CN1916121B - A kind of preparation method of gasoline diene selective hydrogenation catalyst - Google Patents

Abstract

A method for preparing a gasoline diene selective hydrogenation catalyst, using gamma-Al ₂ O ₃ that has been calcined again at a high temperature of 900°C to 1200°C as a carrier, and using an impregnation solution made of ammonia water and an active metal salt solution according to the equal-volume impregnation method Impregnation, wherein the mass ratio of Ni:ammonia water:H ₂ O in the impregnation solution is 1:0.5:5～1:5.0:5.0, and the Ni content is 5～20%; after impregnation, it is dried within the temperature range of 100°C～200°C or vacuum drying, and then roasted in the air at a temperature range of 250°C to 350°C; the resulting Ni-loaded Al ₂ O ₃ is reduced with a hydrogen reducing gas at a temperature range of 350°C to 450°C, and is treated with a vulcanizing agent. Sulfurization, the prepared Ni catalyst not only has high diene hydrogenation activity under the conditions of low temperature, low pressure and low hydrogen-to-oil ratio, but also has high selectivity and stability, which can effectively reduce energy consumption and cost of industrial production .

Description

A kind of preparation method of gasoline diene selective hydrogenation catalyst

Technical field:

The invention relates to a preparation method of a gasoline diene selective hydrogenation catalyst, in particular to a low-temperature diene selective hydrogenation non-precious metal Ni-based catalyst capable of improving the diene hydrogenation activity and stability of catalytic cracking gasoline and steam cracking gasoline. Its preparation method and application process conditions.

Background technique:

At present, the main problems of FCC gasoline are high olefin content and high sulfur content, which cannot meet the quality requirements of motor gasoline. For this reason, it is necessary to carry out subsequent processing of FCC gasoline to improve its quality, such as using a strong solid acid catalyst to increase the octane number of gasoline and reduce the olefin content through isomerization, aromatization and other technologies; through the hydrogen desulfurization technology, reduce Sulfur content in FCC gasoline. However, since cracked gasoline contains 0.35-1.0% w of diolefins and alkynes, compared with monoolefins, diolefins and alkynes are very easy to undergo polymerization reactions under the action of acid catalysts, sulfur, nitrogen, and oxygen impurities. Oligomers and gums are formed. They will deposit on the internal and external surfaces of gasoline processing catalysts, block the pores of the catalyst, and cover the active centers of the catalyst, resulting in rapid deactivation of the catalyst and reduced service life. In order to avoid the impact of diolefins and alkynes on the catalysts for the subsequent processing of gasoline, it is necessary to selectively hydrogenate catalytic cracked gasoline and steam cracked gasoline, so as to remove diolefins and alkynes without reducing the original olefin content in the raw materials, and The octane number remains unchanged, which is conducive to the subsequent processing of gasoline. Using the non-precious metal Ni-based catalyst of the present invention can remove diolefins and alkynes therein at a lower reaction temperature, and can also remove impurities such as part of sulfur, nitrogen, and colloid in gasoline at the same time. It is very important, and it can obviously improve the stability of gasoline.

Currently, there are some patents on catalysts for the selective hydrotreating of dienes and alkynes in gasoline. These patents reflect that the active components of the catalyst are platinum, palladium, silver, tungsten, nickel, molybdenum, iron, etc. loaded on an inert carrier, and catalysts loaded with palladium and nickel are more generally valued. For example, US 3,234,298 (WCVan zijillanghout et al) once described the use of sulfurized Ni/Al ₂ O ₃ or Mo/Al ₂ O ₃ catalysts for the selective hydrogenation of pyrolysis gasoline and kerosene to improve the stability of gasoline and kerosene. US 3,847,835 (JeanCosyns et al) introduced a catalyst for the selective hydrogenation of pyrolysis gasoline diolefins to monoolefins, which was prepared by loading 2% to 10% (w) of Ni or Co on solid alumina As a result, the catalyst needs to be pretreated with H ₂ S, and the active component of the reaction is nickel sulfide or cobalt sulfide, and it gives a better surface area and pore volume. US 3,919,341 (Germanas et al) and 5,417,844 (Boitiaux et al) describe two kinds of catalysts for the selective hydrogenation of pyrolysis gasoline respectively, the active components of both catalysts are Ni, and the carrier is solid alumina, and the two catalysts Both require pretreatment with sulfur-containing organic compounds before use. Chinese patent CN 1,218,822 describes a diene hydrogenation catalyst with Li or alkaline earth metals as additives, Ni as the active component, and alumina as the carrier, which is mainly used in the hydrogenation process of steam cracking gasoline. The characteristics of its preparation are Use Li or alkaline earth metal as the modification aid of the alumina carrier, and after high temperature treatment, make it incorporated into the structure of the alumina carrier; after obtaining a stable carrier, impregnate the carrier with an aqueous solution of nickel salt to load the Ni active component , the catalyst is obtained through treatment at a higher temperature and a longer time. In the above several patents, in the method of loading Ni active components, all of them are prepared by the aqueous solution impregnation method of nickel metal salt. The main problem with this method is that during the impregnation and drying process, the excess active component salts are concentrated and aggregated into crystals. The diffusion of reactants during the phase reaction reduces the activity and stability of the catalyst.

Contents of the invention

The purpose of the present invention is just to provide a kind of with non-precious metal Ni as active component, through the gamma- _Al2O3 of high _temperature treatment as the preparation method of a kind of gasoline diene selective hydrogenation catalyst of carrier, prepared Ni catalyst not only Under the conditions of low temperature (130-200°C), low pressure (1.0-4.0MPa), and low hydrogen-to-oil ratio (hydrogen-to-oil volume ratio is 10:1-60:1), it has high activity in hydrogenation of dienes, and also has a high High selectivity and stability can effectively reduce energy consumption and cost of industrial production.

The present invention is achieved like this:

A catalyst for the selective hydrogenation of gasoline dienes, with γ-Al ₂ O ₃ that has been calcined again at a high temperature of 900°C to 1200°C as the carrier, impregnated with an impregnating solution made of ammonia water and an aqueous solution of an active metal salt by an equal-volume impregnation method, wherein The ratio of Ni:ammonia water:H ₂ O in the immersion solution is 1:0.5:5~1:5.0:5.0 (mass ratio), the Ni content is 5~20%, and the temperature range of 100℃~200℃ after immersion Dry or vacuum dry, and then bake in the air at a temperature range of 250°C to 350°C. The obtained Ni-loaded _Al2O3 is reduced with hydrogen reducing gas at a temperature range of 350°C to 450°C, and vulcanized by _a vulcanizing agent;

The γ-Al ₂ O ₃ is spherical or other shapes, heat-treated in air at 900°C-1200°C for 1-5 hours, its bulk specific gravity is 6.5-7.5mg/L, and its pore volume is 0.4-0.5ml/g. Pores with a diameter larger than 4nm account for more than 80%, and the surface area is larger than 100m ² /g.

The water-soluble active metal salt is transition metal Ni nitrate, acetate, chlorate, etc., and is configured with water and ammonia water to form an impregnation solution, wherein the ratio of Ni:ammonia water:H ₂ O in the impregnation solution is 1 : 0.5:5˜1:5.0:5.0 (mass ratio), the loading of the active metal Ni element is 5˜20%w.

The drying and calcination conditions are as follows: drying at 100°C-180°C or vacuum drying for 3-8 hours, and then treating in air at 250°C-350°C for 0-2 hours.

The hydrogen reduction and sulfidation conditions of the catalyst are: reduction temperature 350-450°C, reduction time 3-8 hours, reduction pressure from normal pressure to 0.3MPa, reduction gas space velocity 420-600h ^-1 (STP). Then pretreatment with sulfide solution at 20-100° C. for 0.1-5 hours.

Catalyst preparation method of the present invention is as follows:

Using γ-Al ₂ O ₃ treated at 900°C to 1200°C as the carrier, use ammonia water and non-noble metal Ni nitrate, acetate, chlorate, etc. to make an ammonia solution, and load it on the prepared by impregnation method On the surface of the alumina carrier, the active metal Ni element content is 5-20%w, preferably 8-17%w; after drying at 100°C-180°C or vacuum drying, treat it at 250°C-350°C. ~2 hours; the prepared sample is then reduced in a hydrogen atmosphere, the reduction temperature is 300°C~450°C, the reduction time is 3~8 hours, the reduction pressure is from normal pressure to 0.3MPa, and the reducing gas space velocity is 420~600h ^-1 (STP), followed by sulfidation to obtain the catalyst of the present invention.

The process of catalytic selective hydrogenation of whole distillate gasoline (initial boiling point ~ 200°C) to remove dienes is usually carried out under gas/liquid/solid three-phase conditions, wherein the gasoline fraction exists in the form of liquid phase, and excess hydrogen is It exists in the gas phase, and part of the hydrogen is dissolved in the gasoline fraction, which is used for the hydrogenation of dienes. The catalyst exists in the reactor in solid form. The catalytic full fraction gasoline diene selective hydrogenation reaction carried out in the present invention adopts the feeding mode of gas-liquid mixing and flowing upward. In addition, the reaction conditions such as pressure, temperature, liquid feed amount and hydrogen amount are set for the purpose of removing diene. Based on the volume of the catalyst, the liquid space velocity of the catalytic gasoline is 2-10h ^-1 , the temperature is 130°C-200°C, the pressure is 1.0MPa-4.0MPa, and the hydrogen-oil volume ratio (STP) is 10:1-60: 1. The catalytic gasoline diene selective hydrogenation method of the present invention can be carried out in one reactor, or in multiple parallel or serial reactors.

The specific operation procedure is:

(1) γ-Al ₂ O ₃ carrier heat-treated in air at 900°C-1200°C for 1-5 hours, with a bulk specific gravity of 6.5-7.5mg/L, a pore volume of 0.4-0.5cc/g, and pores with a diameter greater than 4nm Accounting for more than 80%, the surface area is greater than 100m ² /g.

(2), dissolve the salt of water-soluble active metal Ni with 25w%～28w% ammoniacal liquor, press Ni: ammoniacal liquor: H ₂ O is 1: 0.5: 5～1: 5.0: 5.0 (mass ratio) is made into aqueous ammonia solution .

(3), take a certain amount of the solution prepared in the above (2) step, and impregnate the carrier obtained in the (1) step with an equal volume, so that the loading capacity of the active component Ni element reaches 5-20% w, and at the same time drying at 100°C to 200°C or vacuum drying for 3 to 8 hours, and then treating in air at 250°C to 350°C for 0 to 4 hours to obtain a calcined sample of the catalyst loaded with active component NiO.

(4), at 300-450°C, use hydrogen to reduce the catalyst obtained in step (3) for 3-8 hours, the reduction pressure is from normal pressure to 0.3MPa, and the reducing gas space velocity is 420-600h ^-1 (STP) , followed by pretreatment with sulfidation solution at 20-100° C. for 0.1-5 hours to obtain the catalyst of the present invention for hydrogenation of diene with high activity, high selectivity and long-term stability.

The catalyst of the present invention has excellent diene selective hydrogenation performance, specifically, it has very high diene hydrogenation activity, selectivity and long service life in the process of carrying out selective hydrogenation of dienes in catalytic gasoline , C ₅ and C ₆ diene hydrogenation conversion rate reaches 100%, total monoene reduction is less than 1.0%.

It is characterized by using high-temperature-treated γ-Al ₂ O ₃ as the carrier. On the one hand, this carrier has a high surface area, and on the other hand, it also has a reasonable pore structure, which plays a role in dispersing active metals and facilitating liquid phase reactants. mass transfer. Another feature of the present invention is to use ammonia as a solvent to prepare water-soluble Ni salt impregnating solution, which is prepared by an equal-volume impregnation method. This special impregnation solution can avoid the agglomeration phenomenon of nickel salt during the impregnation and drying process, so that the Ni salt will not migrate and aggregate on the surface of alumina during the entire impregnation and drying process. On the one hand, it can ensure that the Ni salt It is uniformly dispersed on the inner and outer surfaces of the carrier, rather than concentrating on the orifice. On the other hand, it has little effect on the pore distribution of the carrier, ensuring the pore distribution and pore volume for liquid phase reactions.

Description of drawings

Fig. 1 is the contrast figure of catalyst of the present invention and industrial catalyst;

Fig. 2 is a graph showing the hydrogenation performance of Catalyst C of the present invention in continuous operation for more than 1000 hours.

Detailed ways

The catalyst, preparation method and catalytic performance thereof of the present invention are further described below with examples.

Implementation example 1:

An appropriate amount of spherical gamma-Al ₂ O ₃ carrier with a diameter of φ1-2mm was roasted in air in a muffle furnace at 1100°C for 4 hours, and then used as a carrier for subsequent catalysts after cooling, with a bulk specific gravity of 0.72 mg/L. The pore volume is 0.41ml/g, 95% of the pores have a diameter larger than 4nm, and the surface area is 101m ² /g.

Implementation example 2:

Weigh 70.0 grams of the alumina support prepared in Example 1, impregnate it with a solution made of 52.03 grams of nickel nitrate Ni(NO ₃ ) ₂ 6H ₂ O and 35.6 milliliters of distilled water for 2 hours, dry it at room temperature, and then Dry at constant temperature and vacuum for 7 hours at 180°C, and then bake in a muffle furnace at 300°C for 1h. Catalyst A with a Ni metal content of 15.0%wt can be prepared.

Implementation example 3:

140 grams of the alumina carrier prepared in Example 1 was impregnated with a solution prepared from 69.37 grams of nickel nitrate Ni(NO ₃ ) ₂ 6H ₂ O, 35.6 milliliters of distilled water and 45 milliliters of 25w%-28w% ammonia water for 2 hours After preliminary drying at room temperature, vacuum drying at constant temperature at 150°C for 3 hours, and calcination in air at 280°C in a muffle furnace for 2 hours, catalyst B with a Ni metal content of 10.0%wt can be prepared.

Implementation example 4:

With 35 grams of the alumina carrier prepared in Example 1, 26.02 grams of nickel nitrate Ni(NO ₃ ) ₂ 6H ₂ O, 17.6 milliliters of distilled water and 27.0 milliliters of 25w%-28w% ammonia, according to the preparation method of Example 3, Catalyst C with a Ni metal content of 15.0%wt can be prepared.

Implementation example 5:

The non-precious metal catalyst A prepared in Example 2 was calcined in air at 450° C. for 2 hours in a muffle furnace to obtain the Ni catalyst contrast agent D calcined at a higher temperature.

Implementation example 6:

The diene hydrogenation activity and stability of the above-mentioned non-precious metal catalysts A to D were evaluated in a small pressurized fixed-bed reactor by using an upflow feeding method. Place a certain amount of catalyst in the middle of the constant temperature zone of the reactor, fill the top and bottom with quartz sand, raise the temperature to 380°C under the condition of hydrogen, and perform constant temperature reduction for 5 hours, the reduction pressure is normal pressure, and the reducing gas space velocity is 420h ^-1 (STP ), then cool the device to room temperature, and vulcanize with a special vulcanizing agent for 1 hour. Afterwards, the temperature is raised to the reaction temperature, and the catalytic cracking full fraction gasoline reaction raw material liquid is introduced to carry out the diene hydrogenation reaction. The hydrogenation reaction conditions are: reaction temperature 150°C, reaction hydrogen partial pressure 1.5MPa, liquid volume space velocity 9.0h ^-1 , hydrogen to oil volume ratio (STP) 50:1. The content of the main components in the catalytic cracking gasoline reaction raw material liquid is: carbon pentaolefin 13.03% (wt), carbon pentadiene 0.438% (wt), carbon hexaolefin 10.14% (wt), total sulfur 244.9μg/g, total nitrogen 96.9 μg/g. In the test, gas chromatography is used to accurately analyze the conversion of carbon five and carbon six components to analyze the changes of the whole components (this analysis method replaces the analysis of the whole components, and its accuracy has been verified to reach more than 94%). The reaction evaluation results (taking the average value of the reaction 0-20h) are shown in Table 1. From the results in the table, it can be seen that the effect of catalyst C is better.

Table 1. FCC gasoline diene hydrogenation catalytic performance of this patent catalyst

Catalyst A B C D C₅ diene conversion/% 98.86 84.62 100 58.39 C₅pentaene content/%(wt) 13.19 12.74 12.93 12.69 C₆ olefin content/%(wt) 10.51 10.26 10.50 10.47

Implementation example 7:

Using the above-mentioned (Example 6) FCC whole gasoline as raw material, the catalyst C of the present invention was compared with several industrialized catalysts in a small-scale pressurized fixed-bed reactor. CH-24 and MH-3 are catalysts of the same type as catalyst C of the present invention, and QSH-01 is a noble metal Pd catalyst. The reaction conditions are: reaction temperature 150°C, reaction hydrogen partial pressure 1.5MPa, liquid volume space velocity 24.0h ^-1 , hydrogen-oil volume ratio (STP) 50:1. The results show that the C catalyst of the present invention is significantly improved in terms of activity and stability compared with three industrialized catalysts, as shown in FIG. 1 .

Implementation example 8:

Catalyst C of the present invention was operated for a long period of 1029 hours in a small pressurized fixed-bed reactor using catalytically cracked whole distillate gasoline as a raw material. The reaction conditions are: reaction temperature 150°C, reaction hydrogen partial pressure 1.5MPa, liquid volume space velocity 3.0h ^-1 , hydrogen-oil volume ratio (STP) 50:1. Main impurities in raw materials: total sulfur 244.9 μg/g, total nitrogen 96.9 μg/g. The results show that catalyst C has been running continuously for more than 1000 hours, _C5 and _C6 dienes have not been detected, and the reduction of total C5 monoenes and total C6 monoenes is less than 1.0m%, and it is very stable, as Figure 2 shows. This shows that the catalyst of the present invention has high activity and good stability for diene hydrogenation.

Claims (3)

1. A preparation method for a gasoline diene selective hydrogenation catalyst, characterized in that: the gamma-Al ₂ O ₃ that has been calcined again at a high temperature of 900°C to 1200°C is used as a carrier, wherein the burned gamma-Al ₂ O ₃ accumulates The specific gravity is 6.5-7.5mg/L, the pore volume is 0.4-0.5mL/g, the pores with a pore diameter greater than 4nm account for more than 80%, and the surface area is greater than 100m ² /g. The impregnation solution prepared by ammonia water and active metal salt solution is impregnated by equal volume. method impregnation, wherein the mass ratio of Ni:ammonia water:H ₂ O in the impregnation solution is 1:0.5:5～1:5.0:5.0, and the Ni content is 5～20%; Drying, and then roasting in the air at a temperature range of 250°C to 350°C; the obtained Ni-loaded Al ₂ O ₃ is reduced with hydrogen, the reduction temperature is 350-450°C, the reduction time is 3-8 hours, and the reduction pressure is from normal pressure to 0.3MPa, the reducing gas space velocity is 420-600h ^-1 ; then pretreatment with sulfidation solution at 20-100°C for 0.1-5 hours. 2. by the preparation method of a kind of gasoline diene selective hydrogenation catalyst described in claim 1, it is characterized in that: described active metal salt is the nitrate, acetate or chlorate of transition metal Ni, and with Water and ammonia water are prepared as an impregnation solution, wherein the mass ratio of Ni:ammonia water:H ₂ O in the impregnation solution is 1:0.5:5-1:5.0:5.0, and the loading of active metal Ni is 5-20%W. 3. according to the preparation method of a kind of gasoline diene selective hydrogenation catalyst described in claim 1, it is characterized in that: described drying, roasting condition is, dry 3～8 hours under 100 ℃～180 ℃, then at 250 ℃～350℃ for 0～2 hours in the air.

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