Paraffin cracking catalyst, process for its preparation and use

Abstract

The present application relates to the field of paraffin cracking catalyst, discloses a paraffin cracking catalyst and a preparation method and application thereof.The paraffin cracking catalyst comprises a carrier, an active component and an auxiliary agent supported on the carrier, wherein the active component is manganese dioxide, the auxiliary agent is La2O3, the carrier is a magnesium-aluminum composite oxide, the magnesium-aluminum composite oxide comprises MgAl2O4, the content of MgAl2O4 is 93-100wt% based on the total amount of the magnesium-aluminum composite oxide; the content of the active component is 5-15wt% based on the total amount of the paraffin cracking catalyst, the content of the auxiliary agent is 0.1-2wt%, and the content of the carrier is 83-94.9wt%.The paraffin cracking catalyst can avoid the phenomenon of catalyst waxing, protect the methanation refining catalyst, prolong the activity and service life of the methanation refining catalyst, and has lower energy consumption and cost.

Description

Technical Field

[0001] This invention relates to the field of paraffin cracking catalysts, specifically to paraffin cracking catalysts, their preparation methods, and applications. Background Technology

[0002] Slurry bed reactors are a relatively advanced type of reaction equipment in cryogenic processes. Their reaction zones exhibit highly uniform temperature, minimizing the risk of overheating or localized temperature spikes. They also offer rapid heat transfer, high reaction efficiency, and process safety. However, slurry bed processes are subject to limitations. The effluent process gas from a slurry bed contains paraffin vapor and paraffin entrained in the liquid droplets. This requires cooling and condensation separation, followed by heat exchange and reheating before entering subsequent refining processes. This cooling, condensation, and reheating process requires several pieces of equipment, including condensers, separation tanks, cold water circulation pumps, heat exchangers, and heaters, and involves heat loss and power consumption. The separated paraffin-water mixture increases the wastewater discharge pressure. If the effluent process gas from the slurry bed is not condensed and separated before entering the subsequent refining stage, paraffin will accumulate on the catalyst surface in the later stages, forming a phenomenon similar to catalyst wax deposition, gradually leading to physical deactivation of the catalyst.

[0003] Currently available paraffin decomposition catalysts typically use catalytic cracking catalysts, employing ZSM-5 molecular sieves or platinum-impregnated ZSM-5 molecular sieves in fluidized beds for catalytic cracking reactions. However, the process, catalyst lifetime, and catalyst morphology are not suitable for fixed-bed systems. Furthermore, for the removal of trace amounts of paraffin, non-precious metal systems are generally used for cracking to reduce catalyst costs.

[0004] CN104588066A discloses a methanation catalyst and its preparation method. This method involves loading active components and magnesium aluminum spinel onto a mesoporous molecular sieve. Through the interaction between the magnesium aluminum spinel and the active components, and the synergistic effect of the mesoporous molecular sieve, it can improve the CO2 conversion rate in each stage of the multi-stage methanation reaction of coke oven gas. However, this methanation catalyst requires the interaction of multiple active components and the coordination of the mesoporous molecular sieve, and it does not address how to reduce and / or remove paraffin in the process gas during the refining process. Furthermore, the calcination temperature during the preparation of the magnesium aluminum spinel is relatively low, which cannot effectively form a complete spinel morphology and corresponding microstructure. The residual alumina content in the support is relatively high, resulting in significant carbon deposition during paraffin cracking, which affects the catalyst activity and lifespan. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem that paraffin wax tends to accumulate on the catalyst surface during the purification reaction in existing methane synthesis methods, causing catalyst deactivation.

[0006] To achieve the above objectives, the first aspect of the present invention provides a paraffin cracking catalyst, the paraffin cracking catalyst comprising a support and an active component and an auxiliary agent supported on the support, wherein the active component is manganese dioxide, the auxiliary agent is La2O3, the support is a magnesium-aluminum composite oxide, the magnesium-aluminum composite oxide comprising MgAl2O4, and the content of MgAl2O4 is 93-100 wt% based on the total amount of the magnesium-aluminum composite oxide;

[0007] Based on the total amount of the paraffin cracking catalyst, the content of the active component is 5-15 wt%, the content of the auxiliary agent is 0.1-2 wt%, and the content of the support is 83-94.9 wt%.

[0008] The inventors of this invention discovered during their research that using a catalyst with paraffin decomposition effects for subsequent dewaxing and refining reactions in slurry beds significantly shortens the process flow of subsequent refining after slurry bed methanation. Especially in slurry bed methane production systems, the water vapor in the slurry bed outlet gas and the exothermic temperature rise during refining are ideally suited to the process conditions for cracking paraffin into smaller molecules. The paraffin cracking catalyst provided by this invention can decompose paraffin contained in the slurry bed outlet gas. Preferably, when the water-to-paraffin ratio is greater than 10, the paraffin cracking catalyst can completely decompose paraffin vapor up to 2000 ppm, converting it into C1-C4 hydrocarbons. Furthermore, the paraffin cracking catalyst can be used in combination with a methanation refining catalyst to remove paraffin contained in the process gas, thereby protecting the methanation refining catalyst.

[0009] A second aspect of the present invention provides a method for preparing the paraffin cracking catalyst described in the first aspect, the method comprising the following steps:

[0010] (1) A mixture containing magnesium oxide, boehmite and a pore-expanding agent is subjected to a first calcination to obtain a carrier; wherein the temperature of the first calcination is 800-1000℃;

[0011] (2) The active component precursor and the auxiliary agent precursor are loaded onto the support, and then the resulting product is subjected to a second calcination; wherein the temperature of the second calcination is lower than the temperature of the first calcination.

[0012] The third aspect of this invention provides the application of the paraffin cracking catalyst described in the first aspect in the methanation of paraffin-containing syngas to natural gas.

[0013] Through the above technical solution, the paraffin cracking catalyst provided by this invention can decompose and crack the paraffin contained in the slurry bed outlet gas into C1-C4 small molecule hydrocarbons, eliminating the need for conventional cooling and heating processes requiring condensers, separation tanks, cold water circulation pumps, heat exchangers, heaters, and other equipment, resulting in lower energy consumption and costs. Furthermore, the paraffin cracking catalyst can remove paraffin contained in the slurry bed outlet process gas, preventing catalyst wax formation and thus protecting the methanation refining catalyst, extending its activity and service life. Attached Figure Description

[0014] Figure 1 This is the XRD pattern of the carrier obtained in Embodiment 1 of the present invention. Detailed Implementation

[0015] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0016] In this invention, unless otherwise stated, the content of each component in the paraffin cracking catalyst is calculated by the amount of feed.

[0017] In this invention, unless otherwise stated, the pressure is gauge pressure.

[0018] As previously stated, the first aspect of the present invention provides a paraffin cracking catalyst, the paraffin cracking catalyst comprising a support and an active component and an auxiliary agent supported on the support, wherein the active component is manganese dioxide, the auxiliary agent is La2O3, the support is a magnesium-aluminum composite oxide, the magnesium-aluminum composite oxide comprising MgAl2O4, and the content of MgAl2O4 is 93-100 wt% based on the total amount of the magnesium-aluminum composite oxide;

[0019] Based on the total amount of the paraffin cracking catalyst, the content of the active component is 5-15 wt%, the content of the auxiliary agent is 0.1-2 wt%, and the content of the support is 83-94.9 wt%.

[0020] According to some embodiments of the present invention, preferably, the content of MgAl2O4 is 96-100 wt% based on the total amount of the magnesium-aluminum composite oxide.

[0021] According to some embodiments of the present invention, preferably, the magnesium-aluminum composite oxide further includes MgO and / or Al2O3. The MgO is residual magnesium oxide that has not formed magnesium-aluminum spinel (MgAl2O4); the Al2O3 is residual aluminum oxide that has not formed magnesium-aluminum spinel (MgAl2O4).

[0022] Preferably, based on the total amount of the magnesium-aluminum composite oxide, the content of MgO is 0-5 wt%, preferably 0-3 wt%; and the content of Al2O3 is 0-2 wt%, preferably 0-1 wt%.

[0023] In the preferred embodiment described above, the magnesium-aluminum composite oxide contains a low amount of residual alumina, which helps reduce the number of acidic sites. If there is excessive alumina, during paraffin cracking, the relatively stable α-carbon at acidic sites transforms into more reactive β-carbon, easily causing the growth of carbon nanotubes on the catalyst surface, leading to catalyst deactivation due to carbon buildup. The low residual alumina content in the magnesium-aluminum composite oxide avoids this problem of carbon buildup and deactivation, thus improving the catalyst's activity and lifespan.

[0024] According to some embodiments of the present invention, preferably, the grain size of MgAl2O4 is <20 nm, more preferably 4-15 nm, and even more preferably 5-10 nm. Using the above preferred embodiments helps to improve the dispersion of the active component on the carrier surface and, together with the additives, to fix the active component, preventing the carbon nanotubes from lifting the active component from the carrier and causing it to be lost.

[0025] According to some embodiments of the present invention, preferably, the pore volume of MgAl2O4 is >0.15 mL / g, more preferably 0.25-0.35 mL / g, and more preferably 0.27-0.33 mL / g.

[0026] According to some embodiments of the present invention, preferably, the average pore size of MgAl2O4 is 10-50 nm, more preferably 10-30 nm, and even more preferably 13-20 nm.

[0027] By adopting the above preferred embodiment, the grain size, pore volume and average pore size of MgAl2O4 meet the above conditions, which is beneficial to control the impregnation amount of active components during catalyst preparation, as well as the diffusion of paraffin molecules in the catalyst channels and the escape of paraffin cracking products.

[0028] According to some embodiments of the present invention, preferably, the molar ratio of Mg to Al in the magnesium-aluminum composite oxide is 1:2-2.04.

[0029] According to some embodiments of the present invention, the paraffin cracking catalyst does not require activation, is directly active, and can be used directly.

[0030] A second aspect of the present invention provides a method for preparing the paraffin cracking catalyst described in the first aspect, the method comprising the following steps:

[0031] (1) A mixture containing magnesium oxide, boehmite and a pore-expanding agent is subjected to a first calcination to obtain a carrier; wherein the temperature of the first calcination is 800-1000℃;

[0032] (2) The active component precursor and the auxiliary agent precursor are loaded onto the support, and then the resulting product is subjected to a second calcination; wherein the temperature of the second calcination is lower than the temperature of the first calcination.

[0033] According to some embodiments of the present invention, preferably, in step (1), the temperature of the first calcination is 850-950°C. Using the above preferred embodiments is more conducive to increasing the MgAl2O4 content and reducing the Al2O3 content in the magnesium-aluminum composite oxide, thereby reducing carbon deposits generated during paraffin cracking and improving the activity and service life of the catalyst.

[0034] According to some embodiments of the present invention, preferably, in step (1), the first roasting time is 2-10 hours, more preferably 4-8 hours.

[0035] According to some embodiments of the present invention, preferably, in step (1), the magnesium oxide is light magnesium oxide, and the average particle size of the light magnesium oxide is 0.06-0.09 mm.

[0036] According to some embodiments of the present invention, preferably, in step (1), the average particle size of the pseudoboehmite is 0.06-0.09 mm.

[0037] Using the raw materials described in the preferred embodiments above is more conducive to obtaining a carrier that meets the above requirements.

[0038] According to some embodiments of the present invention, preferably, in step (1), the pore-expanding agent is selected from at least one of oxalic acid, nitric acid, acetic acid and sulfuric acid, preferably nitric acid.

[0039] Preferably, the ratio of the pore-expanding agent to the magnesium oxide is 1 mL: 40-60 g.

[0040] According to some embodiments of the present invention, for ease of molding, preferably, in step (1), the mixture also contains an adhesive.

[0041] Preferably, the binder is selected from at least one of guar gum powder, stearate and cellulose and their derivatives, and is preferably sodium carboxymethyl cellulose.

[0042] Preferably, the mass ratio of the adhesive to the magnesium oxide is 1:20-25.

[0043] According to some embodiments of the present invention, in order to ensure that the components in the mixture are sufficiently dispersed and have appropriate strength for subsequent molding, preferably, in step (1), the mixture also contains a solvent.

[0044] Preferably, the solvent is deionized water.

[0045] Preferably, the volume ratio of the solvent to the pore-expanding agent is 80-150:1.

[0046] According to some embodiments of the present invention, preferably, before the first calcination, step (1) further includes the sequential steps of mixing and grinding, sieving, drying, and shaping. The mixing, grinding, sieving, drying, and shaping steps are all conventional methods for preparing catalysts and can be performed with reference to existing technologies.

[0047] According to some embodiments of the present invention, preferably, in step (2), the active component precursor is selected from at least one of manganese nitrate, manganese sulfate, and manganese chloride, preferably manganese nitrate. Preferably, the active component precursor is provided in the form of an aqueous solution. Exemplarily, the manganese nitrate may be provided in the form of a 50 wt% aqueous solution of manganese nitrate.

[0048] According to some embodiments of the present invention, preferably, in step (2), the auxiliary agent precursor is selected from at least one of lanthanum nitrate, lanthanum chloride, and lanthanum sulfate, and preferably lanthanum nitrate. Preferably, the auxiliary agent precursor is provided in the form of an aqueous solution. Exemplarily, the lanthanum nitrate may be provided in the form of a 4 wt% aqueous solution of lanthanum nitrate.

[0049] According to some embodiments of the present invention, preferably, in step (2), the conditions for the second calcination include: a temperature of 350-500°C, preferably 400-450°C; and a time of 4-10 h, preferably 4-8 h.

[0050] According to some embodiments of the present invention, preferably, in step (2), the loading method is an impregnation method;

[0051] Preferably, the impregnation conditions include: a temperature of 60-80°C and a time of 0.5-2 hours;

[0052] Preferably, the active component precursor is first loaded onto the carrier to obtain an intermediate, and then the auxiliary agent precursor is loaded onto the intermediate. After impregnation, each component needs to be dried and calcined to immobilize the component. The drying can be performed according to existing techniques.

[0053] According to a preferred embodiment of the present invention, in step (2), the loading step includes:

[0054] (a) The carrier is contacted with the active component precursor for a first impregnation, the resulting product is then filtered, and the resulting solid is then dried and calcined in sequence to obtain an intermediate.

[0055] (b) The intermediate is contacted with the auxiliary precursor for a second impregnation, the resulting product is then filtered, and the resulting solid is then dried and calcined in sequence.

[0056] The conditions for the first impregnation and the second impregnation each independently include: a temperature of 60-80℃ and a time of 0.5-2h; the conditions for the second calcination I and the second calcination II each independently include: a temperature of 350-500℃, preferably 400-450℃ and a time of 4-10h, preferably 4-8h.

[0057] The third aspect of this invention provides the application of the paraffin cracking catalyst described in the first aspect in the methanation of paraffin-containing syngas to natural gas.

[0058] According to some embodiments of the present invention, preferably, the paraffin-containing synthesis gas is a paraffin-containing slurry bed outlet process gas, wherein the paraffin vapor content is not higher than 2000 ppm and the water-paraffin molar ratio is higher than 10.

[0059] According to some embodiments of the present invention, preferably, the process conditions for the application include: a pressure of 2.0-4.0 MPa, a hot spot temperature of 500-700°C, and a volumetric hourly space velocity of 1000-10000 h⁻¹. -1 .

[0060] More preferably, the process conditions for the application include: pressure 2.5-3.5 MPa, hot spot temperature 550-650°C, and volumetric hourly space velocity 2000-5000 h⁻¹. -1 .

[0061] According to some embodiments of the present invention, in the said application, the paraffin cracking catalyst can be used alone or in combination with other refined catalysts.

[0062] According to some embodiments of the present invention, the reaction temperature and heat required for the paraffin cracking catalyst are provided externally or by the heat of reaction from other reactions. Preferably, the application includes an exothermic process gas system; more preferably, the exothermic process gas system is a slurry-bed methane refining system.

[0063] The present invention will be described in detail below through embodiments.

[0064] Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available products. Among them:

[0065] Light magnesium oxide was purchased from Nanjing Pharmaceutical Company. The grade / type was industrial grade, with a purity >99wt% and an average particle size of 0.063mm.

[0066] The boehmite was purchased from Shandong Aluminum Company, with the model / grade LSi-pfd-7, and its Al2O3 content was 70wt%; the average particle size was 0.09mm.

[0067] Unless otherwise specified, the testing equipment used in the following examples and comparative examples are all commercially available products.

[0068] in:

[0069] The XRD pattern of the support was determined by X-ray diffraction. The powder X-ray diffractometer was purchased from Bruker, model D8 advance.

[0070] The grain size was obtained by X-ray diffraction.

[0071] Pore ​​volume and average pore size were obtained by BET adsorption testing.

[0072] The hydrocarbon content was obtained by chromatographic testing, using an Agilent 8890 three-valve five-column FID analyzer.

[0073] The following examples illustrate the paraffin cracking catalyst and its preparation method provided by the present invention.

[0074] Example 1

[0075] (S1) Light magnesium oxide (400g), pseudoboehmite (1450g), pore expander, binder, and solvent are brought together and sequentially mixed, milled, sieved, dried, shaped, and subjected to a first calcination to obtain a carrier. The XRD test results are as follows: Figure 1 As shown in the figure, there are obvious characteristic peaks of magnesium aluminum spinel at positions 2θ = 37.2°, 45.4°, and 66.25°, indicating that the main body of the support is magnesium aluminum spinel (MgAl2O4). A characteristic peak of magnesium oxide is present at 2θ = 42.9°, which is sharp but has low intensity. No characteristic peak of aluminum oxide is observed at 2θ = 67.2°. Its composition and property parameters are shown in Table 1; where:

[0076] The conditions for the first roasting were: temperature 900℃; time 6 hours.

[0077] The pore-expanding agent is nitric acid, and its ratio with magnesium oxide is 1 mL: 50 g;

[0078] The binder is sodium carboxymethyl cellulose, and its mass ratio with magnesium oxide is 1:21.6;

[0079] The solvent is deionized water, and its volume ratio with the pore-expanding agent is 100:1.

[0080] The sieve used for sieving was a 10-mesh sieve; the drying conditions were: temperature 120℃; time 6 hours.

[0081] The catalyst particles obtained by molding have a size of Φ5*5mm;

[0082] (S2) The above-mentioned carrier (94g) is contacted with the active component precursor for a first impregnation, and then the resulting product is filtered. The resulting solid is then dried and calcined in sequence to obtain an intermediate; wherein:

[0083] The active component precursor is manganese nitrate, which is provided in the form of a 50 wt% aqueous manganese nitrate solution;

[0084] The conditions for the first immersion were: temperature 70℃; time 2 hours.

[0085] The drying conditions were: temperature 120℃; time 6 hours.

[0086] The conditions for the second calcination I are: temperature 420℃; time 4h;

[0087] (S3) The above intermediate is contacted with the auxiliary precursor for a second impregnation, the resulting product is then filtered, and the resulting solid is subsequently dried and then calcined (II); wherein:

[0088] The auxiliary precursor is lanthanum nitrate, which is provided in the form of a 4 wt% aqueous solution of lanthanum nitrate.

[0089] The conditions for the second impregnation were: temperature 70℃; time 2 hours.

[0090] The drying conditions were: temperature 120℃; time 6 hours.

[0091] The conditions for the second calcination (II) are: temperature 420℃; time 4 hours.

[0092] A paraffin cracking catalyst was obtained, wherein the total amount of the paraffin cracking catalyst was 5% by mass, the content of manganese dioxide was 1% by mass, and the remainder was a support.

[0093] Example 2

[0094] The method of Example 1 was followed, except that the amount of support, the loading of active components and additives were different, while the rest were the same. The composition and property parameters of the obtained support are shown in Table 1. The obtained paraffin cracking catalyst, based on the total amount of the paraffin cracking catalyst, contained 15% manganese dioxide by mass, 0.1% lanthanum oxide by mass, and the remainder was support.

[0095] Example 3

[0096] The method of Example 1 was followed, except that the amount of support, the loading of active components and additives were different, while the rest were the same. The composition and property parameters of the obtained support are shown in Table 1. The obtained paraffin cracking catalyst, based on the total amount of the paraffin cracking catalyst, contained 10% manganese dioxide by mass, 0.5% lanthanum oxide by mass, and the remainder was support.

[0097] Example 4

[0098] The method of Example 1 was followed, except that the amount of support, the loading of active components and additives were different, while the rest were the same. The composition and property parameters of the obtained support are shown in Table 1. The obtained paraffin cracking catalyst, based on the total amount of the paraffin cracking catalyst, contained 10% manganese dioxide by mass, 2% lanthanum oxide by mass, and the remainder was support.

[0099] Example 5

[0100] The method of Example 1 was followed, except that the amount of support, the loading of active components and additives were different, while the rest were the same. The composition and property parameters of the obtained support are shown in Table 1. The obtained paraffin cracking catalyst, based on the total amount of the paraffin cracking catalyst, contained 15% manganese dioxide by mass, 2% lanthanum oxide by mass, and the remainder was support.

[0101] Example 6

[0102] The method of Example 1 was followed, except that the amount of support, the loading of active components and additives were different, while the rest were the same. The composition and property parameters of the obtained support are shown in Table 1. The obtained paraffin cracking catalyst, based on the total amount of the paraffin cracking catalyst, contained 5% manganese dioxide by mass, 2% lanthanum oxide by mass, and the remainder was support.

[0103] Example 7

[0104] The method of Example 1 was followed, except that the amount of support, the loading of active components and additives were different, while the rest were the same. The composition and property parameters of the obtained support are shown in Table 1. The obtained paraffin cracking catalyst, based on the total amount of the paraffin cracking catalyst, contained 5% manganese dioxide by mass, 0.1% lanthanum oxide by mass, and the remainder was support.

[0105] Example 8

[0106] The method is the same as in Example 1, except that:

[0107] In step (S1), the temperature of the first calcination is 800℃, and the rest are the same; the composition and property parameters of the obtained carrier are shown in Table 1;

[0108] In step (S2), the conditions for the first impregnation are: temperature 80℃; time 2h;

[0109] The conditions for the second calcination I are: temperature 450℃; time 4h;

[0110] In step (S3), the conditions for the second impregnation are: temperature 80℃; time 2h;

[0111] The conditions for the second calcination (II) are: temperature 450℃; time 4 hours.

[0112] The rest were the same, and a paraffin cracking catalyst was obtained. Based on the total amount of the paraffin cracking catalyst, the content of manganese dioxide was 5% by mass, the content of lanthanum oxide was 1% by mass, and the remainder was a support.

[0113] Example 9

[0114] The method is the same as in Example 1, except that...

[0115] In step (S1), the temperature of the first calcination is 1000℃, and the rest are the same; the composition and property parameters of the obtained carrier are shown in Table 1;

[0116] In step (S2), the conditions for the first impregnation are: temperature 80℃; time 2h;

[0117] The conditions for the second calcination I are: temperature 400℃; time 4h;

[0118] In step (S3), the conditions for the second impregnation are: temperature 80℃; time 2h;

[0119] The conditions for the second calcination I are: temperature 400℃; time 4h;

[0120] The rest were the same, and a paraffin cracking catalyst was obtained. Based on the total amount of the paraffin cracking catalyst, the content of manganese dioxide was 5% by mass, the content of lanthanum oxide was 1% by mass, and the remainder was a support.

[0121] Comparative Example 1

[0122] The method of Example 1 was followed, except that the temperature of the first calcination in step (S1) was 600°C, while the rest were the same. The types and properties of the resulting support are shown in Table 1. The remaining steps were the same, and the catalyst was obtained.

[0123] Table 1

[0124]

[0125]

[0126] Note: Mg:Al refers to the molar ratio of Mg and Al in the carrier (calculated from the amount of feed).

[0127] The average pore size and pore volume are the same as those of MgAl2O4.

[0128] Test case

[0129] In a fixed-bed reactor (15 mm inner diameter, H800 material), the catalysts prepared in the examples and comparative examples were reacted with the slurry bed outlet process gas. The reaction conditions and catalyst activity data are shown in Table 2. The properties of the slurry bed outlet process gas are as follows:

[0130] Process gas 1: Water vapor content is 26.5% by volume, paraffin vapor content is 1000ppm, the remainder is balance gas, and the pressure is 2.5MPa.

[0131] Process gas 2: Water vapor content is 15% by volume, paraffin vapor content is 2000ppm, the remainder is balance gas, and the pressure is 3.5MPa.

[0132] Process gas 3: water vapor content is 21.7% by volume, paraffin vapor content is 1500ppm, the remainder is balance gas, and the pressure is 3.0MPa.

[0133] Table 2

[0134]

[0135]

[0136] The above results demonstrate that the paraffin cracking catalyst provided by this invention can decompose and crack the paraffin contained in the slurry bed outlet process gas into C1-C4 small molecule hydrocarbons. This eliminates the need for conventional cooling and heating processes requiring condensers, separators, cold water circulation pumps, heat exchangers, heaters, and other equipment, resulting in lower energy consumption and costs. Furthermore, the paraffin cracking catalyst can remove paraffin from the slurry bed outlet process gas, preventing catalyst wax formation and thus protecting the methanation refining catalyst, extending its activity and lifespan.

[0137] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A paraffin cracking catalyst characterized by, The paraffin cracking catalyst comprises a carrier, an active component and an auxiliary agent supported on the carrier, wherein the active component is manganese dioxide, the auxiliary agent is La2O3, the carrier is a magnesium-aluminum composite oxide, the magnesium-aluminum composite oxide comprises MgAl2O4, MgO and Al2O3, the content of the MgAl2O4 is 93-100 wt% based on the total amount of the magnesium-aluminum composite oxide, the content of the MgO is 0-5 wt% based on the total amount of the magnesium-aluminum composite oxide, and the content of the Al2O3 is 0-2 wt% based on the total amount of the magnesium-aluminum composite oxide; the grain size of the MgAl2O4 is <20 nm, the pore volume is >0.15 mL / g, and the average pore size is 10-50 nm. The content of the active component is 5-15 wt% based on the total amount of the paraffin cracking catalyst, the content of the auxiliary agent is 0.1-2 wt% based on the total amount of the paraffin cracking catalyst, and the content of the carrier is 83-94.9 wt% based on the total amount of the paraffin cracking catalyst.

2. The paraffin cracking catalyst of claim 1, wherein, The content of the MgO is 0-3 wt% based on the total amount of the magnesium-aluminum composite oxide, and the content of the Al2O3 is 0-1 wt% based on the total amount of the magnesium-aluminum composite oxide.

3. The paraffin cracking catalyst of claim 1, wherein, The content of the MgAl2O4 is 96-100 wt% based on the total amount of the magnesium-aluminum composite oxide.

4. The paraffin cracking catalyst of any of claims 1-3, wherein, The grain size of the MgAl2O4 is 4-15 nm, the pore volume is 0.25-0.35 mL / g, and the average pore size is 10-30 nm.

5. The paraffin cracking catalyst of claim 4, wherein, The grain size of the MgAl2O4 is 5-10 nm, the pore volume is 0.27-0.33 mL / g, and the average pore size is 13-20 nm.

6. The paraffin cracking catalyst of any of claims 1-3, wherein, The molar ratio of Mg to Al in the magnesium-aluminum composite oxide is 1:2-2.

04.

7. A preparation method of the paraffin cracking catalyst according to any one of claims 1-6, the method comprising the following steps: (1) a mixture containing magnesium oxide, pseudoboehmite, and a pore expander is subjected to first calcination to obtain a carrier; wherein, The temperature of the first calcination is 800-1000 ℃. (2) loading the active component precursor and the auxiliary agent precursor on the carrier, and then performing second calcination on the obtained product; wherein the temperature of the second calcination is lower than the temperature of the first calcination.

8. The production method according to claim 7, wherein In step (1), the temperature of the first calcination is 850-950 ℃, and the time of the first calcination is 2-10 h.

9. The production method according to claim 8, wherein The time of the first calcination is 4-8 h.

10. The production method according to claim 7, wherein In step (1), the magnesium oxide is light magnesium oxide, and the average particle size of the light magnesium oxide is 0.06-0.09 mm.

11. The method of making according to claim 7, wherein, In step (1), the average particle size of the pseudo-boehmite is 0.06-0.09 mm.

12. The method of making according to claim 7, wherein, In step (1), the pore-expanding agent is selected from at least one of oxalic acid, nitric acid, acetic acid and sulfuric acid.

13. The production method according to claim 12, wherein The pore-expanding agent is nitric acid.

14. The method of making according to claim 7, wherein, The use amount ratio of the pore-expanding agent to the magnesium oxide is 1 mL:40-60 g.

15. The method of making according to claim 7, wherein, The mixture further contains a binder.

16. The method of manufacturing according to claim 15, wherein, The binder is selected from at least one of sesbania powder, stearate and cellulose and its derivatives.

17. The method of making according to claim 16, wherein, The binder is sodium carboxymethyl cellulose.

18. The method of making according to claim 15, wherein, The use amount mass ratio of the binder to the magnesium oxide is 1:20-25.

19. The method of making according to any one of claims 7-18, wherein, In step (2), the active component precursor is selected from at least one of manganese nitrate, manganese sulfate and manganese chloride.

20. The method of making according to claim 19, wherein, The active component precursor is manganese nitrate.

21. The method of making according to any one of claims 7-18, wherein, In step (2), the assistant precursor is at least one selected from the group consisting of lanthanum nitrate, lanthanum chloride and lanthanum sulfate.

22. The method of making according to claim 21, wherein, The assistant precursor is lanthanum nitrate.

23. The method of making according to any one of claims 7-18, wherein, In step (2), the loading method is impregnation.

24. The method of manufacturing according to claim 23, wherein, The impregnation conditions include: temperature of 60-80℃; time of 0.5-2h.

25. The method of making according to any one of claims 7-18, wherein, In step (2), the active component precursor is first loaded on the carrier to obtain an intermediate, and then the assistant precursor is loaded on the intermediate.

26. The method of making according to any one of claims 7-18, wherein, In step (2), the second calcination conditions include: temperature of 350-500℃, time of 4-10h.

27. The method of manufacturing according to claim 26, wherein, The second calcination conditions include: temperature of 400-450℃, time of 4-8h.

28. Use of the paraffin cracking catalyst according to any one of claims 1-6 in the production of natural gas by synthetic gas methanation containing paraffin.

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