oil may comprise 300 ppm or more of sulfur. As in the case of the waste tire pyrolysis oil, when the sulfur component is comprised in the mixed oil in an amount of less than 300 ppm, the content of the sulfur component supplied is small, such that the effect of preventing deactivation of the molybdenum-based hydrotreating catalyst may be insufficient. In some embodiments, the sulfur component may be comprised in an amount of 1,000 ppm or more, or 5,000 ppm or more, and without limitation, 200,000 ppm or less.
In some embodiments, the waste tire pyrolysis oil may be comprised in an amount of less than 100 parts by weight with respect to 100 parts by weight of the waste plastic pyrolysis oil, or less than 50 parts by weight, or less than 25 parts by weight, and without limitation, more than 5 parts by weight. When the waste tire pyrolysis oil is comprised in an amount of less than 100 parts by weight, a content of chlorine (Cl) or nitrogen (N) is not high, and it is difficult to form an ammonium salt (NH4Cl), which may improve process stability.
Step (S2) of hydrotreating the mixed oil with the reaction gas comprising hydrogen gas (H2) in the presence of the molybdenum-based hydrotreating catalyst refers to a hydrogenation reaction in which hydrogen gas (H2) is added to the hydrocarbon oil comprised in the mixed oil. In some embodiments, the hydrotreating may refer to hydrotreating, which is known in the related art, comprising a hydrodesulfurization reaction, a hydrocracking reaction, a a hydrodechlorination reaction, a hydrodenitrogenation reaction, hydrodeoxygenation reaction, and/or a hydrodemetallization reaction. Through the hydrotreating, impurities comprising chlorine (Cl), nitrogen (N), and/or some olefins may be removed, and/or other metal impurities may also be removed, and a by-product comprising the impurities is produced.
The by-product is produced by reacting impurities such as chlorine (Cl), nitrogen (N), sulfur (S), and/or oxygen (O) comprised in the mixed oil that is mixed with waste plastic pyrolysis oil and waste tire pyrolysis oil. In some embodiments, the by-product may comprise hydrogen sulfide gas (H2S), hydrogen chloride (HCl), ammonia (NH3), water vapor (H2O), and/or the like, and in some embodiments, may comprise unreacted hydrogen gas (H2), and a trace of methane (CH4), ethane (C2H6), or the like.
In some embodiments, the molybdenum-based hydrotreating catalyst may be a catalyst in which a molybdenum-based metal, or a metal comprising one or two or more selected from nickel, cobalt, and tungsten, and a molybdenum-based metal are supported on a support. In some embodiments, the molybdenum-based hydrotreating catalyst has high catalytic activity during hydrotreating, and the molybdenum-based hydrotreating catalysts may be used alone or, if necessary, in the form of a two-way catalyst combined with a metal such as nickel, cobalt, or tungsten.
In some embodiments, as the support, alumina, silica, silica-alumina, titanium oxide, a molecular sieve, zirconia, aluminum phosphate, carbon, niobia, or a mixture thereof may be used, but the present disclosure is not limited thereto.
In some embodiments, the molybdenum-based hydrotreating catalyst may comprise a molybdenum-based sulfide hydrotreating catalyst. In some embodiments, the molybdenum-based hydrotreating catalyst may comprise molybdenum sulfide (MoS) and/or molybdenum disulfide (MoS2), but is not limited thereto, and may comprise a known molybdenum-based sulfide hydrotreating catalyst.
In some embodiments, the reaction gas may further comprise hydrogen sulfide gas (H2S). The hydrogen sulfide gas (H2S) comprised in the reaction gas may act as a sulfur source, and may regenerate the activity of the molybdenum-based hydrotreating catalyst deactivated during the refining process together with the waste tire pyrolysis oil mixed with the waste plastic pyrolysis oil.
In some embodiments, the hydrotreating in step (S2) may be performed at a pressure of 200 bar or less. When the hydrotreating in step (S2) is performed at a pressure of 200 bar or less, formation of NH4Cl impurities is suppressed, such that a rate of increase in differential pressure in the reactor may be suppressed, and reaction stability may be improved. In some embodiments, the hydrotreating in step (S2) may be performed at a pressure of 150 bar or less, or 100 bar or less, and without limitation, 60 bar or more.
In some embodiments, the hydrotreating in step (S2) may be performed at a temperature of 300° C. or higher and lower than 450° C. When the temperature satisfies the above range, the hydrotreating efficiency may be improved. In some embodiments, the hydrotreating in step (S2) may be performed at a temperature of 320° C. to 430° C., or 350° C. to 400° C.
In some embodiments, the hydrotreating in step (S2) may be performed at a liquid hourly space velocity (LHSV) of 0.1 to 10 h−1. When the LHSV satisfies the above range, refined oil from which impurities such as chlorine, nitrogen, and metals are removed may be more stably obtained. In some embodiments, the hydrotreating in step (S2) may be performed at an LHSV of 0.3 to 8 h−1, or 0.5 to 5 h−1.
In some embodiments, the hydrotreating in step (S2) may be performed at a gas oil ratio (GOR) of 300 to 3,000. The GOR (is defined by the relation GOR=Vg/Vo, where Vg and Vo are respectively the volumes of gas and of oil produced at the surface under standard conditions (1 atm and 25° C.). When the GOR satisfies the above range, the hydrotreating efficiency may be improved. In some embodiments, the hydrotreating in step (S2) may be performed at a GOR of 500 to 2,500, or 800 to 1,500.
In some embodiments, the mixed oil may further comprise a sulfur source. Since the waste tire pyrolysis oil comprises a high content of chlorine and/or nitrogen, when the sulfur source is further comprised in place of a part of waste tire pyrolysis oil, it is difficult for an ammonium salt formation temperature to increase to a temperature at which hydrotreating is performed, and as a result, a decrease in pipe flow, an increase in differential pressure, reactor corrosion, and the like may be suppressed.
The sulfur source refers to a sulfur source capable of supplying a sulfur component during the refining process, preferably in a continuous manner.
In some embodiments, the sulfur source may comprise sulfur-containing oil. The sulfur-containing oil refers to oil composed of hydrocarbons comprising sulfur obtained from crude oil as a feedstock. The sulfur-containing oil is not particularly limited as long as it is oil comprising sulfur, and the sulfur-containing oil may be, for example, light gas oil, straight-run naphtha, vacuum naphtha, pyrolysis naphtha, straight-run kerosene, vacuum kerosene, pyrolysis kerosene, straight-run gas oil, vacuum gas oil, pyrolysis gas oil, and/or any mixture thereof.
In some embodiments, the sulfur-containing oil may be light gas oil (LGO) with a specific gravity of 0.7 to 1. When this sulfur-containing oil is used, the sulfur-containing oil may be uniformly mixed with the waste plastic pyrolysis oil and the waste tire pyrolysis oil, and high hydrotreating efficiency may be exhibited. In some embodiments, the specific gravity may be 0.75 to 0.95, or 0.8 to 0.9. In some embodiments sulfur-containing oil may comprise 100 ppm or more of sulfur. When the sulfur component is comprised in an amount of less than 100 ppm, a content of the sulfur component supplied is small, such that the effect of preventing deactivation of the molybdenum-based hydrotreating catalyst may be insufficient. In some embodiments, the sulfur component may be comprised in an amount of 800 ppm or more, or 8,000 ppm or more, and without limitation, 200,000 ppm or less.
In some embodiments, the sulfur-containing oil may be comprised in an amount of 100 parts by weight or less with respect to 100 parts by weight of the waste plastic pyrolysis oil. In some embodiments, the sulfur-containing oil may be comprised in an amount of 70 parts by weight or less, or 50 parts by weight or less, and without limitation, more than 10 parts by weight. As the sulfur-containing oil is comprised in an amount of 100 parts by weight or less, the concentration of chlorine (Cl) or nitrogen (N) comprised in the waste plastic pyrolysis oil is diluted, such that a formation rate of an ammonium salt (NH4Cl) may be controlled, and the process stability may be improved.
In some embodiments, the sulfur source may comprise one or two or more sulfur-comprising organic compounds selected from a disulfide-based compound, a sulfide-based compound, a sulfonate-based compound, and a sulfate-based compound. Specifically, the sulfur source may comprise one or a mixture of two or more selected from dimethyl disulfide, dimethyl sulfide, polysulfide, dimethyl sulfoxide (DMSO), methyl methanesulfonate, ethyl methanesulfonate, propyl methanesulfonate, propenyl propenesulfonate, propenyl cyanoethansulfonate, ethylene sulfate, bicyclo-glyoxal sulfate, and/or methyl sulfate. However, these compounds are only presented as examples and the present disclosure is not limited thereto.
In some embodiments, the sulfur-containing organic compound may be comprised in an amount of 1 to 25 parts by weight with respect to 100 parts by weight of the waste plastic pyrolysis oil. In some embodiments, the sulfur-containing organic compound may be comprised in an amount of 5 to 20 parts by weight, or 10 to 15 parts by weight. When the sulfur-containing organic compound is comprised in an amount of less than 1 part by weight, the content of the sulfur component supplied is small, such that the effect of preventing deactivation of the molybdenum-based hydrotreating catalyst may be insufficient.
In some embodiments, refined oil obtained by the method of refining waste plastic pyrolysis oil may comprise less than 10 ppm of chlorine (Cl), less than 100 ppm of nitrogen (N), and/or less than 50 ppm of sulfur (S). In some embodiments, the obtained refined oil may comprise less than 3 wt % of olefins, and/or may comprise 0.5 wt % or less of conjugated diolefins.
In step (S3) of removing the by-product of the hydrotreating from the product in step (S2) to obtain refined oil, high-quality refined oil with reduced impurities may be finally obtained from the mixed oil.
As described above, the by-product of the hydrotreating is produced by reacting impurities such as chlorine (Cl), nitrogen (N), sulfur (S), and/or oxygen (O) comprised in the waste plastic pyrolysis oil with hydrogen gas (H2). In some embodiments, the by-product may comprise hydrogen sulfide gas (H2S), hydrogen chloride (HCl), ammonia (NH3), water vapor (H2O), and/or the like, and in addition, may comprise unreacted hydrogen gas (H2), and a trace of methane (CH4), ethane (C2H6), and/or the like.
As a method of removing the by-product, for example, the by-product may be removed from the product in step (S2) by a method of discharging mixed gas, which is described as an example of the method, but the present disclosure is not limited thereto. Through the above method, high-quality refined oil with reduced impurities may be finally obtained from the mixed oil.
In some embodiments, the hydrogen sulfide gas (H2S) may be separated from the by-product of the hydrotreating removed in step (S3) and then re-supplied. In some embodiments, the hydrogen sulfide gas (H2S) comprised in the reaction gas in step (S2) may be separated from the by-product of the hydrotreating removed in step (S3) through an adsorption removal step, and then the separated hydrogen sulfide gas (H2S) may be re-supplied and reused as hydrogen sulfide gas (H2S) in step (S2). In the adsorption removal step, hydrogen sulfide gas (H2S) may be separated from the by-product using an adsorbent such as zeolite, carbon, or alumina, and hydrogen gas (H2) may also be separated.
The method of refining waste plastic pyrolysis oil may be performed using a device of refining pyrolysis oil.
In some embodiments, the device of refining pyrolysis oil may comprise: a mixer into which waste plastic pyrolysis oil and waste tire pyrolysis oil are introduced and in which the waste plastic pyrolysis oil and the waste tire pyrolysis oil are mixed to produce a mixed oil; and a reactor into which the mixed oil is introduced from the mixer and a reaction gas comprising hydrogen gas (H2) is introduced and in which the mixed oil is hydrotreated in the presence of a molybdenum-based hydrotreating catalyst. The configuration of the refining device is not limited thereto, and in addition, the refining device may be configured by comprising or modifying configurations known in the related art.
The mixer may comprise a common mixer for uniform mixing. Pyrolysis oil and waste tire pyrolysis oil are introduced into the mixer and stirred to produce uniform mixed oil.
In some embodiments, a sulfur source may be further introduced into the mixer and mixed to produce mixed oil.
The reactor may comprise a reaction zone in which the molybdenum-based hydrotreating catalyst is provided. A dechlorination, denitrification, desulfurization, or demetallization reaction may be performed in the reaction zone. The mixed oil may be introduced into the reactor, the mixed oil may be hydrotreated in the presence of a hydrotreating catalyst, and a reaction in which some olefins and/or metal impurities are removed may also be performed.
The reactor may be provided with a gas outlet, and the by-product of the hydrotreating may be discharged through the gas outlet.
In some embodiments, the refining device may further comprise: a gas separator into which the by-product is introduced and in which hydrogen sulfide gas (H2S) is separated from the by-product of the hydrotreating; and a recirculation line re-supplying the separated hydrogen sulfide gas (H2S) from the gas separator to the reactor. The gas separator may comprise an adsorbent, and may separate the hydrogen sulfide gas (H2S) from the by-product using the adsorbent. In some embodiments, the gas separator may also separate unreacted hydrogen gas (H2).
As illustrated in
In some embodiments, there is provided a continuous operation method of a device of refining waste plastic pyrolysis oil, the continuous operation method comprising: (S1) mixing waste plastic pyrolysis oil and waste tire pyrolysis oil to produce a mixed oil; (S2) hydrotreating the mixed oil with a reaction gas comprising hydrogen gas (H2) and hydrogen sulfide gas (H2S) at a pressure of 200 bar or less in the presence of a molybdenum-based sulfide hydrotreating catalyst; and (S3) removing a by-product of the hydrotreating from a product in step (S2) to obtain refined oil, wherein the hydrogen sulfide gas (H2S) in step (S2) is separated from the by-product of the hydrotreating in step (S3), and the separated hydrogen sulfide gas (H2S) is re-supplied.
The hydrotreating may be performed at a pressure of 200 bar or less. When the hydrotreating is performed at a pressure of 200 bar or less, formation of NH4Cl impurities is suppressed, such that a rate of increase in differential pressure in the reactor may be suppressed, and reaction stability may be improved. In some embodiments, the hydrotreating may be performed at a pressure of 150 bar or less, or 100 bar or less, and without limitation, 60 bar or more.
The hydrogen sulfide gas (H2S) comprised in the reaction gas may act as a sulfur source, and may regenerate the activity of the molybdenum-based hydrotreating catalyst deactivated during the reaction process together with the sulfur source mixed with the waste plastic pyrolysis oil.
The hydrogen sulfide gas (H2S) may be separated from the by-product of the hydrotreating removed in step (S3) and then re-supplied. In some embodiments, the hydrogen sulfide gas (H2S) comprised in the reaction gas in step (S2) may be separated from the by-product of the hydrotreating removed in step (S3) through an adsorption removal step, and then the separated hydrogen sulfide gas (H2S) may be re-supplied and reused as hydrogen sulfide gas (H2S) in step (S2). The process efficiency may be improved by reducing the amount of additionally added hydrogen sulfide gas (H2S) used, and economic efficiency may be improved by reducing the costs of disposing of the by-product of the hydrotreating.
In some embodiments, sulfur may be continuously supplied from the waste tire pyrolysis oil, such that the activity of the molybdenum-based sulfide hydrotreating catalyst may be maintained. The waste tire pyrolysis oil acts as a sulfur source that continuously supplies a sulfur component during the refining process, and has the effect of suppressing deactivation of the molybdenum-based sulfide hydrotreating catalyst and regenerating the catalytic activity. As the catalytic activity is regenerated, the device of refining waste plastic pyrolysis oil may be stably and continuously operated for a long period of time.
In some embodiments, the mixed oil may comprise 300 ppm or more of sulfur. As in the case of the waste tire pyrolysis oil, when the sulfur component is comprised in the mixed oil in an amount of less than 300 ppm, the content of the sulfur component supplied is small, such that the effect of preventing deactivation of the molybdenum-based hydrotreating catalyst may be insufficient. In some embodiments, the sulfur component may be comprised in an amount of 1,000 ppm or more, or 5,000 ppm or more, and without limitation, 200,000 ppm or less.
In some embodiments, the mixed oil may further comprise a sulfur source.
In some embodiments, the sulfur source may comprise sulfur-containing oil. The sulfur-containing oil refers to oil comprised of hydrocarbons comprising sulfur obtained from crude oil as a feedstock. The sulfur-containing oil is not particularly limited as long as it is oil comprising sulfur, and examples of the sulfur-containing oil comprise light gas oil, straight-run naphtha, vacuum naphtha, pyrolysis naphtha, straight-run kerosene, vacuum kerosene, pyrolysis kerosene, straight-run gas oil, vacuum gas oil, pyrolysis gas oil, and/or any mixture thereof.
In some embodiments, the sulfur-containing oil may be comprised in an amount of 100 parts by weight or less with respect to 100 parts by weight of the waste plastic pyrolysis oil, or 70 parts by weight or less, or 50 parts by weight or less, and without limitation, more than 10 parts by weight. As the sulfur-containing oil is comprised in an amount of less than 100 parts by weight, nitrogen (N) impurities may be efficiently removed even when the hydrotreating is performed at a low pressure of 100 bar or less. In a case where the sulfur-containing oil is comprised in an amount of more than 100 parts by weight, when the hydrotreating is performed at a low pressure of 100 bar or less, the nitrogen (N) impurity removal efficiency is reduced. When the hydrotreating is performed at a high pressure of 100 bar or more to remove impurities, the formation rate of NH4Cl increases, and the reaction stability is reduced.
In some embodiments, the sulfur source may comprise one or two or more sulfur-containing organic compounds selected from a disulfide-based compound, a sulfide-based compound, a sulfonate-based compound, and/or a sulfate-based compound. In some embodiments, the sulfur source may comprise one or a mixture of two or more selected from dimethyl disulfide, dimethyl sulfide, polysulfide, dimethyl sulfoxide (DMSO), methyl methanesulfonate, ethyl methanesulfonate, propyl methanesulfonate, propenyl propenesulfonate, propenyl cyanoethansulfonate, ethylene sulfate, bicyclo-glyoxal sulfate, and/or methyl sulfate, but is not limited thereto.
In some embodiments, the sulfur-containing organic compound may be comprised in an amount of 1 to 25 parts by weight with respect to 100 parts by weight of the waste plastic pyrolysis oil, or 5 to 20 parts by weight, or 10 to 15 parts by weight. When the sulfur-containing organic compound is comprised in an amount of less than 1 part by weight, the content of the sulfur component supplied is small, such that the effect of preventing deactivation of the molybdenum-based hydrotreating catalyst may be insufficient.
As for the contents not further described in the continuous operation method of a device of refining waste plastic pyrolysis oil, the description of the method of refining waste plastic pyrolysis oil described above may be used as reference.
Hereinafter, the method of refining waste plastic pyrolysis oil according to the present disclosure and the continuous operation method thereof will be described in more detail with reference to Examples. However, the following Examples are only reference examples for describing the present disclosure in detail, and the present disclosure is not limited thereto and may be implemented in various forms. Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure pertains. In addition, the terms used in the present disclosure are only to effectively describe specific Examples, but are not intended to limit the present disclosure.
Waste tires were pyrolyzed to prepare waste tire pyrolysis oil containing 3,000 ppm or more of nitrogen (N), 150 ppm or more of chlorine (Cl), and 3,500 ppm of sulfur (S).
Waste plastics were pyrolyzed to prepare waste plastic pyrolysis oil containing a high concentration of impurities including 300 ppm or more of nitrogen (N), 30 ppm or more of chlorine (Cl), 20 vol % or more of olefins, and 1 vol % or more of conjugated diolefins.
Mixed oil was produced by adding, to a mixer, 15 parts by weight of the waste tire pyrolysis oil with respect to 100 parts by weight of the waste plastic pyrolysis oil.
The mixed oil was added to the reactor, a reaction gas including hydrogen gas (H2) was added to the reactor, and hydrotreating was performed by operating the reactor. Specifically, after the mixed oil was added to the reactor, the mixed oil was hydrotreated with a reaction gas including hydrogen gas (H2) in the presence of an NiMoS/γ-Al2O3 hydrotreating catalyst under conditions of 350° C., 60 bar, a gas oil ratio of 1,000, and a liquid hourly space velocity of 1,000 to 2.5 h−1. A by-product was produced by the hydrotreating, and hydrogen sulfide gas (H2S), hydrogen chloride (HCl), ammonia (NH3), water vapor (H2O), and traces of methane (CH4) and ethane (C2H6) were included in the by-product. The by-product was discharged through a gas outlet of the reactor, and refined oil from which impurities were removed was finally obtained from the reactor.
Hydrotreating was performed under the same conditions as those in Example 1, except that the hydrotreating was performed at 390° C. in the presence of the hydrotreating catalyst. In addition, a by-product in a fluid removed from the reactor was added to a gas separator. In the gas separator, hydrogen sulfide gas (H2S) and hydrogen gas (H2) were separated from the by-product through a zeolite adsorbent. Refined oil from which impurities were removed was finally obtained by performing a reaction under the same conditions as those in Example 1, except that the separated hydrogen sulfide gas (H2S) and hydrogen gas (H2) were re-supplied to the reactor through the recirculation line and added to the reaction gas.
Refined oil from which impurities were removed was finally obtained by performing a reaction under the same conditions as those in Example 1, except that hydrotreating was performed in the presence of the hydrotreating catalyst under conditions of 320° C. and 90 bar.
Refined oil from which impurities were removed was finally obtained by performing a reaction under the same conditions as those in Example 1, except that the waste tire pyrolysis oil was added to the mixer in an amount of 5 parts by weight with respect to 100 parts by weight of the waste plastic pyrolysis oil.
Refined oil from which impurities were removed was finally obtained by performing a reaction under the same conditions as those in Example 1, except that the waste tire pyrolysis oil was added to the mixer in an amount of 70 parts by weight with respect to 100 parts by weight of the waste plastic pyrolysis oil.
Refined oil from which impurities were removed was finally obtained by performing a reaction under the same conditions as those in Example 1, except that mixed oil was produced by additionally adding, to the mixer, light gas oil (R-LGO) with a specific gravity of 0.85851 containing 20,000 ppm of sulfur as a sulfur source.
Hydrotreating was performed under the same conditions as those in Example 6, except that the hydrotreating was performed at 390° C. in the presence of a hydrotreating catalyst. In addition, a by-product in a fluid removed from the reactor was added to a gas separator. In the gas separator, hydrogen sulfide gas (H2S) and hydrogen gas (H2) were separated from the by-product through a zeolite adsorbent. Refined oil from which impurities were removed was finally obtained by performing a reaction under the same conditions as those in Example 6, except that the separated hydrogen sulfide gas (H2S) and hydrogen gas (H2) were re-supplied to the reactor through the recirculation line and added to the reaction gas.
Refined oil from which impurities were removed was finally obtained by performing a reaction under the same conditions as those in Example 1, except that only waste plastic pyrolysis oil was used.
The content (ppm) of chlorine in the finally obtained refined oil was measured by ICP and XRF analysis methods, and the results were shown.
The catalytic activity duration was measured and expressed in hours based on the time point when the content of nitrogen in the refined oil exceeded 10 ppm by performing a Total Nitrogen & Sulfur (TNS element) analysis.
The measurement results were shown in Table 1.
Referring to Table 1, in the cases of Examples 1 to 7 in which a significant amount of waste tire pyrolysis oil, which supplied sulfur that plays a role in maintaining the catalytic activity during the refining process, was mixed, it was confirmed that the catalytic activity was maintained for a long period of time as the catalytic activity duration was 600 hours or longer. In particular, in Example 7, the catalytic activity duration was about 1,600 hours. This is because the waste plastic pyrolysis oil and the waste tire pyrolysis oil were mixed, and moreover, the refining process was performed by combining the additional supply of the sulfur-containing oil and the use of H2+H2S reaction gas. Meanwhile, in Example 5 in which a large amount of waste tire pyrolysis oil was used, the catalytic activity duration was 1,000 hours or longer, but a small amount of ammonium salt was formed in the reactor. However, in Example 6 in which the sulfur-containing oil was added, almost no ammonium salt was formed in the reactor, and the catalytic activity duration was relatively longer, and as a result, the refining process was stably operated for a longer period of time.
On the other hand, in the case of Comparative Example 1 in which the hydrotreating was performed under the same conditions as those in Example 1 except that only waste plastic pyrolysis oil was used, the catalytic activity duration was 235 hours, which was significantly short.
As set forth above, the method of refining waste plastic pyrolysis oil according to the present disclosure may exhibit an effect of producing refined oil comprising a significantly low content of impurities such as chlorine, nitrogen, oxygen, and/or metals.
Further, the method of refining waste plastic pyrolysis oil according to the present disclosure may exhibit an effect of reducing the environmental load due to waste tires by using waste tire pyrolysis oil.
Further, in the continuous operation method of a device of refining waste plastic pyrolysis oil according to the present disclosure, sulfur is continuously supplied from waste tire pyrolysis oil and the activity of the molybdenum-based sulfide hydrotreating catalyst is maintained, such that an effect of continuously operating the refining device for a long period of time may be exhibited.
Although exemplary embodiments of the present disclosure have been described, the present disclosure is not limited to the exemplary embodiments, but may be prepared in various different forms, and it will be apparent to those skilled in the art to which the present disclosure pertains that the exemplary embodiments may be implemented in other specific forms without departing from the spirit or essential feature of the present disclosure. Therefore, it is to be understood that the exemplary embodiments described hereinabove are illustrative rather than restrictive in all aspects.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0064316 | May 2023 | KR | national |
| 10-2023-0103369 | Aug 2023 | KR | national |
