CN101260320A - Catalyst for selective hydrodeolefination of gasoline for continuous reforming and preparation method thereof - Google Patents

Abstract

A catalyst for selective hydrodeolefination of continuously reformed gasoline and its preparation method, the method belongs to the improvement of hydrofinishing catalysts for petroleum hydrocarbon products, specifically, it is mainly used for selective hydrodeolefination of continuously reformed gasoline Catalysts for the hydrorefining of olefins. The remarkable feature of this catalyst is that the precious metal active components are distributed in an eggshell shape on the carrier, and its advantage is that on the one hand, the utilization rate of the precious metal active components is significantly improved, and the content of the precious metal active components is significantly reduced (compared with the original technology. reduced by 1 times), significantly reduced the cost of the catalyst (in the manufacturing cost of supported noble metal catalysts, noble metals account for more than 90%); on the other hand significantly reduced the activity of aromatics hydrogenation, improved the selectivity of olefin hydrogenation, reduced Aromatic hydrogenation loss.

Description

Catalyst for selective hydrodeolefination of gasoline for continuous reforming and preparation method thereof

technical field

The invention relates to a catalyst for selective hydrogenation of gasoline for continuous reforming and a preparation method thereof. The method belongs to the improvement of hydrofinishing catalysts for petroleum hydrocarbon products, specifically, it is mainly used for selective hydrogenation of gasoline for continuous reforming. Hydrofinishing catalysts for hydrodeolefins.

Background technique

The main function of the catalyst for catalytic continuous reforming gasoline selective hydrodealkenization is to selectively hydrodealkene the reformed gasoline in the state of hydrogenation, and realize deep deolefination under the condition that aromatics are not saturated by hydrogenation. Hydrogen removes the olefins therein. After the naphtha fraction is catalytically reformed, the resulting oil is rich in aromatics and solvent oil fractions, and also contains a small amount of olefins. For reforming units producing chemical-grade BTX aromatics, they all face the problem of how to remove olefins from reformed oil. Because in order to produce qualified chemical raw material aromatic products and solvent oil, in addition to extracting to separate aromatics from non-aromatics, olefins must also be removed, otherwise the product's bromine value and color after pickling are unqualified. The bromine index and copper corrosion test of solvent oil failed. At the same time, the presence of olefins in the generated oil will polymerize in the extraction solvent and contaminate the extraction solvent. In addition, the oxidation of olefins to organic acids can cause corrosion of the extraction system equipment. In addition, in some high-temperature equipment (such as the reboiler of the xylene distillation column), olefins can easily cause fouling and coking, thereby blocking the pipeline, and ultimately affecting the smooth progress of the separation process. This problem becomes more prominent with the commissioning and operation of large-scale continuous reforming aromatics unit, the improvement of reaction depth and the increase of olefin content. In a high-severity continuous catalytic reforming unit, the olefin content of the produced oil will exceed 1 wt%, and the olefin content of the raffinate may reach more than 2 wt%.

The conventional olefin removal method in the continuous reforming unit in the prior art is to use clay adsorption, but when the olefin content exceeds 1wt%, the clay adsorption is difficult to meet the target requirements (bromine value is less than 200mgBr/100g oil), and the clay adsorption The short life of the agent leads to frequent replacement; and the clay cannot be regenerated and reused, and the discarded clay will cause serious environmental pollution.

In some domestic continuous reforming units, a post-hydrogenation reactor is connected in series behind the last reactor in the reforming reaction system, and a conventional sulfided non-noble metal Co-Mo or Ni-Mo hydrogenation catalyst is used. Operating at high temperature (300-320°C) and low space velocity (2-3hr ^-1 ), it is difficult to achieve deep dealkenization (bromine value is less than 200mgBr/100g oil) and to ensure that aromatics are not lost during hydrogenation ( Aromatic loss is less than 0.5wt%) requirement. In addition, since the reformed gasoline and reformed by-product hydrogen do not contain sulfur, the sulfided non-noble metal Co-Mo or Ni-Mo hydrofining catalyst is easy to lose sulfur and cause deactivation; at the same time, the precipitated Sulfur can seriously contaminate ruthenium-based catalysts in reforming reactors.

CN85100215A introduces a catalyst for reforming raffinate hydrofinishing, which consists of 0.02-0.2wt% Ru or Pd supported on γ-Al ₂ O ₃ , the patent application mentions in the description: "The catalyst has high activity and can fully hydrogenate the olefins in the raffinate under mild conditions. It has hydrogenation activity for benzene and toluene at normal pressure and around 200 ° C. Therefore, this catalyst can not only be used for the hydrofining of raffinate , and can also be used in the hydrofinishing of reforming oil". Since the catalyst has hydrogenation activity for aromatics at about 200°C, the catalyst cannot be used for the selective hydrode-olefination of reformed oil when the reaction temperature is 200°C. As the pressure increases, the temperature at which hydrogenation activity for aromatics begins to decrease, and the actual possible application of hydrofining pressure is generally 1.0-3.0 MPa, so it begins to have hydrogenation activity for aromatics under increased pressure. The temperature must be lower than 200°C. Therefore, this catalyst cannot be used for the hydrofinishing of reformed oil to remove olefins, otherwise it will inevitably lead to the loss of aromatics due to excessive hydrogenation.

CN85100760A introduces a catalyst for olefin hydrotreating and its preparation method. The catalyst for olefin hydrogenation of petroleum products is made of 0.2wt%-1wt% of Ru or Pd or Pd and Ru and 0.05%-2wt% of Sn or Pb supported on fibrous alumina. However, since the molding technology of fibrous Al ₂ O ₃ has not yet been realized, it is difficult to shape fibrous Al ₂ O ₃ into an industrial catalyst support with certain mechanical strength, so there is still a lot of work to be done to realize the industrial application of the catalyst of the invention.

CN1210131A introduces a hydrofining process for reformed oil, using reformed oil from which aromatics greater than C9 have been removed, wherein the aromatics content is generally 20-85 wt%, and the bromine value is 0.5-8.0gBr/100g oil as raw material. The reaction conditions of hydrofining are as follows: the hydrogenation catalyst of thin shell type Pd/γ-Al ₂ O ₃ is used, the reaction temperature is 150-200°C, the hydrogen partial pressure in the reactor is 0.5-3.0MPa, and the liquid space velocity is 3-15hr ^-1 , the volume ratio of hydrogen to oil is 100-500:1. The bromine value of the oil produced by hydrofining is far lower than the requirement of 0.2gBr/100g oil for the raw material of the aromatics extraction unit, and there is no loss of aromatics during the hydrogenation process. The disadvantage of this process is that it is only applicable to the reformed gasoline raw material after removal of heavy components. Due to the wide boiling point of continuous reforming fractions, a small amount of high-boiling fractions generated by high-temperature cracking during the reforming process contain more aromatics above C9, which will be strongly adsorbed on the surface of the catalyst when the temperature is lower than 200°C, and gradually accumulate, resulting in catalyst deactivation . Therefore, when this process is used for the hydrodeolefination of whole fractions of reformed gasoline from a continuous reforming unit, the service life of the catalyst is short and cannot meet the requirements of long-term operation.

Contents of the invention

The purpose of the present invention is to avoid the shortcomings of the prior art and propose a catalyst for continuous reforming of gasoline for selective hydrodeolefination and a preparation method thereof. The catalyst is used for catalyzing continuous reforming of gasoline with high hydrogenation depth of olefins, less hydrogenation loss of aromatics, long-term stable operation and industrial scale use. Simultaneously, the present invention provides a catalyst for continuous reforming gasoline hydrofinishing, using the reformed gasoline whole distillate from a continuous reforming unit as a raw material, wherein the content of aromatics is generally 20-85wt%, and the bromine value is 500-8000mgBr/100g oil . The hydrogenation reaction conditions are: reaction temperature 60-200°C, pressure 1.5-3.0MPa, hydrogen-oil volume ratio 100-500:1, volume space velocity 2.0-8.0hr ^-1 .

The catalyst provided by the invention is composed of three parts: main active component, auxiliary agent and carrier, and the structural formula is: Pd-Ma(Mb)/carrier. Among them: the main active component is a double precious metal component, the Pd content is 0.01-0.5wt%, Ma is another active component, the content is 0.01-0.5wt%, the auxiliary agent Mb content is 0-0.5wt%, and the rest is Carrier; Ma is one of Au, Ag, Ru, Ir; Mb is one of Na, K, Ca, Mg. The catalyst carrier is a refractory porous inorganic material, which can be selected from Al ₂ O ₃ , SiO ₂ , activated carbon, diatomaceous earth, etc., and can be in various shapes such as spherical, cylindrical, clover or sheet, etc.

The weight content of Pd, one of the main active components of the catalyst, in the catalyst is preferably 0.05% to 0.2%, and the weight content of the other component Ma in the catalyst is preferably 0.05% to 0.2%.

The weight content of promoter Mb in the catalyst is preferably 0.2-1.0%. The presence of Mb does not change the activity and selectivity of the catalyst. It's used for a long time.

The preparation method of catalyst of the present invention comprises the steps:

(1) Preparation of the catalyst carrier: take the refractory porous inorganic material powder, use pseudo-boehmite as the binder, add celadon powder and nitric acid, then knead and form, dry and roast to obtain a certain shape of the inorganic material carrier; roast The temperature is 500-1000°C, and the time is 4-8 hours;

(2) Preparation of catalyst: The active metal and additives can be supported by distribution impregnation method or co-impregnation method. When distributing and impregnating, the aqueous solution of pre-prepared auxiliary agents is soaked or sprayed to saturate the impregnated carrier, then dried and roasted, and then the impregnated aqueous solution of the dual-active metal is prepared. The impregnated solution uses inorganic acid or organic acid to adjust the pH value, and contains palladium Soak or spray the saturated impregnated carrier with the water-soluble salt solution of Ma, make the active component palladium and co-active component metal be absorbed into the carrier pores together, then dry and roast to obtain the hydrogenation catalyst; during co-impregnation, prepare palladium-containing , Ma, Mb impregnated aqueous solution, the impregnated solution is adjusted pH value with organic acid or organic acid, soaked or sprayed saturated impregnated carrier, then dried and roasted to obtain hydrogenation catalyst.

The impregnated catalyst is dried at 120-250°C, calcined in air flow at 400-600°C, and reduced in hydrogen at 150-350°C.

The solution containing the active metal component and the auxiliary component can generally be a soluble salt solution, such as a nitrate, hydrochloride or organic acid salt solution.

Described competitive adsorbent can be inorganic acid such as hydrochloric acid, acetic acid etc. or organic acid such as trichloroacetic acid, citric acid, maleic acid etc., and its consumption is generally 0.1wt%～1.0wt% (with dry basis alumina amount being benchmark). The effect of using inorganic acid or organic acid is: (1) contribute to the good dispersion of active components, improve the dispersion and utilization of active components; The component presents an eggshell distribution on the carrier particles, that is, the active component is distributed on the surface of the catalyst particle to a shallow layer at a depth of 300 microns, thereby significantly shortening the contact time between unsaturated hydrocarbons and aromatics and the active component, and reducing the hydrogenation reaction Deep, improve olefin hydrogenation selectivity, reduce aromatics hydrogenation loss.

The porous inorganic refractory material used in the catalyst of the present invention is preferably alumina as a catalyst carrier to prepare a thin shell catalyst, the catalyst surface area is ^150-250m2 /g, the pore volume is 0.3-0.8ml/g, and the active component is in the carrier Eggshell-shaped distribution.

During the start-up process of the catalyst, for the catalyst in the reduced state, pre-sulfurization treatment is generally carried out to suppress the excessive initial activity. The vulcanizing agent can be sulfur-containing organic compounds such as dimethyl disulfide, carbon disulfide and sulfide.

The present invention provides a new catalyst start-up process. For the catalyst in the reduced state, low-temperature feed is used, and then the temperature is gradually raised to the required reaction temperature. 20°C, preferably constant temperature for 2 to 4 hours, this start-up process can avoid the use of harmful sulfides. The difference in the start-up process does not affect the performance of the catalyst described in the present invention.

When the catalyst of the present invention is used for the selective hydrodeolefination of gasoline for continuous reforming, the use conditions are generally: under the condition of the presence of hydrogen, the reformed oil is contacted with the catalyst to undergo a hydrogenation reaction, and the reaction conditions are generally: pressure 1.5-3.0MPa, reaction temperature 60-200℃, hydrogen-oil volume ratio 100-500:1, volume space velocity 2.0-8.0hr ^-1 , preferably reaction pressure 1.2-2.5MPa, reaction temperature 80-180℃, hydrogen The oil volume ratio is 200-300:1, and the liquid hourly volume space velocity is 2-6hr ^-1 .

The raw material suitable for the catalyst of the present invention can generally be the whole fraction of reformed gasoline from a continuous reforming unit containing olefins. /100g oil.

When the catalyst of the present invention is used for the selective hydrodeolefination of the whole fraction of gasoline for continuous reforming, the reaction pressure is 1.2-2.5 MPa, the reaction temperature is 80-180°C, the hydrogen-oil volume ratio is 200-300:1, and the liquid hourly volume space velocity is 2 Under the condition of ~6hr ^-1 , the bromine value of the product can be made less than 200mgBr/100g oil, and the loss of aromatics is less than 0.5wt%. Satisfactory results have been obtained. The catalyst does not need to be regenerated and can be used continuously for 2-3 years.

Detailed ways

The technical characteristics of the present invention will be described in detail below in conjunction with the embodiments.

Example 1

With shaped alumina as a carrier, in the presence of competitive adsorbent hydrochloric acid solution, use a Pd salt solution with a content of 0.1wt% (based on dry basis alumina), and the concentration of Ma is determined according to the final content of the catalyst in different molar ratios The catalyst of the present invention can be obtained by impregnating alumina carriers of different specifications, drying at 120°C for 8-12 hours, and roasting at 500°C in air for 4-6 hours. Table 1 lists the catalysts prepared by the method of the present invention.

Catalyst prepared by the present invention in table 1

Example 2

Using the catalyst in Example 1, a test of selective hydrodeolefination of continuously reformed gasoline was carried out on a 100 ml single-tube device. The raw material is the whole distillate of reformed gasoline from a continuous reforming unit, the distillation range is 26.2-218.2°C, the content of aromatics is 60.5wt%, and the bromine value is 3640mgBr/100g oil. The reaction conditions are pressure 2.0MPa, reaction temperature 170°C, hydrogen-oil ratio 250:1, liquid hourly volume space velocity 4hr ^-1 , catalyst reduction in hydrogen at 170°C for 8 hours, and dimethyl disulfide at 170°C. The vulcanizing agent is pre-sulfurized, and the vulcanization amount is 0.5wt% of the catalyst. The results are listed in Table 2.

Table 2 Hydrogenation results of continuous reforming full distillate gasoline

Catalyst A B C D E F Aromatic content, wt% 60.5 60.2 60.3 60.5 60.5 60.1 Bromine value, mgBr/100g oil 90 122 88 66 55 60

Example 3

Using the catalyst E described in Example 1, a test of selective hydrodeolefination of continuously reformed gasoline was carried out on a 100 ml single-tube device. The raw material is the raw material oil in Example 2. The reaction conditions are a pressure of 2.0 MPa, a reaction temperature of 170°C, a volume ratio of hydrogen to oil of 250:1, and a liquid hourly volume space velocity of 4hr ^-1 . The catalyst is first reduced in hydrogen at 170°C for 8 hours. After the reduction is complete, the temperature is lowered to 60°C and then the feed is started. The reaction temperature is gradually increased by 10°C/hr each time, and then kept constant for 3 hours until the final reaction temperature reaches 170°C. , began to respond normally, and the results are listed in Table 3.

Table 3 Hydrogenation results of continuous reforming full distillate gasoline

Example 4

Using the catalyst A described in Example 1, using a 100ml single-tube device, the selective hydrodeolefination ability of the catalyst was investigated under different pressure conditions. Raw material is the same as the raw material oil in embodiment 2. Reaction conditions The reaction temperature is 170°C, the volume ratio of hydrogen to oil is 250:1, the liquid hourly volume space velocity is 4hr ^-1 , the catalyst is reduced in hydrogen at 170°C for 8 hours, and the pretreatment is carried out at 170°C with dimethyl disulfide as the vulcanizing agent. Sulfurization, the amount of sulphurization is 0.5wt% of the catalyst, and the results are listed in Table 4.

The influence of table 4 reaction pressure on catalyst reaction performance

Reaction pressure, MPa 1.5 2.0 2.5 3.0 Aromatic content, wt% 60.4 60.3 60.3 60.1 Bromine value, mgBr/100g oil 95 90 60 55

Example 5

With the catalyst A described in Example 1, a long-term stability test was carried out on a 100ml single-tube device. The raw materials used in the test are the same as in Example 2, and the results are shown in Table 5.

As can be seen from the results in Table 5, the catalyst has been running for 2500 hours, and the bromine price of the product has been lower than the index requirement, and the aromatics have no loss substantially. The need for long-term operation.

Table 5 Stability Test Results of Selective Hydrodeolefination of Continuously Reformed Gasoline

Invention effect

Compared with prior art, catalyst of the present invention has following remarkable advantage:

(1) The remarkable feature of the catalyst prepared by the technology of the present invention is that the precious metal active components are distributed in an eggshell shape on the carrier, which has the advantage of significantly improving the utilization of the precious metal active components and significantly reducing the precious metal activity. The content of components (reduced by 1 time compared with the original technology) significantly reduces the cost of the catalyst (in the manufacturing cost of supported noble metal catalysts, noble metals account for more than 90%); on the other hand, it significantly reduces the activity of aromatic hydrocarbon hydrogenation, The selectivity of hydrogenation of olefins is improved, and the loss of hydrogenation of aromatics is reduced.

(2) The unique pre-sulfurization (namely: passivation) and low-temperature feeding technology after the reduction of the catalyst proposed by the present invention significantly improves the activity stability of the catalyst. Thus, three features of the technology proposed in the present invention are significantly different from existing inventions and technologies: ① cheap catalyst preparation technology; ② excellent low-temperature olefin hydrogenation activity and selectivity; ③ excellent catalyst activity stability.

Claims (5)

1. A catalyst for continuous reforming gasoline hydrofinishing, the catalyst is composed of main active component, auxiliary agent and carrier, its structural formula is: Pd-Ma(Mb)/carrier, it is characterized in that the main activity The component is a double precious metal component, the content of Pd is 0.01-0.5wt%, Ma is another active component, the content is 0.01-0.5wt%, the content of Mb is 0.2-1.0wt%, and the rest is a carrier; Wherein, Ma is a kind of Au, Ag, Ru, Ir, Mb is one of Na, K, Ca, Mg, The catalyst carrier is a refractory porous inorganic material. 2. A preparation method for a catalyst for continuous reforming gasoline hydrofinishing, characterized in that the preparation steps are as follows: (1) Preparation of the catalyst carrier: take the refractory porous inorganic material powder, use pseudo-boehmite as the binder, add celadon powder and nitric acid, then knead and form, dry and roast to obtain a certain shape of the inorganic material carrier; roast The temperature is 500-1000°C, and the time is 4-8 hours; the carrier has the following physical properties: the bulk specific gravity is 0.7-0.9g/ml, the specific surface area is 70-200m ² /g, the pore volume is 0.5-0.9ml/g, the average The pore size is 10-50nm; (2) Catalyst preparation: use distribution impregnation method or co-impregnation method to load active metals and additives. During distribution impregnation, pre-prepared aqueous solution of additives is soaked or sprayed to saturate the impregnated carrier, then dried and roasted, and then prepared The impregnating aqueous solution of double-active metal is produced, and the impregnating liquid is adjusted with inorganic acid or organic acid to adjust the pH value, and the water-soluble salt solution containing palladium and Ma is soaked or sprayed to saturate the impregnated carrier, so that the active component palladium and the co-active component metal are together It is sucked into the pores of the carrier, then dried and roasted to obtain a hydrogenation catalyst; during co-impregnation, an impregnating aqueous solution containing palladium, Ma, and Mb is prepared. carrier, then drying and roasting to obtain a hydrogenation catalyst; (3) Physical properties of the catalyst: the surface area is 150-250m ² /g, the pore volume is 0.3-0.8ml/g, and the active components are distributed in eggshell shape in the carrier. 3. the preparation method of the catalyst that is used for continuous reforming gasoline hydrofinishing according to claim 2 is characterized in that described carrier is refractory porous inorganic material class, can be aluminum oxide, silicon dioxide, gac or silicon algal earth. 4. The method for preparing a catalyst for continuous reforming gasoline hydrofinishing according to claim 2, characterized in that the impregnated catalyst is dried at 120 to 250° C. and carried out in an air flow of 400 to 600° C. Calcination and reduction in hydrogen at 150-350°C. 5. the preparation method of the catalyst that is used for continuous reforming gasoline hydrotreating according to claim 2 is characterized in that described organic acid can be from hydrochloric acid, acetic acid, citric acid, maleic acid and trichloroacetic acid One, based on the dry weight percentage of the carrier, the amount used is 0.1% to 1.0%.