CN107051467A - A kind of preparation method of additive modification ternary metal unsupported catalyst - Google Patents

Abstract

The invention relates to a preparation method of an auxiliary agent modified ternary metal non-supported catalyst, which is to introduce two different auxiliary agents in the process of preparing the non-supported catalyst by the co-precipitation method, and combine the active component and the auxiliary agent , that is, adding different molecular weight polyethylene glycol (PEG) and diatomaceous earth to the mixed solution of nickel molybdate and ammonium metatungstate as dispersant surfactant (wherein the molecular weight of PEG is between 100-10000) and dispersion agent. The preparation method of the modified non-supported catalyst of the present invention can effectively improve the dispersion of the active metal component and the hydrogenation performance of the catalyst, significantly improve the mechanical strength of the non-supported catalyst, and at the same time ensure that the modified catalyst is After the hydrogenation reaction, it meets the strict requirements of the national standard for deep desulfurization of diesel oil.

Description

A kind of preparation method of additive modified ternary metal non-supported catalyst

technical field

The invention relates to a preparation method of an auxiliary agent modified ternary metal non-supported catalyst, and the catalyst can be widely used in the hydrogenation refining of diesel oil.

Background technique

With the continuous development of my country's economy, the scale of vehicle fuel consumption is increasing, the pollution to the environment is increasing, and the people's voice for environmental protection is increasing day by day. Therefore, more and more attention is paid to the research and development of technologies related to clean fuels for vehicles in China, and the sulfur content standards for clean fuels for vehicles are becoming increasingly stringent. At present, the national V standard has been adopted, and the sulfur content is strictly required to be below 10ppm.

At present, there are mainly two types of hydrodesulfurization catalysts: supported catalysts and unsupported catalysts; among them, supported catalysts are widely used in industry, and the active components are often loaded on γ-Al ₂ O ₃ or molecular sieves. Drying, calcination, molding and other steps can obtain the supported catalyst, but the supported catalyst has its own insurmountable shortcomings, such as the limitation of the catalyst by the active metal loading and the influence of the carrier, the active metal density is small, the active center is not concentrated enough, etc. The hydrogenation activity is limited to some extent. Therefore, in recent years, more and more attention has been paid to non-supported hydrodesulfurization catalysts, the research has been deepened, and many gratifying results have been obtained. US6299760B1 introduced that this kind of non-supported catalyst adopts solid surface reaction technology to prepare metal composite oxide with suitable specific surface area and mesoporous structure, and prepares non-supported metal sulfide hydrogenation catalyst through presulfurization. EP0469675 introduces a method for preparing a supported catalyst. The carrier used is a mixture of porous alumina, porous molecular sieve and amorphous aluminum silicate, and the pore structure of the obtained catalyst is relatively developed. CN101255356 has introduced a kind of preparation method of the non-supported catalyst that is used for deep hydrofinishing of middle distillate oil, through urea melting reaction, obtains a kind of catalyst particle thing that itself has nanometer channel and higher specific surface area, and this catalyst has abundant Catalytic hydrogenation active sites.

However, the above-mentioned catalysts also have their own disadvantages, such as poor mechanical strength of the catalyst, low metal recovery rate in the preparation process, and high price. Therefore, it is necessary to develop a new preparation method to improve the performance of unsupported catalysts.

Contents of the invention

The purpose of the present invention is to improve the disadvantages of poor dispersion of catalyst metal active components, underdeveloped pore structure and poor mechanical strength in the existing non-supported catalyst preparation technology. Increase the metal utilization rate of the catalyst and improve its hydrogenation reaction activity.

Its specific preparation scheme is as follows:

Two kinds of VIB group metal compounds are selected as active component materials, dissolved in a certain amount of deionized water to form solution A, and the solution A is adjusted to an appropriate pH range of 8-11 with a precipitating agent; nickel with certain water solubility is selected Salt is the raw material of the catalyst-promoting component, which is dissolved in a certain amount of deionized water to form solution B; adding solution B to solution A, it can be seen that a precipitate is formed; stir the suspension containing the precipitate at 70-100°C for 3-8 hours, and the stirring process Add polyethylene glycol (PEG) and diatomaceous earth to the mixture to make the active components compound completely. After the stirring is completed, let the solution stand at a constant temperature, and perform aging treatment on it for 4-168 hours; after the aging process, the suspension is suction filtered, and removed Wash the filter cake with ion water, dry the filter cake in a constant temperature infrared drying oven for 4-32 hours to obtain a catalyst precursor; after roasting and reduction in the device, a non-supported catalyst with good hydrodesulfurization activity can be obtained.

The selected water-soluble nickel source can be one of nickel nitrate, nickel acetate, nickel chloride and nickel sulfate, and the two VIB group metal compounds are ammonium salts of Mo, W or Cr.

The metal molar ratio of the catalytic promoter component Ni to the two VIB group active components is 1:1:1-4:1:1.

The selected precipitant is one of ammonia water, sodium carbonate, sodium bicarbonate and sodium hydroxide.

The method of adding solution B to solution A is to add dropwise or at one time. When adding dropwise, use the same temperature or different temperature to add dropwise; the way to add polyethylene glycol to the solution is to add slowly or at one time, and add slowly When adding diatomaceous earth, it is poured in at the same temperature or at different temperatures; when diatomite is added to the solution, it is added slowly or at one time, and when it is added slowly, it is poured in at the same temperature or at different temperatures.

The time for the hydrothermal aging is 6-10 hours.

Carry out calcination treatment on the catalyst precursor, the calcination temperature is 300-500 ℃, and the calcination time is 2-6h. After the calcination, the corresponding oxidation state catalyst is obtained; the oxidization state catalyst is subjected to in-vessel sulfuration reduction, and the reduction pressure is 2-4MPa. The temperature is 200-400°C, the space velocity is 1-4h ^-1 , the volume ratio of hydrogen to oil is 200-700, the reduction time is 4-24h, and the corresponding sulfided catalyst is obtained after the reduction process is completed.

The molecular weight of the polyethylene glycol is 100-10000.

The added amount of diatomaceous earth accounts for 10%-30% of the total mass of the catalyst.

The advantages and effects of the present invention are as follows:

The specific surface area of the non-supported ternary metal catalyst prepared by the invention is 70-120m ² /g, the pore volume is 0.15-0.19cm ³ /g, and the average pore diameter is 5.6-6.7nm. The catalyst particle size is fine, the metal utilization rate is high, and the hydrodesulfurization reaction activity is good. The preparation process of the catalyst is simple, easy to operate, and the preparation conditions are mild, which is beneficial to industrial production and application.

The non-supported Ni-based catalyst prepared by the invention is used in diesel oil hydrogenation desulfurization reaction to improve the removal rate of sulfide in diesel oil. Through the catalytic hydrogenation reaction, the sulfide molecules in diesel can be converted into hydrogen sulfide to the greatest extent, which can significantly improve the desulfurization rate of diesel and meet the increasingly stringent national standards for sulfur content in diesel.

Description of drawings

Figure 1 is a schematic diagram of the morphology of the catalyst after adding additives.

detailed description

The present invention will be described in depth below in conjunction with examples.

Example 1

Weigh 9.954g of nickel acetate tetrahydrate, 5.071g of ammonium heptamolybdate, and 3.531g of ammonium metatungstate according to the metal molar ratio of Ni:Mo:W=2:1:1. Pour 5.071g of ammonium heptamolybdate and 3.531g of ammonium metatungstate into a three-necked flask with a capacity of 500ml, and completely dissolve them with 300ml of deionized water at 50°C to obtain solution A. Use ammonia water as the precipitating agent to adjust the pH of solution A to 9, and heat the temperature of solution A to 90° C. in a water bath. Pour nickel acetate tetrahydrate into a beaker and dissolve in 20ml of deionized water to obtain solution B. At the same temperature, slowly change solution B and drop it into solution A, and it can be seen that a precipitate is gradually formed. After the dropwise addition, the solution was stirred at 90° C. for 5 h to fully compound the active components. During the stirring process, 1.856 g of polyethylene glycol C and 1.523 g of diatomaceous earth D were respectively added to the solution. After the stirring was completed, the suspension was allowed to stand for hydrothermal aging treatment, and the aging time was 2 hours. After aging, the suspension was filtered with suction, and the filter cake was washed. The filter cake was placed in an infrared drying oven and dried at 120° C. for 12 hours to obtain a catalyst precursor. The precursor is calcined at a calcining temperature of 450° C. for a calcining time of 4 hours to obtain an oxidized catalyst. The calcined catalyst is pressed into tablets and sieved, and 20-40 mesh particles are selected and loaded into the reactor. Under the conditions of 4MPa, 350°C, 2h ^-1 , and G/L=500, the catalyst was subjected to in-vessel sulfide reduction, and the obtained catalyst had a specific surface area of 79m ² /g, a pore volume of 0.14cm ³ /g, and an average pore diameter of 5.5nm.

Example 2

Weigh 11.632g of nickel nitrate hexahydrate, 5.071g of ammonium heptamolybdate, and 3.531g of ammonium metatungstate according to the metal molar ratio of Ni:Mo:W=2:1:1. Pour the Mo and W compounds into a three-necked flask with a capacity of 500ml, and completely dissolve them with 300ml of deionized water at 50°C to obtain solution A. Use ammonia water as the precipitating agent to adjust the pH of solution A to 9, and heat the temperature of solution A to 90° C. in a water bath. Pour nickel nitrate hexahydrate into a beaker and dissolve in 20ml deionized water to obtain solution B. At the same temperature, slowly change solution B and drop it into solution A, and it can be seen that a precipitate is gradually formed. After the dropwise addition, the solution was stirred at 90° C. for 5 h to fully compound the active components. During the stirring process, 2.023 g of polyethylene glycol C and 4.047 g of diatomaceous earth D were respectively added to the solution. After the stirring was completed, the suspension was allowed to stand for hydrothermal aging treatment, and the aging time was 2 hours. After aging, the suspension was filtered with suction, and the filter cake was washed. The filter cake was placed in an infrared drying oven and dried at 110° C. for 12 hours to obtain a catalyst precursor. The precursor is calcined at a calcining temperature of 450° C. for a calcining time of 4 hours to obtain an oxidized catalyst. The calcined catalyst is pressed into tablets and sieved, and 20-40 mesh particles are selected and loaded into the reactor. Under the conditions of 4MPa, 360°C, 2h ^-1 , and G/L=500, the catalyst was subjected to in-vessel sulfide reduction, and the obtained catalyst had a specific surface area of 86m ² /g, a pore volume of 0.15cm ³ /g, and an average pore diameter of 5.8nm.

Example 3

Weigh 9.520g of nickel chloride hexahydrate, 5.071g of ammonium heptamolybdate, and 3.531g of ammonium metatungstate according to the metal molar ratio of Ni:Mo:W=2:1:1. Pour the Mo and W compounds into a three-necked flask with a capacity of 500ml, and completely dissolve them with 300ml of deionized water at 50°C to obtain solution A. Use ammonia water as the precipitating agent to adjust the pH of solution A to 9, and heat the temperature of solution A to 90° C. in a water bath. Pour nickel chloride hexahydrate into a beaker and dissolve in 20ml deionized water to obtain solution B. At the same temperature, slowly change solution B and drop it into solution A, and it can be seen that a precipitate is gradually formed. After the dropwise addition, the solution was stirred at 90° C. for 5 h to fully compound the active components. During the stirring process, 1.812 g of polyethylene glycol C and 3.624 g of diatomaceous earth D were respectively added to the solution. After the stirring was completed, the suspension was allowed to stand for hydrothermal aging treatment, and the aging time was 2 hours. After aging, the suspension was filtered with suction, and the filter cake was washed. The filter cake was placed in an infrared drying oven and dried at 110° C. for 12 hours to obtain a catalyst precursor. The precursor is calcined at a calcining temperature of 450° C. for a calcining time of 4 hours to obtain an oxidized catalyst. The calcined catalyst is pressed into tablets and sieved, and 20-40 mesh particles are selected and loaded into the reactor. Under the conditions of 4MPa, 360°C, 2h ^-1 , G/L=500, the catalyst was subjected to in-vessel sulfide reduction. The obtained catalyst had a specific surface area of 95m ² /g, a pore volume of 0.15cm ³ /g, and an average pore diameter of 6.0nm.

Example 4

Weigh 9.520g of nickel chloride hexahydrate, 5.071g of ammonium heptamolybdate, and 3.531g of ammonium metatungstate according to the metal molar ratio of Ni:Mo:W=2:1:1. Pour the Mo and W compounds into a three-necked flask with a capacity of 500ml, and completely dissolve them with 300ml of deionized water at 50°C to obtain solution A. Use ammonia water as the precipitating agent to adjust the pH of solution A to 9, and heat the temperature of solution A to 90° C. in a water bath. Pour nickel chloride hexahydrate into a beaker and dissolve in 20ml deionized water to obtain solution B. At the same temperature, slowly change solution B and drop it into solution A, and it can be seen that a precipitate is gradually formed. After the dropwise addition, the solution was stirred at 90° C. for 5 h to fully compound the active components. During the stirring process, 1.812 g of polyethylene glycol C and 3.624 g of diatomaceous earth D were respectively added to the solution. After the stirring was completed, the suspension was allowed to stand for hydrothermal aging treatment, and the aging time was 4 hours. After aging, the suspension was filtered with suction, and the filter cake was washed. The filter cake was placed in an infrared drying oven and dried at 110° C. for 12 hours to obtain a catalyst precursor. The precursor is calcined at a calcining temperature of 450° C. for a calcining time of 4 hours to obtain an oxidized catalyst. The calcined catalyst is pressed into tablets and sieved, and 20-40 mesh particles are selected and loaded into the reactor. Under the conditions of 4MPa, 360°C, 2h ^-1 , and G/L=500, the catalyst was subjected to in-vessel sulfide reduction. The obtained catalyst had a specific surface area of 108m ² /g, a pore volume of 0.17cm ³ /g, and an average pore diameter of 6.4nm.

Example 5

This example illustrates the preparation of a comparative catalyst.

Weigh 9.954g of nickel acetate tetrahydrate, 5.071g of ammonium heptamolybdate, and 3.531g of ammonium metatungstate according to the metal molar ratio of Ni:Mo:W=2:1:1. Pour the Mo and W compounds into a three-necked flask with a capacity of 500ml, and completely dissolve them with 300ml of deionized water at 50°C to obtain solution A. Use ammonia water as the precipitating agent to adjust the pH of solution A to 9, and heat the temperature of solution A to 90° C. in a water bath. Pour nickel acetate tetrahydrate into a beaker and dissolve with an appropriate amount of deionized water to obtain solution B. At the same temperature, slowly change solution B and drop it into solution A, and it can be seen that a precipitate is gradually formed. During the stirring process, 1.856 g of polyethylene glycol C and 3.711 g of diatomaceous earth D were added to the solution respectively. After the dropwise addition was completed, the solution was stirred at 90°C for 5 hours to fully compound the active components. After the stirring was completed, the suspension was filtered with suction, and the filter cake was washed. The filter cake was placed in an infrared drying oven and dried at 110° C. for 12 hours to obtain a catalyst precursor. The precursor is calcined at a calcining temperature of 450° C. for a calcining time of 4 hours to obtain an oxidized catalyst. The calcined catalyst is pressed into tablets and sieved, and 20-40 mesh particles are selected and loaded into the reactor. Under the conditions of 4MPa, 360°C, 2h ^-1 , and G/L=500, the catalyst was subjected to in-vessel sulfide reduction, and the obtained catalyst had a specific surface area of 72m ² /g, a pore volume of 0.13cm ³ /g, and an average pore diameter of 5.2nm.

Example 6

This example illustrates the evaluation method of the catalyst of the present invention

The activity evaluation of the catalyst was carried out on a 20ml high-pressure micro-hydrogenation reaction device. The evaluation raw material is Dalian Xitai Catalytic Cracking Diesel Oil. The raw material is pumped in by a gear pump. After the product is separated into gas and liquid by the cold high-separator and low-pressure separator, the liquid product is connected to the collection tank. After the pre-vulcanization process was completed, the temperature was lowered to 280°C, and the evaluation raw materials were pumped in. Samples were collected 6 hours after the reaction was stable, and samples were collected every 3 hours. The activity evaluation results of several catalysts added with different molecular weight PEG are shown in Table 1.

Example 7

The molar ratio of the catalyst-promoting component Ni to the two VIB group active components is 1:1:1. The selected precipitating agent is sodium bicarbonate, and the precipitating agent adjusts solution A to an appropriate pH range of 11. The way of adding solution B to solution A is one-time addition; the way of adding polyethylene glycol to the solution is one-time addition; the way of adding diatomaceous earth to the solution is one-time addition. The time for the hydrothermal aging is 6 hours. The catalyst precursor was calcined at a temperature of 300 °C and the roasting time was 2 hours. After the roasting was completed, the corresponding catalyst in an oxidized state was obtained; the catalyst in an oxidized state was subjected to in-vehicle sulfidation reduction at a reduction pressure of 2 MPa and a temperature of 200 °C. The speed is 1h ^-1 , the volume ratio of hydrogen to oil is 200:1, and the reduction time is 4h. After the reduction process, the corresponding sulfided catalyst is obtained. The molecular weight of the polyethylene glycol is 100-10000. The added amount of diatomaceous earth accounts for 10% of the total mass of the catalyst. Other steps are the same as in Example 1.

Example 8

The molar ratio of the catalyst-promoting component Ni to the two VIB group active components is 4:1:1. The selected precipitating agent is sodium carbonate, and the precipitating agent adjusts solution A to an appropriate pH value of 8. The way of adding solution B to solution A is to add dropwise at the same temperature; the way to add polyethylene glycol to the solution is to add slowly at the same temperature; the way to add diatomaceous earth to the solution is to add slowly at the same temperature. The time for the hydrothermal aging is 10 hours. The catalyst precursor was calcined at a temperature of 500°C for 6 hours, and the corresponding catalyst in an oxidized state was obtained after the calcination; the catalyst in an oxidized state was subjected to in-vessel sulfidation reduction at a reduction pressure of 4 MPa and a temperature of 400°C in air. The speed is 4h ^-1 , the volume ratio of hydrogen to oil is 700:1, and the reduction time is 24h. After the reduction process, the corresponding sulfided catalyst is obtained. The molecular weight of the polyethylene glycol is 100-10000. The added amount of diatomaceous earth accounts for 30% of the total mass of the catalyst. Other steps are the same as in Example 1.

Example 9

The suspension containing the precipitate was stirred at 70° C. for 3 hours, and aged for 4 hours; the filter cake was dried in a constant temperature infrared drying oven for 4 hours; other steps were the same as in Example 1.

Example 10

The suspension containing the precipitate was stirred at 100° C. for 8 hours, and aged for 18 hours; the filter cake was dried in a constant temperature infrared drying oven for 32 hours. Other steps are the same as in Example 1. Other steps are the same as in Example 1.

Invention effect:

Compared with the existing conventional non-supported catalyst preparation method, the obvious technical feature of the present invention is that a suitable nickel source is selected in the process of preparing the non-supported catalyst by the co-precipitation method, and two kinds of additives are introduced respectively. The addition of the two kinds of additives makes the prepared non-supported catalyst particles uniform, orderly arranged, more developed pore structure, correspondingly increased metal utilization, significantly improved hydrodesulfurization activity, and a desulfurization rate close to 100%. At the same time, the invention has strong operability, mild preparation conditions, and is suitable for large-scale production in batches and industrial application.

Table 1 Bulk density and desulfurization rate of Ni-Mo-W unsupported catalysts added with different molecular weight PEG

Claims (9)

1. A preparation method for an auxiliary agent modified ternary metal non-supported catalyst, characterized in that it may further comprise the steps: Two kinds of VIB group metal compounds are selected as active component materials, dissolved in a certain amount of deionized water to form solution A, and the solution A is adjusted to an appropriate pH range of 8-11 with a precipitating agent; nickel with certain water solubility is selected Salt is the raw material of the catalyst-promoting component, which is dissolved in a certain amount of deionized water to make solution B; adding solution B to solution A, it can be seen that a precipitate is formed; stir the suspension containing the precipitate at 70-100°C for 3-8 hours, and stir During the process, polyethylene glycol (PEG) and diatomaceous earth are added to make the active components compound completely. After the stirring is completed, the solution is left to stand at a constant temperature, and it is subjected to aging treatment for 4-18 h; after the aging process is completed, the suspension is filtered with suction, and Wash the filter cake with deionized water, dry the filter cake in a constant temperature infrared drying oven for 4-32 hours to obtain a catalyst precursor; after roasting and reduction in a device, a non-supported catalyst with good hydrodesulfurization activity can be obtained. 2. preparation method according to claim 1 is characterized in that, the selected water-soluble nickel source can be the one in nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, and two kinds of VIB group metal compounds are Mo , Ammonium salt of W or Cr. 3. The preparation method according to claim 1, characterized in that the metal molar ratio of the catalytic promoter component Ni and the two VIB group active components is 1:1:1-4:1:1. 4. preparation method according to claim 1 is characterized in that, the selected precipitation agent is the one in ammoniacal liquor, sodium carbonate, sodium bicarbonate and sodium hydroxide. 5. preparation method according to claim 1 is characterized in that, the mode that solution B adds solution A is to add dropwise or one-time addition, when adding dropwise, adopt same temperature or different temperature dropwise; Polyethylene glycol The way to add the solution is to add slowly or at one time. When adding slowly, use the same temperature or different temperature to pour in; Pour warm or different temperature. 6. The preparation method according to claim 1, characterized in that, the hydrothermal aging time is 6-10 h. 7. The preparation method according to claim 1, characterized in that the catalyst precursor is subjected to roasting treatment, the roasting temperature is 300-500 ° C, the roasting time is 2-6 h, and the corresponding oxidation state catalyst is obtained after roasting; In-vehicle sulfidation reduction is carried out on the oxidized catalyst, the reduction pressure is 2-4 MPa, the temperature is 200-400 ℃, the space velocity is 1-4 h ^-1 , the hydrogen-oil volume ratio is 200-700:1, and the reduction time is 4 -24 h, the corresponding sulfided catalyst was obtained after the reduction process. 8. The preparation method according to claim 1, characterized in that, the molecular weight of the polyethylene glycol is 100-10000. 9. The preparation method according to claim 1, characterized in that, the added amount of diatomaceous earth accounts for 10%-30% of the total mass of the catalyst.