Heavy oil and residual oil hydrodemetallization catalyst and preparation method thereof

Abstract

The present invention discloses a heavy oil and residual oil hydrodemetallization catalyst and a preparation method thereof. The catalyst comprises an inner catalyst layer and an outer carbon membrane layer coated on the surface of the inner catalyst layer. The inner catalyst layer comprises a first alumina layer loaded with a first active component and a second alumina layer loaded with a second active component. The outer carbon membrane layer has a thickness of 40 to 120 μm, and the ratio of tetrahedral molybdenum to octahedral molybdenum in the catalyst, calculated as Mo atoms, is 0.18 to 0.58. The catalyst provided by the present invention has a high utilization rate of active metals in the inner layer and excellent resistance to carbon deposition. When used in heavy oil and residual oil hydrodemetallization reactions, it exhibits high demetallization activity and metal-tolerant capacity, ensuring stable catalyst activity during long-term operation.

Description

Technical Field

[0001] The present invention relates to a hydrodemetallization catalyst, in particular to a hydrodemetallization catalyst suitable for heavy oil and residual oil hydrotreating processes and a preparation method thereof. Background Art

[0002] In recent years, crude oil has become increasingly heavier and inferior in quality, while market demand for lighter oil products continues to rise. This has led to new challenges for hydrogenation technology, a key route for processing heavy oil. As the core of hydrogenation technology, catalyst preparation and performance are crucial for deep hydrogenation of heavy oil. Specifically, the hydrodemetallization reaction is a key chemical reaction occurring during residue hydroprocessing. In the presence of a catalyst, various metal compounds react with H2S to form metal sulfides, which are then deposited on the catalyst for removal. The presence of active metals on the catalyst support plays a crucial role in the catalyst's activity and stability.

[0003] CN102441399A discloses a method for preparing a hydrodemetallization catalyst, comprising preparing a Group VIB metal compound and / or a Group VIII metal compound into an ammonia solution or aqueous solution, which is then impregnated into an alumina support, dried, and calcined to produce the final catalyst. CN1289640A discloses a method for preparing a supported hydrodemetallization catalyst, which utilizes a macroporous alumina support and sprays an ammonia solution or aqueous solution of the active metal onto the support in a spray drum. This method omits the normal temperature drying process of the support after impregnation, and the sprayed support is directly placed in a calcination furnace at a temperature of 300-450°C for calcination, then gradually raised to 460-550°C and maintained at this temperature in air for 1-5 hours. CN103785400A discloses a method for preparing a highly active residue oil hydrodemetallization catalyst, comprising impregnating an alumina carrier with a polyol and / or monosaccharide aqueous solution, hydrothermally carbonizing the carrier in a sealed container, and then loading the carrier with active metal components Mo and Ni. Finally, the alumina loaded with the active components is first calcined under a nitrogen atmosphere and then calcined under an air atmosphere to produce the residue oil hydrodemetallization catalyst. CN111375419A discloses a hydrogenation catalyst and a method for preparing the same, comprising dissolving an iron-containing inorganic salt and ammonium citrate in water to produce a solution; sphericalizing the small-pore alumina and simultaneously adding the solution obtained in the first step to produce alumina; placing the alumina in a ball rolling machine, and uniformly adding the large-pore alumina and the solution obtained in the first step during rolling to produce alumina again; drying the alumina to obtain the final alumina, and then loading the active metal components to produce the catalyst.

[0004] The activity and stability of the hydrodemetallization catalyst prepared by the above method still need to be further improved. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention provides a heavy oil and residual oil hydrodemetallization catalyst and its preparation method. When used in heavy oil and residual oil hydrodemetallization reactions, the catalyst not only exhibits high demetallization activity but also ensures catalyst stability during long-term operation.

[0006] The first aspect of the present invention provides a heavy and residual oil hydrodemetallization catalyst, comprising a catalyst inner layer and a carbon membrane outer layer coated on the surface of the catalyst inner layer, wherein the catalyst inner layer comprises a first alumina layer loaded with a first active component and a second alumina layer loaded with a second active component, the thickness of the carbon membrane outer layer is 40 to 120 μm, preferably 60 to 90 μm, and the ratio of the content of tetrahedral molybdenum to octahedral molybdenum in the catalyst, calculated as Mo atoms, is 0.18 to 0.58.

[0007] In the present invention, the heavy oil and residual oil hydrodemetallization catalyst is in the form of spherical particles.

[0008] In the present invention, the pore volume of the outer layer of the carbon membrane is between 0.80 and 1.50 cm 3 / g, preferably 1.0 to 1.4 cm 3 / g, and the average pore diameter is 35 to 85 nm, preferably 50 to 75 nm.

[0009] In the present invention, the diameter ratio of the second aluminum oxide layer to the first aluminum oxide layer is 2 to 12, preferably 2 to 8, and the diameter of the first aluminum oxide layer is 0.2 to 1.0 mm, preferably 0.4 to 0.8 mm.

[0010] In the present invention, the pore size of the first aluminum oxide layer is 8 to 16 nm, the pore size of the second aluminum oxide layer is 18 to 30 nm, and the ratio of the pore size of the second aluminum oxide layer to the pore size of the first aluminum oxide layer is 1.4 to 2.5.

[0011] In the present invention, the first active component includes molybdenum and a Group VIII metal, and the second active component includes molybdenum and a Group VIII metal; the Group VIII metal in the first active component is preferably nickel, and the Group VIII metal in the second active component is preferably nickel.

[0012] In the present invention, based on the mass of the catalyst, the content of MoO3 is 6.5% to 26.0%, and the content of the Group VIII metal oxide is 2.5% to 12.5%.

[0013] In the present invention, based on the total mass of MoO3 in the catalyst, the content of MoO3 in the first active component is 25.0% to 55.0%, and the content of MoO3 in the second active component is 45.0% to 75.0%.

[0014] In the present invention, based on the total mass of Group VIII metal oxides in the catalyst, the content of Group VIII metal oxides in the first active component is 25.0% to 55.0%, and the content of Group VIII metal oxides in the second active component is 45.0% to 75.0%.

[0015] In the present invention, the specific surface area of ​​the catalyst is 135 to 185 m 2 / g, and a pore volume of 0.45 to 0.85 mL / g; preferably, the specific surface area of ​​the catalyst is 160 to 180 m 2 / g, and the pore volume is 0.70~0.85mL / g.

[0016] In the present invention, the catalyst further comprises an auxiliary component, which is selected from at least one of fluorine, phosphorus, silicon or boron, preferably phosphorus. The content of the auxiliary component as oxide is 1.5% to 6.5% based on the mass of the catalyst.

[0017] The second aspect of the present invention provides a method for preparing the above-mentioned heavy oil and residual oil hydrodemetallization catalyst, comprising the following steps:

[0018] (1) neutralizing an acidic aluminum salt solution with an alkaline aluminum salt solution and subjecting the solution to primary aging to obtain a slurry;

[0019] (2) the slurry obtained in step (1) is divided equally into slurry I and slurry II, a water-soluble polymer J1 is added to slurry II, slurry I and slurry II are subjected to secondary aging and drying, respectively, to obtain dried products I and dried products II;

[0020] (3) preparing the dried product II obtained in step (2) into a pseudo-boehmite mixed solution II and adjusting its pH value, sealing the solution, and obtaining a mixed solution III;

[0021] (4) adding the dried product I obtained in step (2) and the mixed solution III obtained in step (3) to a rolling ball machine at a certain rate, and simultaneously spraying the first impregnation solution containing the first active component at a uniform rate to obtain an inner layer of alumina loaded with the first active component;

[0022] (5) adjusting the relative dripping rate of the mixed solution III, and simultaneously spraying the mixed solution containing the second active component at a uniform speed, followed by drying and calcining to obtain the inner layer of the catalyst;

[0023] (6) Soaking the inner layer of the catalyst obtained in step (5) in a carbohydrate aqueous solution, drying, and then carbonizing to obtain the heavy oil and residual oil hydrodemetallization catalyst.

[0024] In step (1) of the present invention, the acidic aluminum salt solution and the alkaline aluminum salt solution are added to the reactor in a parallel flow.

[0025] In step (1) of the present invention, the acidic aluminum salt solution is one or more of aluminum sulfate solution, aluminum nitrate solution, or aluminum chloride solution; the concentration of the acidic aluminum salt solution is 5 g / 100 mL to 30 g / 100 mL as calculated on the basis of Al2O3. The alkaline aluminum salt solution is one or more of sodium metaaluminate solution and potassium metaaluminate solution; the concentration of the alkaline aluminum salt solution is 8 g / 100 mL to 58 g / 100 mL as calculated on the basis of Al2O3.

[0026] In step (1) of the present invention, the neutralization reaction temperature is 80 to 130° C., the time is 30 to 150 minutes, and the pH value of the slurry is controlled to be 6.0 to 9.5 during the neutralization reaction. The pH value of the slurry is adjusted by controlling the addition rate of the acidic aluminum salt solution and the alkaline aluminum salt solution or by additionally adding an acid-base regulator during the neutralization reaction.

[0027] In step (1) of the present invention, the temperature of the primary aging is 100-230° C., the time is 60-220 minutes, and the pH value is 9.0-12.0.

[0028] In step (1) of the present invention, after the primary aging is completed, preferably, the slurry is concentrated first and then subjected to secondary aging, wherein the volume of the concentrated slurry is 40% to 70% of the original volume.

[0029] In step (2) of the present invention, the water-soluble polymer J1 is one or more of polyethylene glycol, polyvinyl alcohol, polyacrylamide and methyl cellulose, preferably polyethylene glycol; the viscosity (20°C) of the water-soluble polymer J1 is 10 to 1000 mPa·s, and the viscosity (20°C) of the slurry after adding the water-soluble polymer J1 is 150 to 650 mPa·s.

[0030] In step (2) of the present invention, the secondary aging temperature is 120-260° C., the time is 40-200 minutes, and the secondary aging temperature is 30-60° C. higher than the primary aging temperature.

[0031] In step (2) of the present invention, the drying temperature after secondary aging is 120-180°C for 2-10 hours. Filtration and washing can be performed according to conventional methods before drying. The dry matter content of the dried product I and the dried product II obtained after drying is 40-70 wt%.

[0032] In step (3) of the present invention, the solid content of the obtained mixed solution III is 15% to 40%, the pH value ranges from 6.0 to 8.0, and the adjustment method is solvent adjustment. The solvent can be one or more of phosphoric acid, nitric acid, oxalic acid, citric acid, and tartaric acid. The sealing treatment time is 6 to 10 hours.

[0033] In step (4) of the present invention, the rotation speed of the ball rolling machine is 30-50 r / min. After the first ball forming is completed, the diameter of the obtained small balls is 0.4-0.8 mm.

[0034] In step (4) of the present invention, the ratio of the addition rate of the dried product I to the mixed solution III is 0.60 to 0.95 g / ml.

[0035] In step (4) of the present invention, the amount of the first impregnation liquid used accounts for 15% to 45% of the saturated water absorption of the dried material I. The first impregnation liquid is an impregnation liquid containing Mo and a Group VIII metal (preferably Ni), wherein the active metal component molybdenum is derived from one or both of molybdenum oxide and ammonium heptamolybdate, and the nickel is derived from one or both of basic nickel carbonate and nickel nitrate. The contents of MoO3 and the Group VIII metal oxide in the first impregnation liquid are 32.0 to 72.0 g / 100 ml and 5.0 to 25.0 g / 100 ml, respectively. The amount of MoO3 introduced into the catalyst by the first impregnation liquid is 25% to 55% of the total MoO3 loading in the catalyst; and the amount of the Group VIII metal oxide introduced into the catalyst by the first impregnation liquid is 25% to 55% of the total Group VIII metal oxide loading in the catalyst.

[0036] In step (4) of the present invention, at least one auxiliary agent containing fluorine, phosphorus, silicon or boron may be introduced into the first impregnation solution, and the amount of the auxiliary agent (calculated as oxide) added is 15% to 30% of the total mass of molybdenum oxide in the first impregnation solution, preferably 18% to 26%.

[0037] In step (4) of the present invention, the first impregnation liquid preferably further contains a water-soluble polymer J2. The water-soluble polymer J2 is one or more of polyethylene glycol, polyvinyl alcohol, polyacrylamide, and methylcellulose. The viscosity of the water-soluble polymer J2 (at 20°C) is 10 to 1000 mPa·s. After the addition of the water-soluble polymer J2, the slurry viscosity (at 20°C) is 150 to 650 mPa·s.

[0038] In step (4) of the present invention, the dropping rate ratio of the first impregnation liquid to the dried material I is 0.18-0.42 ml / g, and the dropping time is based on the ball formation time.

[0039] In step (5) of the present invention, the ratio of the addition rate of the dried material I to the mixed solution III is 0.40 to 0.58 g / ml. The second impregnation solution is an impregnation solution containing Mo and a Group VIII metal (preferably Ni), wherein the active metal component molybdenum is derived from one or both of molybdenum oxide and ammonium heptamolybdate, and the nickel is derived from one or both of basic nickel carbonate and nickel nitrate. The amount of MoO3 introduced into the catalyst by the second impregnation solution is 45% to 75% of the total MoO3 loading in the catalyst; and the amount of Group VIII metal oxide introduced into the catalyst by the second impregnation solution is 45% to 75% of the total Group VIII metal oxide loading in the catalyst.

[0040] In step (5) of the present invention, the second impregnation liquid preferably further contains a water-soluble polymer J3. The water-soluble polymer J3 is one or more of polyethylene glycol, polyvinyl alcohol, polyacrylamide, and methylcellulose. The viscosity of the water-soluble polymer J3 (at 20°C) is 10 to 1000 mPa·s. After the addition of the water-soluble polymer J3, the slurry viscosity (at 20°C) is 150 to 650 mPa·s.

[0041] In step (5) of the present invention, the dripping rate ratio of the second impregnation liquid to the dried material I is 1.08-1.25 ml / g, and the dripping time is based on the final sphere size.

[0042] In step (5) of the present invention, the drying temperature is 120-200° C., and the drying time is 2-12 hours.

[0043] In step (5) of the present invention, the calcination is performed by programmed temperature increase. The heating rate is 1°C / min to 3°C / min, the calcination temperature is 450°C to 750°C, the calcination time is 3 to 8 hours, and the calcination atmosphere is one or more of nitrogen, water vapor or air, preferably air.

[0044] In step (6) of the present invention, the carbohydrate solution is preferably an aqueous solution of starch and / or monosaccharides, and the mass percentage of starch and / or monosaccharides in the solution is 20.0% to 30.0%; the monosaccharides include one or more of glucose, ribose, fructose, maltose, etc.

[0045] In step (6) of the present invention, ammonium bicarbonate is added to the carbohydrate solution as a pore-enlarging agent, the mass percentage of ammonium bicarbonate in the carbohydrate solution is 18.0% to 35.0%, and the soaking time is 0.5 min to 10 min, preferably 1.5 min to 5 min.

[0046] In step (6) of the present invention, the carbonization conditions are: pre-oxidation for 4 to 20 hours, preferably 3 to 16 hours, in an air atmosphere at a temperature of 160 to 340°C, preferably 180 to 320°C; then carbonization for 2 to 10 hours in a nitrogen atmosphere at a temperature of 400 to 700°C, preferably 450 to 650°C. After carbonization, the carbon film outer layer can be formed on the surface of the inner layer of the catalyst to obtain the hydrodemetallization catalyst.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] For active metals on hydrodemetallization catalysts, the reduction temperature of tetrahedral Mo species is higher than that of octahedral Mo species. The presence of tetrahedral Mo adversely weakens the interaction between the support and the metal, thereby affecting the catalyst's activity and stability. After extensive research, the inventors discovered that by optimizing the support preparation, the slurry obtained after the neutralization reaction is subjected to a two-stage aging process. Before the second aging, the slurry is either not added or added with a water-soluble polymer, and the second aging is performed at a higher temperature. This yields porous materials with suitable specific surface areas and different pore size distributions, namely, dried materials I and dried materials II. Dried material II is then prepared into pseudo-boehmite mixed solution II. After pH adjustment and sealing for a period of time, mixed solution III is obtained. Dried material I and mixed solution III are then rolled into balls at a specific addition rate. During the balling process, the first impregnation solution is sprayed into the balls at a uniform dripping rate. After the balls have grown to a certain size, the relative dripping rates of mixed solution III are adjusted, while the second impregnation solution is sprayed at a constant rate. The catalyst inner layer is then dried and calcined to obtain the resultant. The inner layer of the catalyst is then soaked in a carbohydrate aqueous solution, dried, and carbonized to produce the hydrodemetallization catalyst. Through these various treatments, the inner layer of the resulting catalyst is coated with an outer carbon membrane layer. This allows coke generated by thermal cracking of the residual oil to be deposited first within the outer carbon membrane layer, thereby increasing the utilization of the active metal in the inner layer and improving the catalyst's resistance to carbon deposition. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a Raman spectrum of the catalyst surface obtained in Example 2;

[0050] Figure 2 This is a Raman spectrum of the catalyst surface obtained in Example 4;

[0051] Figure 3 This is a Raman spectrum of the catalyst surface obtained in Comparative Example 1;

[0052] Figure 4 This is the Raman spectrum of the catalyst surface obtained in Comparative Example 2. DETAILED DESCRIPTION

[0053] In the present invention, the Raman spectroscopic characterization of the catalyst was performed using a DXR Microscope type DXR micro Raman spectrometer from Thermo Scientific. -1 The peak near it is the peak of tetrahedral molybdenum, at 960 cm -1 The nearby peak is the peak of octahedral molybdenum. The contents of tetrahedral molybdenum and octahedral molybdenum are calculated based on the area under the same baseline.

[0054] In the present invention, the pore structure (SVD) and specific surface area of ​​the catalyst were characterized using a Michael ASAP-2420 physical adsorption instrument. The pore volume and pore diameter of the outer layer of the carbon membrane involved were obtained by mercury intrusion testing.

[0055] The technical solutions and effects of the present invention are further described below with reference to the following embodiments, but are not limited to the following embodiments.

[0056] Example 1

[0057] 1.5L of aluminum sulfate aqueous solution (the concentration of Al2O3 is 10.0g / 100mL, the initial temperature is 75℃) is passed from the top into a reactor equipped with 5L of pure water, a stirrer and a heating jacket, and 1L of sodium metaaluminate aqueous solution (the concentration of Al2O3 is 28.0g / 100mL, the initial temperature is 110℃) is passed from the bottom of the reactor into the reactor, and the neutralization reaction temperature is controlled at 105℃; aluminum sulfate solution and sodium metaaluminate solution are added continuously, and the pH value is controlled to 8.5, and the reaction is carried out for 60 minutes; after the parallel flow is completed, an aging is carried out at an aging temperature of 150℃ , aging time is 120 minutes, aging pH value is 9.3; after the completion of the primary aging, the slurry volume is concentrated to 5L, and then evenly divided into two parts, namely slurry I and slurry II, 25g of polyvinyl alcohol (viscosity is 30mPa·s) is added to slurry II, and the slurry viscosity (20°C) after the addition of polyvinyl alcohol is 260mPa·s, while slurry I is not treated in any way. Then, both slurry I and slurry II are heated to 180°C and subjected to secondary aging for 120 minutes, and then washed and dried to obtain dried products I and dried products II with a dry basis of 50wt% respectively;

[0058] Dried material II was mixed with deionized water at a solids content of 16.7% to obtain mixed solution II. The pH was adjusted to 6.5 and sealed for 6 hours to obtain mixed solution III. 800g of dried material I and 960ml of mixed solution III were added to a ball rolling machine at addition rates of 13.3g / min and 16.0ml / min, respectively. Simultaneously, the first impregnation solution was sprayed into the machine at a drip rate of 4.0ml / min. Among them, the MoO3 content in the first impregnation liquid is 22.9g / 100ml, the NiO content is 3.8g / 100ml, the amount of P (calculated as oxide) in the auxiliary phosphoric acid added is 24.4% of the total mass of molybdenum oxide in the impregnation liquid (the amount of the first impregnation liquid used is 25% of the saturated water absorption capacity of the dry matter I), and polyacrylamide (viscosity of 950mPa·s) is added to the first impregnation liquid, and the viscosity after addition is 600mPa·s. Among them, the amount of MoO3 introduced into the catalyst by the first impregnation liquid is 42% of the total MoO3 loading in the catalyst; the amount of NiO introduced into the catalyst by the first impregnation liquid is 42% of the total NiO loading in the catalyst, and the spraying time is controlled within 60min.

[0059] The addition rate of the adjusted dried material I was maintained unchanged, and the dripping rate of the mixed solution III was changed to 24.0 ml / min. At the same time, the second impregnating solution was sprayed therein at a rate of 15.7 ml / min, and polyacrylamide (viscosity of 950 mPa·s) was added to the second impregnating solution, and the viscosity after addition was 400 mPa·s. The amount of MoO3 introduced into the catalyst by the second impregnating solution was 58% of the total MoO3 loading in the catalyst; the amount of NiO introduced into the catalyst by the second impregnating solution was 58% of the total NiO loading in the catalyst, the spraying time was controlled within 60 min, and then dried at 120° C. for 6 h and calcined at 750° C. for 3 h, wherein the heating rate during the calcination process was 3° C. / min, to obtain the inner layer of the catalyst;

[0060] The inner layer of the catalyst was soaked in an aqueous solution of 34.0% by mass of ammonium bicarbonate and 25.0% by mass of starch for 145 seconds, then taken out and pre-oxidized at 260°C in an air atmosphere for 4 hours, and then carbonized at 450°C in a nitrogen atmosphere for 3 hours to obtain a hydrodemetallization catalyst CAT-1.

[0061] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst CAT-1 is 0.19. The thickness of the outer layer of the carbon membrane is 87 μm and the pore volume is 1.27 cm 3 / g, and an average pore diameter of 75nm. Other physical and chemical properties of the catalyst are shown in Table 1.

[0062] Example 2

[0063] The difference from Example 1 is that the initial temperature of the sodium metaaluminate aqueous solution added is 100°C, 50 g of polyvinyl alcohol (viscosity 30 mPa·s) is added to the slurry II after the first aging, and the slurry viscosity (20°C) after the addition of polyvinyl alcohol is 280 mPa·s;

[0064] The dried material II was mixed with deionized water at a solid content of 18.2% to obtain a mixed solution II, which was then adjusted to a pH of 7.0 and sealed for 7 hours to obtain a mixed solution III. 800 g of the dried material I and 1040 ml of the mixed solution III were added to a rolling ball machine at addition rates of 13.3 g / min and 17.3 ml / min, respectively. Simultaneously, the first impregnation solution (same as in Example 1) was sprayed therein at a drip rate of 4.0 ml / min. The first impregnation solution contained 24.5 g / 100 ml of MoO3 and 4.1 g / 100 ml of NiO. The amount of phosphoric acid (calculated as oxide) added was 24.4% of the total mass of molybdenum oxide in the impregnation solution. The amount of MoO3 introduced into the catalyst by the first impregnation solution was 45% of the total MoO3 loading on the catalyst. The amount of NiO introduced into the catalyst by the first impregnation solution was 45% of the total NiO loading on the catalyst. The addition rate of the adjusted dried material I was maintained constant, and the dripping rate of the mixed solution III was changed to 26.0 ml / min. At the same time, the second impregnation solution (same as in Example 1) was sprayed at a rate of 15.7 ml / min. During the calcination process, the temperature was raised to 700°C at a rate of 3°C / min and calcined for 4 hours to obtain the inner layer of the catalyst.

[0065] The inner layer of the catalyst was soaked in an aqueous solution with a mass percentage of 29.0% ammonium bicarbonate and a mass percentage of 23.0% starch for 130 seconds, then taken out and pre-oxidized at 240°C in an air atmosphere for 5 hours, and then carbonized at 500°C in a nitrogen atmosphere for 5 hours to obtain a hydrodemetallization catalyst CAT-2.

[0066] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst CAT-2 is 0.26. The thickness of the outer layer of the carbon membrane is 78 μm and the pore volume is 1.26 cm 3 / g, and an average pore diameter of 69nm. Other physical and chemical properties of the catalyst are shown in Table 1.

[0067] Example 3

[0068] The difference from Example 1 is that the dried material II is mixed with deionized water at a solid content of 20.0% to obtain a mixed solution II, and the pH value is adjusted to 7.5. The mixture is sealed for 8 hours to obtain a mixed solution III. During the ball forming process, 800g of the dried material I and 1120ml of the mixed solution III are added to the ball rolling machine at addition rates of 13.3g / min and 18.7ml / min, respectively. Simultaneously, the first impregnation solution (same as in Example 1) is sprayed therein at a dropwise rate of 4.0ml / min. The content of MoO3 in the first impregnation solution is 26.1g / 100ml, the content of NiO is 4.3g / 100ml, the amount of P (calculated as oxide) in the auxiliary phosphoric acid is 24.4% of the total mass of molybdenum oxide in the impregnation solution, the amount of MoO3 introduced into the catalyst by the first impregnation solution is 48% of the total MoO3 loading on the catalyst, and the amount of NiO introduced into the catalyst by the first impregnation solution is 48% of the total NiO loading on the catalyst. The droplet rate of the mixed solution III was adjusted to 28.0 ml / min, and the second impregnation solution (same as in Example 1) was sprayed into the mixed solution at a rate of 15.7 ml / min. During the calcination process, the temperature was raised to 650°C at a rate of 3°C / min and calcined for 5 hours to obtain the inner layer of the catalyst.

[0069] The inner layer of the catalyst was soaked in an aqueous solution with a mass percentage of 24.0% ammonium bicarbonate and a mass percentage of 21.0% glucose for 115 seconds, then taken out and pre-oxidized at 220°C in an air atmosphere for 6 hours, and then carbonized at 550°C in a nitrogen atmosphere for 7 hours to obtain a hydrodemetallization catalyst CAT-3.

[0070] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst CAT-3 is 0.41. The thickness of the outer layer of the carbon membrane is 69 μm and the pore volume is 1.26 cm 3 / g, and an average pore diameter of 67nm. Other physical and chemical properties of the catalyst are shown in Table 1.

[0071] Example 4

[0072] Compared with Example 1, the difference is that the dried material II is mixed with deionized water at a solid content of 22.2% to obtain a mixed solution II, and the pH value is adjusted to 8.0. The mixture is sealed for 9 hours to obtain a mixed solution III. During the ball forming process, 800g of the dried material I and 1200ml of the mixed solution II are added to the ball rolling machine at addition rates of 13.3g / min and 20.0ml / min, respectively. At the same time, the first impregnation liquid (same as in Example 1) is sprayed therein at a drop rate of 4.0ml / min. The content of MoO3 in the first impregnation liquid is 27.8g / 100ml, the content of NiO is 4.6g / 100ml, the amount of P (calculated as oxide) in the auxiliary phosphoric acid is 24.4% of the total mass of molybdenum oxide in the impregnation liquid, the amount of MoO3 introduced into the catalyst by the first impregnation liquid is 51% of the total MoO3 loading on the catalyst, and the amount of NiO introduced into the catalyst by the first impregnation liquid is 51% of the total NiO loading on the catalyst. The droplet rate of the mixed solution III was adjusted to 30.0 ml / min, and the second impregnation solution (same as in Example 1) was sprayed into the mixed solution at a rate of 15.7 ml / min. During the calcination process, the temperature was raised to 600°C at a rate of 3°C / min and calcined for 6 hours to obtain the inner layer of the catalyst;

[0073] The inner layer of the catalyst was soaked in an aqueous solution with a mass percentage of 19.0% ammonium bicarbonate and a mass percentage of 19.0% glucose for 100 seconds and then taken out. It was pre-oxidized at 200°C in an air atmosphere for 7 hours, and then carbonized at 600°C in a nitrogen atmosphere for 9 hours to obtain a hydrodemetallization catalyst CAT-4.

[0074] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst CAT-4 is 0.57. The thickness of the outer layer of the carbon membrane is 63 μm and the pore volume is 1.16 cm 3 / g, and an average pore diameter of 57nm. Other physical and chemical properties of the catalyst are shown in Table 1.

[0075] Comparative Example 1

[0076] The only difference compared to Example 1 is that the slurry obtained after the primary aging is directly heated and then subjected to a secondary aging to obtain a dried product I; the dried product II is replaced with an equal amount of dried product I for the subsequent pelletization process; and the subsequent carbon membrane outer layer coating process is the same as in Example 1. Thus, a hydrodemetallization catalyst dCAT-1 is obtained.

[0077] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst dCAT-1 is 1.25. The thickness of the outer layer of the carbon membrane is 82 μm and the pore volume is 1.08 cm 3 / g, and an average pore diameter of 54nm. Other physical and chemical properties of the catalyst are shown in Table 1.

[0078] Comparative Example 2

[0079] The only difference from Example 1 is that during the pelletizing process, the second impregnation liquid is added first, and then the first impregnation liquid is added (the addition rates are the same as in Example 1). Hydrodemetallization catalyst dCAT-2 is obtained.

[0080] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst dCAT-2 is 1.43. The thickness of the outer layer of the carbon membrane is 79 μm and the pore volume is 1.12 cm 3 / g, and an average pore diameter of 58nm. Other physical and chemical properties of the catalyst are shown in Table 1.

[0081] Comparative Example 3

[0082] The only difference from Example 1 is that the first and second impregnation solutions are not added during the pelletization process, but the active metal loading process is carried out by saturation impregnation after pelletization is completed, thereby obtaining the hydrodemetallization catalyst dCAT-3.

[0083] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst dCAT-3 is 2.54. The thickness of the outer layer of the carbon membrane is 83 μm and the pore volume is 1.02 cm 3 / g, and an average pore diameter of 52nm. Other physical and chemical properties of the catalyst are shown in Table 1.

[0084] Comparative Example 4

[0085] The only difference compared to Example 1 was that throughout the ball-forming process, the dried material I and the mixed solution III were added to the ball-forming machine at rates of 13.3 g / min and 16.0 ml / min, respectively. All calcinations were performed at a heating rate of 3°C / min to 550°C for 3 hours. This produced the hydrodemetallization catalyst dCAT-4.

[0086] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst dCAT-4 is 3.21. The thickness of the outer layer of the carbon membrane is 81 μm and the pore volume is 1.03 cm 3 / g, and an average pore diameter of 51nm. Other physical and chemical properties of the catalyst are shown in Table 1.

[0087] Comparative Example 5

[0088] Compared with Example 1, the only difference is that the inner layer of the catalyst is not coated with an outer layer of a carbon membrane, and the hydrodemetallization catalyst dCAT-5 is obtained.

[0089] The ratio of tetrahedral molybdenum to octahedral molybdenum in catalyst dCAT-5 is 0.18. Other physicochemical properties of the catalyst are shown in Table 1.

[0090] Table 1 Physicochemical properties of hydrodemetallization catalysts

[0091]

[0092] Evaluation test

[0093] Activity stability tests were conducted on Examples 1-4 and Comparative Examples 1-5 in a 200ml fixed-bed hydrogenation test apparatus. The feedstock was a residual oil with a sulfur content of 2.9 wt%, metallic Ni and V contents of 34.6 μg / g and 64.7 μg / g, respectively, and a CCR content of 12.3 wt%. The reaction conditions were as follows: reaction temperature of 380°C, reaction pressure of 15.0 MPa, and liquid hourly volume space velocity of 1.0 h-1. -1 , the hydrogen-to-oil volume ratio is 800. The demetallization rate of Example 1 when it is operated for 100 hours is 100%, and the others are relative demetallization rates. The specific test results are shown in Table 2.

[0094] Table 2 Test results of hydrodemetallization catalyst

[0095]

[0096] It can be seen from Tables 1 and 2 that the hydrodemetallization catalyst prepared according to the method of the present invention has a high specific surface area and pore volume, and has high reaction activity and stability, and can well meet the requirements of the hydrodemetallization process of heavy oil, especially residual oil.

Claims

1. A heavy oil hydrodemetallization catalyst, comprising an inner catalyst layer and an outer carbon membrane layer coated on the surface of the inner catalyst layer, wherein the inner catalyst layer comprises a first alumina layer supporting a first active component and a second alumina layer supporting a second active component, the outer carbon membrane layer having a thickness of 60 to 90 μm, and the ratio of tetrahedral molybdenum to octahedral molybdenum in the catalyst, calculated as Mo atoms, is 0.18 to 0.58; The pore size of the first aluminum oxide layer is 8-18 nm, the pore size of the second aluminum oxide layer is 16-28 nm, and the ratio of the pore size of the second aluminum oxide layer to the pore size of the first aluminum oxide layer is 1.4-2.5; The diameter ratio of the second aluminum oxide layer to the first aluminum oxide layer is 2-12, and the diameter of the first aluminum oxide layer is 0.2-1.0 mm; The preparation method of the catalyst comprises the following steps: (1) Acidic aluminum salt solution and alkaline aluminum salt solution are subjected to neutralization reaction and primary aging to obtain a slurry; (2) The slurry obtained in step (1) is evenly divided into slurry I and slurry II, a water-soluble polymer J1 is added to slurry II, and slurry I and slurry II are subjected to secondary aging and drying, respectively, to obtain dried products I and dried products II; (3) preparing the dried product II obtained in step (2) into a pseudo-boehmite mixed solution II and adjusting its pH value, sealing the solution, and obtaining a mixed solution III; (4) adding the dried product I obtained in step (2) and the mixed solution III obtained in step (3) to a rolling ball machine at a certain rate, and simultaneously spraying the first impregnation solution containing the first active component at a uniform rate to obtain a first alumina layer loaded with the first active component; (5) adjusting the relative dripping rate of the mixed solution III, and simultaneously spraying the mixed solution containing the second active component at a uniform rate, and then drying and calcining the obtained sample to obtain the catalyst inner layer; (6) soaking the inner layer of the catalyst obtained in step (5) in a carbohydrate aqueous solution, drying and then carbonizing to obtain the heavy oil hydrodemetallization catalyst; In step (1), the temperature of the primary aging is 100-230°C; in step (2), the temperature of the secondary aging is 120-260°C; the temperature of the secondary aging is 30-60°C higher than the temperature of the primary aging; In step (4), the ratio of the addition rate of the dried product I to the mixed solution III is 0.60-0.95 g / mL; the ratio of the dropwise addition rate of the first impregnation solution to the dried product I is 0.18-0.42 mL / g; In step (5), the ratio of the addition rate of the dried product I to the mixed solution III is 0.40-0.58 g / mL; the ratio of the dropwise addition rate of the second impregnation solution to the dried product I is 1.08-1.25 mL / g.

2. The catalyst according to claim 1, characterized in that The diameter ratio of the second aluminum oxide layer to the first aluminum oxide layer is 2-8, and the diameter of the first aluminum oxide layer is 0.4-0.8 mm.

3. The catalyst according to claim 1, characterized in that The first active component includes molybdenum and a Group VIII metal, and the second active component includes molybdenum and a Group VIII metal.

4. The catalyst according to claim 3, characterized in that The Group VIII metal in the first and second active components is nickel.

5. The catalyst according to claim 3 or 4, characterized in that Based on the mass of the catalyst, the content of MoO3 is 6.5%~26.0%, and the content of Group VIII metal oxide is 2.5%~12.5%.

6. The catalyst according to claim 1, characterized in that The specific surface area of ​​the catalyst is 135~185m 2 / g, and the pore volume is 0.45~0.85mL / g.

7. The catalyst according to claim 1, characterized in that The specific surface area of ​​the catalyst is 160~180m 2 / g, and the pore volume is 0.70~0.85mL / g.

8. The catalyst according to claim 1, characterized in that The catalyst includes an auxiliary component, and the auxiliary component is selected from at least one of fluorine, phosphorus, silicon or boron.

9. The catalyst according to claim 8, characterized in that The auxiliary component is phosphorus.

10. The catalyst according to claim 8 or 9, characterized in that Based on the mass of the catalyst, the content of the auxiliary component in terms of oxide is 1.5% to 6.5%.

11. A method for preparing the catalyst according to any one of claims 1 to 10, comprising the steps of: (1) Acidic aluminum salt solution and alkaline aluminum salt solution are subjected to neutralization reaction and primary aging to obtain a slurry; (2) The slurry obtained in step (1) is evenly divided into slurry I and slurry II, a water-soluble polymer J1 is added to slurry II, and slurry I and slurry II are subjected to secondary aging and drying, respectively, to obtain dried products I and dried products II; (3) preparing the dried product II obtained in step (2) into a pseudo-boehmite mixed solution II and adjusting its pH value, sealing the solution, and obtaining a mixed solution III; (4) adding the dried product I obtained in step (2) and the mixed solution III obtained in step (3) to a rolling ball machine at a certain rate, and simultaneously spraying the first impregnation solution containing the first active component at a uniform rate to obtain a first alumina layer loaded with the first active component; (5) adjusting the relative dripping rate of the mixed solution III, and simultaneously spraying the mixed solution containing the second active component at a uniform rate, and then drying and calcining the obtained sample to obtain the catalyst inner layer; (6) soaking the inner layer of the catalyst obtained in step (5) in a carbohydrate aqueous solution, drying and then carbonizing to obtain the heavy oil hydrodemetallization catalyst; In step (1), the temperature of the primary aging is 100-230°C; in step (2), the temperature of the secondary aging is 120-260°C; the temperature of the secondary aging is 30-60°C higher than the temperature of the primary aging; In step (4), the ratio of the addition rate of the dried product I to the mixed solution III is 0.60-0.95 g / mL; the ratio of the dropwise addition rate of the first impregnation solution to the dried product I is 0.18-0.42 mL / g; In step (5), the ratio of the addition rate of the dried product I to the mixed solution III is 0.40-0.58 g / mL; the ratio of the dropwise addition rate of the second impregnation solution to the dried product I is 1.08-1.25 mL / g.

12. The preparation method according to claim 11, characterized in that In step (1), the acidic aluminum salt solution and the alkaline aluminum salt solution are subjected to a parallel neutralization reaction; the concentration of the acidic aluminum salt solution in terms of Al2O3 is 5g / 100mL~30g / 100mL; the concentration of the alkaline aluminum salt solution in terms of Al2O3 is 8g / 100mL~58g / 100mL.

13. The preparation method according to claim 11, characterized in that In step (1), the neutralization reaction temperature is 80-130° C., the time is 30-150 minutes, and the pH value of the slurry is controlled to be 6.0-9.5 during the neutralization reaction.

14. The preparation method according to claim 11, characterized in that In step (1), the time of the primary aging is 60 to 220 minutes, and the pH value is 9.0 to 12.0; and / or, in step (2), the time of the secondary aging is 40 to 200 minutes.

15. The preparation method according to claim 11, characterized in that In step (2), the water-soluble polymer J1 is one or more of polyethylene glycol, polyvinyl alcohol, polyacrylamide and methyl cellulose; the viscosity of the water-soluble polymer J1 at 20°C is 10~1000 mPa·s, and the viscosity of the slurry at 20°C after adding the water-soluble polymer J1 is 150~650 mPa·s.

16. The preparation method according to claim 11, characterized in that In step (2), the water-soluble polymer J1 is polyethylene glycol.

17. The preparation method according to claim 11, characterized in that In step (2), the drying temperature after secondary aging is 120-180° C., the drying time is 2-10 h, and the dry basis contents of the dried products I and II obtained after drying are both 40 wt %-70 wt %.

18. The preparation method according to claim 11, characterized in that In step (3), the solid content of the obtained mixed solution III is 15% to 40%, the pH value ranges from 6.0 to 8.0, and the sealing treatment time is 6 to 10 hours.

19. The preparation method according to claim 11, characterized in that In step (4), at least one auxiliary agent containing fluorine, phosphorus, silicon or boron is introduced into the first impregnation solution, and the amount of the auxiliary agent added is 15% to 30% of the total mass of the molybdenum oxide in the first impregnation solution.

20. The preparation method according to claim 19, characterized in that The amount of the additive added is 18% to 26% of the total mass of the molybdenum oxide in the first impregnation solution.

21. The preparation method according to claim 11, characterized in that In step (4), the amount of the first impregnation liquid used is 15% to 45% of the saturated water absorption of the dried material I.

22. The preparation method according to claim 11, characterized in that In step (5), the calcination adopts programmed temperature rise, the heating rate is 1°C / min~3°C / min, the calcination temperature is 450~750°C, the calcination time is 3~8 hours, and the calcination atmosphere is one or more of nitrogen, water vapor or air.

23. The preparation method according to claim 11, characterized in that In step (5), the calcination atmosphere is air.

24. The preparation method according to claim 11, characterized in that In step (6), the carbohydrate aqueous solution is an aqueous solution of starch and / or monosaccharides, and the mass concentration of starch and / or monosaccharides in the solution is 20.0% to 30.0%; the monosaccharides include one or more of glucose, ribose, and fructose.

25. The preparation method according to claim 11, characterized in that In step (6), ammonium bicarbonate is added to the carbohydrate aqueous solution as a pore-expanding agent, the mass concentration of ammonium bicarbonate in the carbohydrate aqueous solution is 18.0% to 35.0%, and the immersion time is 0.5 min to 10 min.

26. The preparation method according to claim 25, characterized in that The soaking time is 1.5 min to 5 min.

27. The preparation method according to claim 11, characterized in that In step (6), the carbonization conditions are: pre-oxidation in an air atmosphere at a temperature of 160-340°C for 4-20 hours; and then carbonization in a nitrogen atmosphere at a temperature of 400-700°C for 2-10 hours.

28. The preparation method according to claim 11, characterized in that In step (6), the carbonization conditions are: pre-oxidation for 3 to 16 hours at a temperature of 180 to 320° C. in an air atmosphere; and then carbonization for 2 to 10 hours at a temperature of 450 to 650° C. in a nitrogen atmosphere.

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