Method for regenerating catalyst for liquefied-petroleum gas synthesis

Abstract

Provided is a method for regenerating a catalyst for liquefied-petroleum gas synthesis capable of restoring degraded catalytic activity of a catalyst for liquefied-petroleum gas synthesis. The method for regenerating a catalyst for liquefied-petroleum gas synthesis includes: a combustion step in which a catalyst for liquefied-petroleum gas synthesis is brought into contact with an oxygen-containing gas having a temperature higher than a liquefied-petroleum gas synthesis temperature but lower than 360°C; and a reduction step in which the catalyst for liquefied-petroleum gas synthesis is brought into contact with a reducing gas having a temperature higher than the liquefied-petroleum gas synthesis temperature but lower than 360°C.

Description

Method for regenerating catalyst for liquefied petroleum gas synthesis

[0001] The present disclosure relates to a method for regenerating a catalyst for liquefied petroleum gas synthesis.

[0002] A method for synthesizing liquefied petroleum gas from synthesis gas using a catalyst for liquefied petroleum gas synthesis is known. In this synthesis method, when synthesizing propane-rich liquefied petroleum gas from synthesis gas, the synthesis temperature is 350 to 600°C, and it is known that the higher the synthesis temperature, the higher the yield of propane (Patent Document 1).

[0003] When the above synthesis method is carried out over a long period of time, the catalyst for liquefied petroleum gas synthesis gradually deteriorates. In particular, the synthesis temperature of liquefied petroleum gas affects the yield of propane. Increasing the synthesis temperature of liquefied petroleum gas increases the yield of propane, but the catalyst for liquefied petroleum gas synthesis is more likely to deteriorate. As a result, the deterioration of the catalytic activity of the catalyst for liquefied petroleum gas synthesis significantly reduces the yield of liquefied petroleum gas before the specified synthesis time is reached.

[0004] International Publication No. 2008 / 015995

[0005] An object of the present disclosure is to provide a method for regenerating a catalyst for liquefied petroleum gas synthesis, which can regenerate the deteriorated catalytic activity of the catalyst for liquefied petroleum gas synthesis.

[0006] [1] A method for regenerating a catalyst for synthesizing liquefied petroleum gas, comprising: a combustion step of contacting a catalyst for synthesizing liquefied petroleum gas with an oxygen-containing gas that is higher than the synthesis temperature of liquefied petroleum gas but lower than 360°C; and a reduction step of contacting the catalyst for synthesizing liquefied petroleum gas with a reducing gas that is higher than the synthesis temperature of liquefied petroleum gas but lower than 360°C. [2] The method for regenerating a catalyst for synthesizing liquefied petroleum gas as set forth in [1] above, wherein the synthesis temperature of the liquefied petroleum gas is 280°C or higher but lower than 350°C. [3] The method for regenerating a catalyst for synthesizing liquefied petroleum gas as set forth in [1] or [2] above, wherein the oxygen-containing gas is air. [4] The method for regenerating a catalyst for synthesizing liquefied petroleum gas as set forth in any one of [1] to [3] above, wherein the reducing gas is a gas containing hydrogen. [5] The method for regenerating a catalyst for liquefied petroleum gas synthesis according to any one of [1] to [4] above, wherein in the combustion step, the temperature of the oxygen-containing gas is greater than 310°C and less than 360°C, and the catalyst for liquefied petroleum gas synthesis is contacted with the oxygen-containing gas for 0.1 to 48.0 hours. [6] The method for regenerating a catalyst for liquefied petroleum gas synthesis according to any one of [1] to [5] above, wherein in the reduction step, the temperature of the reducing gas is greater than 320°C and less than 360°C, and the catalyst for liquefied petroleum gas synthesis is contacted with the reducing gas for 0.1 to 48.0 hours. [7] The method for regenerating a catalyst for liquefied petroleum gas synthesis according to any one of [1] to [6] above, wherein the combustion step and the reduction step are carried out in a reactor. [8] The method for regenerating a catalyst for liquefied petroleum gas synthesis according to any one of [1] to [7] above, wherein the ratio of the yield of liquefied petroleum gas when liquefied petroleum gas is synthesized using the catalyst for liquefied petroleum gas synthesis immediately after regeneration after the reduction step to the yield of liquefied petroleum gas when liquefied petroleum gas is synthesized using the catalyst for liquefied petroleum gas synthesis immediately before regeneration and before the combustion step is 101% or more. [9] The method for regenerating a catalyst for liquefied petroleum gas synthesis according to any one of [1] to [8] above, wherein the catalyst for liquefied petroleum gas synthesis does not contain any one of the metal elements Fe, Co, and Ru.

[10] The method for regenerating a catalyst for liquefied petroleum gas synthesis according to any one of [1] to [9] above, wherein the catalyst for liquefied petroleum gas synthesis has a methanol synthesis catalyst for synthesizing methanol and a dehydration catalyst for dehydrating methanol.

[11] The method for regenerating a catalyst for liquefied petroleum gas synthesis according to the above

[10] , wherein the methanol synthesis catalyst is a Cu-Zn catalyst.

[12] The method for regenerating a catalyst for liquefied petroleum gas synthesis according to the above

[10] or

[11] , wherein the dehydration catalyst is a zeolite catalyst supporting a noble metal.

[0007] According to the present disclosure, it is possible to provide a method for regenerating a catalyst for synthesizing liquefied petroleum gas, which can regenerate the deteriorated catalytic activity of the catalyst for synthesizing liquefied petroleum gas.

[0008] Fig. 1 is a graph showing the measurement results of CO conversion during synthesis in Examples 1 to 3, Reference Example, and Comparative Example 1. Fig. 2 is a graph showing the measurement results of propane and butane yields during synthesis in Examples 1 to 3, Reference Example, and Comparative Example 1. Fig. 3 is a graph showing the measurement results of CO conversion during synthesis in Examples 4 to 7 and Comparative Examples 2 to 3. Fig. 4 is a graph showing the measurement results of propane and butane yields during synthesis in Examples 4 to 7 and Comparative Examples 2 to 3.

[0009] Hereinafter, a detailed description will be given based on an embodiment.

[0010] As a result of extensive research, the inventors have discovered that the deteriorated catalytic activity of a catalyst for synthesizing liquefied petroleum gas, whose catalytic performance has deteriorated, can be restored by subjecting the catalyst to a prescribed combustion process and a prescribed reduction process, and have completed the present disclosure based on this finding.

[0011] The method for regenerating a catalyst for liquefied petroleum gas synthesis in one embodiment includes a combustion step of contacting the catalyst for liquefied petroleum gas synthesis with an oxygen-containing gas that is higher than the synthesis temperature of liquefied petroleum gas but lower than 360°C, and a reduction step of contacting the catalyst for liquefied petroleum gas synthesis with a reducing gas that is higher than the synthesis temperature of liquefied petroleum gas but lower than 360°C.

[0012] LPG synthesis catalysts are used to synthesize liquefied petroleum gas from carbon-containing raw materials. For example, LPG is synthesized from a raw material gas containing carbon monoxide and hydrogen using a LPG synthesis catalyst. During the synthesis of LPG, the reaction system is heated. This causes the LPG synthesis catalyst to deteriorate.

[0013] The cause of deterioration of the liquefied petroleum gas synthesis catalyst during the synthesis of liquefied petroleum gas is that carbonaceous material (coke) is deposited on the surface of the liquefied petroleum gas synthesis catalyst, and the active points present on the surface of the liquefied petroleum gas synthesis catalyst are covered with coke. Therefore, by carrying out the method for regenerating the liquefied petroleum gas synthesis catalyst of the embodiment, the deteriorated catalytic activity of the liquefied petroleum gas synthesis catalyst can be regenerated.

[0014] The present invention relates to a method for regenerating a liquefied petroleum gas synthesis catalyst, and more particularly to a method for regenerating a liquefied petroleum gas synthesis catalyst, the method comprising the steps of: (a) a combustion step;

[0015] In the combustion step in the method for regenerating a catalyst for liquefied petroleum gas synthesis, the catalyst for liquefied petroleum gas synthesis is contacted with an oxygen-containing gas at a temperature higher than the synthesis temperature of liquefied petroleum gas but lower than 360° C. The catalyst for liquefied petroleum gas synthesis in the combustion step is the catalyst for liquefied petroleum gas synthesis used in the method for regenerating a catalyst for liquefied petroleum gas synthesis of the embodiment, i.e., the catalyst for liquefied petroleum gas synthesis whose catalytic performance has deteriorated as described above.

[0016] In the combustion step, the catalyst for liquefied petroleum gas synthesis, whose catalytic activity has deteriorated, is brought into contact with an oxygen-containing gas at a temperature higher than the synthesis temperature of liquefied petroleum gas but lower than 360°C, whereby coke deposited on the surface of the catalyst for liquefied petroleum gas synthesis is burned and removed by the oxygen-containing gas. The oxygen-containing gas is preferably air.

[0017] When a liquefied petroleum gas synthesis catalyst comes into contact with an oxygen-containing gas at 360°C or higher, the metals contained in the liquefied petroleum gas synthesis catalyst, such as Cu and Zn contained in the methanol synthesis catalyst described below, aggregate, reducing the catalytic activity of the liquefied petroleum gas synthesis catalyst.

[0018] In the combustion step, the temperature of the oxygen-containing gas is preferably higher than 310° C. and lower than 360° C., and the catalyst for liquefied petroleum gas synthesis and the oxygen-containing gas are preferably contacted for 0.1 to 48.0 hours. In this way, by contacting a catalyst for liquefied petroleum gas synthesis whose catalytic activity has deteriorated with an oxygen-containing gas at higher than 310° C. and lower than 360° C. for 0.1 to 48.0 hours, coke covering the surface of the catalyst for liquefied petroleum gas synthesis can be efficiently removed.

[0019] Although the combustion process removes the coke present on the surface of the liquefied petroleum gas synthesis catalyst with an oxygen-containing gas, the liquefied petroleum gas synthesis catalyst is oxidized because it is exposed to the oxygen-containing gas. An oxidized liquefied petroleum gas synthesis catalyst has low catalytic activity. Therefore, the liquefied petroleum gas synthesis catalyst that has been subjected to the combustion process is subjected to a reduction process.

[0020] In the reduction step carried out after the combustion step, the liquefied petroleum gas synthesis catalyst after exposure to the oxygen-containing gas is contacted with a reducing gas at a temperature higher than the synthesis temperature of liquefied petroleum gas but lower than 360°C. By carrying out the reduction step, the oxidized liquefied petroleum gas synthesis catalyst is reduced, thereby improving the catalytic activity of the liquefied petroleum gas synthesis catalyst. In this way, the catalytic activity of the liquefied petroleum gas synthesis catalyst, whose catalytic activity has deteriorated, can be regenerated.

[0021] The reducing gas used in the reduction step is preferably a gas containing hydrogen, the higher the hydrogen concentration the more preferable, and hydrogen is more preferable. When the liquefied petroleum gas synthesis catalyst comes into contact with a reducing gas at 360°C or higher, metals contained in the liquefied petroleum gas synthesis catalyst, such as Cu and Zn contained in the methanol synthesis catalyst described below, aggregate, and the catalytic activity of the liquefied petroleum gas synthesis catalyst decreases.

[0022] In the reduction step, the temperature of the reducing gas is preferably 320° C. or higher but lower than 360° C., and the catalyst for liquefied petroleum gas synthesis is preferably contacted with the reducing gas for 0.1 to 48.0 hours. In this way, by contacting the oxidized catalyst for liquefied petroleum gas synthesis after exposure to the oxygen-containing gas with a reducing gas at 320° C. or higher but lower than 360° C. for 0.1 to 48.0 hours, the oxidized catalyst for liquefied petroleum gas synthesis can be efficiently reduced.

[0023] Furthermore, as described above, in the synthesis of liquefied petroleum gas, if the synthesis temperature is high, the yield of liquefied petroleum gas increases, but the catalyst for synthesizing liquefied petroleum gas rapidly deteriorates. Therefore, from the viewpoint of increasing the yield of liquefied petroleum gas while suppressing the deterioration of the catalyst for synthesizing liquefied petroleum gas, it is preferable that the upper limit of the synthesis temperature of liquefied petroleum gas is 350°C or less. Furthermore, if the lower limit of the synthesis temperature of liquefied petroleum gas is 280°C or more, liquefied petroleum gas can be synthesized stably.

[0024] In addition, the combustion step and the reduction step are preferably carried out in a reactor. If the combustion step and the reduction step, i.e., the method for regenerating a catalyst for liquefied petroleum gas synthesis according to the embodiment, are carried out in the reactor used for synthesizing liquefied petroleum gas, the combustion step, the reduction step, and the linked step described below can be carried out in the same reactor, which is convenient.

[0025] Furthermore, it is preferable to carry out the regeneration method for the liquefied petroleum gas synthesis catalyst until the ratio of the yield of liquefied petroleum gas when liquefied petroleum gas is synthesized from a raw material gas containing carbon monoxide and hydrogen using a liquefied petroleum gas synthesis catalyst immediately after regeneration after the reduction step to the yield of liquefied petroleum gas when liquefied petroleum gas is synthesized from a raw material gas containing carbon monoxide and hydrogen using an unused liquefied petroleum gas synthesis catalyst is 75% or more.

[0026] It is also preferable to carry out the regeneration method for the liquefied petroleum gas synthesis catalyst until the ratio of the carbon monoxide and / or hydrogen conversion rate when liquefied petroleum gas is synthesized using the liquefied petroleum gas synthesis catalyst immediately after regeneration to the carbon monoxide and / or hydrogen conversion rate when liquefied petroleum gas is synthesized using an unused liquefied petroleum gas synthesis catalyst is 75% or more.

[0027] In addition, it is preferable to perform the regeneration method for the liquefied petroleum gas synthesis catalyst until the ratio of the yield of liquefied petroleum gas when liquefied petroleum gas is synthesized using the liquefied petroleum gas synthesis catalyst immediately after regeneration after the reduction step to the yield of liquefied petroleum gas when liquefied petroleum gas is synthesized using the liquefied petroleum gas synthesis catalyst immediately before regeneration and before the combustion step is 101% or more.

[0028] It is also preferable to regenerate the liquefied petroleum gas synthesis catalyst until the ratio of the carbon monoxide and / or hydrogen conversion rate when liquefied petroleum gas is synthesized using the liquefied petroleum gas synthesis catalyst immediately after regeneration to the carbon monoxide and / or hydrogen conversion rate when liquefied petroleum gas is synthesized using the liquefied petroleum gas synthesis catalyst immediately before regeneration is 101% or more.

[0029] The LPG yield when liquefied petroleum gas is synthesized using the liquefied petroleum gas synthesis catalyst immediately after regeneration is preferably 25 Cmol% or more, more preferably 27 Cmol% or more, and particularly preferably 30 Cmol% or more. The upper limit of the LPG yield is not particularly limited, but is, for example, about 50 Cmol%.

[0030] In the synthesis of liquefied petroleum gas, the combustion step, the reduction step, and the interlocking step described below can be carried out in combination. By combining the two, the catalyst for synthesizing liquefied petroleum gas can be used for a longer period of time.

[0031] The method for regenerating a catalyst for synthesizing liquefied petroleum gas according to the embodiment is particularly effective when a Cu-Zn-based catalyst, which will be described later, is used as the catalyst for synthesizing liquefied petroleum gas.

[0032] Generally, metal compounds (elementary metals, metal oxides, etc.) contained in catalysts aggregate when heated during various reactions or regeneration processes, and the reduction in active sites due to aggregation has a negative effect on catalytic activity. Furthermore, since it is difficult to redisperse metal compounds that have aggregated once, how to prevent aggregation is an important issue for businesses.

[0033] Fe-based catalysts used in the Fischer-Tropsch synthesis process (FT synthesis) are known as catalysts for synthesizing hydrocarbons such as liquefied petroleum gas (JP 2022-102703 A). Fe-based catalysts contain iron and / or iron oxide as their primary components, with iron having a melting point of 1538°C and iron oxide having a melting point of 1565°C. Meanwhile, the melting point of copper in Cu-Zn-based catalysts after hydrogen reduction treatment is 1085°C, which is lower than that of iron or iron oxide. The melting point correlates with the degree of agglomeration, with higher melting points being less likely to agglomerate and lower melting points being more likely to agglomerate. Furthermore, copper has a lower activation energy for surface diffusion than iron, allowing copper atoms to migrate more easily across the surface of catalyst particles even at relatively low temperatures. Because copper atoms are more mobile on the surface, atomic mobility increases at low temperatures, promoting the growth of larger copper particles from smaller ones. Therefore, the lower the melting point and the lower the activation energy for surface diffusion of a metal, the more the reaction temperature and temperature adjustment of the regeneration process affect catalytic activity. In the above-mentioned known literature, it was unclear how activity could be regenerated while preventing aggregation when a metal having a lower melting point and a lower activation energy for surface diffusion than iron or iron oxide was used.

[0034] In addition to the above-mentioned issues related to melting point, atomic mobility, and agglomeration, a certain degree of high temperature is required for the removal of coke (oxidation treatment).

[0035] In other words, compared to Fe-based catalysts, Co-based catalysts, and Ru-based catalysts (FT synthesis catalysts), which are well-known catalysts for synthesizing hydrocarbons, Cu-Zn-based catalysts tend to be more susceptible to high-temperature regeneration processes. The inventors have addressed this special situation, which arises with metals that have lower melting points and lower activation energies for surface diffusion than iron or iron oxide, particularly Cu-Zn-based catalysts, by setting the temperatures of the oxidation and reduction processes above the synthesis temperature of liquefied petroleum gas but below 360°C, and have succeeded in restoring activity to the same level as that of an unused catalyst.

[0036] Therefore, it is preferable that the melting point of the metal contained in the liquefied petroleum gas synthesis catalyst used in the combustion step and reduction step (and the linked step described below) is 1600°C or lower. The upper limit of the melting point may be 1500°C, 1400°C, 1300°C, 1200°C, 1100°C, 1000°C, 900°C, 800°C, 700°C, 600°C, 500°C, or 400°C. The lower limit of the melting point is not limited as long as it is higher than the synthesis temperature of liquefied petroleum gas, but may be 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, or 1500°C.

[0037] Therefore, it is preferable that the liquefied petroleum gas synthesis catalyst used in the combustion step and the reduction step (and the linked step described below) is not an FT synthesis catalyst. In other words, it is preferable that the liquefied petroleum gas synthesis catalyst does not contain any one of the metal elements Fe, Co, and Ru.

[0038] Furthermore, if the liquefied petroleum gas synthesis catalyst has a methanol synthesis catalyst that synthesizes methanol and a dehydration catalyst that dehydrates methanol, liquefied petroleum gas can be efficiently synthesized from a feedstock gas containing carbon monoxide and hydrogen during the synthesis of liquefied petroleum gas. Methanol is synthesized from carbon monoxide and hydrogen using the methanol synthesis catalyst, and then the methanol synthesized by the methanol synthesis catalyst is dehydrated and condensed using the dehydration catalyst, followed by cracking and hydrogenation reactions, thereby efficiently synthesizing liquefied petroleum gas containing propane.

[0039] The methanol synthesis catalyst is preferably a Cu—Zn catalyst, which contains copper oxide and zinc oxide as main components, and further contains aluminum oxide and zirconium oxide, which can improve the CO addition rate and enable efficient production of methanol from carbon monoxide and hydrogen.

[0040] The Cu—Zn catalyst may further contain gallium oxide and indium oxide, which improves the dispersibility of copper oxide and zinc oxide.

[0041] The Cu-Zn catalyst is preferably in the form of a powder or a compact. －９ ~10 －４ m.) or granules having a particle size larger than that of the powder, but when the Cu—Zn-based catalyst is a molded body containing the Cu—Zn-based catalyst, the CO conversion rate can be further improved.

[0042] For a molded body containing a Cu—Zn-based catalyst, the content of the Cu—Zn-based catalyst in the molded body is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. When the content is 80% by mass or more, methanol can be efficiently synthesized from carbon monoxide and hydrogen. The content of the Cu—Zn-based catalyst in the molded body may be 100% by mass, i.e., the molded body may be composed solely of the Cu—Zn-based catalyst. Furthermore, the content is preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 94% by mass or less. When the content is 98% by mass or less, the moldability and mechanical strength of the molded body can be improved while maintaining efficient synthesis of methanol from carbon monoxide and hydrogen.

[0043] The molded body containing the Cu—Zn-based catalyst may contain, in addition to the Cu—Zn-based catalyst, various additives that improve moldability and mechanical strength, such as molding binders such as graphite and carbon black.

[0044] Furthermore, the dehydration catalyst is preferably a zeolite catalyst carrying a noble metal (hereinafter simply referred to as a zeolite catalyst). The zeolite constituting the zeolite catalyst has a zeolite skeleton, which gives it high water resistance and prevents deterioration due to water produced as a by-product in Cu-Zn catalysts. Therefore, the zeolite catalyst has excellent long-term stability and a long life.

[0045] Furthermore, since the precious metal supported on the zeolite that constitutes the zeolite catalyst is Pt, the zeolite catalyst can efficiently convert intermediates such as methanol synthesized using a Cu-Zn catalyst and dimethyl ether produced as a by-product using a Cu-Zn catalyst into liquefied petroleum gas, thereby increasing the yield of liquefied petroleum gas.

[0046] The noble metal supported on the zeolite is preferably a platinum group element such as Pt, Pd, Rh, or Ru. The noble metal may be one type or two or more types. When two or more types of noble metals are supported on the zeolite, the state of the noble metals supported on the zeolite is not particularly limited. For example, the noble metals may be mixed as simple metals, may be alloyed, or may be mixed as simple metals and alloys.

[0047] The precious metal supported on the zeolite may be only Pt, only Pd, or may contain Pt and Pd. From the viewpoint of efficiently reacting methanol, the precious metal supported on the zeolite is preferably Pt and Pd, and more preferably Pt alone. Regarding the state of Pt and Pd supported on the zeolite, a mixture of metal Pt and metal Pd may be present, or Pt and Pd may be alloyed, or at least one of metal Pt and Pd may be present as a mixture with an alloy of Pt and Pd.

[0048] Furthermore, the zeolite constituting the zeolite catalyst preferably contains P (phosphorus). That is, the zeolite catalyst preferably contains P. When the zeolite contains P, it is presumed that P will bond to O (oxygen) that bonds with Si and O that bonds with Al present on the surface of the zeolite (zeolite catalyst), as shown in the following formula (1). As a result, the acid sites (solid acid sites) of the zeolite increase and change to weak acid sites, so the zeolite catalyst can increase the yield of liquefied petroleum gas.

[0049]

[0050] The lower limit of the mass of P contained in the zeolite catalyst, relative to the mass of the zeolite catalyst, is preferably more than 0 mass%, more preferably 0.5 mass% or more, and even more preferably 1.0 mass% or more, and the upper limit is preferably less than 5.0 mass%, more preferably 4.0 mass% or less, and even more preferably 3.0 mass% or less.

[0051] When the mass of P is more than 0% by mass relative to the mass of the zeolite catalyst, the yield of liquefied petroleum gas can be increased. Also, when the mass of P is less than 5.0% by mass relative to the mass of the zeolite catalyst, a decrease in the surface area of ​​zeolite due to an increase in the P content can be suppressed for zeolites having a porous structure, thereby enabling efficient production of liquefied petroleum gas.

[0052] The zeolite catalyst may contain Y (yttrium). By including Y in the zeolite catalyst, it is possible to suppress the generation of coke during the synthesis of liquefied petroleum gas. A zeolite catalyst with suppressed coke generation can sufficiently burn the coke without requiring high temperatures for regeneration treatment, thereby suppressing the aggregation of Cu-Zn catalyst and precious metal particles and enabling the catalyst to be used for a longer period of time.

[0053] The zeolite catalyst is preferably in the form of a powder or a molded body. －９ ~10 －４ m.) or granules having a particle size larger than that of the powder, but when the zeolite catalyst is a molded body containing the zeolite catalyst, the yield of liquefied petroleum gas can be further improved.

[0054] Although various known zeolites can be used as the zeolite constituting the zeolite catalyst, MFI zeolite, CHA zeolite, BEA zeolite, TON zeolite, MWW zeolite, FAU zeolite, FER zeolite, ERI zeolite, and MOR zeolite are preferred. In particular, when the zeolite constituting the zeolite catalyst is MFI zeolite or CHA zeolite, the yield of liquefied petroleum gas can be further improved.

[0055] The zeolite constituting the zeolite catalyst can be replaced with various known porous materials. Examples include SAPO, ELAPO, ALPO, alumina (Al ２ O ３ ) etc.

[0056] For a molded body containing a zeolite catalyst, the content of the zeolite catalyst contained in the molded body is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. When the content is 70% by mass or more, liquefied petroleum gas can be efficiently synthesized from methanol. The content of the zeolite catalyst contained in the molded body may be 100% by mass, i.e., the molded body may be composed solely of zeolite catalyst. Furthermore, the content is preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 94% by mass or less. When the content is 98% by mass or less, the moldability and mechanical strength of the molded body can be improved while maintaining efficient synthesis of liquefied petroleum gas from methanol.

[0057] The molded body containing the zeolite catalyst may contain, in addition to the zeolite catalyst, various additives that improve moldability and mechanical strength. Examples of the various additives include molding binders such as various clay binders, alumina-based binders, and silica-based binders. Preferred clay binders are kaolin-based, bentonite-based, talc-based, pyrophyllite-based, molysite-based, verculolite-based, montmorillonite-based, chlorite-based, and halloysite-based binders. The molding binder is preferably a silica-based binder, as it efficiently improves the catalytic activity of the zeolite catalyst and suppresses the formation of catalyst-poisoning substances such as coke.

[0058] When the Cu—Zn-based catalyst and the zeolite catalyst are in the form of a molded body, the shape of these molded bodies is not particularly limited, and a desired shape can be selected, for example, a cylindrical, cloverleaf, ring-like, spherical, multi-hole, etc. In the case of a cylindrical or cloverleaf-like molded body, it is preferable that it is an extrusion molded product.

[0059] The particle size of the molded body containing a Cu-Zn catalyst and the molded body containing a zeolite catalyst preferably has a lower limit of 200 μm or more, more preferably 300 μm or more, and an upper limit of 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. If the particle size is 200 μm or more, pressure loss in the reactor can be prevented during synthesis of liquefied petroleum gas. Furthermore, if the particle size is 10 mm or less, the contact efficiency between these catalysts and the reaction raw materials can be increased.

[0060] Furthermore, in the synthesis of liquefied petroleum gas, if the synthesis temperature is high, the yield of liquefied petroleum gas increases, but the liquefied petroleum gas synthesis catalyst rapidly deteriorates. Therefore, if a method for synthesizing liquefied petroleum gas from a feedstock gas containing carbon monoxide and hydrogen using a liquefied petroleum gas synthesis catalyst includes a linking step for linking the liquefied petroleum gas yield during the synthesis of liquefied petroleum gas with the synthesis temperature of liquefied petroleum gas, liquefied petroleum gas can be synthesized stably over a long period of time while suppressing deterioration of the liquefied petroleum gas synthesis catalyst.

[0061] In the synthesis of liquefied petroleum gas, the yield of the synthesized liquefied petroleum gas can be measured during the synthesis, and the synthesis temperature of the liquefied petroleum gas can be adjusted during the synthesis. The measurement of the yield of the liquefied petroleum gas may be continuous or intermittent with respect to the synthesis time. Furthermore, the adjustment of the synthesis temperature of the liquefied petroleum gas may be continuous or intermittent with respect to the synthesis time.

[0062] In this application, "linkage" means that a parameter and another parameter change in a unified manner, or that a parameter is changed by another parameter, or that a change in a parameter is predicted and another parameter is changed in a unified manner based on the prediction.

[0063] Some parameters may be of one type or of multiple types, and other parameters may be of one type or of multiple types.

[0064] Change refers to increase, decrease, or maintenance over time.

[0065] In this application, the term "synthesis temperature" refers to the catalyst bed temperature of the catalyst for synthesizing liquefied petroleum gas.

[0066] For example, if the liquefied petroleum gas yield is higher than the predetermined range, the high synthesis temperature of the liquefied petroleum gas causes rapid deterioration of the liquefied petroleum gas synthesis catalyst, leading to a rapid decrease in the liquefied petroleum gas yield as the synthesis of the liquefied petroleum gas progresses. In such a situation, by lowering the synthesis temperature of the liquefied petroleum gas in the interlocking process so that the liquefied petroleum gas yield falls within the predetermined range, it is possible to synthesize liquefied petroleum gas stably at a yield within the predetermined range while suppressing the rate of deterioration of the liquefied petroleum gas synthesis catalyst. If the synthesis temperature of the liquefied petroleum gas is lowered to the point where the liquefied petroleum gas yield falls below the predetermined range, it will no longer be possible to synthesize liquefied petroleum gas at a yield within the predetermined range.

[0067] Furthermore, if the liquefied petroleum gas yield gradually drops below the predetermined range as the synthesis of liquefied petroleum gas progresses, it becomes impossible to synthesize liquefied petroleum gas at a yield within the predetermined range. In such a situation, by increasing the liquefied petroleum gas synthesis temperature in the interlocking process so that the liquefied petroleum gas yield increases to within the predetermined range, it is possible to synthesize liquefied petroleum gas stably at a yield within the predetermined range while suppressing the rate of deterioration of the liquefied petroleum gas synthesis catalyst. If the liquefied petroleum gas synthesis temperature is increased until the liquefied petroleum gas yield exceeds the predetermined range, the deterioration of the liquefied petroleum gas synthesis catalyst will progress rapidly, leading to a rapid decrease in the liquefied petroleum gas yield.

[0068] In this way, in the linking process, liquefied petroleum gas is synthesized while linking the yield of the liquefied petroleum gas being synthesized with the synthesis temperature of the liquefied petroleum gas so that the yield of the liquefied petroleum gas falls within a predetermined range, and liquefied petroleum gas can be synthesized stably over a long period of time while suppressing deterioration of the liquefied petroleum gas synthesis catalyst.

[0069] The link between the liquefied petroleum gas yield and the liquefied petroleum gas synthesis temperature does not need to be always performed during the synthesis of liquefied petroleum gas, but is performed, for example, when the liquefied petroleum gas yield falls outside the specified range, as described above. Increasing the liquefied petroleum gas synthesis temperature can increase the liquefied petroleum gas yield, and decreasing the liquefied petroleum gas synthesis temperature can decrease the liquefied petroleum gas yield. In this way, the link between the liquefied petroleum gas yield and the liquefied petroleum gas synthesis temperature can be controlled.

[0070] In particular, when the liquefied petroleum gas yield is lower than a predetermined range, it is preferable to gradually increase the liquefied petroleum gas synthesis temperature in accordance with the liquefied petroleum gas yield in the interlocking process. In this way, gradually increasing the liquefied petroleum gas synthesis temperature relative to the liquefied petroleum gas synthesis time can suppress deterioration of the liquefied petroleum gas synthesis catalyst due to coke coating and deterioration due to active metal aggregation, which are associated with a sudden increase in synthesis temperature, as well as suppressing a decrease in the liquefied petroleum gas yield due to excessive cracking of the target product. In particular, in the interlocking process, when the liquefied petroleum gas yield is lower than a predetermined range, it is preferable to increase the liquefied petroleum gas synthesis temperature at a rate of 0.05°C / day or more and 5.00°C / day or less.

[0071] Furthermore, when the synthesis temperature of liquefied petroleum gas is increased to increase the yield of liquefied petroleum gas, from the viewpoint of suppressing deterioration of the catalyst for synthesizing liquefied petroleum gas, the upper limit of the synthesis temperature of liquefied petroleum gas is preferably 350° C. or less. Furthermore, if the lower limit of the synthesis temperature of liquefied petroleum gas is 280° C. or more, liquefied petroleum gas can be synthesized stably.

[0072] In the interlocking process, the lower limit of the predetermined range of the yield of liquefied petroleum gas is 25 Cmol% or more and the upper limit is 40 Cmol% or less.

[0073] In addition, instead of detecting the yield of liquefied petroleum gas, it is also possible to detect the amount of synthesis gas (carbon monoxide and / or hydrogen) that is an unreacted product in the synthesis of liquefied petroleum gas. In the interlocking process, if the amount of synthesis gas after synthesis is greater than a predetermined range, it can be estimated that the yield of liquefied petroleum gas is low, and if the amount of synthesis gas after synthesis is less than a predetermined range, it can be estimated that the yield of liquefied petroleum gas is high.

[0074] In addition, substances other than synthetic gas that can be used as substitutes for the yield of liquefied petroleum gas include methane, ethane, hydrocarbons of C5 or higher, methanol, and dimethyl ether, which are produced by the synthesis of liquefied petroleum gas. For these gases, including synthetic gas, the amount of a single gas may be detected, or the total amount of multiple gases may be detected.

[0075] Furthermore, in the linking step, it is preferable that the yield of liquefied petroleum gas and the synthesis temperature of the liquefied petroleum gas are linked during the synthesis of the liquefied petroleum gas, and that the selectivity of propane and the synthesis temperature of the liquefied petroleum gas are linked. In the method for synthesizing liquefied petroleum gas having such a configuration, the selectivity of propane contained in the synthesized liquefied petroleum gas is measured during the synthesis. The measurement of the selectivity of propane may be continuous or intermittent with respect to the synthesis time.

[0076] For example, when the propane selectivity is higher than the predetermined range, the high synthesis temperature of the liquefied petroleum gas causes rapid deterioration of the liquefied petroleum gas synthesis catalyst, leading to a rapid decline in propane selectivity as the synthesis of the liquefied petroleum gas progresses. In such a situation, by lowering the synthesis temperature of the liquefied petroleum gas in the interlocking process so that the propane selectivity falls within the predetermined range, it is possible to synthesize liquefied petroleum gas stably with a propane selectivity within the predetermined range while suppressing the rate of deterioration of the liquefied petroleum gas synthesis catalyst. If the synthesis temperature of the liquefied petroleum gas is lowered to the point where the propane selectivity falls below the predetermined range, it becomes impossible to synthesize liquefied petroleum gas with a propane selectivity within the predetermined range.

[0077] Furthermore, if the propane selectivity gradually drops below the predetermined range as the synthesis of liquefied petroleum gas progresses, it becomes impossible to synthesize liquefied petroleum gas with a propane selectivity within the predetermined range. In such a situation, by increasing the synthesis temperature of liquefied petroleum gas in the interlocking process so that the propane selectivity increases to within the predetermined range, it is possible to synthesize liquefied petroleum gas stably with a propane selectivity within the predetermined range while suppressing the degradation rate of the liquefied petroleum gas synthesis catalyst. If the synthesis temperature of liquefied petroleum gas is increased until the propane selectivity exceeds the predetermined range, the degradation of the liquefied petroleum gas synthesis catalyst will progress rapidly, leading to a rapid drop in propane selectivity.

[0078] In this way, in the linking process, liquefied petroleum gas is synthesized while linking the selectivity of propane in the liquefied petroleum gas being synthesized with the synthesis temperature of the liquefied petroleum gas so that the selectivity of propane falls within a predetermined range, thereby making it possible to synthesize liquefied petroleum gas and propane stably over a long period of time while suppressing deterioration of the liquefied petroleum gas synthesis catalyst.

[0079] The linking of the propane selectivity and the synthesis temperature of liquefied petroleum gas does not need to be performed all the time during the synthesis of liquefied petroleum gas, but is performed, for example, when the propane selectivity falls outside the predetermined range as described above. Increasing the synthesis temperature of liquefied petroleum gas can increase the propane selectivity, and decreasing the synthesis temperature of liquefied petroleum gas can decrease the propane selectivity. In this way, the linking of the propane selectivity and the synthesis temperature of liquefied petroleum gas can be controlled.

[0080] In particular, when the propane selectivity is lower than a predetermined range, it is preferable to gradually increase the liquefied petroleum gas synthesis temperature in accordance with the propane selectivity in the interlocking step. In this way, gradually increasing the liquefied petroleum gas synthesis temperature relative to the liquefied petroleum gas synthesis time can suppress deterioration of the liquefied petroleum gas synthesis catalyst due to coke coating and active metal aggregation, which are associated with a sudden increase in synthesis temperature, as well as a decrease in the liquefied petroleum gas yield due to excessive cracking of the target product. In particular, in the interlocking step, when the propane selectivity is lower than a predetermined range, it is preferable to increase the liquefied petroleum gas synthesis temperature at a rate of 0.05°C / day or more and 5.00°C / day or less.

[0081] Furthermore, when the synthesis temperature of liquefied petroleum gas is increased to increase the selectivity of propane, from the viewpoint of suppressing deterioration of the catalyst for synthesizing liquefied petroleum gas, the upper limit of the synthesis temperature of liquefied petroleum gas is preferably 350° C. or lower, more preferably 340° C. or lower, even more preferably 330° C. or lower, still more preferably 320° C. or lower, and most preferably 310° C. or lower. Furthermore, if the lower limit of the synthesis temperature of liquefied petroleum gas is preferably 280° C. or higher, more preferably 290° C. or higher, and even more preferably 300° C. or higher, liquefied petroleum gas and propane can be synthesized stably.

[0082] In the interlocking step, the lower limit of the predetermined range of the selectivity of propane is 70% by volume or more, and the upper limit is 90% by volume or less.

[0083] Furthermore, instead of detecting the selectivity of propane, it is also possible to detect the yield of butane, which is synthesized simultaneously with propane. In the interlocking process, if the yield of butane after synthesis is higher than a predetermined range, it can be estimated that the selectivity of propane is low, and if the yield of butane after synthesis is lower than the predetermined range, it can be estimated that the selectivity of propane is high.

[0084] It is also preferable that the methanol synthesis catalyst or the liquefied petroleum synthesis catalyst be subjected to a further hydrogen reduction treatment immediately before use.

[0085] In this way, by performing the above-mentioned linked process in addition to the above-mentioned combustion process and reduction process, it is possible to regenerate the deteriorated catalytic activity of the liquefied petroleum gas synthesis catalyst, and to synthesize liquefied petroleum gas stably over a long period of time while suppressing deterioration of the liquefied petroleum gas synthesis catalyst.

[0086] According to the embodiment described above, by subjecting a catalyst for synthesizing liquefied petroleum gas whose catalytic performance has deteriorated to the above-mentioned combustion process and reduction process, the deteriorated catalytic activity of the catalyst for synthesizing liquefied petroleum gas can be regenerated.

[0087] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure.

[0088] Next, examples and comparative examples will be described, but the present disclosure is not limited to these examples.

[0089] (Examples 1 to 4, Comparative Examples 1 and 2) The catalysts for liquefied petroleum gas synthesis shown in Table 1, which had deteriorated to the same extent as the catalytic activity, were subjected to the following regeneration of catalytic activity. Here, a Cu-Zn catalyst (CuOZnOZrO ２ Al ２ O ３) (chemical composition: copper oxide 62.6 mass%, zinc oxide 27.2 mass%, zirconium oxide 4.9 mass%, aluminum oxide 5.3 mass%) was used, and a precious metal-supported zeolite catalyst ((Pt 0.5% / P 2% ZSM-5 (ZSM-5 (SiO ２ / Al ２ O ３ Pt is supported on ZSM-5 (ratio 40) and P is contained in ZSM-5. The mass of Pt contained in the zeolite catalyst is 0.5% and the mass of P is 2%. ) and (Pt 0.5% / P 1.5% ZSM-5 (ZSM-5(SiO ２ / Al ２ O ３ The mass of Pt contained in the zeolite catalyst was 0.5% and the mass of P was 1.5%.

[0090] First, a catalyst for liquefied petroleum gas synthesis shown in Table 1 was placed in a reactor, and LPG synthesis was carried out for 25 days. Thereafter, air was supplied into the reactor, and a combustion step was carried out in which the catalyst for liquefied petroleum gas synthesis was brought into contact with the air at a temperature shown in Table 1 for the time shown in Table 1. Subsequently, hydrogen was supplied into the reactor, and a reduction step was carried out in which the catalyst for liquefied petroleum gas synthesis that had been subjected to the combustion step was brought into contact with hydrogen at a temperature shown in Table 1 for the time shown in Table 1. In this way, the catalyst for liquefied petroleum gas synthesis was regenerated.

[0091]

[0092] (Examples 5 to 7, Comparative Example 3) The catalysts for liquefied petroleum gas synthesis shown in Table 2, which had deteriorated but had the same catalytic activity, were subjected to the following regeneration of catalytic activity. Here, the same catalysts as in Example 1 were used as the methanol synthesis catalyst for the liquefied petroleum gas synthesis catalyst and the dehydration catalyst for the liquefied petroleum gas synthesis catalyst.

[0093] First, a catalyst for liquefied petroleum gas synthesis shown in Table 2 was placed in a reactor, and LPG synthesis was carried out for 25 days. Thereafter, air was supplied into the reactor, and a combustion step was carried out in which the catalyst for liquefied petroleum gas synthesis was brought into contact with the air at the temperature shown in Table 2 for the time shown in Table 2. Subsequently, hydrogen was supplied into the reactor, and a reduction step was carried out in which the catalyst for liquefied petroleum gas synthesis that had been subjected to the combustion step was brought into contact with hydrogen at the temperature shown in Table 2 for the time shown in Table 2. In this way, the catalyst for liquefied petroleum gas synthesis was regenerated.

[0094]

[0095] The following synthesis of liquefied petroleum gas was carried out using the regenerated liquefied petroleum gas synthesis catalyst. First, a feed gas containing carbon monoxide and hydrogen was supplied into a reactor containing the liquefied petroleum gas synthesis catalyst, while the reactor was heated to 280°C and the pressure inside the reactor was increased to 5 MPa. Next, while supplying the feed gas into the reactor, the temperature inside the reactor was increased from 280°C to 310°C at a rate of 1°C / min, and then liquefied petroleum gas was synthesized. In other words, the synthesis temperature of liquefied petroleum gas was set to 310°C. Figures 1 and 3 show the measurement results of the CO conversion rate during synthesis. Figures 2 and 4 also show the measurement results of the propane and butane yields during synthesis. As a reference example, Figures 1 and 2 show the measurement results of the CO conversion rate and the propane and butane yields during synthesis when liquefied petroleum gas was synthesized under the same conditions as above using a new liquefied petroleum gas synthesis catalyst whose catalytic activity had not deteriorated.

[0096] CO conversion rate (%) = [(CO flow rate at inlet (μmol / min) - CO flow rate at outlet (μmol / min)) / CO flow rate at inlet (μmol / min)] × 100 CO conversion rate indicates the rate at which carbon monoxide (CO) in the feed gas is converted to hydrocarbons, etc. Propane yield (C mol%) = [(C3 production rate × 3) / (CO flow rate at inlet) × 106 / 22400] × 100 The unit of C3 production rate is C μmol / min, and the unit of CO flow rate at inlet is ml (Normal) / min. C3 is propane. Butane yield (C mol%) = [(C4 production rate × 4) / (CO flow rate at inlet) × 106 / 22400] × 100 The unit of C4 production rate is C μmol / min, and the unit of CO flow rate at inlet is ml (Normal) / min. C4 is butane. Liquefied petroleum gas yield (C mol %) = propane yield (C mol %) + butane yield (C mol %) Propane selectivity (volume %) = number of moles of propane produced / (number of moles of propane produced + number of moles of butane produced) × 100

[0097] As shown in Tables 1-2 and Figures 1-4, in Examples 1-3 and 5-7, a combustion step was performed in which a liquefied petroleum gas synthesis catalyst with deteriorated catalytic activity was contacted with an oxygen-containing gas above the synthesis temperature of the liquefied petroleum gas but below 360°C, and a reduction step was performed in which the liquefied petroleum gas synthesis catalyst after the combustion step was contacted with a reducing gas above the synthesis temperature of the liquefied petroleum gas but below 360°C. This allowed the deteriorated catalytic activity of the liquefied petroleum gas synthesis catalyst to be regenerated. As a result, the CO conversion rate was 90% or more and the propane selectivity was 75% or more by volume, and the catalyst was regenerated to the same level as the Reference Example. On the other hand, in Comparative Examples 1 and 3, at least one of the predetermined combustion step and the predetermined reduction step was not performed, and therefore the deteriorated catalytic activity of the liquefied petroleum gas synthesis catalyst could not be fully regenerated. As a result, at least one of the CO conversion rate of less than 90% and the propane selectivity of less than 75% by volume was observed, and the catalyst was not regenerated to the same level as the Reference Example.

[0098] In addition, in Example 4, as in Examples 1 to 3, the above-mentioned predetermined combustion step and predetermined reduction step were performed, and therefore the deteriorated catalytic activity of the liquefied petroleum gas synthesis catalyst could be regenerated to the same level as in the Reference Example. In other words, the CO conversion rate was 90% or more and the propane selectivity was 75% or more by volume, and the catalyst could be regenerated to the same level as in the Reference Example. On the other hand, in Comparative Example 2, as in Comparative Example 1, at least one of the above-mentioned predetermined combustion step and predetermined reduction step was not performed, and therefore the deteriorated catalytic activity of the liquefied petroleum gas synthesis catalyst could not be regenerated to the same level as in the Reference Example. In other words, at least one of the CO conversion rate of less than 90% and the propane selectivity of less than 75% by volume was exhibited, and the catalyst could not be regenerated to the same level as in the Reference Example.

Claims

1. A method for regenerating a catalyst for liquefied petroleum gas synthesis, comprising: a combustion step of contacting the catalyst for liquefied petroleum gas synthesis with an oxygen-containing gas at a temperature higher than the synthesis temperature of liquefied petroleum gas but lower than 360°C; and a reduction step of contacting the catalyst for liquefied petroleum gas synthesis with a reducing gas at a temperature higher than the synthesis temperature of liquefied petroleum gas but lower than 360°C.

2. A method for regenerating a catalyst for liquefied petroleum gas synthesis according to claim 1, wherein the synthesis temperature of the liquefied petroleum gas is 280°C or higher and 350°C or lower.

3. The method for regenerating a catalyst for liquefied petroleum gas synthesis according to claim 1, wherein the oxygen-containing gas is air.

4. The method for regenerating a catalyst for liquefied petroleum gas synthesis according to claim 1, wherein the reducing gas is a gas containing hydrogen.

5. A method for regenerating a catalyst for liquefied petroleum gas synthesis as described in claim 1, wherein in the combustion process, the temperature of the oxygen-containing gas is greater than 310°C and less than 360°C, and the catalyst for liquefied petroleum gas synthesis and the oxygen-containing gas are contacted for 0.1 hours or more and within 48.0 hours.

6. A method for regenerating a catalyst for liquefied petroleum gas synthesis as described in claim 1, wherein in the reduction step, the temperature of the reducing gas is 320°C or higher but lower than 360°C, and the catalyst for liquefied petroleum gas synthesis and the reducing gas are contacted for 0.1 hours or higher but not exceeding 48.0 hours.

7. The method for regenerating a catalyst for liquefied petroleum gas synthesis according to claim 1, wherein the combustion step and the reduction step are carried out in a reactor.

8. A method for regenerating a catalyst for liquefied petroleum gas synthesis as described in claim 1, wherein the ratio of the yield of liquefied petroleum gas when liquefied petroleum gas is synthesized using a catalyst for liquefied petroleum gas synthesis immediately after regeneration after the reduction step to the yield of liquefied petroleum gas when liquefied petroleum gas is synthesized using a catalyst for liquefied petroleum gas synthesis immediately before regeneration and before the combustion step is performed is 101% or more.

9. A method for regenerating a catalyst for liquefied petroleum gas synthesis according to claim 1, wherein the catalyst for liquefied petroleum gas synthesis does not contain any one of the metal elements Fe, Co, and Ru.

10. A method for regenerating a catalyst for liquefied petroleum gas synthesis according to any one of claims 1 to 9, wherein the catalyst for liquefied petroleum gas synthesis comprises a methanol synthesis catalyst for synthesizing methanol and a dehydration catalyst for dehydrating methanol.

11. The method for regenerating a catalyst for liquefied petroleum gas synthesis according to claim 10, wherein the methanol synthesis catalyst is a Cu-Zn catalyst.

12. The method for regenerating a catalyst for synthesizing liquefied petroleum gas according to claim 10, wherein the dehydration catalyst is a zeolite catalyst carrying a noble metal.

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