A pre-reduced type hydrofining catalyst and a method for preparing the same

Abstract

The present application belongs to the technical field of hydrogenation catalyst preparation, and particularly relates to a preparation technology of a pre-reduction type hydrogenation catalyst. The preparation method of the catalyst comprises catalyst impregnation, catalyst drying and catalyst pre-reduction. The hydrogenation catalyst carrier prepared by the method is composed of an alumina carrier, active metals and a reducing agent. The pre-reduction type catalyst is not easy to be oxidized in air, and when sulfidation, part of the active metals are reduced into low-valence metals, so that the metals are more easily sulfidized into activity, which is beneficial to the generation of more active sites. Compared with the catalyst prepared by the traditional method, the catalyst shows excellent hydrogenation desulfurization and denitrification capacity.

Description

Technical Field

[0001] This invention belongs to the field of hydrogenation catalyst technology, specifically relating to a pre-reduction catalyst preparation technology. This method can be used to prepare catalysts for the hydrorefining of middle distillate oils, and the prepared catalysts have excellent hydrodesulfurization and denitrification capabilities. Background Technology

[0002] Currently, with increasing societal energy demand and dwindling petroleum resources, oil products are becoming increasingly heavy and of lower quality. Simultaneously, facing increasingly stringent environmental regulations, developing more advanced oil cleaning technologies has been a relentless pursuit in the refining and chemical industry. Catalytic hydrotreating to remove sulfur, nitrogen, and saturated aromatics from feedstocks is one of the most commonly used oil cleaning methods.

[0003] The activity of widely used industrial hydrorefining catalysts is typically determined by the active metal, which is generally a Group VIB metal such as Mo and W, or a Group VIII metal such as Co and Ni bimetals. These metals work synergistically to achieve good refining activity. Therefore, designing and improving the synergistic effect between active metals has always been a focus of research in catalyst development. Among existing technologies, Chinese patent CN 106457236B discloses a method for preparing a hydrorefining catalyst. This patent develops a silica-alumina composite support through modification and structural optimization, and then loads Group VIB and Group VIII metals and organic additives onto this support to prepare a catalyst that is highly effective for the hydrorefining of hydrocarbon oils. Chinese patent CN1289828A discloses an oil hydrorefining catalyst, using alumina or silica-containing alumina as a support, and adding W, Mo, and Ni as active components and phosphorus additives. By employing a segmented co-impregnation technique, the metal distribution on the catalyst is more uniform, and the catalyst activity, especially the hydrodenitrification activity, is significantly improved. Chinese patent CN107297209B discloses a method for preparing a hydrotreating catalyst. The catalyst is prepared through steps including support preparation, partial active metal impregnation, drying and calcination, reduction in a high-pressure reactor, secondary impregnation, secondary drying, and calcination. The resulting catalyst exhibits a gradual increase in the active component from the catalyst center to the outer surface.

[0004] Existing technologies involve complex preparation processes and increased costs. Furthermore, the prepared supports or catalysts often have defects, such as limited pore volume or pore blockage, ultimately affecting catalyst performance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a simplified method for preparing a hydrotreating catalyst. Compared to catalysts prepared using traditional methods, the catalyst prepared by this method is simpler and faster, eliminating the lengthy calcination step, thus saving energy and reducing production costs. Furthermore, this method can weakly reduce Group VIB metals, allowing these metal components to preferentially convert to the sulfided state during sulfidation, forming more intrinsic active sites for hydrodesulfurization and hydrodenitrogenation, thereby exhibiting better hydrodesulfurization and denitrogenation capabilities.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The method for preparing the hydrogenation catalyst includes:

[0008] (1) Prepare or select an alumina support;

[0009] (2) Dissolve the metal precursor salt, inorganic auxiliaries and organic reducing agents in an aqueous solution;

[0010] (3) The aqueous solution obtained in (2) is impregnated in the carrier in an equal volume and aged for a period of time;

[0011] (4) The catalyst precursor obtained in (3) is dried to remove moisture, and then the catalyst is microwave-reduced by microwave rapid dehydration method to obtain the shaped catalyst.

[0012] In step (2), the metal precursor salt forms include one or more of oxides, hydroxides, nitrates, carbonates, and organic acid salts;

[0013] Preferably, the metal precursor salt in step (2) contains metal elements A and B, wherein A is one or both of molybdenum and tungsten, and B is one or both of cobalt and nickel;

[0014] Preferably, the inorganic additive in step (2) comprises one or two of phosphoric acid, organic phosphorus, magnesium salt and titanium salt; more preferably, the inorganic additive is mainly one or two of phosphoric acid and magnesium nitrate.

[0015] Preferably, the organic reducing agent in step (2) includes one or two of ethanol, isopropanol, butanol, ethylene glycol, diethylene glycol, triethylene glycol, glycerol, PEG-200 to PEG-400, acetaldehyde, propionaldehyde, and citric acid.

[0016] Preferably, the total mass fraction of the metal precursor salt converted into oxides in step (2) is 15-35 wt% of the total mass of the catalyst, and more preferably, the total mass fraction of the metal oxides is 20-30 wt%.

[0017] Preferably, the drying in step (4) is performed at 80℃~130℃ for 2h~8h; more preferably, the drying temperature in step (4) is 95℃~110℃ for 4h~6h.

[0018] Preferably, the microwave reduction power in step (4) is 500-1000w and the reduction time is 5-15min.

[0019] The newly prepared hydrorefining catalyst comprises, by weight percentage:

[0020] The active metal compounds account for 15 wt% to 35 wt%, with the preferred active metals being two or more of molybdenum, tungsten, nickel, or cobalt; at least 20 wt% of the group VIB metals are converted from a positive hexavalent state to a lower valence reduced state metal.

[0021] The additives account for 0-10 wt%, including one or more of phosphorus, titanium, and magnesium;

[0022] The organic reducing agent and its oxides account for 2 wt% to 12 wt%, and their carbon chains account for 1 wt% to 6 wt% of the total mass of the catalyst.

[0023] The alumina carrier accounts for 50wt%-70wt%;

[0024] The total mass fraction is 100%.

[0025] The physical properties of the catalyst support described in this invention are as follows: specific surface area is 150 m². 2 / g~350m 2 / g, preferably, with a specific surface area of ​​200m². 2 / g~300m 2 / g; pore volume is 0.6mL / g to 1.0mL / g, preferably 0.7mL / g to 0.9mL / g; average pore size is 5nm to 20nm, preferably 10nm to 15nm.

[0026] The physical properties of the catalyst described in this invention are as follows: specific surface area is 50 m². 2 / g~300m 2 / g, preferably, with a specific surface area of ​​150m² 2 / g~250m 2 / g; pore volume is 0.2mL / g to 0.7mL / g, preferably 0.3mL / g to 0.5mL / g; average pore size is 5nm to 20nm, preferably 9nm to 14nm.

[0027] The significant advantages of this invention are:

[0028] This invention provides a method for preparing a hydrotreating catalyst. Compared with catalysts prepared by traditional methods, the catalyst prepared by this method is simple and rapid, eliminating the need for high-temperature calcination, which not only saves energy but also has advantages in reducing production costs. Furthermore, this method can weakly reduce Group VIB metals, allowing the metal components to preferentially convert to the sulfided state during sulfidation, forming more intrinsic active sites for hydrodesulfurization and hydrodenitrogenation, thus exhibiting better hydrodesulfurization and denitrogenation capabilities. Attached Figure Description

[0029] Figure 1 Comparison of the valence states of group VIB metals on the catalyst surface of Example 3 and Comparative Example 1. Detailed Implementation

[0030] To further disclose, and not limit, the present invention, the invention will be further described in detail below with reference to examples.

[0031] The preparation method and application of the present invention will be further described below with reference to specific embodiments. However, the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention.

[0032] Example 1

[0033] Weigh out 8.36g of basic nickel carbonate, 31.88g of molybdenum trioxide, 1.43g of phosphoric acid, and 50g of water to form a slurry. Heat the slurry at 85℃ with stirring until it becomes clear. Add 5.59g of PEG-200 to the mixed metal solution and continue stirring at 85℃ for 2 hours to obtain an active metal impregnation solution. Impregnate the above solution with an equal volume of 100g of alumina support and age for 1 hour. Dry the obtained catalyst at 100℃ for 4 hours, then place it in a vacuum microwave dryer and microwave-heat at 800W for 10 minutes. After cooling to room temperature, remove the catalyst. The prepared catalyst is labeled DN-01.

[0034] Example 2

[0035] Weigh out 8.36g of basic nickel carbonate, 31.88g of molybdenum trioxide, 1.43g of phosphoric acid, and 50g of water to form a slurry. Heat the slurry at 85℃ with stirring until it becomes clear. Add 11.18g of PEG-200 to the mixed metal solution and continue stirring at 85℃ for 2 hours to obtain an active metal impregnation solution. Impregnate the above solution with an equal volume of 100g of alumina support and age for 1 hour. Dry the obtained catalyst at 100℃ for 4 hours, then place it in a vacuum microwave dryer and microwave-heat at 800W for 10 minutes. After cooling to room temperature, remove the catalyst. The prepared catalyst is labeled DN-02.

[0036] Example 3

[0037] Weigh out 8.36g of basic nickel carbonate, 31.88g of molybdenum trioxide, 1.43g of phosphoric acid, and 50g of water to form a slurry. Heat the slurry at 85℃ with stirring until it becomes clear. Add 16.77g of PEG-200 to the mixed metal solution and continue stirring at 85℃ for 2 hours to obtain an active metal impregnation solution. Impregnate the above solution with an equal volume of 100g of alumina support and age for 1 hour. Dry the obtained catalyst at 100℃ for 4 hours, then place it in a vacuum microwave dryer and microwave-heat at 800W for 10 minutes. After cooling to room temperature, remove the catalyst. The prepared catalyst is labeled DN-03.

[0038] Example 4

[0039] Weigh out 8.36g of basic nickel carbonate, 31.88g of molybdenum trioxide, 1.43g of phosphoric acid, and 50g of water to form a slurry. Heat the slurry at 85℃ with stirring until it becomes clear. Add 22.36g of PEG-200 to the mixed metal solution and continue stirring at 85℃ for 2 hours to obtain an active metal impregnation solution. Impregnate the above solution with an equal volume of 100g of alumina support and age for 1 hour. Dry the obtained catalyst at 100℃ for 4 hours, then place it in a vacuum microwave dryer and microwave-heat at 800W for 10 minutes. After cooling to room temperature, remove the catalyst. The prepared catalyst is labeled DN-04.

[0040] Example 5

[0041] Weigh out 8.36g of basic nickel carbonate, 31.88g of molybdenum trioxide, 1.43g of phosphoric acid, and 50g of water to form a slurry. Heat the slurry at 85℃ with stirring until it becomes clear. Add 16.77g of PEG-200 to the mixed metal solution and continue stirring at 85℃ for 2 hours to obtain an active metal impregnation solution. Impregnate the above solution with an equal volume of 100g of alumina support and age for 1 hour. Dry the obtained catalyst at 100℃ for 4 hours, then place it in a vacuum microwave dryer and microwave-heat at 800W for 2 minutes. After cooling to room temperature, remove the catalyst. The prepared catalyst is labeled DN-05.

[0042] Example 6

[0043] Weigh out 8.36g of basic nickel carbonate, 31.88g of molybdenum trioxide, 1.43g of phosphoric acid, and 50g of water to form a slurry. Heat the slurry at 85℃ with stirring until it becomes clear. Add 16.77g of PEG-200 to the mixed metal solution and continue stirring at 85℃ for 2 hours to obtain an active metal impregnation solution. Impregnate the above solution with an equal volume of 100g of alumina support and age for 1 hour. Dry the obtained catalyst at 100℃ for 4 hours, then place it in a vacuum microwave dryer and microwave-heat at 800W for 30 minutes. After cooling to room temperature, remove the catalyst. The prepared catalyst is labeled DN-06.

[0044] Comparative Example 1

[0045] Weigh out 8.36g of basic nickel carbonate, 31.88g of molybdenum trioxide, 1.43g of phosphoric acid, and 50g of water, mix them to form a slurry, and heat the slurry at 85℃ until it becomes clear to obtain an active metal impregnation solution. Impregnate the above solution with 100g of alumina support in an equal volume and age for 1 hour. Dry the obtained catalyst at 100℃ for 4 hours, place it in a vacuum microwave dryer, microwave at 800W power for 10 minutes, cool to room temperature, and remove it. The prepared catalyst is labeled DNC-01.

[0046] Comparative Example 2

[0047] Weigh out 8.36g of basic nickel carbonate, 31.88g of molybdenum trioxide, 1.43g of phosphoric acid, and 50g of water to form a slurry. Heat the slurry at 85℃ with stirring until it becomes clear. Add 11.18g of PEG-200 and the mixed metal solution, and continue stirring at 85℃ for 2 hours to obtain an active metal impregnation solution. Impregnate the above solution with an equal volume of 100g of alumina support and age for 1 hour. Dry the obtained catalyst at 100℃ for 4 hours and cool to room temperature. The resulting catalyst is labeled DNC-02.

[0048] Table 1 Physical properties of the prepared catalysts

[0049]

[0050] The specific surface area results of the catalysts in the examples and comparative examples are shown in Table 1. The results show that the catalysts prepared in Examples 1 to 4 differ only in the content of the organic reducing agent. The specific surface area and pore volume of the catalysts increase with increasing organic reducing agent content, but the average pore size shows the opposite trend. This is because the addition of the organic reducing agent clogs some small and micropores in the catalyst, and the higher the content of the organic reducing agent, the more severe the clogging. The situation is better when no organic reducing agent is added, as seen in the catalyst prepared in Comparative Example 1. However, when the same organic reducing agent is added, the physical properties of the catalyst are also affected by different microwave reduction times. For example, the catalysts prepared in Examples 3, 5, and 6 show that the specific surface area of ​​the catalyst increases with increasing microwave reduction time. This is because increasing the microwave time not only increases the degree of catalyst reduction and dehydration but also causes some organic additives to volatilize. Excessive microwave time can even lead to carbonization of the organic reducing agent. Carbonization increases the specific surface area of ​​the catalyst but correspondingly decreases the pore volume.

[0051] Hydrogenation activity test:

[0052] The above-mentioned catalyst was used to evaluate the deep desulfurization performance of diesel fuel in a high-pressure fixed-bed reactor. The properties of the feedstock are shown in Table 2. After mixing 20 mL of catalyst with 30 mL of quartz sand and loading the reactor, the catalyst was sulfided using an in-reactor wet sulfidation process. The evaluation conditions for the catalyst's relative desulfurization (denitrification) activity were: reaction temperature 370℃, reaction hydrogen pressure 15 MPa, and reaction liquid hourly space velocity 2 h⁻¹. -1 The hydrogen-to-oil ratio was 1000, and samples were taken after 100 hours of reaction. The sulfur content in the feedstock oil was determined using an X-ray fluorescence sulfur analyzer, and the sulfur content in each product oil was detected using a chemiluminescence sulfur analyzer. The nitrogen content was determined using a chemiluminescence nitrogen analyzer. The relative desulfurization activity was calculated using the following formula.

[0053]

[0054] Among them, S f The sulfur (nitrogen) content (percentage) of the feedstock oil; S p The sulfur (nitrogen) content of the oil produced by the hydrorefining of the catalyst in the example; S pr The sulfur (nitrogen) content of the oil produced by the catalyst in Comparative Example 1 is shown.

[0055] The comparison of its hydrodesulfurization activity and relative denitrification activity is shown in Table 3.

[0056] Table 2 Properties of Raw Material Wax Oil

[0057]

[0058] Table 3 Comparison of catalyst activities for hydrodesulfurization and denitrogenation

[0059] catalyst Relative desulfurization activity % Relative denitrification activity % Example 1 / DN-01 108 115 Example 2 / DN-02 113 121 Example 3 / DN-03 110 116 Example 4 / DN-04 106 106 Example 5 / DN-05 105 108 Example 6 / DN-06 108 107 Comparative Example 1 / CHC-1 100 100 Comparative Example 2 / CHC-2 102 103

[0060] Table 3 shows the catalyst activity test results for each embodiment and comparative example. The data in the table indicates that the microwave reduction method only shows its effect in the presence of an organic reducing agent. For example, in Comparative Example 1, the activity is the worst without an organic reducing agent. Adding an organic reducing agent slightly improves the catalyst activity using ordinary drying methods, as in Comparative Example 2. However, when microwave reduction is used, the catalyst activity is significantly improved, as in Example 2. This is because during microwave drying, some molybdenum is reduced from +6 valence to a lower valence state, making it easier to sulfide than nickel, forming more nickel-modified molybdenum sulfide clusters. In the actual preparation of the catalyst of this invention, it is necessary to pay attention to the control of the organic reducing agent content. Too much organic reducing agent will cover the active metal, leading to a reduction in active sites and decreased activity, as seen in the catalysts prepared in Examples 4 and 5. Simultaneously, the degree of reduction also needs to be controlled during microwave reduction. Too short a microwave time will result in insufficient weak metal reduction, while too long a microwave time will lead to carbonization of the organic reducing agent and the metal being reduced to a lower valence state, reaching 0 valence, which will reduce the catalyst activity, as seen in Examples 5 and 6.

[0061] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a pre-reduced hydrorefining catalyst, characterized in that: (1) Preparation or selection of alumina support; (2) Dissolve the metal precursor salt, inorganic auxiliaries and organic reducing agents in an aqueous solution; (3) Impregnate the carrier with the aqueous solution obtained in (2) in equal volume and age it for a period of time; (4) The catalyst precursor obtained in (3) is dried to remove moisture, and then the catalyst is microwave-reduced by microwave rapid dehydration method to obtain the shaped catalyst. In step (2), the metal precursor salt contains metal elements A and B, where A is one or both of molybdenum and tungsten, and B is one or both of cobalt and nickel. In step (2), the inorganic auxiliaries include one or two of phosphoric acid, magnesium salts and titanium salts; In step (2), the organic reducing agent is PEG-200 to PEG-400; In step (4), the microwave reduction power is 500-1000w and the reduction time is 5-15min.

2. The preparation method according to claim 1, characterized in that: In step (2), the metal precursor salt forms include one or more of nitrates, carbonates, and organic acid salts.

3. The preparation method according to claim 1, characterized in that: The total mass fraction of the metal precursor salt converted into oxides in step (2) is 15-35 wt% of the total mass of the catalyst.

4. The preparation method according to claim 1, characterized in that: In step (4), the drying process involves drying at 80℃~130℃ for 2h~8h.

5. The pre-reduced hydrorefining catalyst obtained by the preparation method according to any one of claims 1-4, characterized in that: In the catalyst, at least 20 wt% of the group VIB metals are converted from a positive hexavalent state to a lower valence reduced state.

6. The catalyst according to claim 5, characterized in that: Catalyst weight percentage includes: The active metal compounds account for 15wt% to 35wt%, and the active metals include A and B; The inorganic additives account for 0.5wt% to 10wt%, including one or more of phosphorus, titanium, and magnesium; The organic reducing agent and its oxides account for 2wt% to 12wt%, and their carbon chains account for 1wt% to 6wt% of the total mass of the catalyst. The alumina carrier accounts for 50wt%-70wt%; The total mass fraction is 100%.

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