阅读说明：本技术 氧化铝载体及其制备方法、c16~c20长链烷烃脱氢催化剂 (Alumina carrier and preparation method thereof, C16~C20Long-chain alkane dehydrogenation catalyst ) 是由 冯振学 顾彬 曹凤英 孙承林 陈东 荣欣 刘凯军 于 2020-04-01 设计创作，主要内容包括：本发明提供了一种氧化铝载体及其制备方法、C-(16)～C-(20)长链烷烃脱氢催化剂。氧化铝载体的制备方法包括步骤S1,使金属铝、盐酸和柠檬酸的混合酸混合反应形成包含铝溶胶的第一混合体系；步骤S2,将第一混合体系、扩孔剂和促凝剂混合形成第二混合体系；步骤S3,将第二混合体系进行老化、干燥、焙烧得到氧化铝载体。该制备方法利用柠檬酸、扩孔剂以及焙烧条件增大了氧化铝载体的孔容和比表面积。且制备方法简单、原料来源广泛,为满足C-(16)～C-(20)正构烷烃脱氢催化剂所需的催化剂载体提供了一种高效的制备方法。(The invention provides an alumina carrier, a preparation method thereof and a preparation method thereof 16 ～C 20 A long chain alkane dehydrogenation catalyst. The method for preparing the alumina carrier includes the step of S1, making metallic aluminum, hydrochloric acid and sodium citrateMixed acid mixing reaction of citric acid to form a first mixing system containing alumina sol; step S2, mixing the first mixed system, the pore-expanding agent and the coagulant to form a second mixed system; and step S3, aging, drying and roasting the second mixed system to obtain the alumina carrier. The preparation method utilizes citric acid, pore-expanding agent and roasting conditions to increase the pore volume and specific surface area of the alumina carrier. The preparation method is simple, the raw material source is wide, and the requirement of C is met 16 ～C 20 The catalyst carrier required by the normal alkane dehydrogenation catalyst provides an efficient preparation method.)

1. A preparation method of an alumina carrier is characterized by comprising the following steps:

step S1, mixed acid of metallic aluminum, hydrochloric acid and citric acid is subjected to mixed reaction to form a first mixed system containing alumina sol;

step S2, mixing the first mixed system, the pore-expanding agent and the coagulant to form a second mixed system; and

and step S3, aging, drying and roasting the second mixed system to obtain the alumina carrier.

2. The preparation method according to claim 1, wherein the molar ratio of the citric acid to the metallic aluminum is 0.01:1 to 3: 1.

3. The method according to claim 1 or 2, wherein the molar ratio of the metallic aluminum to the HCl in the hydrochloric acid is 1:1 to 2: 1.

4. The method according to claim 1, wherein the pore-expanding agent is selected from one or more of PEG, polyacrylamide, polyvinyl alcohol, water-soluble starch, and lignocellulose; preferably, the relative molecular weight of the PEG is 1000-20000; the aluminum sol is Al₂O₃Preferably, the PEG is bonded to the Al₂O₃The mass ratio of (A) to (B) is 0.001:1 to 0.5: 1.

5. The method according to claim 1, characterized in that the setting accelerator is an amine setting accelerator; preferably, the amine-based coagulant is selected from one or more of urea, hexamethylenetetramine and biuret; preferably, the molar ratio of the amine coagulant to Al in the aluminum sol is 0.2: 1-1: 1.

6. The method of claim 1, wherein an alkylene oxide is further added in step S2, preferably wherein the alkylene oxide is C₂～C₆The lower alkylene oxide of (1); preferably, the lower alkylene oxide is selected from one or more of propylene oxide, 1, 2-butylene oxide and cyclohexene oxide; preferably, the molar ratio of the low-carbon alkylene oxide to Al in the aluminum sol is 0.05: 1-0.5: 1.

7. The method for preparing a composite material according to claim 1, wherein the step S1 includes:

dissolving the metal aluminum in the mixed acid to react to form the first mixed system, preferably dissolving the metal aluminum at 90-110 ℃;

and filtering the first mixed system to obtain the aluminum sol.

8. The method for preparing a composite material according to claim 1, wherein the step S3 includes:

s31, dripping the second mixed system into a liquid paraffin oil column to form gel pellets, and aging the gel pellets for the first time in the liquid paraffin oil column for 2-12 hours;

step S32: carrying out secondary aging on the gel pellets, preferably, the temperature of the secondary aging is 80-160 ℃, and the time of the secondary aging is 4-24 h, so as to obtain aged pellets; and

and step S33, washing, drying and roasting the aged pellets to obtain the alumina carrier.

9. The method according to claim 1, wherein the metallic aluminum is one or more of aluminum foil, aluminum particles, and aluminum powder.

10. An alumina carrier is characterized in that the pore volume of the alumina carrier is 1.75-2.50 mL/g; preferably, the pore diameter of the alumina carrier is 85-350 nm; preferably, the bulk density of the alumina carrier is 0.20-0.45 g/mL; preferably, the specific surface area of the alumina carrier is 190-300 m²(ii)/g; preferably, the alumina carrier has a crush strength of 5 to 40N.

11. The alumina carrier of claim 10, which is obtained by the preparation method of any one of claims 1 to 9.

12. C₁₆～C₂₀A long-chain alkane dehydrogenation catalyst, wherein the dehydrogenation catalyst comprises an active component and an alumina carrier for supporting the active component, and is characterized in that the alumina carrier is oxygen as described in claim 10An alumina carrier.

13. The dehydrogenation catalyst of claim 12 wherein the active components comprise a primary catalytic active component and a co-catalytic active component, the primary catalytic active component is Pt, the co-catalytic active component comprises a first promoter and a second promoter, the first promoter is Sn, and the second promoter is one or more selected from the group consisting of K, Na, Mg, Ca.

14. The dehydrogenation catalyst of claim 12 wherein the alumina support has a pore volume of 1.75 to 2.50 mL/g; preferably, the pore diameter of the alumina carrier is 85-350 nm; preferably, the bulk density of the alumina carrier is 0.20-0.45 g/mL; preferably, the specific surface area of the alumina carrier is 190-300 m²(ii)/g; preferably, the alumina carrier has a crush strength of 5 to 40N.

15. The dehydrogenation catalyst of claim 13 wherein, in weight percent: the Pt accounts for 0.3-0.6% of the alumina carrier, the first auxiliary agent accounts for 0.5-5.0% of the alumina carrier, and the second auxiliary agent accounts for 0.2-2.0% of the alumina carrier.

Technical Field

The invention relates to the technical field of catalysts and carriers, in particular to an alumina carrier and a preparation method thereof, and a catalyst C₁₆～C₂₀A long chain alkane dehydrogenation catalyst.

Background

The alkylbenzene is the main raw material for producing detergent and anionic surfactant alkylbenzene sulfonate, and can be used as base oil of lubricating oil and heat-conducting oil. Wherein has C₁₆～C₂₀The alkyl chain heavy alkylbenzene sulfonate can form an ultra-low interfacial tension system with crude oil of most of Chinese oil fields, and the crude oil recovery rate is improved, so the alkyl chain heavy alkylbenzene sulfonate becomes an important oil displacement surfactant. With the successive water flooding abandonment of most oil fields in China, the demand of heavy alkylbenzene sulfonate surfactant for tertiary oil recovery is increasing.

In industrial production, the long-chain alkane dehydrogenation-alkylation process accounts for more than 70% of the global alkylbenzene yield, and is also the main production development direction of detergent raw materials in China. The key of the technical route is the dehydrogenation of long-chain alkane to prepare linear mono-olefin, wherein the long-chain alkane dehydrogenation catalyst is the key of the step. Linear alkylbenzene sulfonates were first produced synthetically by the Pt catalyst based catalytic dehydrogenation process of long chain alkanes developed by UOP corporation in the 60's of the 20 th century. At present, widely usedThe long-chain alkane dehydrogenation catalyst mainly comprises Pt-Sn bimetal and Pt-Sn modified multi-metal catalyst, and the carrier is alumina. At present, there are some patents related to the preparation of large pore volume alumina, mainly including two methods of oil column forming and oil ammonia column forming. The Chinese patent application with the application publication number of CN104492407A uses NaAlO₂-Al₂(SO₄)₃Taking an aluminum sulfate solution and a sodium metaaluminate solution as raw materials, neutralizing, precipitating and peptizing, and preparing large-pore-volume alumina by an oil ammonia column method, wherein the specific surface is only 80-100 m²(ii) in terms of/g. For example, the application publication number is CN103172097A, the alumina synthesized by adopting a nucleation crystallization isolation method has the pore volume of 0.5-1.2 mL/g and the pore diameter of 10-30 nm; chinese patent applications with application publication numbers CN1114290A and CN1068975A both adopt aluminum salt or aluminate to precipitate and peptize, and then are molded by an oil column method to prepare spherical alumina with large pore volume; the application publication No. CN104907103A Chinese patent application adopts a hydrochloric acid reflux method to prepare an aluminum sol A and an ammonia precipitation method to prepare a wet filter cake B, then the aluminum sol A and the wet filter cake B are mixed to prepare a mixed aluminum sol, and the mixed aluminum sol is subjected to oil column molding to prepare the spherical alumina carrier.

However, up to now, it has been reported that large pore volume spherical alumina supports are mainly used for the preparation of n-C₁₃The following normal paraffin dehydrogenation catalysts, but due to n-C₁₆～C₂₀The normal alkane dehydrogenation catalyst carrier needs to have larger pore volume and higher specific surface area, so the existing alumina carrier is not suitable for the normal alkane (n-C) with longer carbon chain₁₆～C₂₀) A dehydrogenation catalyst support.

Disclosure of Invention

The invention mainly aims to provide an alumina carrier, a preparation method thereof and a preparation method thereof₁₆～C₂₀A long-chain alkane dehydrogenation catalyst, aiming at solving the problem that the dehydrogenation catalyst carrier in the prior art can not meet C₁₆～C₂₀The problem of the need for dehydrogenation of n-alkanes.

In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing an alumina carrier, the method comprising the steps of S1, reacting a mixed acid of metallic aluminum, hydrochloric acid and citric acid to form a first mixed system containing an alumina sol; step S2, mixing the first mixed system, the pore-expanding agent and the coagulant to form a second mixed system; and step S3, aging, drying and roasting the second mixed system to obtain the alumina carrier.

Further, the molar ratio of the citric acid to the metal aluminum is 0.01:1 to 3: 1.

Further, the molar ratio of the metallic aluminum to HCl in hydrochloric acid is 1: 1-2: 1.

Further, the pore-expanding agent is selected from one or more of PEG, polyacrylamide, polyvinyl alcohol, water-soluble starch and lignocellulose; preferably, the relative molecular weight of PEG is 1000-20000; aluminium sol with Al₂O₃Preferably PEG and Al₂O₃The mass ratio of (A) to (B) is 0.001:1 to 0.5: 1.

Further, the accelerator is an amine accelerator; preferably, the amine-based coagulant is selected from one or more of urea, hexamethylenetetramine and biuret; the molar ratio of the amine coagulant to Al in the aluminum sol is preferably 0.2:1 to 1: 1.

Further, alkylene oxide is added in the step S2, preferably, the alkylene oxide is C₂～C₆The lower alkylene oxide of (1); preferably the lower alkylene oxide is selected from one or more of propylene oxide, 1, 2-butylene oxide and cyclohexene oxide; preferably, the mol ratio of the low-carbon alkylene oxide to Al in the aluminum sol is 0.05: 1-0.5: 1.

Further, the step S1 includes dissolving metallic aluminum in a mixed acid to react to form a first mixed system, preferably dissolving metallic aluminum at 90-110 ℃; and filtering the first mixed system to obtain the aluminum sol.

Further, the step S3 includes a step S31 of dropping the second mixed system into the liquid paraffin oil column to form gel beads, and aging the gel beads in the liquid paraffin oil column for a first time for 2 to 12 hours; step S32: carrying out secondary aging on the gel pellets, preferably, the temperature of the secondary aging is 80-160 ℃, and the time of the secondary aging is 4-24 h, so as to obtain aged pellets; and step S33, washing, drying and roasting the aged pellets to obtain the alumina carrier.

Further, the metal aluminum is one or more of aluminum foil, aluminum particles and aluminum powder.

According to another aspect of the present invention, there is provided an alumina carrier, wherein the pore volume of the alumina carrier is 1.75-2.50 mL/g; the pore diameter of the alumina carrier is preferably 85-350 nm; preferably, the bulk density of the alumina carrier is 0.20-0.45 g/mL; the specific surface area of the preferred alumina carrier is 190-300 m²(ii)/g; the alumina carrier preferably has a crush strength of 5 to 40N.

Further, the alumina carrier is obtained by the preparation method.

According to still another aspect of the present invention, there is provided C₁₆～C₂₀The dehydrogenation catalyst comprises an active component and an alumina carrier for loading the active component, wherein the alumina carrier is the alumina carrier.

Further, the active components comprise a main catalytic active component and a cocatalyst active component, the main catalytic active component is Pt, the cocatalyst active component comprises a first auxiliary agent and a second auxiliary agent, the first auxiliary agent is Sn, and the second auxiliary agent is one or more selected from K, Na, Mg and Ca.

Furthermore, the pore volume of the alumina carrier is 1.75-2.50 mL/g; the pore diameter of the alumina carrier is preferably 85-350 nm; preferably, the bulk density of the alumina carrier is 0.20-0.45 g/mL; the specific surface area of the preferred alumina carrier is 190-300 m²(ii)/g; the alumina carrier preferably has a crush strength of 5 to 40N.

Further, in the above dehydrogenation catalyst, by weight: pt accounts for 0.3-0.6% of the alumina carrier, the first auxiliary agent accounts for 0.5-5.0% of the alumina carrier, and the second auxiliary agent accounts for 0.2-2.0% of the alumina carrier.

The technical scheme of the invention is that firstly, mixed acid of hydrochloric acid and citric acid is adopted to react with aluminum to form aluminum sol, and carboxyl on citric acid molecules is coordinated with Al of the aluminum sol to form complexation in the forming process of the aluminum solThe citric acid is decomposed to form more defect sites in the later heating aging and roasting processes, so that the aperture and the pore volume of the alumina carrier are increased; secondly, the pore structure of the carrier is changed in the roasting process, wherein part of the pore walls are sintered and collapsed to form macropores due to high temperature, and more importantly, the particle gaps among the alumina powder particles are generated by removing the pore-expanding agent. Based on the two factors, the pore volume and the specific surface area of the alumina carrier are increased, and the preparation method is simple, has wide raw material sources and meets the requirement of C₁₆～C₂₀The catalyst carrier required by the normal alkane dehydrogenation catalyst provides an efficient preparation method, and has good industrial application value.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

figure 1 shows the ". delta. pore volume/. delta. pore diameter" -pore diameter distribution plot for alumina supports according to examples 1,2, 3 and 4 of the present invention;

FIG. 2 shows a SEM picture of an alumina support according to example 5 of the present invention; and

figure 3 shows a SEM image of an alumina support according to example 10 of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As analyzed by the background, the prior art alumina supports are not suitable as longer carbon chain n-alkanes (n-C)₁₆～C₂₀) A dehydrogenation catalyst support. In order to solve the technical problem, the technical personnel of the invention carry out the treatment on an alumina carrier and n-alkane (n-C)₁₆～C₂₀) Dehydrogenation process studies have found that alumina supports are not suitable as longer carbon chain n-alkanes (n-C)₁₆～C₂₀) Dehydrogenation catalyst supportBecause of the limitation of the specific surface area and pore volume of long-chain n-alkanes (n-C)₁₆～C₂₀) Contact with the catalytically active component on the support. Based on the discovery, the invention provides an alumina carrier, a preparation method thereof and a preparation method thereof₁₆～C₂₀A long-chain alkane dehydrogenation catalyst, aiming at solving the problem that the dehydrogenation catalyst carrier in the prior art can not meet C₁₆～C₂₀The problem of the need for dehydrogenation of n-alkanes.

In one exemplary embodiment of the present application, there is provided a method of preparing an alumina support, the method comprising: step S1, mixed acid of metallic aluminum, hydrochloric acid and citric acid is subjected to mixed reaction to form a first mixed system containing alumina sol; step S2, mixing the first mixed system, the pore-expanding agent and the coagulant to form a second mixed system; and step S3, aging, drying and roasting the second mixed system to obtain the alumina carrier.

According to the preparation method of the alumina carrier, firstly, mixed acid of hydrochloric acid and citric acid is adopted to react with aluminum to form aluminum sol, carboxyl on citric acid molecules is coordinated with Al of the aluminum sol to form a complex in the forming process of the aluminum sol, and the citric acid is decomposed to form a plurality of defect positions in the later heating aging and roasting processes, so that the aperture and the pore volume of the alumina carrier are increased; secondly, the pore structure of the carrier is changed in the roasting process, wherein part of the pore walls are sintered and collapsed to form macropores due to high temperature, and more importantly, the particle gaps among the alumina powder particles are generated by removing the pore-expanding agent. Based on the two factors, the pore volume and the specific surface area of the alumina carrier are increased, and the preparation method is simple, has wide raw material sources and meets the requirement of C₁₆～C₂₀The catalyst carrier required by the normal alkane dehydrogenation catalyst provides an efficient preparation method, and has good industrial application value.

In order to coordinate citric acid with Al to form a complex as much as possible so as to form more defect sites and increase the specific surface area of the alumina carrier, and not to influence the peptization process of the alumina sol due to too much acidity of the citric acid, the amount of the citric acid is preferably controlled, namely the molar ratio of the citric acid to the metallic aluminum is 0.01: 1-3: 1.

In the process of dilute acid peptization, along with the increase of the addition of acid, the peptization speed becomes fast, and the alumina sol with higher solid content can be easily obtained, however, the excessive and insufficient acid content is unfavorable for the subsequent oil column molding; for example, the amount of the added dilute acid is large, so that the obtained aluminum sol becomes thin, the fluidity is too strong, and the balls dropped into the oil column are adhered together, which is not beneficial to solidification and molding; if the amount of the added dilute acid is small, the thixotropy of the obtained aluminum sol is too strong, and the sphericity of the spherical carrier obtained by molding in an oil column is too poor. In order to adapt to oil column forming, the molar ratio of the metal aluminum to HCl in the hydrochloric acid is preferably 1: 1-2: 1.

In order to better mix with the alumina sol, the invention preferably uses a physical pore-expanding agent, generally selects a water-soluble high molecular organic polymer, and more preferably selects one or more pore-expanding agents selected from PEG, polyacrylamide, polyvinyl alcohol, water-soluble starch and lignocellulose. In order to obtain alumina having an increased specific surface area and pore volume, PEG preferably has a relative molecular weight of 1000 to 20000.

In the stirring process, the pore-expanding agent molecules are uniformly dispersed in the alumina carrier and are wrapped by the alumina powder particles, and after heating, aging and roasting, the pore-expanding agent molecules are oxidized into gas to escape, so that the space occupied before is reserved. In principle, the more pore-expanding agent is used, the more pores should be formed after calcination, but the more pores will affect the strength and specific surface area of alumina, and in order to balance pore volume, specific surface area and strength, the above PEG and Al are preferred₂O₃The mass ratio of (A) to (B) is 0.001:1 to 0.5: 1. Limiting the molecular weight and amount of PEG to the above ranges helps PEG to exert its pore-enlarging effect as much as possible and allows alumina to maintain high strength.

The accelerators used in the present application may be those commonly used in the preparation of alumina in the prior art, and preferably in the present application they are amine accelerators which decompose on heating during ageing to release ammonia which is then incorporated into the alumina solAl of (2)³⁺Neutralization promotes the solidification of the aluminum sol. Preferably, the amine-based coagulant is selected from one or more of urea, hexamethylenetetramine and biuret; the molar ratio of the amine coagulant to Al in the aluminum sol is preferably 0.2:1 to 1: 1.

In an embodiment of the present application, in step S2, an alkylene oxide is further added, and under a heating condition, the alkylene oxide is subjected to ring opening under the action of anions in the aluminum sol, such as chloride ions and citrate ions, so as to form a polymer precipitate with Al in the sol, thereby promoting solidification and molding during aging of the aluminum sol. The ring-opened alkane serving as a part of the structure of the solidified globule is released in the space occupied by the ring-opened alkane in the heating and roasting processes, so that the pore volume and the specific surface area of the alumina carrier are increased, and the prepared alumina carrier solves the problem of C in the prior art due to high specific surface area and large pore volume₁₆～C₂₀The problem of the n-alkane dehydrogenation catalyst support requiring a support having a larger pore volume and a higher specific surface area. Preferred alkylene oxides are C₂～C₆The low-carbon alkylene oxide has more active property, is easy to generate ring opening reaction, and the low-carbon alcohol generated by ring opening has large polarity and is easy to combine with hydroxyl (Al-OH) combined on aluminum, thereby stabilizing defect sites and increasing the specific surface area of the aluminum oxide; preferably the lower alkylene oxide is selected from one or more of propylene oxide, 1, 2-butylene oxide and cyclohexene oxide; preferably, the mol ratio of the low-carbon alkylene oxide to Al in the aluminum sol is 0.05: 1-0.5: 1. The molar ratio of the low-carbon alkylene oxide to Al in the aluminum sol is controlled to be 0.05: 1-0.5: 1, so that the curing effect of the low-carbon alkylene oxide is favorably exerted, the aluminum sol is better cured and formed, the low-carbon alkylene oxide is decomposed in the heating and roasting process, and the space occupied by gel beads is released, so that the specific surface area and the pore volume of the alumina carrier are increased.

In order to make the prepared aluminum sol more favorable for solidification and molding in an oil column and thus make the prepared alumina carrier have larger pore volume and higher specific surface area, preferably, the step S1 includes dissolving metallic aluminum in a mixed acid to react to form a first mixed system, preferably, dissolving the metallic aluminum foil is performed at 90-110 ℃; and filtering the first mixed system to obtain the aluminum sol. The method is beneficial to more complete aluminum dissolution at 90-110 ℃, partial solid particle impurities can be removed by filtering the first mixed system, the method is more beneficial to forming of aluminum sol in an oil column, and the influence of the impurities on the performance of the finally prepared alumina carrier is reduced to a greater extent.

In an embodiment of the present application, the step S3 further includes a step S31, in which the second mixed system is dropped into the liquid paraffin oil column to form gel beads, and the gel beads are aged in the liquid paraffin oil column for the first time for 2 to 12 hours; step S32: carrying out secondary aging on the gel pellets, preferably, the temperature of the secondary aging is 80-160 ℃, and the time of the secondary aging is 4-24 hours, so as to obtain aged pellets; and step S33, washing, drying and roasting the aged pellets to obtain the alumina carrier.

The primary aging of the second mixed system is to make the sol act with PEG, low-carbon alkylene oxide and amine coagulant in an oil column to solidify into small balls, the temperature of the secondary aging is raised to 80-160 ℃, the primary purpose is to decompose PEG and ring-opening alkane which forms oligomer precipitate with aluminum and are uniformly dispersed in the gel small balls so as to release the space occupied by the PEG and the ring-opening alkane in the gel small balls, and the aged small balls are washed with water so as to remove unreacted amine coagulant, alkylene oxide and ring-opening alkane thereof, citric acid and partial water-soluble byproducts obtained by reaction, so that residual organic matters and the like are reduced to be decomposed into substances polluting the environment in the roasting process. Further drying to obtain a relatively pure aluminum hydroxide precipitate, wherein the purpose of roasting is to heat and dehydrate the aluminum hydroxide and further decompose volatile impurities, and burn off organic matters to increase the pore size and the pore diameter of the alumina carrier, so as to increase the pore volume and the specific surface area of the alumina carrier. The specific operation processes of the first aging, the second aging, the water washing, the drying and the roasting can refer to the prior art, for example, the first aging temperature is controlled to be 40-100 ℃, and the details are not repeated in the specific application.

The metallic aluminum used in the present application may be derived from metallic aluminum scraps, crushed metallic aluminum ingots, aluminum foils, etc., and in order to make the prepared aluminum sol purer and further make the obtained corresponding alumina carrier better in performance, the metallic aluminum is preferably one or more of aluminum foils, aluminum particles and aluminum powder. The purity of aluminum foil currently on the market is more than 96%, so that the purity of the aluminum sol can be optimized.

In another exemplary embodiment of the present application, an alumina carrier is provided, wherein the pore volume of the alumina carrier is 1.75 to 2.50 mL/g; the pore diameter of the alumina carrier is preferably 85-350 nm; preferably, the bulk density of the alumina carrier is 0.20-0.45 g/mL; the specific surface area of the preferred alumina carrier is 190-300 m²(ii)/g; the alumina carrier preferably has a crush strength of 5 to 40N.

The alumina carrier prepared by the preparation method has the pore volume and the specific surface area within the range, so the specific surface area and the pore volume of the alumina carrier increase the long-chain n-alkane (n-C)₁₆～C₂₀) Contact with the catalytically active component on the support. Thereby solving the problem that the dehydrogenation catalyst carrier in the prior art can not meet the requirement of C₁₆～C₂₀The problem of the need for dehydrogenation of n-alkanes.

The above alumina carrier is an alumina carrier obtained by any one of the above preparation methods, and has a larger pore volume and a higher specific surface area.

The specific surface area and the pore volume of the alumina carrier obtained by the preparation method of the alumina carrier are increased by long-chain n-alkane (n-C)₁₆～C₂₀) Contact with the catalytically active component on the support. Thereby solving the problem that the dehydrogenation catalyst carrier in the prior art can not meet the requirement of C₁₆～C₂₀The problem of the need for dehydrogenation of n-alkanes.

In another exemplary embodiment of the present application, there is provided a method for producing a semiconductor device₁₆～C₂₀The dehydrogenation catalyst comprises an active component and an alumina carrier loaded with the active component, and the alumina carrier included in the dehydrogenation catalyst is the alumina carrier. Alumina supports as found by the skilled person are not suitable as longer carbon chain n-alkanes (n-C)₁₆～C₂₀) Dehydrogenation catalyst supports because of their specific surface area and pore volume limitations of long chain n-alkanes (n-C)₁₆～C₂₀) Contact with the catalytically active component on the support. The specific surface area and the pore volume of the alumina carrier obtained by the preparation method of the alumina carrier are increased by long-chain n-alkane (n-C)₁₆～C₂₀) Contact with the catalytically active component on the support. Thereby the prepared dehydrogenation catalyst satisfies C₁₆～C₂₀The need of dehydrogenation reaction of long-chain alkane is further solved, and the problem that the dehydrogenation catalyst carrier in the prior art can not meet the requirement of C₁₆～C₂₀The problem of the need for dehydrogenation of n-alkanes.

The active component of the dehydrogenation catalyst of the present application can employ C of the prior art₁₆～C₂₀The active components commonly used in the long-chain alkane dehydrogenation catalyst, such as the active components of the above dehydrogenation catalyst, include a main catalytic active component and a co-catalytic active component, preferably, the main catalytic active component is Pt, the co-catalytic active component includes a first assistant and a second assistant, the first assistant is Sn, and the second assistant is one or more selected from K, Na, Mg, and Ca. The second auxiliary agent also comprises Na, Mg and Ca besides K which is commonly used in the field, and because the alumina carrier of the invention has the advantages of the specific surface and the pore volume, the auxiliary catalytic function of the promoters of the components can be exerted, and the ideal catalytic effect can be achieved.

In order to increase the specific surface area and the pore volume of the alumina carrier, thereby increasing the long-chain n-alkane (n-C)₁₆～C₂₀) Contact with the catalytically active component on the support. Thereby making the prepared dehydrogenation catalyst satisfy C₁₆～C₂₀The need of dehydrogenation reaction of long-chain alkane is further solved, and the problem that the dehydrogenation catalyst carrier in the prior art cannot meet the requirement of C₁₆～C₂₀The problem of the need for dehydrogenation of n-alkanes. The dehydrogenation catalyst provided by the application comprises an alumina carrier, wherein the pore volume of the alumina carrier is 1.75-2.50 mL/g; the pore diameter of the alumina carrier is preferably 85-350 nm; preferably, the bulk density of the alumina carrier is 0.20-0.45 g/mL; the specific surface area of the preferred alumina carrier is 190-300 m²(ii)/g; the alumina carrier preferably has a crush strength of 5 to 40N.

In percentage by weight, Pt in the dehydrogenation catalyst is 0.3-0.6% of the alumina carrier, the first auxiliary agent is 0.5-5.0% of the alumina carrier, and the second auxiliary agent is 0.2-2.0% of the alumina carrier. The parameter ranges of the components of the dehydrogenation catalyst are limited in the ranges so as to provide the dehydrogenation catalyst with higher activity, so as to solve the problem that the dehydrogenation catalyst carrier in the prior art cannot meet the requirement of C₁₆～C₂₀The problem of the need for dehydrogenation of n-alkanes. In addition, the long-chain alkane C prepared by the invention₁₆～C₂₀The dehydrogenation catalytic reaction can be carried out at the temperature of 440-490 ℃, the pressure of 0.05-0.2 MPa and the liquid hourly space velocity of 5-25 h^-1And the volume ratio of hydrogen to hydrocarbon is 200-600: 1.

The advantageous effects of the present application will be further described below with reference to specific examples and comparative examples.

Examples 1 to 23, comparative examples 1 and 2 are examples of alumina carrier production

Example 1

Adding 71g of metal aluminum with the purity of more than 99% into a mixed acid of hydrochloric acid with the mass concentration of 13% and citric acid with the mass concentration of 1.0% to ensure that the molar ratio of Al to Cl is 1.55:1 and the molar ratio of citric acid to Al is 0.5:1, reacting at the temperature of 95 ℃ until the metal aluminum is completely dissolved, and filtering to obtain Al₂O₃Aluminum sol with a solid content of 26.3%.

Adding 15.3g of PEG-6000 into the aluminum sol, and mixing with the aluminum sol to obtain Al₂O₃In a mass ratio of 0.114:1, 21.6g of 1, 2-epoxybutane to Al in the alumina sol³⁺300g of 40 wt% (mass concentration, the same applies hereinafter) hexamethylenetetramine solution in a molar ratio of 0.11:1 with Al in the aluminum sol³⁺The molar ratio of the raw materials is 0.3:1, the raw materials are stirred uniformly and then dropped into a liquid paraffin oil column at 60 ℃ to form gel pellets, the gel pellets are aged in the oil column for the first time for 12 hours, the gel pellets are taken out and transferred into an aging kettle, the aging is continued for the second time at 80 ℃ and aged for 24 hours to obtain aged pellets, the aged pellets are washed by water, dried at 120 ℃ to obtain dried aluminum hydroxide precipitate, and the dried aluminum hydroxide precipitate is roasted at 600 ℃ for 4 hours to obtain a macroporous volume-to-height ratio tableThe surface alumina carrier is marked as carrier Al₂O₃-A。

Example 2

Adding 71g of metal aluminum with the purity of more than 99% into a mixed acid of 9.5% hydrochloric acid and 2.5% citric acid by mass concentration to ensure that the molar ratio of Al/Cl is 1.1:1 and the molar ratio of citric acid to Al is 1:1, reacting at 90 ℃ until the metal aluminum is completely dissolved, and filtering to obtain Al₂O₃Aluminum sol with a solid content of 19.5%.

Adding 15.3g of PEG-6000 into the aluminum sol, and mixing with the aluminum sol to obtain Al₂O₃In a mass ratio of 0.114:1, 34.8g of propylene oxide to Al in the aluminum sol³⁺In a molar ratio of 0.23:1, 117g of urea to Al in the alumina sol³⁺The molar ratio of the alumina to the water is 0.7:1, the mixture is stirred uniformly and then dropped into a liquid paraffin oil column at 45 ℃ to form gel pellets, the gel pellets are aged in the oil column for the first time for 12 hours, the gel pellets are taken out and transferred into an aging kettle, the aging is continued for the second time at 110 ℃ and aged for 8 hours to obtain aged pellets, the aged pellets are washed with water, dried at 120 ℃ to obtain dried aluminum hydroxide precipitate, and the dried aluminum hydroxide precipitate is roasted at 600 ℃ for 4 hours to obtain an alumina carrier with large pore volume and high specific surface, and the alumina carrier is marked as carrier Al₂O₃-B。

Example 3

Adding 71g of metal aluminum with the purity of more than 99% into a mixed acid of 9.5% hydrochloric acid and 2.5% citric acid by mass concentration to ensure that the molar ratio of Al/Cl is 1.1:1 and the molar ratio of citric acid to Al is 2:1, reacting at the temperature of 110 ℃ until the metal aluminum is completely dissolved, and filtering to obtain Al₂O₃Aluminum sol with a solid content of 19.5%.

Adding 15.3g of PEG-6000 into the aluminum sol, and mixing with the aluminum sol to obtain Al₂O₃In a mass ratio of 0.114:1, 51g of propylene oxide to Al in the alumina sol³⁺In a molar ratio of 0.33:1, 98g of urea to Al in the alumina sol³⁺The molar ratio of the gel to the solvent is 0.6:1, the gel is uniformly stirred and then dripped into a liquid paraffin oil column at 40 ℃ to form gel pellets, the gel pellets are aged for 12 hours in the oil column, the gel pellets are taken out and transferred into an aging kettle, the aging is continued for the second time at 160 ℃, and the aging is continued for 4 hours to obtain the aged pelletsWashing the pellets with water, drying at 120 ℃ to obtain dried aluminum hydroxide precipitate, roasting at 600 ℃ for 4 hours to obtain an alumina carrier with large pore volume and high specific surface, and marking as carrier Al₂O₃-C。

Example 4

Example 4 differs from example 3 in that PEG-6000 in example 3 was replaced by PEG-12000 to give an alumina carrier with large pore volume and high specific surface, which is denoted as carrier Al₂O₃-D。

Example 5

Example 5 differs from example 3 in that PEG-6000 in example 3 is replaced by PEG-20000 to obtain an alumina carrier with large pore volume and high specific surface, which is marked as carrier Al₂O₃-E, SEM picture as in FIG. 2.

Example 6

Example 6 differs from example 5 in that the molar ratio of citric acid to Al is 0.008:1, an alumina support with large pore volume and high specific surface is obtained, which is noted as carrier Al₂O₃-F。

Example 7

Example 7 differs from example 5 in that the molar ratio of citric acid to Al is 0.01:1, giving an alumina support with large pore volume and high specific surface, noted as support Al₂O₃-G。

Example 8

Example 8 differs from example 5 in that the molar ratio of citric acid to Al is 3:1, giving an alumina support with large pore volume and high specific surface, noted as support Al₂O₃-H。

Example 9

Example 9 differs from example 5 in that the molar ratio of citric acid to Al is 4:1, giving an alumina support with large pore volume and high specific surface, noted as support Al₂O₃-I。

Example 10

Example 10 differs from example 5 in that the alumina carrier obtained in example 5 by removing propylene oxide was designated as carrier Al₂O₃-J, SEM image thereof is shown in fig. 3.

Example 11

Example 11 differs from example 5 in that the molar ratio of propylene oxide to Al is 0.04:1, giving an alumina support with large pore volume and high specific surface, denoted as carrier Al₂O₃-K。

Example 12

Example 12 differs from example 5 in that the molar ratio of propylene oxide to Al is 0.05:1, giving an alumina support with a large pore volume and a high specific surface, denoted as carrier Al₂O₃-L。

Example 13

Example 13 differs from example 5 in that the molar ratio of propylene oxide to Al is 0.5:1, giving an alumina support with large pore volume and high specific surface, denoted as carrier Al₂O₃-M。

Example 14

Example 14 differs from example 5 in that 51g of propylene oxide in example 5 was replaced by 63g of 1, 2-butylene oxide to give an alumina support with large pore volume and high specific surface, noted as support Al₂O₃-N。

Example 15

Example 15 differs from example 5 in that 98g of urea in example 5 was replaced with 3.2g, and Al in the alumina sol³⁺At a molar ratio of 0.15:1, an alumina carrier with a large pore volume and a high specific surface was obtained, which was designated as carrier Al₂O₃-O。

Example 16

Example 16 differs from example 5 in that 98g of urea in example 5 was replaced with 32g, and Al in the aluminum sol³⁺At a molar ratio of 0.2:1, an alumina carrier with a large pore volume and a high specific surface is obtained, and is marked as carrier Al₂O₃-P。

Example 17

Example 17 differs from example 5 in that 98g of urea in example 5 was replaced by 158g, and Al in the alumina sol was used³⁺At a molar ratio of 1.0:1, an alumina carrier with a large pore volume and a high specific surface was obtained, which was designated as carrier Al₂O₃-Q。

Example 18

Example 18 difference from example 5In example 5, 98g of urea was replaced by 600g of a 40 wt% hexamethylenetetramine solution to give an alumina support with a large pore volume and a high specific surface, denoted as support Al₂O₃-R。

Example 19

Example 19 differs from example 5 in that the Al/Cl molar ratio is 2.0:1, giving an alumina support with a large pore volume and a high specific surface, noted as carrier Al₂O₃-S。

Example 20

Example 20 differs from example 5 in that the Al/Cl molar ratio is 0.9:1, giving an alumina support with a large pore volume and a high specific surface, noted as carrier Al₂O₃-T。

Example 21

Example 21 differs from example 5 in that PEG-20000 in example 5 is replaced by PEG-25000 to obtain an alumina carrier with large pore volume and high specific surface, which is marked as carrier Al₂O₃-U。

Example 22

Example 22 differs from example 5 in that 15.3g of PEG-20000 in example 5 is replaced by 0.134g, and in that the aluminium sol has a solid content of Al₂O₃In a mass ratio of 0.001:1, to obtain an alumina carrier with large pore volume and high specific surface, which is marked as carrier Al₂O₃-V。

Example 23

Example 23 differs from example 5 in that 15.3g of PEG-20000 in example 5 was replaced by 67.1g, and the alumina sol solid content Al₂O₃In a mass ratio of 0.5:1, to obtain an alumina carrier with large pore volume and high specific surface, which is marked as carrier Al₂O₃-W。

Comparative example 1

Comparative example 1 differs from example 5 in that citric acid was removed and the resulting alumina support, designated as support Al₂O₃-X。

Comparative example 2

Comparative example 2 differs from example 5 in that PEG-20000 was removed and the resulting alumina support, designated as support Al₂O₃-Y。

The structural parameters of the alumina supports prepared in examples 1 to 23 and comparative examples 1 to 2 are shown in Table 1.

Preparation examples of dehydrogenation catalysts

Example 24

10g of carrier Al prepared in examples 1 to 23 and comparative examples 1 to 2 were weighed out separately₂O₃-A～Al₂O₃Y, placing the powder in a vacuum impregnator, and simultaneously taking 2.6mL of chloroplatinic acid aqueous solution with platinum concentration of 0.02g/mL, 0.82mL of concentrated hydrochloric acid, 2.2mL of stannous chloride aqueous solution with tin content of 0.06g/mL, and 1.0mL of potassium chloride aqueous solution with potassium concentration of 0.04 g/mL. Adding the above impregnation solution into a vacuum impregnator filled with carrier, uniformly impregnating, drying at 120 deg.C for 2 hr, and calcining at 520 deg.C in muffle furnace for 4 hr to obtain pure hydrogen (purity) containing water less than 20ppm>99.9%) was reduced at 470 ℃ for 2h, in order to obtain the catalyst Cat-A, Cat-B, Cat-C, Cat-D … Cat-Y, in which: platinum is 0.52% of the carrier, tin is 1.3% of the carrier, and potassium is 0.4% of the carrier.

Example 25

10g of the carrier Al from example 4 were weighed out₂O₃And (D) placing the mixture in a vacuum impregnator, and simultaneously taking 1.5mL of chloroplatinic acid aqueous solution with platinum concentration of 0.02g/mL, 1.46mL of concentrated hydrochloric acid, 8.3mL of stannous chloride aqueous solution with tin content of 0.06g/mL and 0.5mL of potassium chloride aqueous solution with potassium concentration of 0.04 g/mL. Adding the above impregnation solution into a vacuum impregnator filled with carrier, uniformly impregnating, drying at 120 deg.C for 2 hr, and calcining at 520 deg.C in muffle furnace for 4 hr to obtain pure hydrogen (purity) containing water less than 20ppm>99.9%) at 470 ℃ for 2h to obtain the catalyst Cat-D₂₅And in the catalyst obtained: platinum being Al₂O₃0.3% of-D, tin being Al₂O₃5.0% of-D, potassium being Al₂O₃0.2% of D.

Example 26

10g of the carrier Al from example 4 were weighed out₂O₃And (D) placing the mixture in a vacuum impregnator, and simultaneously taking 3.0mL of chloroplatinic acid aqueous solution with platinum concentration of 0.02g/mL, 1.25mL of concentrated hydrochloric acid, 0.83mL of stannous chloride aqueous solution with tin content of 0.06g/mL and 5.0mL of potassium chloride aqueous solution with potassium concentration of 0.04 g/mL. Soaking the above materials in waterAdding the impregnation solution into a vacuum impregnator filled with carrier, uniformly impregnating, drying at 120 deg.C for 2 hr, and calcining at 520 deg.C in muffle furnace for 4 hr to obtain pure hydrogen (purity) containing water less than 20ppm>99.9%) at 470 ℃ for 2h to obtain the catalyst Cat-D₂₆And in the catalyst obtained: platinum being Al₂O₃0.6% of-D, tin being Al₂O₃0.5% of-D, potassium being Al₂O₃2.0% of D.

Example 27

10g of the carrier Al from example 4 were weighed out₂O₃And (D) placing the mixture in a vacuum impregnator, and simultaneously taking 1.0mL of chloroplatinic acid aqueous solution with platinum concentration of 0.02g/mL, 0.82mL of concentrated hydrochloric acid, 2.2mL of stannous chloride aqueous solution with tin content of 0.06g/mL and 1.0mL of potassium chloride aqueous solution with potassium concentration of 0.04 g/mL. Adding the above impregnation solution into a vacuum impregnator filled with carrier, uniformly impregnating, drying at 120 deg.C for 2 hr, and calcining at 520 deg.C in muffle furnace for 4 hr to obtain pure hydrogen (purity) containing water less than 20ppm>99.9%) at 470 ℃ for 2h to obtain the catalyst Cat-D₂₇And in the catalyst obtained: platinum being Al₂O₃0.2% of-D, tin being Al₂O₃1.3% of-D, potassium being Al₂O₃0.4% of D.

Example 28

10g of the carrier Al from example 4 were weighed out₂O₃And (D) placing the mixture in a vacuum impregnator, and simultaneously taking 2.6mL of chloroplatinic acid aqueous solution with platinum concentration of 0.02g/mL, 0.82mL of concentrated hydrochloric acid, 2.2mL of stannous chloride aqueous solution with tin content of 0.06g/mL and 1.0mL of magnesium chloride aqueous solution with magnesium concentration of 0.04 g/mL. Adding the above impregnation solution into a vacuum impregnator filled with carrier, uniformly impregnating, drying at 120 deg.C for 2 hr, and calcining at 520 deg.C in muffle furnace for 4 hr to obtain pure hydrogen (purity) containing water less than 20ppm>99.9%) at 470 ℃ for 2h to obtain the catalyst Cat-D₂₈And in the catalyst obtained: platinum being Al₂O₃0.52% of-D, tin being Al₂O₃1.3% of-D, magnesium being Al₂O₃0.4% of D.

Long chain n-alkanes₁₆～C₂₀Evaluation of reaction Performance of dehydrogenation catalyst

Example 29

Catalysts prepared in examples 24 to 28, Cat-A, Cat-B, Cat-C, Cat-D … Cat-D, were reacted in a fixed bed reactor₂₈Carrying out long-chain alkane (C)₁₆～C₂₀) And (4) evaluating the performance of the dehydrogenation reaction, wherein a tubular fixed bed reactor is adopted, and the loading amount of the catalyst is 10.0 mL. The catalyst of this example was evaluated under the following conditions: the reaction temperature is 450 ℃, the reaction pressure is 0.14MPa, and the liquid hourly space velocity is 20h^-1The volume ratio of hydrogen to hydrocarbon is 600:1, and the initial activity (conversion rate) is measured; then, the temperature is increased to 480 ℃, and the dehydrogenation experiment is carried out under the condition that the volume ratio of hydrogen to hydrocarbon is 200: 1. The results of the evaluation test of the reaction performance of the catalyst Cat-A, Cat-B, Cat-C, Cat-D … Cat-Y are shown in Table 2.

TABLE 1

TABLE 2

From the data in Table 1, it can be seen that the alumina support Al prepared according to the process of the invention₂O₃-A～Al₂O₃Y has a large pore volume and a large specific surface area, and it can be seen from the data in Table 2 that the long-chain alkane dehydrogenation catalysts Cat-A, Cat-B, Cat-C, Cat-D … Cat-D prepared by the methods of examples 24 to 28 using the alumina supports shown in Table 1₂₈To C₁₆～C₂₀The dehydrogenation of the long-chain normal alkane has higher dehydrogenation reaction performance and good industrial application value. The invention provides an alumina carrier with large pore volume and high specific surfaceAnd the long-chain alkane dehydrogenation catalyst has good application prospect.

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:

according to the preparation method of the alumina carrier, firstly, mixed acid of hydrochloric acid and citric acid is adopted to react with aluminum to form aluminum sol, carboxyl on citric acid molecules is coordinated with Al of the aluminum sol to form a complex in the forming process of the aluminum sol, and the citric acid is decomposed to form a plurality of defect positions in the later heating aging and roasting processes, so that the aperture and the pore volume of the alumina carrier are increased; secondly, the pore structure of the carrier is changed in the roasting process, wherein part of the pore walls are sintered and collapsed to form macropores due to high temperature, and more importantly, the particle gaps among the alumina powder particles are generated by removing the pore-expanding agent. Based on the two factors, the pore volume and the specific surface area of the alumina carrier are increased, and the preparation method is simple, has wide raw material sources and meets the requirement of C₁₆～C₂₀The catalyst carrier required by the normal alkane dehydrogenation catalyst provides an efficient preparation method, and has good industrial application value.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.