CN1272103C - Selective hydrogenation catalyst for alkadiene - Google Patents

Abstract

The present invention relates to a catalyst for selectively hydrogenating diolefin. The present invention contains alumina supporters, cobalt and/or nickel selected from the VIII group, molybdenum and/or tungsten selected from the VIB group and alkali metals, wherein the cobalt and/or nickel, the molybdenum and/or tungsten are loaded on the alumina supporters. The present invention is characterized in that the present invention contains the components in the form of oxide adopting the catalyst weight as the reference: 0.5 to 8 wt% of the cobalt and/or nickel selected from the VIII group, 2 to 15 wt% of the molybdenum and/or tungsten selected from the VIB group, more than 2 to 8 wt% of the alkali metals and an equilibrium amount of the alumina supporters. Compared with the existing catalyst, when the catalyst for selectively hydrogenating diolefin, which is provided by the present invention, is used for hydrogenating gasoline distillate oil, the hydrogenation activity and the selectivity of diolefin are high.

Description

A kind of diene selective hydrogenation catalyst

Technical field

The present invention relates to a hydrorefining catalyst, more particularly to a diolefin selective hydrogenation catalyst.

Background technique

FCC gasoline contains more diolefins. At a certain reaction temperature, in addition to their own polymerization, the diolefins will also react with other hydrocarbons in FCC gasoline to form gums and other coking precursors. It is usually selectively removed by hydrogenation.

US6,084,140 discloses a method for preparing a catalyst for the selective hydrogenation of highly unsaturated hydrocarbons in olefin fractions. The catalyst consists of alumina and metallic palladium supported on the alumina. The content of metallic palladium is 0.02-3.0% by weight. The catalyst can effectively remove highly unsaturated hydrocarbons in olefin fractions.

US6,255,548 discloses a method for preparing a catalyst for the selective hydrogenation of unsaturated hydrocarbons such as alkynes and dienes. The catalyst is prepared by loading at least one group VIII metal and at least one auxiliary metal M on a carrier. The Group VIII metal can be one or more of nickel, palladium, platinum, rhodium, ruthenium, iridium, preferably palladium, nickel, platinum, the upper range is 0.01-50% by weight, if it is a noble metal, it is preferably 0.05-1% by weight , preferably 5-30% by weight if the metal is nickel. The metal M is selected from one or more of germanium, tin, gold and silver, and the amount of the metal M ranges from 0.01 to 10% by weight, preferably 0.02 to 5% by weight. The catalyst may also contain 0.1-3% by weight of an alkali metal such as potassium or sodium and/or 0.01-2.0% by weight of elemental sulfur.

US 6,388,162 discloses a process for the removal of diolefins from olefin feedstocks. The method is to refine raw materials rich in olefins with carbon numbers ranging from 10 to 20, and remove diolefins therein. The catalyst used in the method is composed of alumina carrier and metal palladium supported on the alumina carrier, the amount of metal is 0.05-0.2% by weight, preferably 0.2% by weight, wherein the specific surface area of alumina is not more than 15 ^m2 /g, preferably 2-5 ^m2 /g.

Selective hydrogenation using noble metal catalysts can well remove diolefins in raw oil. However, for the whole distillate or heavy distillate FCC gasoline with high sulfur and nitrogen content, noble metals are easy to deactivate, which limits the use of this type of catalyst.

In general, hydrogenation of olefins, especially dienes, is readily carried out under hydrorefining conditions. However, when non-precious metal hydrofinishing catalysts are used to selectively hydroremove diolefins in raw oil, the problem is how to avoid or reduce olefin polymerization and monoolefin hydrogenation saturation while ensuring the removal of diolefins. , to increase the selectivity of the hydrogenation reaction.

The presence of alkali metals is beneficial for suppressing carbon on the surface of catalysts. Therefore, in the prior art, alkali metals are often introduced as auxiliary components when preparing hydrorefining catalysts for raw oils with high olefin content.

CN 1113829A discloses a method for preparing a hydrorefining catalyst containing molybdenum, nickel, and potassium metal components. Its main feature is that the preformed transition state alumina carrier is impregnated with ammonia-containing molybdenum, nickel, and potassium solutions once, The catalyst is obtained by drying and roasting. Transition state alumina includes η, γ, θ alumina, preferably γ-alumina. The metal component content of the catalyst is 10.0-24.0% of MoO ₃ , 2.6-8.8% of NiO and 0.3-1.5% of K. The catalyst can be used for hydrodesulfurization of light oil fraction or gas containing organic sulfur, especially for hydrodesulfurization of naphtha and coking dry gas.

CN 1302849A discloses a hydrogenation active protective agent and its preparation method. The carrier used in the protective agent contains both γ-alumina and δ-alumina; the protective agent contains 3-22% of VIB group metal oxide and VIII group metal The oxide is 0.5-5m%, contains IA group elements 0-2m%, contains VA group elements 0-3m%, and has a specific surface area of 100-250m ² /g. The pore volume is 0.4～0.8ml/g. In the protective agent, the VIB group metal oxides are Mo and W oxides, the VIII group metal oxides are Fe, Co and Ni oxides, and the VA group elements are P, As, Sb and Bi elements. The catalyst is suitable for use as a protective agent for heavy oil hydrotreating catalysts.

Such hydrorefining catalysts containing alkali metal components can be used for the selective hydrogenation of diolefins in gasoline fractions, but their activity is low.

Contents of Invention

The purpose of the present invention is to overcome the shortcoming of low activity of existing hydrorefining catalysts when used for selective hydrogenation of diolefins, and provide a new catalyst for selective hydrogenation of diolefins with higher activity.

The inventors of the present invention have found that in the hydrorefining catalysts containing alkali metal components provided by the prior art, the content of alkali metals is low (less than 2% by weight), which leads to the low activity of this type of catalyst for the selective hydrogenation of diolefins important reason.

The diene selective hydrogenation catalyst provided by the present invention contains an alumina carrier and cobalt and/or nickel selected from group VIII, molybdenum and/or tungsten and alkali metal components supported on the carrier , characterized in that, calculated as oxides and based on the catalyst, the catalyst contains 0.5-8% by weight of cobalt and/or nickel selected from Group VIII, 2-15% by weight of molybdenum selected from Group VIB and and/or tungsten, >2-8% by weight of alkali metals and a balance of alumina support.

Compared with the existing catalysts, the catalyst provided by the invention has higher diolefin hydrogenation activity when used in gasoline distillate hydrotreating.

For example, under the same reaction conditions, a heavy distillate of FCC gasoline with a diene value of 1.6gI.(100g) ^-1 and a bromine value of 37.1gBr.(100ml) ^-1 is hydrodedienized, using When the catalyst provided by the present invention (the content of nickel oxide is 1.4% by weight, the content of molybdenum oxide is 4.5% by weight, and the content of potassium oxide is 2.1% by weight), the diene value of the generated oil is reduced to 0.3gI.(100g) ^{- 1} , bromine value is 36.1gBr.(100ml) ^-1; And comparative example catalyst (carrier is identical with precursor, the content of nickel oxide is 1.4% by weight, the content of molybdenum oxide is 4.6% by weight, the content of potassium oxide is 1.4% by weight %), the diene value of the resulting oil was reduced to 0.5gI.(100g) ^-1 and the bromine value was 34.7gBr.(100ml) ^-1 .

Detailed ways

Catalysts provided according to the invention, calculated as oxides and based on the catalyst, preferably contain 1-6% by weight of cobalt and/or nickel from group VIII, 4-12% by weight of molybdenum from group VIB and/or tungsten, 2.5-6% by weight of an alkali metal and a balance of an alumina support. Wherein, the atomic ratio of the Group VIII metal component to the Group VIB metal component is 0.5-2, preferably 0.7-1.5.

The Group VIII metal component is preferably nickel and the alkali metal is preferably potassium.

The alumina carrier is one or more transition phase aluminas selected from γ, η, θ, δ and χ, or contains one or more transition phases selected from silicon, titanium, magnesium, boron, One or more transition phase aluminas among γ, η, θ, δ, and χ of one or more of zirconium, thorium, niobium, and rare earth, preferably γ-alumina and containing One or more γ-alumina with one or more added components selected from silicon, titanium, magnesium, boron, zirconium, thorium, niobium, and rare earth.

The alumina can be commercially available or prepared by any method in the prior art. For example, it can be a mixture of one or more selected from trihydrate alumina, monohydrate alumina and amorphous aluminum hydroxide, or a mixture containing silicon, titanium, magnesium, boron, zirconium, thorium, niobium , Rare earth trihydrate alumina, monohydrate alumina and amorphous aluminum hydroxide, one or more mixtures are prepared after molding and roasting.

The preparation method of the catalyst provided by the present invention includes under conditions sufficient to deposit cobalt and/or nickel selected from group VIII, molybdenum and/or tungsten and alkali metal components selected from group VIB on the alumina carrier , bringing the alumina support into contact with a solution containing cobalt and/or nickel from group VIII, molybdenum and/or tungsten from group VIB and an alkali metal compound, for example by impregnation, co-precipitation, etc., preferably impregnation. Wherein, cobalt and/or nickel selected from group VIII, molybdenum and/or tungsten and alkali metals selected from group VIB can be introduced into the alumina carrier simultaneously or separately.

The molybdenum-containing compound is selected from one or more of molybdenum-containing soluble compounds, such as one or more of molybdenum oxide, molybdate, paramolybdate, preferably molybdenum oxide and ammonium molybdate , Ammonium paramolybdate.

The tungsten-containing compound is selected from one or more of tungsten-containing soluble compounds, such as one or more of tungstate, metatungstate, ethyl metatungstate, preferably among them, metatungstate ammonium ammonium tungstate, ethyl tungstate ammonium.

The cobalt-containing compound is selected from one or more of cobalt-containing soluble compounds, such as one or more of cobalt nitrate, cobalt acetate, basic cobalt carbonate, cobalt chloride and cobalt soluble complexes , preferably cobalt nitrate and basic cobalt carbonate.

The nickel-containing compound is selected from one or more of nickel metal soluble compounds, such as one or more of nickel nitrate, nickel acetate, basic nickel carbonate, nickel chloride and nickel soluble complexes, Nickel nitrate and basic nickel carbonate are preferred.

The alkali metal-containing compound is preferably one or more of hydroxides, inorganic or organic acid salts. For example, one or more selected from potassium hydroxide, potassium nitrate, potassium chloride, potassium acetate, potassium phosphate, potassium hydrogen phosphate and potassium dihydrogen phosphate among potassium-containing compounds.

According to the catalyst provided by the present invention, depending on different purposes or requirements, it can be made into various shapes that are easy to handle, such as microspheres, spheres, tablets or strips, etc. Forming can be carried out by conventional methods, such as tablet pressing, ball rolling, extrusion and other methods.

According to conventional methods in this field, the catalyst provided by the present invention can be presulfurized with sulfur-containing raw materials at a temperature of 140-370 ° C in the presence of hydrogen before use, and this presulfurization can be carried out outside the device or It can be vulcanized in situ in the device to convert it to the sulfide type.

The catalyst provided by the invention has high hydrogenation activity and selectivity for diolefins in gasoline distillates, and is particularly suitable for the hydrofinishing of diolefin-containing gasoline diolefins for the purpose of hydrodediolefining. The gasoline fraction may be catalytic cracking gasoline, coker gasoline, straight-run gasoline, thermal cracking gasoline and the like.

The following examples will further illustrate the present invention.

Example 1

This example illustrates the catalyst provided by the invention and its preparation method.

Weighed 800 grams of dry rubber powder produced by the Catalyst Factory of Changling Oil Refinery, extruded into a trilobal strip with a circumscribed circle diameter of 1.4 mm, dried at 120°C, and roasted at 630°C for 3 hours in an air atmosphere to obtain 584 grams of carrier Z.

Take by weighing 4 grams of nickel nitrate, 6 grams of ammonium molybdate, and 3.3 grams of potassium hydroxide (82% KOH content, product of Beijing Chemical Reagent Factory, the same below), adopt 16% by weight of _NH solution to dissolve, and make 90 milliliters of impregnation solution . Use this solution to impregnate 100 grams of carrier Z for 4 hours, dry at 120°C for 4 hours, and bake at 420°C for 4 hours. Calcined for 4 hours to obtain catalyst C1. The contents of nickel, molybdenum and potassium oxides in catalyst C1 are listed in Table 1.

The contents of nickel, molybdenum and potassium were measured by X-ray fluorescence spectrometry (the same below).

Comparative example 1

This comparative example illustrates a comparative example catalyst and its preparation method.

Weigh 4.0 grams of nickel nitrate, 6 grams of ammonium molybdate, and 2.2 grams of potassium hydroxide, dissolve them in an aqueous solution of 16% by weight NH ₃ , and prepare 90 milliliters of impregnation solution. 100 g of carrier Z was impregnated with this solution for 4 hours, then dried at 120° C. for 4 hours, and calcined at 420° C. for 4 hours to obtain catalyst B1. The contents of nickel, molybdenum and potassium oxides in catalyst B1 are listed in Table 1.

Comparative example 2

This comparative example illustrates a comparative example catalyst and its preparation method.

Weigh 4 grams of nickel nitrate, 6 grams of ammonium molybdate, and 2.2 grams of potassium hydroxide, dissolve them in 16% by weight of NH ₃ aqueous solution, and prepare 90 milliliters of impregnation solution. Use this solution to impregnate 100 grams of carrier Z for 4 hours, dry at 120°C for 4 hours, and bake at 420°C for 4 hours. Calcined for 4 hours to obtain catalyst B2. The contents of nickel, molybdenum and potassium oxides in catalyst B2 are listed in Table 1.

Example 2

This example illustrates the catalyst provided by the invention and its preparation method.

Weigh 4 grams of nickel nitrate, 6 grams of ammonium molybdate, and 9 grams of potassium hydroxide, and dissolve them in 16% by weight of NH ₃ aqueous solution to prepare 90 milliliters of impregnation solution. Use this solution to impregnate 100 grams of carrier Z for 4 hours, dry at 120°C for 4 hours, and bake at 420°C for 4 hours. ℃ for 4 hours to obtain catalyst C2. The contents of nickel, molybdenum and potassium oxides in catalyst C2 are listed in Table 1.

Example 3

This example illustrates the catalyst provided by the invention and its preparation method.

Weigh 10 grams of nickel nitrate, 14 grams of ammonium molybdate, and 6.5 grams of potassium hydroxide, dissolve them in 16% by weight of NH ₃ aqueous solution, and prepare 90 milliliters of impregnation solution. Use this solution to impregnate 100 grams of carrier Z for 4 hours, dry at 120°C for 4 hours, and bake at 420°C for 4 hours. ℃ for 4 hours to obtain catalyst C3. The contents of nickel, molybdenum and potassium oxide in catalyst C3 are listed in Table 1.

Example 4

This example illustrates the catalyst provided by the invention and its preparation method.

Weigh 800 grams of SB aluminum hydroxide powder produced by the German CONDEA company, mix evenly with 750 milliliters of aqueous solution containing 115 grams of magnesium nitrate [Mg(NO ₃ ) ₂ 6H ₂ O], and extrude into a three- Leaf-shaped strips were dried at 120° C. and calcined at 550° C. in an air atmosphere for 2 hours to obtain 602 grams of alumina carrier Z2 containing 3.1% by weight of magnesium oxide.

Weigh 7.5 grams of nickel nitrate, 11 milliliters of ammonium metatungstate solution (79.3 grams of tungsten trioxide/100 milliliters of solution), and 11.8 grams of potassium nitrate, and adopt 16% by weight of NH _{The aqueous} solution is dissolved and made into 90 milliliters of co-immersion solution. 100 g of carrier Z was impregnated with this solution for 24 hours, then dried at 120° C. for 4 hours, and calcined at 420° C. for 4 hours to obtain catalyst C4. The contents of nickel, tungsten and potassium oxides in catalyst C4 are listed in Table 1.

Table 1 example Catalyst number Content, wt% Nickel/Molybdenum or Tungsten (atomic) Nickel oxide Molybdenum oxide Tungsten oxide potassium oxide 1 C1 1.4 4.5 2.1 0.6 Comparative example 1 B1 0.9 4.6 1.4 0.4 Comparative example 2 B2 1.4 4.6 1.4 0.6 2 C2 3.1 4.3 - 5.4 1.4 3 C3 5.5 10.5 - 4.1 1.0 4 C4 1.7 - 7.9 5.0 0.7

Instance 5-8

This example illustrates the performance of the present invention to provide catalysts for the selective hydrogenation of diolefins in gasoline distillates.

Catalysts C1, C2, C3, and C4 were evaluated on a 50ml fixed-bed reactor using FCC heavy distillate oil as raw material (see Table 2 for its properties). Before formally feeding the catalyst, the catalyst was vulcanized with straight-run gasoline containing 2% by weight of carbon disulfide. The vulcanization conditions were: hydrogen partial pressure 1.6 MPa, temperature 290°C, liquid hourly space velocity 2h ^-1 , hydrogen-to-oil volume ratio 300, The vulcanization time is 9 hours, and then the raw material is cut into the reaction. The reaction temperature is 240°C, the hydrogen partial pressure is 1.6 MPa, the volume space velocity is 20 hours ^-1 , and the hydrogen-oil ratio (volume) is 100. After 100 hours of reaction, the sample is analyzed, and the results are listed in Table 3.

Determination method of diene value: use a pipette to accurately draw 5 milliliters of the sample into a ground-mouthed Erlenmeyer flask, and then use a pipette to accurately add 20 milliliters of benzene-anhydrous maleic anhydride solution (30 grams per liter of benzene) Anhydrous maleic anhydride) and 0.2 ml of iodine-xylene solution (0.1N), and 10 ml of benzene instead of the sample for blank test. Install a spherical reflux condenser on the Erlenmeyer flask, put it in an 80°C constant temperature water bath to reflux for 30 minutes, then add 5 ml of deionized water from the top of the condenser, and continue to reflux for 30 minutes to fully hydrolyze the remaining maleic anhydride. Cool to room temperature, rinse the condenser with 5 ml of ether and 20 ml of deionized water, and then remove the Erlenmeyer flask. Pour the mixture in the bottle into a 250ml separatory funnel for separation. Finally, titrate the separated aqueous solution with 0.5N sodium hydroxide solution, and record the consumed volume.

Diene value=12.692×N×(B-A)L×d

In the formula: N-NaOH standard solution concentration

B-The volume of NaOH solution consumed by the blank test, ml

A-The volume of NaOH solution consumed by the sample, ml

L-sample volume, ml

d-sample density at 20°C, g/ml

The determination method of bromine value is RIPP 66-90.

Comparative example 3-4

This comparative example illustrates the performance of the reference catalyst for the hydrofinishing of gasoline distillates.

The same method as Example 4 was used to evaluate and evaluate comparative catalysts B1 and B2, and the reaction results are shown in Table 3.

Table 2 Oil name FCC gasoline heavy fraction Density (20°C), g/cm ³ sulfur, ppm diene value, gI ₂ /100g bromine value, gBr/100g Distillation range D-86, °C initial boiling point 10% 50% 90% 95% dry point 0.785516801.637.192112135165174190

table 3 example 5 Contrast agent 3 contrast agent 4 6 7 8 catalyst C1 B1 B2 C2 C3* C4 Product Properties Diene Value, gI ₂ /100g Bromine Value, gBr/100g 0.336.1 0.633.9 0.534.7 <0.236.3 <0.236.4 <0.235.4

*C3 reaction temperature is 230℃

The results in Table 3 show that, compared with existing catalysts, the catalyst provided by the present invention has a higher diolefin hydrogenation activity when used in gasoline distillate hydrotreating.

The bromine value of raw oil is 37.1gBr/100ml, and the bromine value of the produced oil after hydrogenation all decreases. However, as can be seen from the results in Table 3, when the catalyst provided by the present invention is adopted, the reduction in bromine value of the oil generated is lower than that of the existing catalyst, which indicates that the catalyst provided by the present invention has better selectivity.

Claims (6)

1, a kind of alkadienes selective hydrocatalyst, this catalyst contains a kind of alumina support and loads on the cobalt that is selected from group VIII on this carrier and/or molybdenum and/or the tungsten and the alkaline components of nickel, group vib, it is characterized in that, in oxide and with the catalyst is benchmark, this catalyst contain the molybdenum that is selected from group vib of the cobalt that is selected from group VIII of 0.5-8 weight % and/or nickel, 2-15 weight % and/or tungsten,＞alkali metal of 2-8 weight % and the alumina support of aequum.

2, catalyst according to claim 1, it is characterized in that, in oxide and with the catalyst is benchmark, and this catalyst contains the molybdenum that is selected from group vib and/or tungsten, the alkali metal of 2.5-6 weight % and the alumina support of aequum of the cobalt that is selected from group VIII of 1-6 weight % and/or nickel, 4-12 weight %.

3, catalyst according to claim 1 and 2 is characterized in that, described group VIII metal component is a nickel.

4, catalyst according to claim 1 and 2 is characterized in that, described alkali metal is potassium.

5, catalyst according to claim 1 is characterized in that, the atomic ratio of described group VIII metal component and group vib metal component is 0.5-2.

6, catalyst according to claim 5 is characterized in that, the atomic ratio of described group VIII metal component and group vib metal component is 0.7-1.5.