A titanium-modified hydrorefining catalyst, its preparation method and application

Abstract

This disclosure relates to a titanium-modified hydrorefining catalyst, its preparation method, and its application. Based on the total weight of the titanium-modified hydrorefining catalyst, the catalyst comprises 50-80 wt% of a support, 10-40 wt% of a main active metal component, 1-15 wt% of a first co-active metal component, and 1-30 wt% of a second co-active metal component. The main active metal component is selected from one or more Group VIB metals, the first co-active metal component is selected from one or more Group VIII metals, and the second co-active metal component includes titanium. The support comprises alumina. This disclosure allows for the simple preparation of a titanium-modified hydrorefining catalyst, which exhibits high catalytic activity.

Description

Technical Field

[0001] This disclosure relates to the field of petrochemical technology, specifically to a titanium-modified hydrorefining catalyst, its preparation method, and its application. Background Technology

[0002] Combustion of petroleum produces SO x and NO x Pollutants such as sulfur and nitrogen are present in crude oil, necessitating restrictions on the sulfur and nitrogen content in refined oil products to promote quality upgrades and the production of cleaner oils. However, after a century of development, the quality of crude oil is declining. How to effectively balance the trend of high sulfur and deteriorating crude oil quality with the strong societal demand for cleaner oils is a core issue facing the entire petroleum refining industry, especially in refining processes primarily focused on fuel oil.

[0003] Hydrodesulfurization, a crucial process in oil refining, is a key technology for producing clean oils, and its core lies in the development of hydrodesulfurization catalysts. After years of development, commonly used industrial hydrodesulfurization catalysts have formed traditional supported Co(Ni)Mo(W) sulfide-state catalytic systems with Mo and / or W as the main active metal components and Co and / or Ni as co-active metal components. To address the contradiction between declining crude oil quality and the need for cleaner oil production, developing supported Co(Ni)Mo(W) catalysts with higher activity and stability is the future direction for ensuring the production of clean oils.

[0004] Currently, the development focus of supported Co(Ni)Mo(W) catalysts mainly lies in three aspects: First, by introducing different promoters to modulate the interaction between the active metal and the support or the electronic state of the active metal, the dispersibility and reducibility of the active metal are improved, thereby regulating the microstructure of the sulfide-state active phase and thus enhancing the hydrodesulfurization activity of the catalyst. Second, by introducing acidic sites into the system, the adsorption capacity of active species on the catalyst surface is modulated or the formation of active sites (sulfur vacancies) is promoted, thereby improving the catalyst activity and modulating the catalyst selectivity. Third, high specific surface area supports are constructed for supporting active metals, thereby improving the dispersibility of the active metals, exposing more active centers, and enhancing the hydrodesulfurization activity of the catalyst.

[0005] Among the three methods mentioned above, introducing promoters into traditional supported Co(Ni)Mo(W) catalysts to improve their activity is relatively simple and low-cost, which is beneficial for the subsequent industrialization of the catalyst. Because there are few types of Ti metal salts and they are prone to hydrolysis during use, early methods for using Ti-modified Co(Ni)Mo(W) catalysts often used pre-prepared solid TiO2 or TiO(OH) as the titanium source, mechanically mixing the Ti source with the support through kneading. This inevitably led to uneven dispersion of Ti species and poor thermal stability of agglomerated Ti species, resulting in limited activity improvement and poor stability of the Ti-modified Co(Ni)Mo(W) catalyst. To address these issues, literature reports the use of organic or sulfated titanium as the titanium source, dissolving it in alcohols or acidic water, and preparing a Ti-modified composite support through a series of steps including precipitation, filtration, washing, drying, and calcination. The active metal is then loaded through impregnation, followed by secondary drying and calcination to obtain the Ti-modified Co(Ni)Mo(W) catalyst. However, the existing preparation process requires the use of alcohols or acidic water as solvents, which will significantly increase the wastewater discharge in the catalyst preparation process. At the same time, the preparation process of such catalysts is long and costly. Summary of the Invention

[0006] The purpose of this disclosure is to provide a titanium-modified hydrogenation refining catalyst, its preparation method, and its application. This method allows for the simple preparation of titanium-modified hydrogenation refining catalysts, which exhibit high catalytic activity.

[0007] To achieve the above objectives, the first aspect of this disclosure provides a titanium-modified hydrorefining catalyst, wherein, based on the total weight of the titanium-modified hydrorefining catalyst, the catalyst comprises 50-80% by weight of a support, 10-40% by weight of a main active metal component, 1-15% by weight of a first co-active metal component, and 1-30% by weight of a second co-active metal component; the main active metal component is selected from one or more Group VIB metals, the first co-active metal component is selected from one or more Group VIII metals, and the second co-active metal component includes titanium; the support comprises alumina.

[0008] Optionally, the primary active metal component comprises an oxide of one or two metal elements selected from Mo and W; the first auxiliary active metal component comprises an oxide of one or two metal elements selected from Ni and Co; and the second auxiliary active metal component comprises an oxide of titanium.

[0009] Optionally, the total acidity of the titanium-modified hydrorefining catalyst, as determined by pyridine infrared spectroscopy at 150 °C, is 140–190 μmol / g. The acid center content is less than 10 μmol / g;

[0010] Optionally, the BET specific surface area of ​​the titanium-modified hydrorefining catalyst is 150–250 m². 2 / g, total pore volume greater than 0.4cm³ 3 / g.

[0011] Optionally, the titanium-modified hydrorefining catalyst comprises Ti 3+ Species;

[0012] Preferably, in the titanium-modified hydrorefining catalyst, Ti 2p 3 / 2 In the XPS spectrum of the orbital, based on the peak area of ​​all titanium elements, the Ti 3+ The peak area of ​​the species accounts for 3-40%, preferably 8-20%.

[0013] A second aspect of this disclosure provides a method for preparing a titanium-modified hydrorefining catalyst, comprising the following steps:

[0014] S1. The main active metal component precursor, the first auxiliary active metal component precursor, the second auxiliary active metal component precursor, water and alumina precursor are mixed and aged to obtain a catalyst intermediate; wherein the metal element of the main active metal component precursor is selected from one or more of the group VIB metal elements, the metal element of the first auxiliary active metal component precursor is selected from one or more of the group VIII metal elements, and the second auxiliary active metal component precursor includes a titanium-containing compound.

[0015] S2. The catalyst intermediate is mixed with the additives and then subjected to molding and calcination.

[0016] Optionally, the main active metal component precursor is selected from one or more of molybdenum metal precursors and tungsten metal precursors; preferably, the molybdenum metal precursor is selected from one or more of sodium molybdate, ammonium molybdate, molybdenum chloride and molybic acid, preferably ammonium molybdate; the tungsten metal precursor is selected from one or more of ammonium metatungstate, phosphotungstic acid and silicotungstic acid, preferably ammonium metatungstate and / or phosphotungstic acid;

[0017] The first auxiliary active metal component precursor is selected from one or more of nickel metal precursor and cobalt metal precursor; preferably, the nickel metal precursor is selected from one or more of nickel nitrate, basic nickel carbonate and nickel sulfate, and more preferably basic nickel carbonate and / or nickel nitrate; the cobalt metal precursor is selected from one or more of cobalt sulfate, cobalt carbonate, cobalt oxalate and cobalt nitrate, and more preferably cobalt nitrate and / or cobalt oxalate.

[0018] The second auxiliary active metal component precursor is selected from one or more of titanium tetrachloride, methyl titanate, tetraethyl titanate, titanium n-propoxide, isopropyl titanate, tetrabutyl titanate, titanium tert-butoxide, and titanium isooctoxide; preferably selected from one or more of tetraethyl titanate, isopropyl titanate, and tetrabutyl titanate.

[0019] The alumina precursor is selected from one or more of boehmite, aluminum hydroxide, and aluminum nitrate; preferably boehmite.

[0020] Optionally, in step S1, the aging treatment conditions include: natural aging at 0–50°C for 12–24 hours;

[0021] Optionally, the method further includes drying the product obtained from the aging treatment at 80–160°C for 4–12 hours.

[0022] Optionally, in step S2, the calcination conditions include: calcining at 300–700°C for 3–10 hours; and the calcination atmosphere being one or more of air, nitrogen, oxygen, argon, and water vapor.

[0023] Optionally, before performing the roasting treatment, the product obtained from the molding treatment is dried at 80–160°C for 4–12 hours.

[0024] This disclosure provides a third aspect of a titanium-modified hydrorefining catalyst prepared according to the method described in the second aspect of this disclosure.

[0025] This fourth aspect of the disclosure provides the application of the titanium-modified hydrorefining catalysts described in the first and third aspects of the disclosure in the hydrorefining reaction of feedstock oil.

[0026] Optionally, the following steps are included:

[0027] Under hydrogen-containing conditions, the feedstock oil is brought into contact with the titanium-modified hydrorefining catalyst to carry out a hydrorefining reaction;

[0028] Optionally, the conditions for the hydrorefining reaction include: a reaction temperature of 260–380°C; a hydrogen pressure of 4–10 MPa; a hydrogen-to-oil volume ratio of 300–800:1; and a feedstock mass hourly space velocity of 0.1–6 h⁻¹. -1 ;

[0029] Optionally, the feedstock is selected from gasoline and / or diesel fractions;

[0030] Preferably, the process further includes: subjecting the titanium-modified hydrorefining catalyst to sulfidation treatment prior to the hydrorefining reaction.

[0031] Through the above technical solution, this disclosure provides a titanium-modified hydrorefining catalyst, its preparation method, and its application. This titanium-modified hydrorefining catalyst uses a Group VIB metal element as the main active metal component, a Group VIII metal element as the first co-active metal component, and titanium as the second co-active metal component. The preparation method is simple and effective, effectively avoiding the use of organic alcohols or acidic water in traditional preparation processes, thus reducing production costs. Simultaneously, this titanium-modified hydrorefining catalyst promotes the uniform dispersion of Ti species in the catalyst, strengthens the electronic interaction between the active metal and Ti species, modulates the interaction force between the active metal and the support, improves the dispersion of the active metal and the microstructure of the active species, resulting in a catalyst with a "surface microsphere structure," significantly enhancing the activity of the catalyst in hydrodesulfurization and hydrodenitrogenation reactions.

[0032] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 Here is a scanning electron microscope image of the titanium-modified hydrorefining catalyst prepared in Example 1;

[0035] Figure 2 The Ti 2p of the titanium-modified hydrorefining catalyst prepared in Example 1 3 / 2 XPS spectrum. Detailed Implementation

[0036] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0037] The first aspect of this disclosure provides a titanium-modified hydrorefining catalyst, wherein, based on the total weight of the titanium-modified hydrorefining catalyst, the titanium-modified hydrorefining catalyst comprises 50-80% by weight of a support, 10-40% by weight of a main active metal component, 1-15% by weight of a first co-active metal component, and 1-30% by weight of a second co-active metal component; the main active metal component is selected from one or more Group VIB metal elements, the first co-active metal component is selected from one or more Group VIII metal elements, and the second co-active metal component includes titanium; the support comprises alumina.

[0038] This disclosure provides a titanium-modified hydrorefining catalyst, in which a Group VIB metal element is used as the main active metal component, a Group VIII metal element as the first co-active metal component, and titanium as the second co-active metal component. The preparation method is simple and effective, effectively avoiding the use of organic alcohols or acidic water in traditional preparation processes, thus reducing production costs. Simultaneously, this titanium-modified hydrorefining catalyst promotes the uniform dispersion of Ti species within the catalyst, strengthens the electronic interaction between the active metal and Ti species, modulates the interaction force between the active metal and the support, improves the dispersion of the active metal and the microstructure of the active species, resulting in a catalyst with a "surface microsphere structure," significantly enhancing the activity of the catalyst in hydrodesulfurization and hydrodenitrogenation reactions.

[0039] In this disclosure, the contents of the main active metal component, the first co-active metal component, and the second co-active metal component in the catalyst are calculated in the form of metal oxides.

[0040] In a preferred embodiment, the titanium-modified hydrorefining catalyst comprises 50-70% by weight of a support, 20-30% by weight of a main active metal component, 4-10% by weight of a first co-active metal component, and 5-15% by weight of a second co-active metal component.

[0041] In one embodiment, the primary active metal component comprises an oxide of one or two metal elements selected from Mo and W; the first auxiliary active metal component comprises an oxide of one or two metal elements selected from Ni and Co; and the second auxiliary active metal component comprises titanium oxide.

[0042] In a preferred embodiment, the total acidity of the titanium-modified hydrorefining catalyst, as determined by pyridine infrared spectroscopy at 150°C, is 140–190 μmol / g, preferably 160–185 μmol / g. The acid center content is less than 10 μmol / g;

[0043] Optionally, the BET specific surface area of ​​the titanium-modified hydrorefining catalyst is 150–250 m². 2 / g, total pore volume greater than 0.4cm³ 3 / g.

[0044] In one embodiment, the titanium-modified hydrorefining catalyst comprises Ti 3+ Species.

[0045] In a preferred embodiment, the Ti 2p of the titanium-modified hydrorefining catalyst... 3 / 2 In the XPS spectrum of the orbital, based on the peak area of ​​all titanium elements, the Ti 3+The peak area of ​​the species accounts for 3-40%, preferably 8-20%. In this disclosure, the Ti 2p catalyst modified with the titanium is used for hydrogenation refining. 3 / 2 The peak area at 456.9 eV in the XPS spectrum of the orbital represents Ti. 3+ Species content; the peak area at 458.7 eV represents Ti. 4+ Species content, in terms of Ti 3+ Species and Ti 4+ The total area of ​​the species spectral peaks represents the total content of titanium, Ti 3+ The content of species is attributed to Ti 3+ Peak area of ​​species and attribution to Ti 3+ Species and Ti 4+ The ratio of the sum of the peak areas of the species.

[0046] A second aspect of this disclosure provides a method for preparing a titanium-modified hydrorefining catalyst, comprising the following steps:

[0047] S1. The main active metal component precursor, the first auxiliary active metal component precursor, the second auxiliary active metal component precursor, water and alumina precursor are mixed and aged to obtain a catalyst intermediate; wherein the metal element of the main active metal component precursor is selected from one or more of the group VIB metal elements, the metal element of the first auxiliary active metal component precursor is selected from one or more of the group VIII metal elements, and the second auxiliary active metal component precursor includes a hydrolyzable titanium-containing compound.

[0048] S2. The catalyst intermediate is mixed with the additives and then subjected to molding and calcination.

[0049] In the method for preparing titanium-modified hydrorefining catalysts provided in this disclosure, water is used as a solvent, which can effectively avoid the use of organic alcohols or acidic water in traditional preparation processes, thereby reducing production costs. Furthermore, this disclosure uses a hydrolyzable titanium-containing compound as a second auxiliary active metal component precursor, together with the main active metal component precursor, the first auxiliary active metal component precursor, and the alumina precursor, to prepare the titanium-modified hydrorefining catalyst. The titanium-containing compound precursor can be hydrolyzed in situ, which is beneficial for the uniform dispersion of Ti species in the catalyst, strengthens the electronic interaction between the active metal and Ti species, modulates the interaction force between the active metal and the support, improves the dispersion of the active metal and the microstructure of the active species, and significantly enhances the activity of the catalyst in hydrodesulfurization and hydrodenitrogenation reactions.

[0050] In this disclosure, the amount and proportion of each raw material added can be adjusted according to the target component composition of the titanium-modified hydrorefining catalyst.

[0051] In one specific embodiment, in step S1, the weight ratio of the main active metal component precursor: the first auxiliary active metal component precursor: the second auxiliary active metal component precursor: water: alumina precursor is 0.2–2: 0.1–1.5: 0.1–2.5: 1–4:1. By preparing the catalyst according to the raw material weight ratio specified in this embodiment, a titanium-modified hydrorefining catalyst with better catalytic performance can be obtained.

[0052] In one specific embodiment, the main active metal component precursor is selected from one or more of molybdenum metal precursors and tungsten metal precursors; preferably, the molybdenum metal precursor is selected from one or more of sodium molybdate, ammonium molybdate, molybdenum chloride, and molybic acid, and more preferably ammonium molybdate; the tungsten metal precursor is selected from one or more of ammonium metatungstate, phosphotungstic acid, and silicotungstic acid, and more preferably ammonium metatungstate and / or phosphotungstic acid;

[0053] The first auxiliary active metal component precursor is selected from one or more of nickel metal precursor and cobalt metal precursor; preferably, the nickel metal precursor is selected from one or more of nickel nitrate, basic nickel carbonate and nickel sulfate, and more preferably basic nickel carbonate and / or nickel nitrate; the cobalt metal precursor is selected from one or more of cobalt sulfate, cobalt carbonate, cobalt oxalate and cobalt nitrate, and more preferably cobalt nitrate and / or cobalt oxalate.

[0054] The alumina precursor is selected from one or more of boehmite, aluminum hydroxide, and aluminum nitrate; preferably boehmite.

[0055] In a preferred embodiment, the second co-active metal component precursor is selected from one or more of titanium tetrachloride, methyl titanate, tetraethyl titanate, titanium n-propoxide, isopropyl titanate, tetrabutyl titanate, titanium tert-butoxide, and titanium isooctoxide; preferably, it is selected from one or more of tetraethyl titanate, isopropyl titanate, and tetrabutyl titanate.

[0056] In one specific embodiment, the main active metal component precursor and the first auxiliary active metal component precursor are prepared into a solution with water, and then added dropwise together with the second auxiliary active metal component precursor onto the alumina precursor; after stirring to mix, an aging treatment is performed. The stirring and mixing can be carried out using conventional equipment and conditions to ensure that all raw materials and reagents are mixed uniformly.

[0057] In one embodiment, the aging treatment conditions in step S1 include: natural aging at 0–50°C for 12–24 hours; preferably, natural aging at 5–30°C for 12–20 hours.

[0058] In one embodiment, the method further includes drying the product obtained from the aging treatment at 80–160°C for 4–12 hours.

[0059] In one specific embodiment, step S2 includes one of extrusion molding and die molding, preferably extrusion molding. The specific processes and apparatus for extrusion molding are well known to those skilled in the art.

[0060] In one embodiment, the additives include extrusion aids and binders;

[0061] The extrusion aid is selected from one or more of starch, guar gum, polyethylene glycol and methylcellulose; preferably, the amount of extrusion aid added is 1 to 10% by weight, more preferably 3 to 8% by weight, based on the total weight of all components.

[0062] The adhesive is selected from one or more of nitric acid, citric acid, tartaric acid, oxalic acid and oxalic acid; preferably, the amount of adhesive added is 1 to 10% by weight, more preferably 3 to 8% by weight, based on the total weight of all components.

[0063] All reagents used in this disclosure can be purchased through conventional channels or prepared by known methods.

[0064] In one specific embodiment, the catalyst product obtained by the molding process can be in the shape of strips, clover, granules, or toothed spheres.

[0065] In one embodiment, in step S2, the calcination conditions include: calcining at 300–700°C for 3–10 hours, preferably calcining at 400–600°C for 4–7 hours; the calcination atmosphere is one or more of air, nitrogen, oxygen, argon, and water vapor.

[0066] Optionally, before performing the roasting treatment, the product obtained from the molding treatment is dried at 80–160°C for 4–12 hours.

[0067] Each step in the preparation of the catalyst can be carried out using conventional equipment in the field.

[0068] This disclosure provides a third aspect of a titanium-modified hydrorefining catalyst prepared according to the method described in the second aspect of this disclosure.

[0069] This disclosure provides a fourth aspect regarding the application of the titanium-modified hydrorefining catalyst described in the first or third aspect in the hydrorefining reaction of feedstock oil.

[0070] In one embodiment, the method includes the following steps: under hydrogen-exposed conditions, the feedstock oil is brought into contact with a titanium-modified hydrorefining catalyst to carry out a hydrorefining reaction.

[0071] In one specific embodiment, the conditions for the hydrorefining reaction include: a reaction temperature of 260–380°C; a hydrogen pressure of 4–10 MPa; a hydrogen-to-oil volume ratio of 300–800:1; and a feedstock mass hourly space velocity of 0.1–6 h⁻¹. -1 ;

[0072] Optionally, the feedstock is selected from gasoline and / or diesel fractions.

[0073] In this disclosure, the titanium-modified hydrorefining catalyst is subjected to sulfidation treatment before the hydrorefining reaction is carried out.

[0074] In a preferred embodiment, the vulcanization temperature is 200–500°C, the pressure is 0.1–10 MPa, the vulcanization time is 1–60 h, and the liquid hourly space velocity is 0.1–20 h⁻¹. -1 The hydrogen-to-oil volume ratio is 100–800.

[0075] The present disclosure is further described in detail below through examples. All raw materials used in the examples are commercially available. The instruments used for performance testing are also standard testing instruments from manufacturers in the art.

[0076] The methods for determining and calculating the total oxide content of the active metal component in the catalyst are all well-known in the art, specifically including XRF and ICP methods.

[0077] Methods for testing acidity include pyridine infrared spectroscopy.

[0078] The method for testing the BET specific surface area of ​​the sample includes low-temperature nitrogen physical adsorption.

[0079] The Ti species content in the catalyst was tested using Ti 2p. 3 / 2 Testing of XPS orbital spectra.

[0080] Example 1

[0081] This embodiment provides a titanium-modified hydrogenation refining catalyst, and the specific preparation method includes the following steps:

[0082] (1) Dissolve 3.14g of ammonium metatungstate and 1.95g of nickel nitrate in 24.77g of deionized water to prepare a mixed impregnation solution. Separately prepare 4.34g of tetrabutyl titanate and 8.26g of boehmite. Add the mixed impregnation solution and tetrabutyl titanate dropwise to the boehmite simultaneously (the weight ratio of the main active metal component precursor: the first auxiliary active metal component precursor: the second auxiliary active metal component precursor: water: alumina precursor is 0.38:0.24:0.53:3:1), stir vigorously for 2 hours to mix evenly, age naturally at 10℃ for 12 hours, and then dry at 100℃ for 8 hours to obtain the catalyst semi-finished product;

[0083] (2) The above catalyst powder was uniformly mixed with 0.4g of Tianqing powder, 0.2g of nitric acid, 0.2g of citric acid and an appropriate amount of deionized water, and extruded into clover-shaped catalysts with a diameter of 1.5mm. The obtained clover-shaped catalysts were dried at 80℃ for 12h, then calcined at 500℃ in a 15% O2 / N2 atmosphere for 4h, and naturally cooled to obtain titanium-modified hydrogenation refining catalysts, labeled as TC-1.

[0084] The contents of tungsten oxide (the main active metal component) in the TC-1 catalyst were measured to be 27 wt%, nickel oxide (the first auxiliary active metal component) to be 5 wt%, and titanium oxide (the second auxiliary active metal component) to be 10.2 wt%.

[0085] Scanning electron microscope image of TC-1 catalyst as follows Figure 1 As shown, by Figure 1 It can be seen that the catalyst surface has a microsphere structure.

[0086] Ti 2p of TC-1 catalyst 3 / 2 XPS spectra as follows Figure 2 As shown, by Figure 2 It can be seen that the Ti 2p of this catalyst 3 / 2 The XPS spectrum contains Ti 3+ Species and Ti 4+ The characteristic peaks of the species, calculated by peak area, include Ti 3+ The peak area of ​​the species is 260, Ti 4+ The peak area of ​​the species is 1473, Ti 3+ Species peak area / (Ti 3+ Species peak area + Ti 4+ The percentage of species peak area (×100%) is 15%.

[0087] Comparative Example 1

[0088] This comparative example provides a titanium-free hydrogenation catalyst, and the specific preparation method includes the following steps:

[0089] (1) Dissolve 3.14g of ammonium metatungstate and 1.95g of nickel nitrate in 29.14g of deionized water to prepare a mixed impregnation solution. Separately prepare 9.71g of boehmite. Add the mixed impregnation solution dropwise to the boehmite, stir vigorously for 2 hours to mix evenly, age naturally at 10℃ for 12 hours, and then dry at 100℃ for 8 hours to obtain a catalyst semi-finished product;

[0090] (2) The above catalyst powder was uniformly mixed with 0.4g of Tianqing powder, 0.2g of nitric acid, 0.2g of citric acid and an appropriate amount of deionized water, and extruded into a clover-shaped catalyst with a diameter of 1.5mm. The obtained clover-shaped catalyst was dried at 80℃ for 12h, then calcined at 500℃ in a 15% O2 / N2 atmosphere for 4h, and naturally cooled to obtain a titanium-modified hydrogenation refining catalyst, labeled as D-1.

[0091] The D-1 catalyst was found to contain 27% by weight of tungsten oxide, 5% by weight of nickel oxide, and a total content of 32.0% by weight of nickel oxide and tungsten oxide (based on the total weight of the catalyst).

[0092] Example 2

[0093] This embodiment provides a titanium-modified hydrogenation refining catalyst, and the specific preparation method includes the following steps:

[0094] (1) Dissolve 2.82g of ammonium molybdate and 2.72g of cobalt nitrate in 26.40g of deionized water to prepare a mixed impregnation solution. Separately prepare 2.99g of isopropyl titanate and 8.80g of boehmite. Add the mixed impregnation solution and isopropyl titanate dropwise to the boehmite simultaneously (the weight ratio of the main active metal component precursor: the first auxiliary active metal component precursor: the second auxiliary active metal component precursor: water: alumina precursor is 0.32:0.31:0.34:3:1), stir vigorously for 2 hours to mix evenly, age naturally at 20℃ for 16 hours, and then dry at 110℃ for 6 hours to obtain the catalyst semi-finished product;

[0095] (2) The above-mentioned catalyst semi-finished product was uniformly mixed with 0.4g polyethylene glycol, 0.2g nitric acid, 0.3g citric acid and an appropriate amount of deionized water, and extruded into strip-shaped catalyst with a diameter of 1.5mm. The obtained strip-shaped catalyst was dried at 120℃ for 7h, then calcined in air at 500℃ for 4h, and naturally cooled to obtain titanium-modified hydrogenation refining catalyst, labeled as TC-2.

[0096] The contents of molybdenum oxide (the main active metal component) in the TC-2 catalyst were measured to be 23% by weight, cobalt oxide (the first co-active metal component) 7% by weight, and titanium oxide (the second co-active metal component) 8.4% by weight (all based on the total weight of the catalyst).

[0097] Comparative Example 2

[0098] This comparative example provides a titanium-free hydrogenation catalyst, and the specific preparation method includes the following steps:

[0099] (1) Dissolve 2.82g of ammonium molybdate and 2.72g of cobalt nitrate in 30.00g of deionized water to prepare a mixed impregnation solution. Separately prepare 10.00g of boehmite. Add the mixed impregnation solution dropwise to the boehmite, stir vigorously for 2 hours to mix evenly, age naturally at 20℃ for 16 hours, and then dry at 110℃ for 6 hours to obtain a catalyst semi-finished product;

[0100] (2) The above-mentioned catalyst semi-finished product was uniformly mixed with 0.4g polyethylene glycol, 0.2g nitric acid, 0.3g citric acid and an appropriate amount of deionized water, and extruded into strip-shaped catalyst with a diameter of 1.5mm. The obtained strip-shaped catalyst was dried at 120℃ for 7h, then calcined in air at 500℃ for 4h, and naturally cooled to obtain titanium-modified hydrogenation refining catalyst, labeled as D-2.

[0101] The D-2 catalyst was found to contain 23% by weight of molybdenum oxide and 7% by weight of cobalt oxide (both based on the total weight of the catalyst).

[0102] Example 3

[0103] This embodiment provides a titanium-modified hydrogenation refining catalyst, and the specific preparation method includes the following steps:

[0104] (1) Dissolve 1.72g ammonium molybdate, 1.63g ammonium metatungstate, and 2.72g nickel nitrate in 22.29g deionized water to prepare a mixed impregnation solution. Separately prepare 2.23g tetraethyl titanate, 1.85g titanium propoxide, and 7.43g boehmite. Add the mixed impregnation solution, tetraethyl titanate, and titanium propoxide dropwise to the boehmite (the weight ratio of the main active metal component precursor: the first auxiliary active metal component precursor: the second auxiliary active metal component precursor: water: alumina precursor is 0.45:0.37:0.3:3:1), stir vigorously for 2 hours to mix evenly, age naturally at 8℃ for 15 hours, and then dry at 120℃ for 6 hours to obtain the catalyst semi-finished product;

[0105] (2) The above catalyst powder was uniformly mixed with 0.4g methylcellulose, 0.2g nitric acid, 0.2g tartaric acid and an appropriate amount of deionized water, and extruded into granular catalyst with a diameter of 1.5mm. The obtained granular catalyst was dried at 80℃ for 15h, then calcined in air at 450℃ for 4h, and naturally cooled to obtain titanium-modified hydrogenation refining catalyst, labeled as TC-3.

[0106] The contents of molybdenum oxide and tungsten oxide in the TC-3 catalyst were measured to be 14 wt%, 14 wt% (total content of main active metal components was 28 wt%), 7 wt% (first auxiliary active metal component) (nickel oxide), and 13.0 wt% (titanium oxide), which were all based on the total weight of the catalyst.

[0107] Comparative Example 3

[0108] This comparative example provides a titanium-free hydrogenation catalyst, and the specific preparation method includes the following steps:

[0109] (1) Dissolve 2.72g of nickel nitrate, 1.72g of ammonium molybdate and 1.63g of ammonium metatungstate in 27.86g of deionized water to prepare a mixed impregnation solution. Separately prepare 9.29g of boehmite. Add the mixed impregnation solution dropwise to the boehmite, stir vigorously for 2 hours to mix evenly, age naturally at 8℃ for 15 hours, and then dry at 120℃ for 6 hours to obtain a catalyst semi-finished product;

[0110] (2) The above catalyst powder was uniformly mixed with 0.4g methylcellulose, 0.2g nitric acid, 0.2g tartaric acid and an appropriate amount of deionized water, and extruded into granular catalyst with a diameter of 1.5mm. The obtained granular catalyst was dried at 80℃ for 15h, then calcined in air at 450℃ for 4h, and naturally cooled to obtain titanium-modified hydrogenation refining catalyst, labeled as D-3.

[0111] The D-3 catalyst was found to contain 14% by weight of molybdenum oxide, 14% by weight of tungsten oxide, and 7% by weight of nickel oxide (all based on the total weight of the catalyst).

[0112] Comparative Example 4

[0113] This comparative example follows the preparation method of Example 1, but differs from Example 1 in that the amount of raw materials added is changed, specifically including:

[0114] (1) Dissolve 0.81g of ammonium metatungstate and 9.73g of nickel nitrate in 14.57g of deionized water to prepare a mixed impregnation solution. Separately prepare 14.48g of tetrabutyl titanate and 4.86g of boehmite. Add the mixed impregnation solution and tetrabutyl titanate dropwise to the boehmite simultaneously (the weight ratio of the main active metal component precursor: the first auxiliary active metal component precursor: the second auxiliary active metal component precursor: water: alumina precursor is 0.17:2:2.98:3:1), stir vigorously for 2 hours to mix evenly, age naturally at 10℃ for 12 hours, and then dry at 100℃ for 8 hours to obtain the catalyst semi-finished product;

[0115] (2) The above catalyst powder was uniformly mixed with 0.4g of Tianqing powder, 0.2g of nitric acid, 0.2g of citric acid and an appropriate amount of deionized water, and extruded into clover-shaped catalysts with a diameter of 1.5mm. The obtained clover-shaped catalysts were dried at 80℃ for 12h, then calcined at 500℃ in a 15% O2 / N2 atmosphere for 4h, and naturally cooled to obtain titanium-modified hydrogenation refining catalysts, labeled as D-4.

[0116] The contents of the D-4 catalyst were measured to be 7 wt% tungsten oxide (the main active metal component), 25 wt% nickel oxide (the first auxiliary active metal component), and 50 wt% titanium oxide (the second auxiliary active metal component).

[0117] Example 4

[0118] This embodiment refers to the preparation method of Example 1, but differs from Example 1 in that the preparation conditions are changed, specifically including:

[0119] (1) Dissolve 3.14g of ammonium metatungstate and 1.95g of nickel nitrate in 24.77g of deionized water to prepare a mixed impregnation solution. Separately prepare 4.34g of tetrabutyl titanate and 8.26g of boehmite. Add the mixed impregnation solution and tetrabutyl titanate dropwise onto the boehmite simultaneously, stir vigorously for 1 hour to mix evenly, age naturally at 60℃ for 3 hours, and then dry at 80℃ for 6 hours to obtain a catalyst semi-finished product;

[0120] (2) The above catalyst powder was uniformly mixed with 0.4g of Tianqing powder, 0.2g of nitric acid, 0.2g of citric acid and an appropriate amount of deionized water, and extruded into clover-shaped catalysts with a diameter of 1.5mm. The obtained clover-shaped catalysts were dried at 150℃ for 4h, and then calcined at 900℃ in a 15% O2 / N2 atmosphere for 8h. After natural cooling, titanium-modified hydrogenation refining catalyst was obtained, labeled as TC-4.

[0121] The contents of tungsten oxide (the main active metal component) in the TC-4 catalyst were measured to be 27 wt%, nickel oxide (the first auxiliary active metal component) to be 5 wt%, and titanium oxide (the second auxiliary active metal component) to be 10.2 wt%.

[0122] Example 5

[0123] This embodiment refers to the preparation method of Example 1, but differs from Example 1 in that the amount of raw materials added is changed, specifically including:

[0124] 1.16 g of ammonium metatungstate and 0.78 g of nickel nitrate were dissolved in 24.85 g of deionized water to prepare a mixed impregnation solution. Separately, 12.78 g of tetrabutyl titanate and 8.28 g of boehmite were prepared. The mixed impregnation solution and tetrabutyl titanate were simultaneously added dropwise to the boehmite, and the remaining process was the same as in Example 1, to obtain a titanium-modified hydrogenation refining catalyst, labeled TC-5.

[0125] The contents of tungsten oxide (the main active metal component) in the TC-5 catalyst were measured to be 10 wt%, nickel oxide (the first auxiliary active metal component) to be 2 wt%, and titanium oxide (the second auxiliary active metal component) to be 30 wt%.

[0126] Example 6

[0127] This embodiment refers to the preparation method of Example 1, but differs from Example 1 in that the preparation conditions are changed, specifically including:

[0128] Aging conditions include: natural aging at 50℃ for 20 hours;

[0129] The calcination conditions included calcination at 700°C for 3 hours; the remaining processes were the same as in Example 1, resulting in a titanium-modified hydrogenation refining catalyst, labeled TC-6.

[0130] The contents of tungsten oxide (the main active metal component) in the TC-6 catalyst were measured to be 27 wt%, nickel oxide (the first auxiliary active metal component) to be 5 wt%, and titanium oxide (the second auxiliary active metal component) to be 10.2 wt%.

[0131] The composition of the catalyst products obtained in the above examples and comparative examples, the total acidity determined by pyridine infrared spectroscopy at 150℃, and the Ti were compared. 3+ Data such as species peak area ratio and BET specific surface area are listed in Table 1 below.

[0132] Table 1

[0133]

[0134]

[0135] In Table 1, “——” indicates that it does not exist.

[0136] Reaction Test Example 1

[0137] This test example provides a test experiment on the hydrogenation treatment of coking diesel by the catalysts prepared in the above embodiments and comparative examples.

[0138] The catalysts in the examples and the comparative catalysts were compared, and their reaction processes are as follows: Pre-sulfurization treatment was performed before application to improve the hydrogenation effect of the catalysts. Pre-sulfurization was carried out using a 10 mL high-temperature, high-pressure hydrogenation microreactor, which was a wet in-situ pre-sulfurization process. That is, wet pre-sulfurization was used, and the catalyst was not removed after pre-sulfurization; the hydrogenation reaction continued directly in the reactor. The pre-sulfurization oil was a n-decane solution containing 5% by weight CS2. The pre-sulfurization temperature was 320°C, the pressure was 4 MPa, and the liquid hourly space velocity (LHSV) was 1.5 h⁻¹. -1 The hydrogen-to-oil volume ratio is 300.

[0139] The hydrotreating in this test case was carried out using a 10 mL high-temperature, high-pressure hydrotreating microreactor. The evaluation feedstock was Daqing coking diesel oil, whose specific gravity (d4) was... 20 The concentration of phosphorus was 0.8274, the sulfur content was 1067 ppm, and the total nitrogen content was 883 ppm. The feedstock was pumped in using a plunger pump. After reaction, the oil sample was cooled in a high-pressure separator and then collected and analyzed in a low-pressure separator. The hydrotreating temperature was 300℃, the pressure was 4 MPa, and the liquid hourly space velocity (LHSV) was 3.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 500. The evaluation results of the hydrogenation catalyst are shown in Table 2.

[0140] The sulfur and nitrogen contents of the reactants and products were obtained by ultraviolet fluorescence detection and chemiluminescence detection methods.

[0141] Desulfurization rate (mol%) = (Sulfur content of raw material - Sulfur content of product) / Sulfur content of raw material × 100%;

[0142] Denitrification rate (mol%) = (raw material nitrogen content - product nitrogen content) / raw material nitrogen content × 100%.

[0143] Table 2

[0144]

[0145]

[0146] Based on the data in Table 2 above, we can see that:

[0147] (1) Comparing catalysts TC-1 with D-1, TC-2 with D-2, and TC-3 with D-3, it can be seen that the titanium-modified hydrorefining catalysts TC-1 to TC-3 prepared in Examples 1 to 3 have higher desulfurization and denitrification rates in the hydrorefining reaction of coking diesel.

[0148] (2) Comparing Examples 1 to 4 with Comparative Example 4, it can be seen that the composition of catalyst D-4 prepared in Comparative Example 4 is not within the range of "50 to 80% by weight of support, 10 to 40% by weight of main active metal component, 1 to 15% by weight of first auxiliary active metal component and 1 to 30% by weight of second auxiliary active metal component". Compared with D-4, catalysts TC-1 to TC-4 prepared in Examples 1 to 4 have higher desulfurization and denitrification rates.

[0149] (3) Comparing Example 1 and Example 4, it can be seen that the preparation conditions of the catalyst preparation process in Example 4 are not within the scope of this disclosure. Compared with the catalyst TC-4 prepared in Example 4, the catalyst TC-1 prepared in Example 1 has a higher desulfurization rate and denitrification rate.

[0150] (4) Comparing Example 1 and Example 5, it can be seen that the component content of the catalyst TC-1 prepared in Example 1 is within the preferred range of this disclosure (50-70% by weight of support, 20-30% by weight of main active metal component, 4-10% by weight of first auxiliary active metal component and 5-15% by weight of second auxiliary active metal component). Compared with the catalyst TC-5 prepared in Example 5, the catalyst TC-1 prepared in Example 1 has a higher desulfurization rate and denitrification rate.

[0151] (5) Comparing Example 1 with Example 6, it can be seen that the catalyst prepared in Example 1 according to the preferred reaction conditions of this disclosure has a higher desulfurization rate and denitrification rate than the catalyst TC-6 prepared in Example 6.

[0152] Reaction Test Example 2

[0153] This test example provides a test experiment on the hydrotreating of catalytic cracked diesel fuel with the catalysts prepared in the above embodiments and comparative examples.

[0154] The catalysts in the examples and the comparative catalysts were compared, and their reaction processes are as follows: Pre-sulfurization treatment was performed before application to improve the hydrogenation effect of the catalysts. Pre-sulfurization was carried out using a 10 mL high-temperature, high-pressure hydrogenation microreactor, which was a wet in-situ pre-sulfurization process. That is, wet pre-sulfurization was used, and the catalyst was not removed after pre-sulfurization; the hydrogenation reaction continued directly in the reactor. The pre-sulfurization oil was a n-decane solution containing 5% by weight CS2. The pre-sulfurization temperature was 320°C, the pressure was 4 MPa, and the liquid hourly space velocity (LHSV) was 1.5 h⁻¹. -1 The hydrogen-to-oil volume ratio is 300.

[0155] The hydrotreating in this test case was performed using a 10 mL high-temperature, high-pressure hydrotreating microreactor. The evaluation feedstock was Daqing catalytic cracking diesel, whose specific gravity (d4) was...20 The concentration of phosphorus was 0.8894, the sulfur content was 1178 ppm, and the total nitrogen content was 915 ppm. The feedstock was pumped in using a plunger pump. After reaction, the oil sample was cooled in a high-pressure separator and then collected and analyzed in a low-pressure separator. The hydrotreating temperature was 300℃, the pressure was 4 MPa, and the liquid hourly space velocity was 4.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 600. The evaluation results of the catalyst after hydrotreating are shown in Table 3.

[0156] The sulfur and nitrogen contents of the reactants and products were obtained by ultraviolet fluorescence detection and chemiluminescence detection methods.

[0157] Desulfurization rate (mol%) = (Sulfur content of raw material - Sulfur content of product) / Sulfur content of raw material × 100%;

[0158] Denitrification rate (mol%) = (raw material nitrogen content - product nitrogen content) / raw material nitrogen content × 100%.

[0159] Table 3

[0160]

[0161]

[0162] Based on the data in Table 3 above, it can be seen that:

[0163] (1) Comparing catalysts TC-1 with D-1, TC-2 with D-2, and TC-3 with D-3, it can be seen that the titanium-modified hydrorefining catalysts TC-1 to TC-3 prepared in Examples 1 to 3 have higher desulfurization and denitrification rates in the catalytic cracking diesel hydrorefining reaction.

[0164] (2) Comparing Examples 1 to 4 with Comparative Example 4, it can be seen that the composition of catalyst D-4 prepared in Comparative Example 4 is not within the range of "50 to 80% by weight of support, 10 to 40% by weight of main active metal component, 1 to 15% by weight of first auxiliary active metal component and 1 to 30% by weight of second auxiliary active metal component". Compared with D-4, catalysts TC-1 to TC-4 prepared in Examples 1 to 4 have higher desulfurization and denitrification rates in catalytic cracking diesel hydrotreating reaction.

[0165] (3) Comparing Example 1 and Example 4, it can be seen that the preparation conditions of the catalyst preparation process in Example 4 are not within the scope of this disclosure. Compared with the catalyst TC-4 prepared in Example 4, the catalyst TC-1 prepared in Example 1 has a higher desulfurization rate and denitrification rate in the catalytic cracking diesel hydrogenation reaction.

[0166] (4) Comparing Example 1 and Example 5, it can be seen that the component content of the catalyst TC-1 prepared in Example 1 is within the preferred range of this disclosure. Compared with the catalyst TC-5 prepared in Example 5, the catalyst TC-1 prepared in Example 1 has a higher desulfurization rate and denitrification rate.

[0167] (5) Comparing Example 1 with Example 6, it can be seen that the catalyst prepared in Example 1 according to the preferred reaction conditions of this disclosure has a higher desulfurization rate and denitrification rate than the catalyst TC-6 prepared in Example 6.

[0168] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0169] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0170] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A titanium-modified hydrorefining catalyst, characterized in that, Based on the total weight of the titanium-modified hydrorefining catalyst, the titanium-modified hydrorefining catalyst comprises 50-80 wt% of a support, 10-40 wt% of a main active metal component, 1-15 wt% of a first co-active metal component, and 1-30 wt% of a second co-active metal component; the main active metal component is selected from one or more Group VIB metals, the first co-active metal component is selected from one or more Group VIII metals, and the second co-active metal component includes titanium; the support comprises alumina; the titanium-modified hydrorefining catalyst contains Ti. 3+ Species; Ti 2p in the titanium-modified hydrorefining catalyst 3 / 2 In the XPS spectrum of the orbital, based on the peak area of ​​all titanium elements, the Ti 3+ The peak area of ​​the species accounts for 3-40%; The titanium-modified hydrorefining catalyst was prepared by a method comprising the following steps: S1. Mix the main active metal component precursor, the first auxiliary active metal component precursor, the second auxiliary active metal component precursor, water and alumina precursor, and perform aging treatment to obtain a catalyst intermediate. The metal element of the main active metal component precursor is selected from one or more of the group VIB metal elements, the metal element of the first auxiliary active metal component precursor is selected from one or more of the group VIII metal elements, and the second auxiliary active metal component precursor includes a hydrolyzable titanium-containing compound. S2. The catalyst intermediate is mixed with the additives and then subjected to molding and calcination. In step S1, the aging treatment conditions include: natural aging at 0~50℃ for 12~24h; in step S2, the calcination treatment conditions include: calcination at 300~700℃ for 3~10h; the calcination atmosphere is one or more of air, nitrogen, oxygen, argon and water vapor.

2. The titanium-modified hydrorefining catalyst according to claim 1, characterized in that, The primary active metal component comprises an oxide of one or two metal elements selected from Mo and W; the first auxiliary active metal component comprises an oxide of one or two metal elements selected from Ni and Co; and the second auxiliary active metal component comprises an oxide of titanium.

3. The titanium-modified hydrorefining catalyst according to claim 1, characterized in that, The total acid content of the titanium-modified hydrogenation refining catalyst, as determined by pyridine infrared spectroscopy at 150℃, was 140~190 μmol / g, and the Brønsted acid center content was less than 10 μmol / g.

4. The titanium-modified hydrorefining catalyst according to claim 1, characterized in that, The titanium-modified hydrorefining catalyst has a BET specific surface area of ​​150-250 m². 2 / g, total pore volume greater than 0.4cm³ 3 / g.

5. The titanium-modified hydrorefining catalyst according to claim 1, characterized in that, Ti 2p in the titanium-modified hydrorefining catalyst 3 / 2 In the XPS spectrum of the orbital, based on the peak area of ​​all titanium elements, the Ti 3+ The peak area of ​​species accounts for 8-20%.

6. The titanium-modified hydrorefining catalyst according to claim 1, characterized in that, The main active metal component precursor is selected from one or more of molybdenum metal precursor and tungsten metal precursor; The first auxiliary active metal component precursor is selected from one or more of nickel metal precursors and cobalt metal precursors; The second auxiliary active metal component precursor is selected from one or more of titanium tetrachloride, methyl titanate, tetraethyl titanate, titanium n-propoxide, isopropyl titanate, tetrabutyl titanate, titanium tert-butoxide, and titanium isooctoxide. The alumina precursor is selected from one or more of boehmite, aluminum hydroxide, and aluminum nitrate.

7. The titanium-modified hydrorefining catalyst according to claim 6, characterized in that, The molybdenum metal precursor is selected from one or more of sodium molybdate, ammonium molybdate, molybdenum chloride, and molybdic acid; the tungsten metal precursor is selected from one or more of ammonium metatungstate, phosphotungstic acid, and silicotungstic acid. The nickel metal precursor is selected from one or more of nickel nitrate, basic nickel carbonate, and nickel sulfate; the cobalt metal precursor is selected from one or more of cobalt sulfate, cobalt carbonate, cobalt oxalate, and cobalt nitrate. The second auxiliary active metal component precursor is selected from one or more of tetraethyl titanate, isopropyl titanate, and tetrabutyl titanate; The alumina precursor is boehmite.

8. The titanium-modified hydrorefining catalyst according to claim 7, characterized in that, The molybdenum metal precursor is ammonium molybdate; the tungsten metal precursor is ammonium metatungstate and / or phosphotungstic acid; The nickel metal precursor is basic nickel carbonate and / or nickel nitrate; the cobalt metal precursor is cobalt nitrate and / or cobalt oxalate.

9. The titanium-modified hydrorefining catalyst according to claim 1, characterized in that, The method also includes drying the product obtained from the aging treatment at 80~160℃ for 4~12h.

10. The titanium-modified hydrorefining catalyst according to claim 1, characterized in that, Before the roasting process, the product obtained from the molding process is dried at 80~160℃ for 4~12h.

11. The application of the titanium-modified hydrorefining catalyst according to any one of claims 1 to 10 in the hydrorefining reaction of feedstock oil.

12. The application according to claim 11, characterized in that, Includes the following steps: Under hydrogen-containing conditions, the feedstock oil is brought into contact with the titanium-modified hydrorefining catalyst to carry out a hydrorefining reaction.

13. The application according to claim 12, characterized in that, The conditions for the hydrorefining reaction include: a reaction temperature of 260-380℃; a hydrogen pressure of 4-10 MPa; a hydrogen-to-oil volume ratio of 300-800:1; and a feedstock mass hourly space velocity of 0.1-6 h⁻¹. -1 .

14. The application according to claim 12, characterized in that, The feedstock is selected from gasoline and / or diesel fractions.

15. The application according to claim 12, characterized in that, The method further includes: subjecting the titanium-modified hydrorefining catalyst to sulfidation treatment prior to the hydrorefining reaction.

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