A method for hydrorefining paraffin wax

Abstract

The present invention discloses a method for hydrofining of paraffin. The method comprises the following steps: mixing hydrogen with paraffin raw materials, first passing through a microinterface generator, breaking the hydrogen into microbubbles with a diameter of 1 μm to 1 mm, and then entering a reactor to contact with a catalyst for a hydrofining reaction; wherein the reactor comprises three catalyst beds, along the flow direction of the reactants, the first bed is filled with a protective agent, the second bed is filled with a type I paraffin hydrofining catalyst, and the third bed is filled with a type II paraffin hydrofining catalyst; wherein the filling volumes of the protective agent, the type I paraffin hydrofining catalyst, and the type II paraffin hydrofining catalyst account for 2% to 10%, 20% to 40%, and 50% to 78% of the total volume of the reactor, respectively. The method of the present invention solves the problem that the life of the paraffin hydrofining catalyst is shortened due to the deposition of carbon deposits, prolongs the life of the paraffin hydrofining catalyst, and improves the operation cycle of the paraffin hydrogenation device.

Description

Technical Field

[0001] The invention relates to a paraffin hydrogenation refining method, and in particular to a preparation method of a catalyst used in the paraffin hydrogenation refining process, a catalyst grading method and a hydrogenation process thereof. Background Art

[0002] Paraffin wax is an important petroleum processing product. It is obtained by solvent refining, solvent dewaxing or wax freezing crystallization, squeeze dewaxing to obtain wax paste, and then solvent deoiling and refining to obtain flake or needle-shaped crystals from the lubricating oil fraction obtained from crude oil distillation. Paraffin wax is widely used in many fields of the national economy, such as food, medicine, precision instruments, and daily chemicals.

[0003] The paraffin hydrorefining process mainly includes the hydrogenation of non-hydrocarbon compounds containing sulfur, nitrogen and oxygen, the hydrogenation of olefins and the hydrogenation saturation of condensed aromatic hydrocarbons. Paraffin hydrorefining generally uses a fixed bed reactor, which is a typical trickle bed liquid phase reaction process with low reaction heat. The existing paraffin hydrorefining process flow is similar in principle, and the main difference lies in the nature of the raw materials, the catalyst used and the refining depth. The typical process is a single-stage and two-stage hydrorefining process.

[0004] CN103773499A discloses a petroleum wax hydrorefining method, comprising: a petroleum wax raw material and hydrogen are passed through a gas-liquid countercurrent hydrogenation reactor in a countercurrent manner, and after contacting and reacting with a non-precious metal hydrorefining catalyst therein, a gas phase is discharged from the top of the reactor for other uses, and a liquid phase effluent directly enters a second hydrogenation reaction zone, passes through a hydrogenation protection reaction zone and a main hydrorefining reaction zone in sequence, and contacts with a hydrogenation protection agent and a reducing hydrorefining catalyst therein in sequence for hydrogenation reaction, and after the hydrorefining product is separated, the gas phase is circulated back to the gas-liquid countercurrent hydrogenation reactor, and the liquid phase is a refined petroleum wax product.

[0005] CN109988627A discloses a flexible paraffin hydrogenation process. Paraffin raw materials enter the hydrofining reactor, and the materials after passing through the upper hydrofining catalyst bed are divided into two streams; one stream of materials is drawn out of the hydrofining reactor through the middle of the bed, and enters the hydroisomerization reactor for isomerization reaction; the other stream of materials continues to flow downward through the lower hydrofining catalyst bed; the obtained hydrofining reaction materials and hydroisomerization reaction materials are respectively subjected to gas-liquid separation and fractionation to obtain paraffin products of different specifications.

[0006] In the process of hydrogenation, the existing paraffin hydrorefining catalyst will block the pores and cover the active sites as the operation time of the hydrogenation unit increases, which reduces the utilization rate of active metals and shortens the operation cycle of the hydrogenation unit. In the traditional fixed bed hydrogenation reaction unit, the gas-liquid mass transfer interface area is small and the apparent reaction rate is slow. Therefore, it is of great significance to develop a paraffin hydrorefining catalyst that is resistant to carbon deposition and has a long service life and to improve the process. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for hydrorefining of paraffin, so as to solve the problem that the life of the paraffin hydrorefining catalyst is shortened due to the deposition of carbon deposits, thereby extending the life of the paraffin hydrorefining catalyst and improving the operating cycle of the paraffin hydrogenation device.

[0008] The invention provides a paraffin hydrorefining method, comprising: mixing hydrogen with paraffin raw material, first passing through a microinterface generator, breaking the hydrogen into microbubbles with a diameter of 1 μm to 1 mm, the formed microbubbles being evenly distributed in the raw wax, and then the gas-liquid mixed phase entering the reactor from the bottom of the reactor to contact with a catalyst for a hydrorefining reaction; the paraffin hydrorefining reactor comprises three catalyst beds, along the flow direction of the reactants, the first bed is filled with a protective agent, the second bed is filled with a type I paraffin hydrorefining catalyst, and the third bed is filled with a type II paraffin hydrorefining catalyst; wherein the filling volumes of the protective agent, the type I paraffin hydrorefining catalyst and the type II paraffin hydrorefining catalyst account for 2% to 10%, 20% to 40% and 50% to 78% of the total volume of the reactor respectively.

[0009] In the method of the present invention, the paraffin raw material is solvent dewaxing and deoiling crude paraffin of two or three lines.

[0010] In the method of the present invention, the reaction temperature is 230-310°C, the reaction pressure is 3.0-8.0 MPa, and the liquid hourly volume space velocity is 0.3-1.5 h -1 , the volume ratio of hydrogen to wax is 100-500.

[0011] In the method of the present invention, the protective agent can be selected from conventional commercial protective agents in the art, or protective agents prepared by other conventional methods, such as the protective agent series developed by Dalian Petrochemical Research Institute of China Petrochemical Corporation.

[0012] In the method of the present invention, the type I paraffin hydrorefining catalyst comprises a catalyst body composed of a carrier and an active component supported on the carrier, and a macroporous alumina layer is provided on the outer surface of the catalyst body. The pore volume of the macroporous alumina is 0.50 cm higher than that of the catalyst body. 3The macroporous alumina layer contains at least one auxiliary agent selected from fluorine, phosphorus, silicon or boron, and the amount of the auxiliary agent added is 0.5% to 20% of the mass of the alumina, preferably 1% to 16%, and more preferably 2% to 16%.

[0013] In the method of the present invention, in the type I paraffin hydrogenation refining catalyst, the total acid content of the macroporous alumina layer is 0.47 to 0.75 mmol / g.

[0014] In the method of the present invention, in the type I paraffin hydrorefining catalyst, the macroporous alumina layer has a pore volume greater than 0.90 cm 3 / g (mercury intrusion method), pores with a pore size of >45nm account for 20% to 50% of the total pore volume, which can accommodate more carbon deposits. Since the macroporous alumina with additives has a higher acidity, more carbon deposits will be deposited in the pores. In order to prevent pore blockage, the alumina film layer needs to have more large-diameter pores.

[0015] In the method of the present invention, in the type I paraffin hydrorefining catalyst, the macroporous alumina layer has a thickness of 1 to 500 μm, preferably 50 to 200 μm.

[0016] In the method of the present invention, in the type I paraffin hydrorefining catalyst, the characteristics of the catalyst body are as follows: the pore volume is greater than 0.35 cm 3 / g, with Group VIB and Group VIII metals as active metals, preferably molybdenum and cobalt. Based on the mass of the catalyst body, the content of molybdenum oxide is 4.0% to 30.0%, and the content of cobalt oxide is 1.0% to 10.0%.

[0017] In the method of the present invention, the type II paraffin hydrorefining catalyst comprises a catalyst body composed of a carrier and an active component supported on the carrier, and a macroporous alumina layer is provided on the outer surface of the catalyst body. The pore volume of the macroporous alumina is 0.40 cm higher than that of the catalyst body. 3 / g or more, preferably 0.45 to 0.55 cm 3 / g.

[0018] In the method of the present invention, in the type II paraffin hydrorefining catalyst, the macroporous alumina layer has a pore volume greater than 0.80 cm 3 / g (mercury intrusion method), preferably 0.85 to 0.95 cm 3 / g, the pore volume of pores with a pore diameter of more than 30 nm is 20% to 60% of the total pore volume, preferably 40 to 55%, which can accommodate more carbon deposits.

[0019] In the method of the present invention, in the type II paraffin hydrorefining catalyst, the macroporous alumina layer has a thickness of 1 to 400 μm, preferably 60 to 180 μm.

[0020] In the method of the present invention, in the type II paraffin hydrorefining catalyst, the characteristics of the catalyst body are as follows: the pore volume is greater than 0.35 cm 3 / g, based on the mass of the catalyst body, the content of tungsten oxide is 2.0% to 25.0%, the content of molybdenum oxide is 2.0% to 20.0%, and the content of nickel oxide is 0.4% to 8.0%.

[0021] In the method of the present invention, the preparation method of the type I paraffin hydrorefining catalyst comprises the following steps:

[0022] a. impregnating a paraffin hydrorefining catalyst carrier with an active metal to prepare a paraffin hydrorefining catalyst as a catalyst body;

[0023] b. Add the catalyst body of step a to a macroporous pseudo-boehmite gel containing at least one additive of fluorine, phosphorus, silicon or boron, stir and soak, take out after the surface is coated with the gel, dry and calcine to obtain the type I paraffin hydrorefining catalyst.

[0024] In step a, the catalyst carrier is selected from alumina or modified alumina, and the specific surface area of ​​the catalyst carrier is 160 to 400 m 2 / g, the pore volume is 0.60~1.00mL / g, and the average pore diameter is 7~16nm.

[0025] In step a, the active metal is preferably molybdenum or cobalt. Based on the mass of the catalyst, the content of molybdenum oxide is 4.0% to 30.0%, preferably 6.0% to 28.0%, and more preferably 10.0 to 26.0%. The content of cobalt oxide is 1.0% to 10.0%, preferably 2.0% to 10.0%, and more preferably 2.0 to 8.0%.

[0026] In step b, before adding the catalyst body to the macroporous pseudo-boehmite gel, the catalyst body is preferably soaked in a binder solution. The binder content in the binder solution is 1% to 80%, preferably 2% to 25%. The binder solution is composed of a binder and pure water. The binder can be at least one of starch, dextrin, polyvinyl alcohol or carboxymethyl cellulose.

[0027] Preferably, the catalyst body is immersed in the binder solution for 10 to 50 seconds, excess binder solution is drained off, and the catalyst body is left at room temperature for 15 to 60 minutes.

[0028] In step b, the macroporous pseudo-boehmite gel is converted into macroporous alumina and has the following properties: pore volume greater than 0.90 cm 3 / g (mercury intrusion method), with through-hole channels, pores with pore diameters greater than 45nm occupy 20% to 50% of the total pore volume, and can accommodate more carbon deposits. Among them, the macroporous pseudo-boehmite gel is converted into macroporous alumina by calcining at 450 to 650°C for 3 to 6 hours. The macroporous pseudo-boehmite gel can be obtained by the following method, using an inorganic aluminum source as a raw material, adding an auxiliary agent, and not adding a template agent, and hydrothermally treating at 180 to 300°C for 3 to 6 hours to prepare it. The modified alumina with the addition of auxiliary agents has a slightly higher surface acidity than pure alumina, so that more carbon deposits are deposited in the alumina film layer and less deposited in the catalyst body. The concentration of alumina in the macroporous pseudo-boehmite gel is 20g / L to 100g / L, and the preferred concentration of alumina is 20g / L to 75g / L.

[0029] In step b, the catalyst particles are added to the macroporous pseudo-boehmite gel and stirred for 10 seconds to 20 minutes. After the surface is coated with gel, the particles are taken out and centrifuged to remove excess gel on the surface for 1 to 20 minutes. The particles are then dried at 80 to 150° C. for 2 to 12 hours. The thickness of the alumina film layer can be controlled by controlling the concentration of alumina in the macroporous pseudo-boehmite gel, the immersion time and the centrifugation time.

[0030] In step b, the calcination is performed by programmed temperature rise. The calcination conditions are: a heating rate of 1°C / min to 3°C / min, a calcination temperature of 450°C to 650°C, and a calcination time of 3 to 6 hours. After calcination, an aluminum oxide coating layer of 1 to 500 μm, preferably 50 to 200 μm, can be formed on the catalyst surface.

[0031] In the method of the present invention, the preparation method of the type II paraffin hydrorefining catalyst comprises the following steps:

[0032] ①Prepare a paraffin hydrorefining catalyst as a catalyst body;

[0033] ② Add the catalyst body of step ① into the macroporous pseudo-boehmite gel, stir and soak, take out after the surface is coated with the gel, dry and roast to obtain the paraffin hydrogenation refining catalyst.

[0034] The paraffin hydrorefining catalyst in step ① has a pore volume greater than 0.35 cm 3 / g of paraffin hydrorefining catalyst, the active metals in the catalyst are preferably tungsten, molybdenum and nickel. Based on the mass of the catalyst body, the content of tungsten oxide is 2.0% to 25.0%, the content of molybdenum oxide is 2.0% to 20.0%, and the content of nickel oxide is 0.4% to 8.0%.

[0035] In step ②, before adding the catalyst body to the macroporous pseudo-boehmite gel, the catalyst body is preferably soaked in a binder solution. The binder content in the binder solution is 1% to 80%, preferably 2% to 30%. The binder solution is composed of a binder and pure water. The binder can be one or more of starch, dextrin, polyvinyl alcohol or carboxymethyl cellulose.

[0036] Preferably, the catalyst body is immersed in the binder solution for 10 to 50 seconds, excess binder solution is drained off, and the catalyst body is left at room temperature for 15 to 60 minutes.

[0037] In step ②, the macroporous pseudo-boehmite gel is converted into macroporous alumina and has the following properties: pore volume greater than 0.80 cm 3 / g (mercury intrusion method), with through-hole channels, pores with a pore size of >30nm occupying 20% ​​to 60% of the total pore volume, and can accommodate more carbon deposits. Among them, the macroporous pseudo-boehmite gel is converted into macroporous alumina by calcining at 450 to 650°C for 3 to 6 hours. The macroporous pseudo-boehmite gel can be obtained by the following method, using an inorganic aluminum source as a raw material, without adding a template agent, adjusting the pH value to 2.8 to 3.2, and preparing it after hydrothermal treatment at 180 to 300°C for 3 to 6 hours. The concentration of alumina in the macroporous pseudo-boehmite gel is 20g / L to 100g / L, and the preferred concentration of alumina is 20g / L to 70g / L.

[0038] In step ②, the catalyst particles are added to the macroporous pseudo-boehmite gel and stirred for 10s to 20min. After the surface is coated with gel, the particles are taken out and centrifuged to remove excess gel on the surface, and then dried at 80 to 150°C for 2 to 12 hours. The thickness of the alumina film layer can be controlled by controlling the concentration of alumina in the macroporous pseudo-boehmite gel, the immersion time and the centrifugation time.

[0039] In step ②, the calcination is performed by programmed heating. The heating rate is 1°C / min to 3°C / min, the calcination temperature is 450 to 650°C, and the calcination time is 3 to 6 hours. After calcination, an aluminum oxide coating layer of 1 to 400 μm, preferably 60 to 180 μm, can be formed on the catalyst surface.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. In the paraffin hydrorefining method of the present invention, hydrogen is first broken into microbubbles with a diameter of micrometers by a microinterface generator before entering the reactor. The microbubbles have the advantages of good independence, uniform distribution and not easy to merge, which increases the contact probability between hydrogen and raw wax, strengthens the gas-liquid reaction, and improves the mass transfer efficiency.

[0042] 2. The inventors have found through extensive research that in the paraffin hydrorefining process, by adopting the catalyst grading method of the present invention, a protective agent, a type I paraffin hydrorefining catalyst and a type II paraffin hydrorefining catalyst are sequentially loaded in a specific proportion along the flow direction of the reactants, and then combined with the hydrogenation process provided by the present invention, the life of the paraffin hydrorefining catalyst can be extended and the operation cycle of the paraffin hydrogenation device can be improved. Specifically, the surface of the Type I paraffin hydrorefining catalyst body is coated with macroporous alumina, and additives are added thereto, so that during the hydrogenation process, the catalyst has good desulfurization and denitrification performance, and at the same time, more carbon deposits can be first deposited in the alumina pores on the surface. Since the membrane layer has penetrating pores, carbon deposits are deposited but do not block the pores, and wax materials can enter the catalyst body for hydrogenation reaction, reducing the deposition of carbon deposits in the catalyst body and improving the catalyst's resistance to carbon deposition; Type II paraffin hydrorefining catalyst, the active metal adopts a tungsten-molybdenum-nickel system, the surface of the body is coated with macroporous alumina, the catalyst has good aromatic saturation performance, during the hydrogenation process, the carbon deposits generated by the reaction are first deposited in the alumina pores on the surface. Since the membrane layer has penetrating pores, carbon deposits are deposited but do not block the pores, and wax materials can enter the catalyst body for hydrogenation reaction, reducing the deposition of carbon deposits in the catalyst body, improving the catalyst's resistance to carbon deposition and extending the service life of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention is a process flow diagram of a paraffin hydrorefining method;

[0044] The reference numerals are explained as follows: I-new hydrogen, II-raw wax, III-circulating hydrogen; 1-degassing tower, 2-heating furnace, 3-microinterface generator, 4-reactor, 5-hot high fractionator, 6-cold high fractionator. DETAILED DESCRIPTION

[0045] The technical solutions and effects of the present invention are further described below in conjunction with embodiments, but are not limited to the following embodiments.

[0046] The present invention provides a process flow diagram of a paraffin hydrorefining method (see Figure 1 ). Specifically, the raw wax II is mixed with hydrogen after passing through the degassing tower 1, first heated by the heating furnace 2, and then passed through the micro-interface generator 3, the hydrogen is broken into micro bubbles, and the gas-liquid mixed phase enters the reactor 4 from the bottom of the reactor, and passes through the protective agent, type I paraffin hydrorefining catalyst and type II paraffin hydrorefining catalyst in sequence. The hydrogenation product comes out from the top of the reactor and enters the hot high fraction 5 and the cold high fraction 6 for separation.

[0047] In the present invention, the pore volume and pore diameter of the external surface macroporous alumina involved in the embodiments and comparative examples are obtained by testing using the instrument MicroActive AutoPore V 9600 by mercury intrusion method, and the pore volume, pore diameter and specific surface area of ​​the catalyst and carrier are obtained by testing using the ASAP-2420 physical adsorption instrument.

[0048] In the present invention, the method for determining the total acid content of macroporous alumina is to scrape the alumina on the outer surface of the catalyst after calcination, then press it into tablets, use the instrument AUTOCHEM 2910 programmed temperature adsorption instrument, purge with nitrogen at room temperature, dehydrate by heating, pass ammonia at a set temperature, and adsorb the sample until it is saturated with ammonia, then purge with nitrogen to remove the ammonia physically adsorbed on the surface of the sample, and finally desorb NH3 adsorbed on the sample under programmed temperature conditions, and obtain the acid content by calculating the area of ​​the desorption peak.

[0049] Example 1

[0050] The wax material (melting point 58.5°C, oil content 0.33wt%, color (Saybolt)-7, light stability 7-8) prepared by vacuum distillation of the second-line fraction and ketone-benzene dewaxing and deoiling is used as the raw wax, and the Figure 1 , mixed with hydrogen after passing through the degassing tower 1, first heated by the heating furnace 2, then passing through the microinterface generator 3, the hydrogen is broken into microbubbles (diameter 200-800μm), and then enters the reactor 4. The paraffin hydrogenation reactor is filled with 5% of the reactor volume of the protective agent, 35% of the type I paraffin hydrogenation refining catalyst, and 60% of the type II paraffin hydrogenation refining catalyst. At the reaction temperature of 255℃, the reaction pressure of 5.0MPa, the liquid hourly volume space velocity of 1.0h- 1 The paraffin hydrogenation reaction is carried out under the process conditions of a hydrogen-wax volume ratio of 500:1.

[0051] Preparation of Type I Paraffin Hydrorefining Catalyst:

[0052] a Take the catalyst alumina carrier (the specific surface area of ​​the carrier is 336m 2 / g, pore volume of 0.72mL / g, average pore diameter of 9.7nm) was impregnated with molybdenum-cobalt solution. After impregnation, the content of molybdenum oxide on the catalyst was 23.7%, and the content of cobalt oxide was 4.7%.

[0053] b. Prepare adhesive solution: dissolve 25g starch in 500g clean water under heating and stirring, and stir to dissolve evenly;

[0054] c. Preparation of macroporous pseudo-boehmite gel: Weigh 50 g of aluminum sulfate and 5 g of silica sol (containing 30 wt% silicon dioxide), and perform hydrothermal treatment at 180° C. for 4 hours. The concentration of aluminum oxide in the macroporous pseudo-boehmite is 25 g / L.

[0055] d. After drying, immerse the catalyst particles in step a into the binder in step b for 15 seconds, take them out, drain off the excess binder solution, and leave them at room temperature for 25 minutes.

[0056] e. Add the catalyst particles obtained in step d to the macroporous pseudo-boehmite gel prepared in step c and stir for 2 minutes. After the surface is coated with the gel, take it out, centrifuge it in a high-speed centrifuge for 2 minutes, and then dry it at 120° C. for 5 hours.

[0057] f Calcination: The temperature was raised to 550°C at a rate of 1°C / min for 4 hours to obtain a type I paraffin hydrorefining catalyst. The macroporous alumina film had a thickness of 122 μm and a pore volume of 0.95 cm 3 / g, the pore volume of pores with a pore size of more than 45nm accounts for 38% of the total pore volume. The pore volume of the macroporous alumina membrane layer is 0.53cm higher than that of the paraffin hydrorefining catalyst body. 3 / g, the total acid content of macroporous alumina is 0.541mmol / g.

[0058] Preparation of Type II Paraffin Hydrorefining Catalyst:

[0059] (1) Prepare 100 g of paraffin hydrorefining catalyst with a pore volume of 0.40 cm 3 / g, the content of tungsten oxide in the catalyst is 13.5%, the content of molybdenum oxide is 15.0%, and the content of nickel oxide is 4.5%

[0060] (2) preparing the adhesive solution: dissolving 25 g of starch in 500 g of pure water under heating and stirring conditions, stirring and dissolving uniformly;

[0061] (3) Preparation of macroporous pseudo-boehmite gel: Weigh 50 g of aluminum sulfate, adjust the pH value to 3.0, and perform hydrothermal treatment at 180° C. for 3 hours. The concentration of aluminum oxide in the macroporous pseudo-boehmite is 28 g / L.

[0062] (4) The catalyst particles dried in step (1) are immersed in the binder prepared in step (2) for 15 seconds, then taken out, excess binder solution is drained off, and the particles are allowed to stand at room temperature for 30 minutes.

[0063] (5) The catalyst particles obtained in step (4) are added to the macroporous pseudo-boehmite gel in step (3) and stirred for 2 min. After the surface is coated with the gel, the particles are taken out, centrifuged in a high-speed centrifuge for 2 min, and then dried at 120° C. for 5 hours.

[0064] (6) Calcination: The temperature was raised to 500°C at a rate of 1°C / min for 4 hours by programmed heating to obtain a type II paraffin hydrorefining catalyst. The macroporous alumina membrane layer had a thickness of 124 μm and a pore volume of 0.86 cm 3 / g, the pore volume of pores with pore diameters greater than 30nm accounts for 43% of the total pore volume. The pore volume of the macroporous alumina membrane layer is 0.46cm higher than that of the paraffin hydrorefining catalyst body. 3 / g.

[0065] Example 2

[0066] Same as Example 1, except that the hydrogenation reaction was carried out under the process condition of reaction temperature 265° C. The paraffin hydrogenation reactor was filled with 3% of the reactor volume of protective agent, 37% of type I paraffin hydrogenation refining catalyst, and 60% of type II paraffin hydrogenation refining catalyst.

[0067] Preparation of Type I Paraffin Hydrorefining Catalyst:

[0068] Same as Example 1, except that 6 g of boric acid was added in step c, the concentration of alumina in the macroporous pseudo-boehmite was adjusted to 35 g / L, the thickness of the macroporous alumina film layer was 132 μm, and the pore volume was 0.93 cm 3 / g, pores with pore diameters greater than 45nm account for 36% of the total pore volume. The pore volume of the macroporous alumina membrane layer is 0.51cm higher than that of the paraffin hydrorefining catalyst body. 3 / g, and the total acid content of macroporous alumina is 0.550mmol / g.

[0069] Preparation of Type II Paraffin Hydrorefining Catalyst:

[0070] The same as Example 1, except that in step (3), the pH value is adjusted to 2.9, and the hydrothermal treatment is performed at 180°C for 3.5 hours. The concentration of alumina in the macroporous pseudo-boehmite is 50 g / L, and a paraffin hydrorefining catalyst coated with alumina is obtained. The thickness of the macroporous alumina film layer is 147 μm, and the pore volume is 0.89 cm 3 / g, pores with pore diameters greater than 30nm account for 47% of the total pore volume. The pore volume of macroporous alumina is 0.49cm higher than that of the catalyst body. 3 / g.

[0071] Example 3

[0072] The same as Example 1, except that the paraffin hydrogenation reactor is filled with 10% of the reactor volume of the protective agent, 20% of the type I paraffin hydrogenation refining catalyst, and 70% of the type II paraffin hydrogenation refining catalyst.

[0073] Preparation of Type I Paraffin Hydrorefining Catalyst:

[0074] In step e, the catalyst particles are immersed in macroporous pseudo-boehmite gel and stirred, and the surface is taken out after being coated with gel, centrifuged in a high-speed centrifuge for 7 minutes, dried at 110°C for 6 hours, and calcined at 520°C at a heating rate of 3°C / min for 5 hours to obtain a type I paraffin hydrorefining catalyst, wherein the macroporous alumina membrane layer has a thickness of 80 μm and a pore volume of 0.92 cm 3 / g, the pore volume of pores with pore diameters greater than 45nm accounts for 35% of the total pore volume. The total acid content of macroporous alumina is 0.559mmol / g.

[0075] Preparation of Type II Paraffin Hydrorefining Catalyst:

[0076] In step (3), the concentration of alumina in the macroporous pseudo-boehmite is adjusted to 50 g / L. At the same time, the catalyst particles in step (5) are immersed in the macroporous pseudo-boehmite gel of step (3) and stirred for 10 minutes. After the surface is coated with the gel, the catalyst particles are taken out and centrifuged in a high-speed centrifuge for 7 minutes to obtain a type II paraffin hydrogenation refining catalyst. The thickness of the macroporous alumina membrane layer is 138 μm and the pore volume is 0.87 cm 3 / g, pores with pore diameters greater than 30nm account for 44% of the total pore volume. The pore volume of macroporous alumina is 0.47cm higher than that of the catalyst body. 3 / g.

[0077] Example 4

[0078] Same as in Example 1, the reaction conditions were: reaction temperature 260°C, reaction pressure 4.5 MPa, volume space velocity 1.0 h- 1 The paraffin hydrogenation reaction is carried out under the process conditions of a hydrogen-wax volume ratio of 500:1.

[0079] The same as in Example 1, the preparation of Type I catalyst only includes steps (a), (c), (e), and (f), without steps (b) and (d), to obtain a paraffin hydrorefining catalyst wrapped with alumina. The thickness of the macroporous alumina membrane layer is 27 μm, and the other properties are the same as in Example 1.

[0080] The same as in Example 1, the preparation of Type II catalyst only includes steps (1)(3)(5)(6), without steps (2) and (4), and thus a paraffin hydrorefining catalyst coated with alumina is obtained. The thickness of the macroporous alumina membrane layer is 38 μm, and the other properties are the same as in Example 1.

[0081] Comparative Example 1

[0082] The same as Example 1, except that the type I paraffin hydrorefining catalyst in this example adopts the catalyst obtained in step a of Example 1, that is, the specific surface area of ​​the carrier is 336m 2 / g, pore volume of 0.72mL / g, average pore diameter of 9.7nm. After impregnation with molybdenum-cobalt solution, the content of molybdenum oxide on the catalyst was 23.7%, and the content of cobalt oxide was 4.7%.

[0083] Same as Example 1, except that: the type II paraffin hydrorefining catalyst adopts the paraffin hydrorefining catalyst prepared in step (1), i.e., the pore volume of the catalyst is 0.40 cm 3 / g, the content of tungsten oxide in the catalyst is 13.5%, the content of molybdenum oxide is 15.0%, and the content of nickel oxide is 4.5%.

[0084] Comparative Example 2

[0085] The same as Example 1, except that in this example, a commercially available paraffin hydrorefining catalyst is directly used to replace the type I paraffin hydrorefining catalyst and the type II paraffin hydrorefining catalyst, and the pore volume of the catalyst is 0.39 cm 3 / g, the content of tungsten oxide in the catalyst is 28.5%, and the content of nickel oxide is 5.5%.

[0086] Comparative Example 3

[0087] The same as Example 1, except that no additive was added in the preparation of macroporous pseudo-boehmite gel in the preparation process of type I paraffin hydrorefining catalyst. The thickness of the macroporous alumina film layer in the prepared catalyst was 120 μm, and the pore volume was 0.90 cm 3 / g, the pore volume of pores with a pore size of more than 45nm accounts for 31% of the total pore volume. The pore volume of the macroporous alumina membrane layer is 0.48cm higher than that of the paraffin hydrorefining catalyst body. 3 / g, the total acid content of macroporous alumina is 0.431mmol / g.

[0088] In this example, the type II paraffin hydrorefining catalyst is prepared by the aluminum sulfate method of the ordinary parallel flow method in step (3). 2L of sodium aluminate aqueous solution (the concentration is 15g / 100mL in terms of Al2O3) and 3L of aluminum sulfate aqueous solution (the concentration is 8g / 100mL in terms of Al2O3) are gelled at a gelling temperature of 60°C and a gelling pH of 7.7. The resulting alumina film does not have penetrating pores. Finally, pseudo-boehmite gel is obtained to prepare the type II paraffin hydrorefining catalyst. The thickness of the alumina film is 127μm and the pore volume is 0.67cm 3 / g, the pore volume of pores with a pore diameter of more than 30nm accounts for 15% of the total pore volume, and the pore volume of macroporous alumina is 0.27cm higher than that of the catalyst body. 3 / g.

[0089] Comparative Example 4

[0090] The same as Example 1, except that in this example, the filling ratios of the protective agent, the type I paraffin hydrorefining catalyst and the type II paraffin hydrorefining catalyst are the same.

[0091] Comparative Example 5

[0092] The same as Example 1, except that hydrogen directly enters the reactor to react with the raw wax.

[0093] Table 1 Properties of products after 2000h of hydrotreating reaction

[0094]

[0095]

[0096] Table 1 Properties of products after 2000h of hydrotreating reaction in various cases (continued)

[0097]

[0098] It can be seen from Table 1 that after 2000 hours of hydrofining at a relatively low reaction pressure, the performance of the hydrogenated product obtained by the method of the present invention is better than that of the comparative example, and still has good hydrogenation performance, which provides a guarantee for extending the operation period of the device.

Claims

1. A paraffin hydrofining method, comprising mixing hydrogen with a paraffin raw material, first passing through a microinterface generator, breaking the hydrogen into microbubbles with a diameter of 1 μm to 1 mm, the formed microbubbles are evenly distributed in the raw wax, and then enter the reactor from the bottom of the reactor to contact with a catalyst for a hydrofining reaction; the paraffin hydrofining reactor comprises three catalyst beds, along the flow direction of the reactants, the first bed is filled with a protective agent, the second bed is filled with a type I paraffin hydrofining catalyst, and the third bed is filled with a type II paraffin hydrofining catalyst; wherein the filling volumes of the protective agent, the type I paraffin hydrofining catalyst and the type II paraffin hydrofining catalyst account for 2% to 10%, 20% to 40% and 50% to 78% of the total volume of the reactor respectively; The type I paraffin hydrorefining catalyst comprises a catalyst body composed of a carrier and an active component supported on the carrier, and a macroporous alumina layer is provided on the outer surface of the catalyst body, wherein the macroporous alumina layer contains at least one auxiliary agent selected from fluorine, phosphorus, silicon or boron; the pore volume of the macroporous alumina is 0.51-0.60 cm higher than that of the catalyst body. 3 / g; in the type I paraffin hydrorefining catalyst, the thickness of the macroporous alumina layer is 50-200 μm; The type II paraffin hydrorefining catalyst comprises a catalyst body composed of a carrier and an active component supported on the carrier, and a macroporous alumina layer is provided on the outer surface of the catalyst body; the pore volume of the macroporous alumina is 0.45-0.55 cm higher than that of the catalyst body. 3 / g; in the type II paraffin hydrorefining catalyst, the thickness of the macroporous alumina layer is 60~180μm.

2. The method according to claim 1, characterized in that: The hydrofining reaction temperature is 230~310℃, the reaction pressure is 3.0~8.0MPa, and the liquid hourly volume space velocity is 0.3~1.5h -1 , the volume ratio of hydrogen to wax is 100~500.

3. The method according to claim 1, characterized in that In the type I paraffin hydrorefining catalyst, the amount of the additive added is 0.5% to 20% of the mass of the alumina, calculated as the element.

4. The method according to claim 1, characterized in that: In the type I paraffin hydrorefining catalyst, the amount of the additive added is 1% to 16% of the mass of the alumina, calculated as the element.

5. The method according to claim 1, characterized in that In the type I paraffin hydrorefining catalyst, the amount of the additive added is 2% to 16% of the mass of the alumina, calculated as the element.

6. The method according to claim 1, characterized in that In the type I paraffin hydrorefining catalyst, the total acid content of the macroporous alumina layer is 0.47-0.75 mmol / g.

7. The method according to claim 1, characterized in that In the type I paraffin hydrorefining catalyst, the macroporous alumina layer has a pore volume greater than 0.90 cm 3 / g, the pore volume of pores with a pore diameter of more than 45nm accounts for 20%~50% of the total pore volume.

8. The method according to claim 1, characterized in that In the type II paraffin hydrorefining catalyst, the macroporous alumina layer has a pore volume greater than 0.80 cm 3 / g, the pore volume of pores with a pore diameter of more than 30nm accounts for 20%~60% of the total pore volume.

9. The method according to claim 1, characterized in that: In the type II paraffin hydrorefining catalyst, the macroporous alumina layer has a pore volume of 0.85-0.95 cm 3 / g, the pore volume of pores with pore diameter > 30nm accounts for 40%~55% of the total pore volume.

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