Residual oil hydrodemetallization catalyst and preparation method thereof
Technical Field
The invention relates to the field of catalyst preparation, in particular to a residual oil hydrodemetallization catalyst and a preparation method thereof.
Background
With the deterioration and heaviness of crude oil, the efficient conversion of heavy oil and the improvement of the yield of light oil products become an important trend in the development of oil refining technology. The residue fixed bed hydrogenation technology is an effective means for realizing the high-efficiency conversion of heavy oil. By adopting the technical route, the impurities such as metal, sulfur, nitrogen, carbon residue and the like in the residual oil can be effectively removed, high-quality feed is provided for catalytic cracking, and the strict environmental protection regulation requirements are met while the yield of light oil products is increased. During the processing of heavy oil, the metal compounds therein are decomposed, and the metal impurities are deposited on the inner and outer surfaces of the catalyst to block the pore channels, even cause the catalyst to be poisoned and deactivated, so that the metal impurities contained therein must be removed firstly during the catalytic cracking of heavy oil. The hydrodemetallization catalyst mainly removes metal impurities including nickel and vanadium in raw oil, so as to protect downstream catalysts from losing activity due to deposition of a large amount of metals.
At present, most of the commercial Hydrodemetallization (HDM) catalysts are made of Al2O3Being a support, the pore structure of the support can significantly affect its catalytic activity as well as its stability. The results of previous studies show that: suitable Al2O3The pore size distribution of the carrier can provide a proper diffusion rate of metal compounds, the existence of a certain proportion of super-large pores in the alumina carrier can promote the diffusion and deposition of macromolecular asphaltene molecules, reduce the blockage of coke deposition to orifices, and even under the condition of serious nickel and vanadium deposition, the large pores can also allow the macromolecules to pass through, thereby improving the stability of the catalyst.
CN1160602A discloses a macroporous alumina carrier suitable for use as a hydrodemetallization catalyst carrier and a preparation method thereof. The preparation method of the macroporous alumina carrier comprises the steps of mixing the pseudo-boehmite dry glue powder with water or aqueous solution, kneading into a plastic body, extruding the obtained plastic body into a strip-shaped object on a strip extruding machine, drying and roasting to obtain a product; in the above-mentioned process also the carbon black powder is added as physical pore-expanding agent and chemical pore-expanding agent containing phosphorus, silicon or boron compound which can produce chemical action with pseudo-boehmite or alumina. Wherein the amount of the carbon black powder is 3-10% (based on the weight of the alumina). The prepared alumina carrier can be used for preparing heavy oil, in particular a heavy oil hydrodemetallization and/or hydrodesulfurization catalyst.
US4448896 proposes the use of carbon black as a pore-enlarging agent. Uniformly mixing a pore-expanding agent and pseudo-boehmite dry rubber powder, adding a nitric acid aqueous solution with the mass fraction of 4.3% into the mixture, kneading for 30 minutes, then adding an ammonia aqueous solution with the mass fraction of 2.1%, kneading for 25 minutes, extruding into strips and forming after uniform kneading, and roasting the formed carrier to obtain the final alumina carrier. Wherein the addition amount of the carbon black powder is preferably more than 20% of the weight of the activated alumina or the precursor thereof.
CN102441436A discloses a preparation method of an alumina carrier. The method for preparing the alumina carrier comprises the following steps: the pseudo-boehmite dry glue powder and the extrusion aid are mixed uniformly, then the aqueous solution in which the physical pore-enlarging agent and the chemical pore-enlarging agent are dissolved is added, the mixture is mixed uniformly, the mixture is extruded on a strip extruder to be formed, and the alumina carrier is prepared after drying and roasting.
The physical pore-expanding agent can increase the proportion of macropores, but in the case of industrial catalysts, certain specific surface area and mechanical strength are required in order to improve the activity of the catalyst. However, the specific surface area and the mechanical strength are reduced while the macropores are increased, so that the physical pore-expanding agent is limited by other performance requirements of the catalyst when being used for pore expansion, and the physical pore-expanding agent cannot be taken into consideration.
CN103785396A and CN102861617A disclose a preparation method of a dual pore structure alumina carrier for heavy oil hydrodemetallization catalyst. The method comprises the following steps: weighing a certain amount of pseudo-boehmite dry glue powder, uniformly mixing the pseudo-boehmite dry glue powder with a proper amount of peptizer and extrusion aid, then adding a proper amount of ammonium bicarbonate aqueous solution into the materials, kneading the obtained materials into a plastic body, extruding the plastic body into strips for forming, placing the formed materials into a sealed container, carrying out hydrothermal treatment, and roasting to obtain the alumina carrier. The heavy oil hydrodemetallization catalyst is prepared by taking the alumina as a carrier and loading active metal components Mo and Ni by an impregnation method. Although the catalyst prepared by the technology has double-pore distribution, the pore diameter of a large-pore part is larger, so that the time for reaction molecules to stay in a pore channel is shorter, the utilization rate of a carrier is reduced, and the stability needs to be further improved.
CN106140183A discloses a preparation method of zirconium-containing hydrodemetallization catalyst, which comprises: respectively dipping the physical pore-expanding agent by using dipping liquid containing the hydrogenation active component and solution containing zirconium; mixing and kneading the impregnated physical pore-enlarging agent, pseudo-boehmite, a chemical pore-enlarging agent, an extrusion aid and a peptizing agent into a plastic body, extruding strips, drying and roasting to prepare a modified alumina carrier; the modified alumina carrier is impregnated by hydrogenation active component impregnating solution, and the zirconium-containing hydrogenation demetallization catalyst is prepared after drying and roasting. The activity and long-term running stability of the catalyst prepared by the method are still to be further improved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a residual oil hydrodemetallization catalyst and a preparation method thereof. The hydrodemetallization catalyst prepared by the method has proper pore size distribution and through pore channels, has higher specific surface area and proper mechanical strength, and has higher activity and activity stability when being used for a heavy oil hydrodemetallization catalyst.
The first aspect of the invention provides a preparation method of a residual oil hydrodemetallization catalyst, which comprises the following steps:
(1) dipping the dipping solution I containing the first active metal component into a physical pore-enlarging agent, and then drying to prepare a modified physical pore-enlarging agent;
(2) mixing and kneading the modified physical pore-expanding agent obtained in the step (1), pseudo-boehmite and a second active metal component source for molding, drying and roasting to obtain a modified alumina carrier SI;
(3) immersing the modified alumina carrier SI obtained in the step (2) into an ammonium bicarbonate solution, then carrying out sealing heat treatment, drying and roasting the heat-treated material to obtain a modified alumina carrier SII;
(4) and (3) dipping the modified alumina carrier SII obtained in the step (3) by using dipping solution II containing a third active component, and drying and roasting to obtain the hydrodemetallization catalyst.
In the method of the present invention, the active metal component can be an active metal component adopted in a conventional residue hydrotreating catalyst, and is generally a group VIB metal and/or a group VIII metal, the group VIB metal is generally selected from one or two of Mo and W, and the group VIII metal is generally selected from one or two of Co and Ni. Based on the weight of the hydrodemetallization catalyst, the total content of active metals is 2.3-28.0% calculated by metal oxides, preferably the content of VIB group metals is 2.0-20.0% calculated by metal oxides, and the content of VIII group metals is 0.3-8.0% calculated by metal oxides. The first active metal component, the second active metal component or the third active metal component may be the same active metal component or different active metal components. The first active metal component is preferably Mo and Ni, the second active metal component is preferably Mo and Ni, and the third active metal component is preferably Mo and Ni. The mass ratio of the first active metal component to the second active metal component to the third active metal component is 1.5-1: 3: 1-7.
In the method, the first active metal component in the step (1) is VIB group and/or VIII group metal, the impregnation liquid I containing the first active metal component is a solution containing the VIB group and/or VIII group metal, the VIB group metal is selected from one or more of W, Mo, and the VIII group metal is selected from one or more of Co and Ni. The impregnation liquid II containing the first active metal component can be one of an acid solution, an aqueous solution or an ammonia solution containing a hydrogenation active component. The following are preferred: the impregnation liquid I containing the first active metal component is a solution containing VIB group metals and VIII group metals, wherein the content of the VIB group metals is 2.0-4.0g/100mL calculated by metal oxides, and the content of the VIII group metals is 0.4-0.8g/100mL calculated by metal oxides. The impregnation may be carried out by a conventional impregnation method, and may be carried out by an unsaturated impregnation method, a saturated impregnation method, or the like, preferably a saturated impregnation method.
In the method, the physical pore-enlarging agent in the step (1) can be one or more of activated carbon and wood chips, and the particle size of the physical pore-enlarging agent is about 2-10 mu m, preferably about 3-8 mu m.
In the method of the present invention, the pseudoboehmite described in the step (2) may be a pseudoboehmite prepared by any method, for example, prepared by a precipitation method, an aluminum alkoxide hydrolysis method, an inorganic salt sol-gel method, a hydrothermal method, a vapor deposition method, and the like.
In the method, the mass ratio of the modified physical pore-expanding agent in the step (2) to the pseudo-boehmite is 1:10-1: 5. The kneading molding is carried out by adopting a conventional method in the field, and in the molding process, conventional molding aids, such as one or more of peptizing agents, extrusion aids and the like can be added according to the needs. The peptizing agent is one or more of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, oxalic acid and the like; the addition amount of the peptizing agent is 0.5 to 3 weight percent of the weight of the modified alumina carrier SI. The extrusion aid is sesbania powder; the addition amount of the extrusion aid is 0.1-0.5 wt% of the modified alumina carrier SI.
The roasting temperature in the step (2) is 550-650 ℃, and the roasting time is 4-6 hours; the calcination is carried out in an oxygen-containing atmosphere, preferably an air atmosphere. The modified alumina carrier SI may be in the shape of conventional alumina carrier, such as sphere, with particle size of 0.5-8.0mm, such as strip, clover, etc., with diameter of 0.2-3.0mm and length of 0.5-8.0 mm.
In the method of the present invention, the second active metal component in step (2) is a group VIB and/or group VIII metal-containing compound, and the source of the second active metal component is preferably a group VIB and/or group VIII metal-containing compound. The group VIB metal is preferably one or more of W, Mo; the group VIB metal source is preferably one or more of ammonium molybdate, ammonium paramolybdate, ammonium tungstate, ammonium metatungstate. The VIII group metal is preferably one or more of Co and Ni; the group VIII metal source is preferably one or more of nickel nitrate and cobalt nitrate. The following are preferred: the second active metal component source is a compound containing VIB group and VIII group metals, and the mass ratio of the addition amount of the VIB group metals to the addition amount of the VIII group metals is 1.3:1-3: 1.
In the method, the mass ratio of the using amount of the ammonium bicarbonate solution in the step (3) to the modified alumina SI added in the step (3) is 6:1-12:1, and the mass concentration of the ammonium bicarbonate solution is 15-25%.
In the method of the invention, the sealing heat treatment temperature in the step (3) is 120-.
In the method, the step (3) is preferably carried out before the sealing heat treatment, the sealing pretreatment is carried out, the pretreatment temperature is 60-100 ℃, the constant temperature treatment time is 2-4 hours, the temperature rise rate before the pretreatment is 10-20 ℃/min, the temperature rise rate after the pretreatment is 5-10 ℃/min, and the temperature rise rate after the pretreatment is at least 3 ℃/min lower than that before the pretreatment, preferably at least 5 ℃/min lower than that before the pretreatment.
In the method, the roasting temperature in the step (3) is 550-650 ℃, and the roasting time is 4-6 hours.
In the method, the third active metal component in the step (4) is a group VIB and/or group VIII metal, the impregnation liquid II containing the third active metal component is a solution containing the group VIB and/or group VIII metal, the group VIB metal is preferably one or more than one of W, Mo, and the group VIII metal is preferably one or more than one of Co and Ni. The impregnation liquid II containing the third active metal component can be one of an acid solution, an aqueous solution or an ammonia solution containing the hydrogenation active component. The following are preferred: the impregnation liquid II containing the third active metal component is a solution containing VIB group metals and VIII group metals, wherein the content of the VIB group metals is 4.5-15.0g/100ml calculated by metal oxides, and the content of the VIII group metals is 1.2-3.5g/100ml calculated by metal oxides. The roasting temperature in the step (4) is 450-550 ℃, and the roasting time is 4-6 hours. The impregnation may be carried out by a conventional impregnation method, and may be carried out by an unsaturated impregnation method, a saturated impregnation method, or the like, preferably a saturated impregnation method.
In the method, the roasting temperature in the step (4) is 450-550 ℃, and the roasting time is 4-6 hours.
In the method, the drying is generally carried out until the material has no obvious weight loss phenomenon, and the drying condition can be drying for 6-10 hours at 80-160 ℃. The same drying conditions may be used in the step (1), the step (2), the step (3) or the step (4), or different drying conditions may be used.
In a second aspect, the present invention provides a resid hydrodemetallization catalyst prepared by the process of the first aspect.
The hydrodemetallization catalyst comprises a main body part and rod-shaped parts, wherein the main body part is provided with micron-sized pore channels, and at least part of the rod-shaped parts are distributed on the outer surface of the main body part and in the micron-sized pore channels. The diameter D of the micron-sized pore channel in the main body part of the hydrodemetallization catalyst is 3-10 mu m, the length of the rod-shaped part is 1-12 mu m, and the diameter is 100-300 nm.
In the hydrodemetallization catalyst, the rod-shaped parts are basically distributed on the outer surface of the main body part and in the micron-sized pore channels. The rod-shaped parts distributed on the outer surface of the main body part and in the micron-sized pore channels account for more than 95 percent of the total weight of all the rod-shaped parts, and preferably more than 97 percent.
In the hydrodemetallization catalyst, the rod-shaped parts are basically distributed on the outer surface of the main body part and in the micron-sized pore channels. The length of the rod-shaped part in the micron-sized pore channels is mainly 0.3D-0.9D (which is 0.3-0.9 times of the diameter of the micron-sized pore channels), namely the length of more than 85 percent of the rod-shaped part in the micron-sized pore channels is 0.3D-0.9D by weight; the length of the outer surface rod-like parts is predominantly 3-8 μm, i.e. more than about 85% by weight of the rod-like parts on the outer surface have a length of 3-8 μm.
In the hydrogenation demetalization catalyst, rod-shaped parts are distributed in a disordered and mutually staggered state in micron-sized pore channels of a main body part. Wherein at least one end of the rod-like part in the micron-sized pore channel is bonded to the wall of the micron-sized pore channel and is integrated with the main body part.
The hydrodemetallization catalyst of the invention has rod-shaped parts which are distributed in a disordered and mutually staggered state on the outer surface of a main body part. Wherein one end of the rod-shaped alumina on the outer surface of the main body part is bonded to the outer surface of the main body part, and the other end thereof is extended outward to be integrated with the main body.
In the hydrodemetallization catalyst, the coverage rate of the rod-shaped part in the micron-sized pore channels of the main body part is 70-95%, wherein the coverage rate refers to the percentage of the surface of the inner surface of the micron-sized pore channels of the main body part, which is occupied by the rod-shaped part, in the inner surface of the micron-sized pore channels of the main body part. The rod portion covers 70% to 95% of the outer surface of the body portion, wherein the coverage is the percentage of the outer surface of the body portion that is occupied by the rod portion.
The hydrodemetallization catalyst of the invention has the following properties: the specific surface area is 150-300m2(iv)/g, pore volume of 0.8-2.0mL/g, crush strength of 10-20N/mm.
In the hydrodemetallization catalyst, the pores formed by the rod-shaped parts which are staggered with each other in a disordered way are concentrated at 100-800 nm.
The pores of the hydrodemetallization catalyst are distributed as follows: the pore volume occupied by the pores with the pore diameter of 15-35nm is 35% -50% of the total pore volume, and the pore volume occupied by the pores with the pore diameter of 100-800nm is 15% -30% of the total pore volume.
The residual oil hydrodemetallization catalyst is suitable for being used as a residual oil hydrodemetallization catalyst, and is particularly used for treating inferior residual oil with high metal and carbon residue values.
Compared with the prior art, the invention has the following advantages:
1. according to the modified alumina carrier SII, micron-scale pore channels of the modified alumina carrier SI are fully utilized, and the rod-shaped alumina is distributed in the micron-scale pore channels in a staggered mode in a random mode, so that on one hand, the penetrability of the micron-scale pore channels is maintained, the specific surface area of the carrier is improved, the mechanical strength is enhanced, on the other hand, the carrier plays a certain hole expanding role in the nanometer-scale pore channels in the alumina carrier during heat treatment in an ammonium bicarbonate solution, and the penetrability and the uniformity of the nanometer-scale pore channels are further promoted. Therefore, the catalyst of the invention overcomes the problem that the large aperture and the specific surface area and the mechanical strength are not compatible because of adopting a physical pore-expanding agent.
2. In the process of preparing the modified alumina carrier SII, the modified alumina carrier SII is pretreated at a certain temperature before sealing heat treatment, the pretreatment condition is relatively mild, and NH is slowly formed on the outer surface of the alumina carrier in a sealed and hydrothermal mixed atmosphere of carbon dioxide and ammonia gas4Al(OH)2CO3Crystal nuclei, raising the reaction temperature NH during the post-heat treatment4Al(OH)2CO3The crystal nucleus continues to grow evenly to make rod-shaped NH4Al(OH)2CO3Having uniform diameter and length while increasing rod-like NH4Al(OH)2CO3The coverage rate on the external surface of the SI of the modified alumina carrier and the internal surface of the micron-sized pore channel.
3. The active component is impregnated by the physical pore-enlarging agent, the content of active component metal in micron-sized pore channels of an alumina carrier is increased in advance, the active metal component in the micron-sized pore channels and alumina are grown together to form the active metal-alumina composite oxide with a rod-like structure in the heat treatment process, the activity of the reaction is greatly improved due to the increase of the content of the active metal at the micron-sized pore channels during the hydrodemetallization reaction, meanwhile, the through pore channels formed by the cross accumulation of the rod-like composite oxide are beneficial to the mass transfer and diffusion of macromolecular reactants in residual oil and the content of macropores, and the metal deposition resistance and the carbon deposition resistance of the catalyst are improved.
4. According to the invention, part of active metal components are added in advance when the modified alumina carrier SI is molded, the active metal components are loaded on the surface of the alumina carrier in an oxide form during roasting, and when the carrier is subjected to sealing heat treatment in an ammonium bicarbonate aqueous solution, the active metal is redispersed on the surface of the carrier, and the action of the active metal and the carrier is improved, so that the activity of the final catalyst is improved.
5. The hydrodemetallization catalyst has high hydrodemetallization activity and hydrodesulfurization activity when being used in residual oil hydrodemetallization reaction, and has good stability and the operation period of a device can be prolonged.
Drawings
FIG. 1 is an SEM image of a cut surface of a hydrodemetallization catalyst obtained in example 1;
wherein the reference numbers are as follows: 1-main body part, 2-rod-shaped part and 3-micron-sized pore channel.
Detailed Description
The following examples are provided to further illustrate the technical solutions of the present invention, but the present invention is not limited to the following examples. In the present invention, wt% is a mass fraction.
Application N2Physical adsorption-desorption characterization of the pore structures of the catalysts in the examples and the comparative examples, the specific operations are as follows: adopting ASAP-2420 type N2And the physical adsorption-desorption instrument is used for characterizing the pore structure of the sample. A small amount of samples are taken to be treated for 3 to 4 hours in vacuum at the temperature of 300 ℃, and finally, the product is placed under the condition of liquid nitrogen low temperature (-200 ℃) to be subjected to nitrogen absorption-desorption test. Wherein the specific surface area is obtained according to a BET equation, and the distribution rate of the pore volume and the pore diameter below 50nm is obtained according to a BJH model.
Mercury pressing method: the mercury porosimeter is used for representing the pore diameter distribution of the catalysts in the examples and the comparative examples, and the specific operation is as follows: and characterizing the distribution of sample holes by using an American microphone AutoPore9500 full-automatic mercury porosimeter. The samples were dried, weighed into an dilatometer, degassed for 30 minutes while maintaining the vacuum conditions given by the instrument, and filled with mercury. The dilatometer was then placed in the autoclave and vented. And then carrying out a voltage boosting and reducing test. The mercury contact angle is 130 degrees, and the mercury interfacial tension is 0.485N.cm-1The distribution ratio of pore diameter of 100nm or more is measured by mercury intrusion method.
The microstructure of the catalyst and the carrier is characterized by a scanning electron microscope, and the method specifically comprises the following operation: and characterizing the microstructure of the catalyst and the carrier by adopting a JSM-7500F scanning electron microscope, wherein the accelerating voltage is 5KV, the accelerating current is 20 muA, and the working distance is 8 mm.
Example 1
(1) Weighing 100 g of activated carbon particles with the particle size of 6 mu m, carrying out saturated impregnation by using an active component impregnation liquid I with the molybdenum oxide concentration of 3.30g/100ml and the nickel oxide concentration of 0.56g/100ml, and drying the impregnated material at 120 ℃ for 4 hours to obtain the modified physical pore-expanding agent.
(2) Weighing 200 g of pseudo-boehmite (self-made by an aluminum sulfate method), 23.5 g of modified physical pore-enlarging agent in the step (1), 0.4 g of sesbania powder, 1.9 g of ammonium heptamolybdate and 2.95 g of nickel nitrate hexahydrate, uniformly mixing the above materials physically, adding a proper amount of acetic acid aqueous solution with the mass concentration of 1.5%, kneading, extruding into strips, drying the formed product at 100 ℃ for 6 hours, and roasting the dried product at 600 ℃ for 5 hours in an air atmosphere to obtain the modified alumina carrier SI.
(3) Weighing 100 g of the modified alumina carrier SI in the step (2), placing the modified alumina carrier SI in 760 g of ammonium bicarbonate solution with the mass concentration of 21.5%, transferring the mixed material into a high-pressure kettle, sealing, heating to 100 ℃ at the speed of 15 ℃/min, keeping the temperature for 3 hours, heating to 135 ℃ at the speed of 10 ℃/min, keeping the temperature for 6 hours, drying the carrier at 100 ℃ for 6 hours, and roasting at 710 ℃ for 5 hours to obtain the modified alumina carrier SII-1.
(4) Weighing 50 g of the modified alumina carrier in the step (3), and adding 100mLMo-Ni-P solution (MoO in impregnating solution)3Concentration of 5.35g/100mL, NiO concentration of 2.35g/100 mL) for 2 hours, filtering out excessive solution, drying at 120 ℃ for 6 hours, and roasting at 500 ℃ for 5 hours to obtain the hydrodemetallization catalyst Cat1, wherein the content of molybdenum oxide and nickel oxide in the catalyst are 6.14wt% and 2.64wt%, respectively.
The properties of catalyst Cat1 are shown in table 1. In the catalyst Cat1, the length of the rod-shaped part in the micron-sized pore channel is mainly 2-5 μm, and the length of the rod-shaped part on the outer surface of the main body part is mainly 3-8 μm. The coverage of the rod-shaped parts in the micron-sized pore channels of the main body part is 89%, the coverage of the rod-shaped parts on the outer surface of the main body part is 92%, and the pores formed by the rod-shaped parts in a staggered mode in a random order are concentrated at 100-800 nm.
Example 2
The same as example 1, except that the particle size of the activated carbon in the step (1) is 5 microns, the concentration of molybdenum oxide in the active component impregnation solution I is 3.55g/100mL, and the concentration of nickel oxide is 0.45g/100 mL; the adding amount of the modified physical pore-expanding agent in the step (2) is 27 g, the adding amount of ammonium heptamolybdate is 1.76 g, and the adding amount of nickel nitrate hexahydrate is 2.82 g;the concentration of the ammonium bicarbonate solution in the step (3) is 17.5 percent, the adding amount of the solution is 1150 g, the sealing pretreatment temperature is 90 ℃, the treatment time is 2 hours, the heat treatment temperature is 145 ℃, the treatment time is 7 hours, and the MoO in the active component impregnating solution II in the step (4) of the modified alumina carrier SII-2 is prepared3The concentration is 4.7g/100mL, the NiO concentration is 2.75g/100mL, and the hydrodemetallization catalyst Cat2 is prepared, wherein the content of molybdenum oxide in the catalyst is 5.65wt%, and the content of nickel oxide in the catalyst is 2.93 wt%.
The properties of catalyst Cat2 are shown in table 1. In the catalyst Cat2, the length of the rod-shaped part in the micron-sized pore channel is mainly 2-4.5 μm, and the length of the rod-shaped part on the outer surface of the main body part is mainly 4-8 μm. The coverage rate of the rod-shaped parts in the micron-sized pore channels of the main body part is 90%, the coverage rate of the rod-shaped parts on the outer surface of the main body part is 92%, and the pores formed by the rod-shaped parts in a staggered mode in a random order are concentrated at 100-600 nm.
Example 3
The same as example 1, except that the particle size of the activated carbon in the step (1) is 9 microns, the concentration of molybdenum oxide in the active component impregnation solution I is 2.15g/100mL, and the concentration of nickel oxide is 0.71g/100 mL; the adding amount of the modified physical pore-expanding agent in the step (2) is 30.8 g, the adding amount of ammonium heptamolybdate is 2.24 g, and the adding amount of nickel nitrate hexahydrate is 2.41 g; and (3) the concentration of the ammonium bicarbonate solution in the step (3) is 16.5 percent, the adding amount of the solution is 980 g, the heat treatment temperature is 125 ℃, and the treatment time is 8 hours, so that the modified alumina carrier SII-3 is prepared. MoO in active component impregnating solution II in step (4)3The concentration is 4.95g/100mL, the NiO concentration is 3.15g/100mL, and the hydrodemetallization catalyst Cat3 is prepared, wherein the content of molybdenum oxide in the catalyst is 5.34wt%, and the content of nickel oxide in the catalyst is 3.24 wt%.
The properties of catalyst Cat3 are shown in table 1. In the catalyst Cat3, the length of the rod-shaped part in the micron-sized pore channel is mainly 3-7 μm, and the length of the rod-shaped alumina on the outer surface of the main body part is mainly 3-7 μm. The coverage of the rod-shaped parts in the micron-sized pore channels of the main body part is 87%, the coverage of the rod-shaped parts on the outer surface of the main body part is 90%, and the pores formed by the rod-shaped parts in a staggered mode in a random order are concentrated at 100-700 nm.
Example 4
The same as example 1, except that the particle size of the activated carbon in the step (1) is 3 microns, the concentration of molybdenum oxide in the active component impregnation solution I is 2.65g/100mL, and the concentration of nickel oxide is 0.64g/100 mL; the adding amount of the modified physical pore-expanding agent in the step (2) is 21.5 g, the adding amount of ammonium heptamolybdate is 1.64 g, and the adding amount of nickel nitrate hexahydrate is 3.53 g; and (3) the concentration of the ammonium bicarbonate solution in the step (3) is 23.5 percent, the adding amount of the solution is 660 grams, the heat treatment temperature is 155 ℃, and the treatment time is 5 hours, so that the modified alumina carrier SII-4 is prepared. MoO in active component impregnating solution II in step (4)3The concentration is 5.2g/100mL, the NiO concentration is 2.55g/100mL, and the hydrodemetallization catalyst Cat4 is prepared, wherein the content of molybdenum oxide in the catalyst is 5.41wt%, and the content of nickel oxide in the catalyst is 2.69 wt%.
The properties of catalyst Cat4 are shown in table 1. In the catalyst Cat4, the length of the rod-shaped part in the micron-sized pore channel is mainly 1-2.5 μm, and the length of the rod-shaped alumina on the outer surface of the main body part is mainly 4-8 μm. The coverage rate of the rod-shaped parts in the micron-sized pore channels of the main body part is 90 percent, the coverage rate of the rod-shaped parts on the outer surface of the main body part is 90 percent, and the pores formed by the rod-shaped parts in a staggered mode in a disordered mode are concentrated at 100-800 nm.
Comparative example 1
Comparative alumina carrier S-5 and comparative catalyst Cat5 were prepared as in example 1 except that in step (3), the alumina carrier was not heat-treated in an aqueous solution of ammonium bicarbonate but was heat-treated in distilled water, and the same mass of ammonium bicarbonate was added during the formation of the alumina carrier, and the properties of the catalyst are shown in Table 1, with a molybdenum oxide content of 6.16wt% and a nickel oxide content of 2.59 wt%.
The microstructures of the comparative catalyst Cat5 and the support S-5 were observed by scanning electron microscopy, in which only the main portion was observed in the catalyst and the support, and no rod-like portion was found in the micron-sized pores and on the outer surface.
Comparative example 2
Comparative alumina support S-6 and comparative catalyst Cat6 were prepared as in example 1 except that the ammonium bicarbonate in step (3) was changed to the same amount of ammonium carbonate, and the properties of the catalysts are shown in Table 1, with a molybdenum oxide content of 6.11wt% and a nickel oxide content of 2.57 wt%.
The microstructures of the comparative catalyst Cat6 and the support S-6 were observed by scanning electron microscopy, in which only the main portion was observed in the catalyst and the support, and no rod-like portion was found in the micron-sized pores and on the outer surface.
Comparative example 3
In the same manner as in example 1 except that the alumina carrier SI was not subjected to the heat treatment in an aqueous ammonium bicarbonate solution in the step (3), but directly subjected to the step (4), a comparative alumina carrier S-7 and a comparative catalyst Cat7 were obtained, and the properties of the catalysts are shown in Table 1, wherein the content of molybdenum oxide and the content of nickel oxide in the catalysts were 6.17wt% and 2.54 wt%. The microstructures of the comparative catalyst Cat7 and the support S-7 were observed by scanning electron microscopy, in which only the main portion was observed in the catalyst and the support, and no rod-like portion was found in the micron-sized pores and on the outer surface.
TABLE 1 Properties of the catalysts
|
Example 1
|
Example 2
|
Example 3
|
Example 4
|
Comparative example 1
|
Comparative example 2
|
Comparative example 3
|
Numbering
|
Cat1
|
Cat2
|
Cat3
|
Cat4
|
Cat5
|
Cat6
|
Cat7
|
Specific surface area, m2/g
|
213
|
196
|
189
|
204
|
181
|
167
|
203
|
Pore volume, mL/g
|
0.93
|
0.91
|
0.89
|
0.92
|
0.84
|
0.79
|
0.83
|
Pore distribution:, v%
|
|
|
|
|
|
|
|
15-35nm
|
41
|
42
|
45
|
36
|
24
|
21
|
19
|
100-800nm
|
26
|
24
|
22
|
27
|
12
|
9
|
11
|
Over 3 mu m
|
-
|
-
|
-
|
-
|
12
|
14
|
14
|
Crush strength, N/mm
|
10.7
|
10.1
|
11.0
|
10.4
|
8.4
|
8.8
|
8.5 |
Note: pore distribution refers to the percentage of the pore volume of pores within a certain diameter range in the support to the total pore volume.
Example 5
The following examples illustrate the catalytic performance of the hydrodemetallization catalyst Cat1-Cat 7.
Raw oil listed in Table 2 is used as a raw material, catalytic performances of Cat1-Cat7 are respectively evaluated on a fixed bed residual oil hydrogenation reaction device, the catalyst is a strip with the length of 2-3 mm, the reaction temperature is 375 ℃, the hydrogen partial pressure is 13MPa, and the liquid hourly volume space velocity is 1.0 hour-1The volume ratio of hydrogen to oil was 1000, the content of each impurity in the produced oil was measured after 2000 hours of reaction, the impurity removal rate was calculated, and the evaluation results are shown in table 3.
TABLE 2 Properties of the feed oils
Item
|
|
Density (20 ℃ C.), g/cm3 |
1.02
|
S,wt%
|
1.46
|
N,wt%
|
0.48
|
Ni,µg/g
|
92.4
|
V,µg/g
|
53.7
|
CCR,wt%
|
14.7 |
TABLE 3 comparison of catalyst hydrogenation performance
Catalyst numbering
|
Cat1
| Cat | 2
|
Cat3
|
Cat4
|
Cat5
|
Cat6
|
Cat7
|
Ni + V removal rate wt%
|
65.4
|
66.2
|
63.7
|
62.5
|
43.7
|
42.8
|
41.6
|
Desulfurization degree, wt%
|
51.4
|
50.7
|
51.6
|
49.7
|
34.5
|
33.1
|
32.7 |
As can be seen from the data in Table 3, the catalyst prepared by the method of the present invention has higher hydrodemetallization activity and activity stability compared with the comparative catalyst.