Modified alumina, and preparation method and application thereof

Abstract

The application discloses modified alumina and a preparation method and application thereof, wherein the specific surface area of the modified alumina is 80-160 m 2 / g, the pore volume is 0.45-0.65 cm 3 / g, and the average pore diameter is 9-16 nm. The preparation method comprises the following steps: mixing alumina with an aqueous organic acid solution, and obtaining the modified alumina through treatment. The modified alumina is used as a dehydration catalyst in the process of preparing alpha-methylstyrene or cumene from alpha,alpha-dimethylbenzyl alcohol, and exhibits good catalytic performance, high conversion rate of alpha,alpha-dimethylbenzyl alcohol, high selectivity of cumene and good stability of the catalyst.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalysts, and particularly relates to a modified alumina as well as a preparation method and application thereof. BACKGROUND

[0002] Propylene oxide (PO for short) is an important organic chemical raw material, which is mainly used for producing polyether polyols, propylene glycol, propylene glycol ether and the like, wherein the consumption proportion of polyether polyols accounts for about 70%. At present, the commercial production methods of PO mainly include chlorohydrination method, co-oxidation method and cumene hydroperoxide circulation method. The cumene hydroperoxide circulation method has the following advantages: the conversion rate and selectivity of the whole process are very high; the product is only PO, which is not affected by the price fluctuation of by-product styrene, and can bring more stable economic benefits to the producer; the process flow is relatively simple, the fixed investment is 1 / 3 lower than that of the co-oxidation method, and the cumene hydroperoxide circulation method process also has relatively low requirements for equipment corrosion resistance. In the production of propylene oxide by the cumene hydroperoxide circulation method, a large amount of α,α-dimethylbenzyl alcohol is generated in the propylene epoxidation process, which needs to be converted into cumene by hydrogenolysis reaction to participate in the reaction cycle again.

[0003] CN1732139A discloses a method for manufacturing cumene, providing cumyl alcohol and hydrogen to a dehydration catalyst to obtain a mixture containing α-methyl styrene and water, hydrogen; and providing the mixture to a hydrogenation catalyst. Among them, the dehydration catalyst and the hydrogenation catalyst are filled in a single fixed bed flow reactor. A large number of studies have shown that the structure of alumina (including physical structure such as specific surface area, pore volume, pore size distribution and chemical structure such as surface acid site and electronic property) not only has important influence on the dispersion of active components, but also directly affects the mass transfer and diffusion in the reaction process. Therefore, the catalytic performance of heterogeneous catalysts such as activity, selectivity and stability depends on not only the catalytic characteristics of active components, but also the physical structure of catalysts. Appropriate methods are used for modification to obtain suitable carrier structure such as mechanical strength, pore structure and acidity of alumina, and then obtain catalysts with excellent performance. Alumina is widely used as a carrier or a catalyst in the field of chemical catalysis. For different reaction systems, people have carried out a lot of research and modification work on alumina. For example: the pore size of alumina carrier can be adjusted by steam treatment method or adding pore-expanding agent (Journal of Molecular Catalysts A: Chemical, 2002, 181(1-2): 33-39; Industrial Catalysis, 2006, 14(11): 56-59; Inorganic Chemistry Journal, 2005, 21(2): 212-216; Inorganic Chemistry Journal, 2007, 23(4): 563-568); the acidity of alumina surface can be adjusted by adding metal elements, metal oxides and non-metal elements (Higher Education in Chemistry, 2002, 23(10): 1952-1955; Petroleum Chemical Industry, 2005, 34(Suppl.): 445-446); the hydrothermal stability of alumina carrier can be improved by adding rare earth metals, alkaline earth metals, non-metals and their oxides (US4722920, CN1958456, US4677095). The alumina carrier is contacted with an aqueous inorganic acid solution, the reaction product is separated, and then the separated solid product is washed, dried and calcined, which effectively improves the acidity of the surface of the alumina carrier, makes it more conducive to the dispersion of active metal components, and reduces the risk of carbon deposition and improves the selectivity of the target product (CN107303508A). SUMMARY

[0004] In order to overcome the problems in the prior art, the present application provides a modified alumina and a preparation method and application thereof, wherein the alumina is treated with an aqueous organic acid solution to obtain a modified alumina. The dehydration catalyst containing the modified alumina is used in the process of dehydrating α,α-dimethylbenzyl alcohol-containing hydrocarbon materials to α-methyl styrene, which can improve the conversion rate of the reaction.

[0005] One of the objects of the present application is to provide a modified alumina having a specific surface area of 80-160 m 2 / g, a pore volume of 0.45-0.65 cm 3 / g, and an average pore diameter of 9-16 nm.

[0006] In a preferred embodiment, the modified alumina has an ammonia-programmed temperature desorption spectrum tested in the range of 50-600°C, and an area ratio of ammonia-desorption peak in the range of 290-440°C to NH3-desorption peak in the range of 80-210°C less than 0.2.

[0007] The above peak area ratio of the present application indicates that the medium-strong acid sites on the surface of the alumina are reduced, and the relative amount of weak acid sites is increased; the decrease of the ratio can improve the hydrophilicity of the alumina surface, and has a significant promoting effect on the dehydration activity thereof. The area ratio of ammonia-desorption peak in the range of 290-440°C to NH3-desorption peak in the range of 80-210°C of the alumina without modification is 0.3-0.8.

[0008] In a preferred embodiment, the modified alumina is alumina treated with an aqueous organic acid solution.

[0009] In a preferred embodiment, the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, phenol, tartaric acid, malic acid, succinic acid, citric acid, and oxalic acid, and preferably from one or more of formic acid, acetic acid, propionic acid, and phenol.

[0010] In a preferred embodiment, the pH of the aqueous organic acid solution is 1.5-6, and preferably 2.5-4.5.

[0011] For example, the pH of the aqueous organic acid solution is 2.5, 3, 3.5, 4, or 4.5.

[0012] In a preferred embodiment, the space velocity of the aqueous organic acid solution through the alumina bed is 2-10 h -1 .

[0013] For example, the space velocity of the aqueous organic acid solution through the alumina bed is 2 h -1 , 3 h -1 , 4 h -1 , 5 h -1 , 6 h -1 , 7 h -1 , 8 h -1 , 9 h -1 , or 10 h -1 .

[0014] In a preferred embodiment, the alumina contains a co-ingredient.

[0015] In a further preferred embodiment, the co-ingredient is at least one or both of phosphorus and silicon. Among them, phosphorus is a key component for the structural stability of the alumina during hydrothermal treatment.

[0016] In a still further preferred embodiment, the content of the co-ingredient is not less than 3wt%, preferably 4wt% to 8wt%, based on 100wt% of the total weight of the alumina.

[0017] For example, the content of the co-ingredient is 3wt%, 4wt%, 5wt%, 6wt%, 7wt% or 8wt%, based on 100wt% of the total weight of the alumina.

[0018] In a preferred embodiment, the treatment is carried out at a temperature greater than 150°C.

[0019] In a further preferred embodiment, the treatment is carried out at a temperature of 150°C to 350°C, preferably 150°C to 250°C.

[0020] For example, the treatment is carried out at a temperature of 150°C, 180°C, 200°C, 220°C, 250°C, 280°C, 300°C or 350°C.

[0021] In a preferred embodiment, the treatment is carried out for a time not less than 8h.

[0022] In a further preferred embodiment, the treatment is carried out for a time of 12h to 120h.

[0023] For example, the treatment is carried out for a time of 8h, 12h, 20h, 40h, 60h, 80h, 100h or 120h.

[0024] In a preferred embodiment, the treatment is carried out in a hydrogen atmosphere.

[0025] In a hydrogen atmosphere, the dehydration activity of the alumina can be improved.

[0026] In a preferred embodiment, the aqueous organic acid solution is continuously passed through the alumina bed to obtain the modified alumina.

[0027] In a further preferred embodiment, the temperature of the alumina bed is greater than 150°C, preferably 150°C to 350°C, more preferably 150°C to 250°C.

[0028] In a still further preferred embodiment, the aqueous organic acid solution and hydrogen are passed through the alumina bed together.

[0029] In the present application, the modified alumina is in the form of particles, which can be spherical, cylindrical or clover-shaped or a mixture of several shapes.

[0030] The second object of the present application is to provide a preparation method of modified alumina, preferably for the preparation of the modified alumina of the first object of the present application, which comprises mixing alumina with an aqueous organic acid solution to obtain the modified alumina.

[0031] In a preferred embodiment, the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, phenol, tartaric acid, malic acid, succinic acid, citric acid, oxalic acid, preferably one or more of formic acid, acetic acid, propionic acid, phenol.

[0032] In a preferred embodiment, the pH of the aqueous organic acid solution is 1.5-6, preferably 2.5-4.5.

[0033] For example, the pH of the aqueous organic acid solution is 2.5, 3, 3.5, 4 or 4.5.

[0034] In a preferred embodiment, the space velocity of the aqueous organic acid solution through the alumina bed is 2-10 h -1 .

[0035] For example, the space velocity of the aqueous organic acid solution through the alumina bed is 2 h -1 , 3 h -1 , 4 h -1 , 5 h -1 , 6 h -1 , 7 h -1 , 8 h -1 , 9 h -1 or 10 h -1 .

[0036] In a preferred embodiment, the alumina contains a co-ingredient.

[0037] In a further preferred embodiment, the co-ingredient is at least one or both of phosphorus and silicon.

[0038] Among them, phosphorus is a key component for the structural stability of alumina during hydrothermal treatment.

[0039] In a still further preferred embodiment, the content of the co-ingredient is not less than 3wt%, preferably 4wt%-8wt% based on 100wt% of the total weight of the alumina.

[0040] For example, the content of the co-ingredient is 3wt%, 4wt%, 5wt%, 6wt%, 7wt% or 8wt% based on 100wt% of the total weight of the alumina.

[0041] In a preferred embodiment, the treatment is carried out at a temperature greater than 150°C.

[0042] In a further preferred embodiment, the treatment is carried out at a temperature of 150-350°C, preferably 150-250°C.

[0043] For example, the treatment is carried out at a temperature of 150°C, 180°C, 200°C, 220°C, 250°C, 280°C, 300°C or 350°C.

[0044] In a preferred embodiment, the treatment is carried out for a time period of no less than 8h.

[0045] In a further preferred embodiment, the treatment is carried out for a time period of 12-120h.

[0046] For example, the treatment is carried out for a time period of 8h, 12h, 20h, 40h, 60h, 80h, 100h or 120h.

[0047] In a preferred embodiment, the treatment is carried out in a hydrogen atmosphere.

[0048] In a preferred embodiment, the treatment is carried out in a hydrogen atmosphere.

[0049] In a preferred embodiment, the treatment is carried out in a hydrogen atmosphere.

[0050] In a further preferred embodiment, the temperature of the alumina bed is greater than 150°C, preferably 150-350°C, more preferably 150-250°C.

[0051] In a further preferred embodiment, the treatment is carried out in a hydrogen atmosphere.

[0052] The third object of the present application is to provide a modified alumina prepared by the method according to the second object of the present application.

[0053] The fourth object of the present application is to provide a dehydration catalyst comprising the modified alumina according to the first object of the present application or the modified alumina prepared by the method according to the second object of the present application.

[0054] In a preferred embodiment, the dehydration catalyst can comprise other components in addition to the modified alumina, such as the components commonly used in dehydration catalysts.

[0055] The fifth object of the present application is to provide the use of the modified alumina according to the first object of the present application or the modified alumina obtained by the preparation method according to the second object of the present application or the dehydration catalyst according to the fourth object of the present application in the dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene or in the hydrogenolysis of α,α-dimethylbenzyl alcohol to cumene.

[0056] The sixth object of the present application is to provide a method for the hydrogenolysis of α,α-dimethylbenzyl alcohol to cumene, comprising:

[0057] (1) contacting a material containing α,α-dimethylbenzyl alcohol with a catalyst under a hydrogen atmosphere or a protective atmosphere to obtain a mixture;

[0058] (2) contacting the mixture with a hydrogenation catalyst under a hydrogen atmosphere to obtain cumene;

[0059] In step (1), the catalyst is selected from the modified alumina according to the first object of the present application or the modified alumina obtained by the preparation method according to the second object of the present application or the dehydration catalyst according to the fourth object of the present application.

[0060] In the present application, the dehydration catalyst bed is used to dehydrate α,α-dimethylbenzyl alcohol at a higher temperature to convert it to α-methylstyrene, and then the α-methylstyrene is hydrogenated to cumene by a hydrogenation catalyst, thereby improving the conversion rate and selectivity, especially the cumene yield per unit time.

[0061] In a preferred embodiment, in step (1), when a hydrogen atmosphere is used, the mixture obtained contains α-methylstyrene, water and hydrogen.

[0062] In a preferred embodiment, in step (1), when a protective atmosphere is used, the mixture obtained contains α-methylstyrene, water and the protective atmosphere.

[0063] In a further preferred embodiment, the protective atmosphere is nitrogen.

[0064] In a preferred embodiment, the water and hydrogen or the water and the protective atmosphere in the mixture are separated before step (2), and the oil phase is contacted with the hydrogenation catalyst.

[0065] In a preferred embodiment, the hydrogenation catalyst comprises a support, a metal component supported on the support and optionally an auxiliary metal component supported on the support.

[0066] In a further preferred embodiment, the carrier, the metal component and the promoter metal component are each independently selected from the carriers, the metal components and the promoter metal components commonly used in the prior art, preferably but not limited to: the carrier is selected from at least one of alumina, silica, activated carbon, alumina-silica composite carrier; and / or, the active component is selected from at least one of metal palladium, nickel, copper; and / or, the promoter metal component is selected from at least one of metal copper, metal calcium, metal cobalt, metal tin, metal nickel and metal silver.

[0067] The hydrogenation method has the technical features of high conversion rate of a,a-dimethylbenzyl alcohol hydrogenolysis, less by-products and high selectivity of cumene.

[0068] In a preferred embodiment, in the hydrogenation catalyst, the content of the metal component is 0.06 g / L to 30 g / L, and the content of the promoter metal component is 0 to 1.0 g / L (preferably 0.0006 g / L to 1.0 g / L), wherein the content of the metal component is calculated based on the content of the metal element therein, and the content of the promoter metal component is calculated based on the content of the promoter metal element therein.

[0069] In a further preferred embodiment, in the hydrogenation catalyst, the content of the metal component is 0.1 g / L to 10 g / L, and the content of the promoter metal component is 0.01 g / L to 0.5 g / L, wherein the content of the metal component is calculated based on the content of the metal element therein, and the content of the promoter metal component is calculated based on the content of the promoter metal element therein.

[0070] In a preferred embodiment, the reaction temperature of step (1) is 130 to 230°C, and the reaction pressure is 0.5 to 2.0 MPa.

[0071] In a further preferred embodiment, the reaction temperature of step (1) is 140 to 200°C, and the reaction pressure is 1.2 to 2.0 MPa.

[0072] For example, the reaction temperature of step (1) is 130°C, 150°C, 180°C, 200°C, 210°C or 230°C, and the reaction pressure is 0.5 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa or 2.0 MPa.

[0073] In a preferred embodiment, the liquid phase volume space velocity of step (1) is 2 to 15 h -1 , and the gas phase volume space velocity is 50 to 200 h -1 .

[0074] In a further preferred embodiment, the liquid phase volume space velocity of step (1) is 4 to 12 h -1 , and the gas phase volume space velocity is 80 to 160 h -1 .

[0075] For example, the liquid phase volume space velocity of step (1) is 2h -1 , 4h -1 , 6h -1 , 8h -1 , 10h -1 , 12h -1 or 15h -1 , and the gas phase volume space velocity is 50h -1 , 80h -1 , 100h -1 , 120h -1 , 150h -1 , 180h -1 or 200h -1 .

[0076] In a preferred embodiment, the reaction temperature of step (2) is 50-100℃, and the reaction pressure is 0.3-1.0 MPa.

[0077] In a further preferred embodiment, the reaction temperature of step (2) is 60-80℃, and the reaction pressure is 0.5-0.8 MPa.

[0078] For example, the reaction temperature of step (2) is 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃, and the reaction pressure is 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa or 1.0 MPa.

[0079] The present application mainly solves the technical problems in the prior art, such as the unenvironmental protection in the process of hydrogenation of the α,α-dimethylbenzyl alcohol hydrocarbon material, poor stability of the catalyst used, and low selectivity of cumene.

[0080] The endpoints of the ranges and any numerical values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the present application. The ranges and values should be construed and interpreted as being inclusive of values adjacent to the recited ranges and / or values and / or as being inclusive of ranges and / or values derived from the recited ranges and / or values by applying the rule of reason. In the following, the technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as being specifically disclosed herein.

[0081] Compared with the prior art, the present application has the following beneficial effects:

[0082] (1) The preparation method of the modified alumina can further improve the pore size of the alumina, which is more conducive to the diffusion of the reactants and products, thereby improving the conversion rate of the reactants;

[0083] (2) The preparation method of the modified alumina can effectively improve the acid properties of the surface of the alumina, so that the modified alumina has higher dehydration activity;

[0084] (3) The preparation method of the modified alumina has simple process and easy-to-control conditions, and the product has good repeatability;

[0085] (4) The modified alumina prepared by the method has higher dehydration conversion rate of dimethyl benzyl alcohol per unit mass of catalyst, and effectively reduces the use amount of the catalyst;

[0086] (5) The modified alumina prepared by the method has good catalytic performance when used as a dehydration catalyst in the process of preparing alpha-methyl styrene or cumene from alpha, alpha-dimethyl benzyl alcohol, the conversion rate of alpha, alpha-dimethyl benzyl alcohol is high, the selectivity of cumene is good, and the catalyst has good stability. The content of isopropyl cyclohexane in the hydrogenation product is less than 5 ppm, the content of ethylbenzene is less than 200 ppm, the conversion rate of alpha, alpha-dimethyl benzyl alcohol is greater than 99.9%, the selectivity of cumene is greater than 99.8%, and a good technical effect is achieved, which has wide industrial utilization value. DETAILED DESCRIPTION

[0087] It is necessary to point out that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments to the present application made by those skilled in the art based on the content of the present application still fall within the protection scope of the present application.

[0088] In addition, it should be noted that each specific technical feature described in the following specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present application.

[0089] In addition, various different embodiments of the present application can be combined in any manner, as long as they do not contradict the idea of the present application, and the technical solutions thus formed are part of the original disclosure of the present specification and fall within the protection scope of the present application.

[0090] The raw materials used in the examples and comparative examples are publicly known in the prior art, for example, can be directly purchased or prepared according to the preparation method disclosed in the prior art.

[0091] The liquid phase feed composition is shown in Table 1.

[0092] Table 1:

[0093] Raw material composition Composition by weight wt% Cumene 86.5 n-Propylbenzene 0.12 Methylstyrene 0.03 Acetophenone 0.35 α,α-Dimethylbenzyl alcohol 13.6

[0094] wherein: the content of each component in Table 1 is obtained by gas chromatography.

[0095] In the analysis of the product:

[0096] Conversion of α,α-dimethylbenzyl alcohol (%) = (W1 0 - W1 t ) / W1 0 x 100%;

[0097] Selectivity of cumene (%) = (W2 t - W2 0 ) / (W1 0 - W1 t ) x 100%;

[0098] W1 0 : mass content of α,α-dimethylbenzyl alcohol in the raw material; W1 t : mass content of α,α-dimethylbenzyl alcohol in the hydrogenation product; W2 0 : mass content of cumene in the raw material; W2 t : mass content of cumene in the hydrogenation product.

[0099] Example 1

[0100] Preparation of modified alumina:

[0101] Preparation of aqueous solution containing organic acid: a certain amount of acetic acid and phenol were accurately weighed and then added to deionized water, the content of the two in the solution was 150 ppm and 2000 ppm respectively, and the pH value of the solution was 1.8.

[0102] The modified alumina 1 was prepared by continuously passing the above aqueous solution containing organic acid through the fixed bed reactor filled with regular-shaped alumina particles under the following operating conditions. The specific surface area of the modified alumina 1 was 102 m 2 / g, the pore volume was 0.45 cm 3 / g, and the average pore size was 15.8 nm. The ratio of the ammonia desorption peak area in the range of 290-440°C to the NH3desorption peak area in the range of 80-210°C in the ammonia-programmed temperature desorption spectrum of the modified alumina tested in the range of 50-600°C was 0.18.

[0103] The operating conditions were as follows:

[0104] Bed temperature ~ 200°C

[0105] Liquid hourly space velocity ~ 4 h -1

[0106] Aging time ~ 72 h.

[0107] Dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene

[0108] A fixed bed continuous reactor was packed with modified alumina 1, and a solution containing 13 wt% of α,α-dimethylbenzyl alcohol and hydrogen was passed through the reactor at a pressure of 1.5 MPa, a reactor inlet temperature of 160°C, a liquid hourly space velocity of 10 h -1 , and a hydrogen hourly space velocity of 100 h -1 . The conversion of α,α-dimethylbenzyl alcohol at the reactor outlet was 77.3%.

[0109] Example 2: Hydrogenolysis of α,α-dimethylbenzyl alcohol to cumene

[0110] Preparation of modified alumina: The modified alumina was prepared as in Example 1.

[0111] Dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene:

[0112] A fixed bed continuous reactor was packed with modified alumina 1, and a solution containing 13 wt% of α,α-dimethylbenzyl alcohol and nitrogen was passed through the reactor at a pressure of 1.5 MPa, a reactor inlet temperature of 160°C, a liquid hourly space velocity of 10 h -1 , and a nitrogen hourly space velocity of 100 h -1 . The conversion of α,α-dimethylbenzyl alcohol at the reactor outlet was 90.2%.

[0113] Example 3

[0114] Preparation of modified alumina:

[0115] Preparation of aqueous solution containing organic acid: A certain amount of acetic acid and phenol were accurately weighed and added to deionized water, and the contents of the two in the solution were 50 ppm and 1000 ppm, respectively, and the pH value of the solution was 3.2.

[0116] A fixed bed reactor was packed with alumina particles of regular shape, and under the following operating conditions, the above aqueous solution containing organic acid was passed through the reactor in a continuous manner to prepare modified alumina 2. The specific surface area of modified alumina 2 was 112 m 2 / g, the pore volume was 0.46 cm 3 / g, and the average pore size was 15.8 nm. The ratio of the ammonia desorption peak area in the range of 290-440°C to the NH3desorption peak area in the range of 80-210°C in the ammonia-programmed temperature desorption spectrum of the modified alumina tested in the range of 50-600°C was 0.16.

[0117] The operating conditions were as follows:

[0118] Bed temperature ~ 200°C

[0119] Liquid hourly space velocity ~ 4 h -1

[0120] Ageing time ~ 72 h.

[0121] Dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene

[0122] A solution containing 13 wt% of α,α-dimethylbenzyl alcohol and hydrogen was passed through a fixed bed continuous reactor packed with modified alumina 2, at a reactor pressure of 1.5 MPa, a reactor inlet temperature of 160°C and a liquid hourly space velocity of 10 h -1 , a hydrogen hourly space velocity of 100 h -1 , and a conversion of α,α-dimethylbenzyl alcohol at the reactor outlet of 82.6%.

[0123]

Example 4

[0124] Preparation of an aqueous solution containing organic acids: an amount of acetic acid and phenol was accurately weighed and added to deionized water, the contents of which in the solution were 30 ppm and 500 ppm, respectively, and the pH of the solution was 4.5.

[0125] Modified alumina 3 was prepared by passing the above aqueous solution containing organic acids through a fixed bed reactor packed with alumina particles of regular shape under the following operating conditions in a continuous manner. The specific surface area of modified alumina 3 was 116 m 2 / g, the pore volume was 0.48 cm 3 / g, and the average pore diameter was 16.8 nm. The ratio of the area of the ammonia desorption peak in the range of 290-440°C to the area of the NH3desorption peak in the range of 80-210°C in the ammonia-programmed temperature desorption spectrum of the modified alumina tested in the range of 50-600°C was 0.12.

[0126] The operating conditions were as follows:

[0127] Bed temperature ~ 250°C

[0128] Liquid hourly space velocity ~ 4 h -1

[0129] Ageing time ~ 72 h.

[0130] Dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene

[0131] A solution containing 13 wt% of α,α-dimethylbenzyl alcohol and hydrogen was passed through a fixed bed continuous reactor packed with modified alumina 3, at a reactor pressure of 1.5 MPa, a reactor inlet temperature of 160°C and a liquid hourly space velocity of 10 h -1, hydrogen gas hourly space velocity was 100 h -1 , the conversion of α,α-dimethylbenzyl alcohol at the reactor outlet was 86.7%.

[0132]

Example 5

[0133] Preparation of modified alumina:

[0134] Preparation of aqueous solution containing organic acid: A certain amount of acetic acid and phenol were accurately weighed and then added to deionized water, and the contents of the two in the solution were 100 ppm and 1200 ppm respectively, and the pH value of the solution was 2.5.

[0135] The modified alumina 4 was prepared by packing the regular-shaped alumina particles in a fixed bed reactor and continuously feeding the above aqueous solution containing organic acid under the following operating conditions. The specific surface area of the modified alumina 4 was 108 m 2 / g, the pore volume was 0.46 cm 3 / g, and the average pore size was 17.2 nm. The ratio of the ammonia desorption peak area in the range of 290-440°C to the NH3 desorption peak area in the range of 80-210°C in the ammonia-programmed temperature desorption spectrum of the modified alumina tested in the range of 50-600°C was 0.12.

[0136] The operating conditions were as follows:

[0137] Bed temperature ~ 250°C

[0138] Liquid hourly space velocity ~ 4 h -1

[0139] Aging time ~ 72 h.

[0140] Dehydration of α,α-dimethylbenzyl alcohol to prepare α-methylstyrene

[0141] The fixed bed continuous reactor packed with modified alumina 4 was fed with hydrogen containing 13% by weight of α,α-dimethylbenzyl alcohol, and at this time the pressure of the reactor was 1.5 MPa, the inlet temperature of the reactor was 160°C, and the liquid hourly space velocity was 10 h -1 , the hydrogen gas hourly space velocity was 100 h -1 , and the conversion of α,α-dimethylbenzyl alcohol at the reactor outlet was 90.6%.

[0142]

Example 6

[0143] Preparation of modified alumina:

[0144] Preparation of aqueous solution containing organic acid: A certain amount of acetic acid and phenol were accurately weighed and then added to deionized water, and the contents of the two in the solution were 100 ppm and 1200 ppm respectively, and the pH value of the solution was 2.5.

[0145] A fixed bed reactor was packed with the shaped alumina particles, and the above-mentioned aqueous solution containing an organic acid was passed therethrough in a continuous manner under the following operating conditions to produce modified alumina 4. The specific surface area of the modified alumina 4 was 108 m 2 / g, the pore volume was 0.46 cm 3 / g, and the average pore diameter was 17.2 nm. The modified alumina had an ammonia- desorption peak area ratio of 0.12 in the range of 290 to 440°C to that in the range of 80 to 210°C in the ammonia-temperature programmed desorption spectrum tested in the range of 50 to 600°C.

[0146] The operating conditions were as follows:

[0147] Bed temperature ~ 250°C

[0148] Liquid hourly space velocity ~ 4 h -1

[0149] Aging time ~ 72 h.

[0150] Preparation of hydrogenation catalyst:

[0151] The above-mentioned modified alumina 1 liter was mixed with a 2000-gram aqueous solution of chloropalladic acid containing 1.0 gram of palladium, dried at 110°C, and calcined at 500°C to produce a hydrogenation catalyst.

[0152] Dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene

[0153] An aqueous solution containing 13% by weight of α,α-dimethylbenzyl alcohol and hydrogen gas was passed through a fixed bed continuous reactor packed with the modified alumina 4, where the pressure of the reactor was 1.5 MPa, the reactor inlet temperature was 180°C, the liquid hourly space velocity was 8 h -1 , the hydrogen gas hourly space velocity was 100 h -1 , and the conversion of α,α-dimethylbenzyl alcohol at the outlet of the reactor was 99.9%.

[0154] Hydrogenation of α-methylstyrene to cumene

[0155] The above-mentioned dehydrated mixture was passed through a fixed bed continuous reactor packed with the hydrogenation catalyst together with hydrogen gas, where the pressure of the reactor was 0.5 MPa, the reactor inlet temperature was 60°C, the content of isopropylcyclohexane in the hydrogenation product was less than 5 ppm, the content of ethylbenzene was less than 200 ppm, and the selectivity of cumene was greater than 99.8%.

[0156]

Example 7

[0157] Preparation of modified alumina:

[0158] A 1 liter of alumina was mixed with 600 grams of an aqueous solution of phosphoric acid containing 15 grams of P, dried at 110°C for 8 hours, and calcined at 400°C for 4 hours to produce a P-containing catalyst support.

[0159] The P-containing catalyst support 1L was mixed with 600 grams of an aqueous solution of silica gel having a SiO2 mass concentration of 5%, dried, and calcined at 500°C to produce a P / Si-containing support.

[0160] An aqueous solution containing an organic acid was prepared by accurately weighing a certain amount of acetic acid and phenol, and then adding them to deionized water, the contents of the two in the solution being 50 ppm and 1000 ppm, respectively, and the pH value of the solution being 3.2.

[0161] A fixed bed reactor was packed with regular-shaped P / Si-modified alumina particles, and the above aqueous solution containing an organic acid was passed through the reactor in a continuous manner under the following operating conditions to produce modified alumina 5. The specific surface area of the modified alumina 5 was 122 m 2 / g, the pore volume was 0.48 cm 3 / g, and the average pore diameter was 17.8 nm. The ratio of the peak area of ammonia desorption in the range of 290-440°C to that of NH3 desorption in the range of 80-210°C in the ammonia-programmed temperature desorption spectrum of the modified alumina tested in the range of 50-600°C was less than 0.08.

[0162] The operating conditions were as follows:

[0163] Bed temperature ~ 200°C

[0164] Liquid hourly space velocity ~ 4 h -1

[0165] Aging time ~ 72 h.

[0166] Dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene

[0167] A fixed bed continuous reactor packed with modified alumina 2 was passed through an aqueous solution containing 13% by weight of α,α-dimethylbenzyl alcohol and hydrogen, the pressure of the reactor being 1.5 MPa, the inlet temperature of the reactor being 160°C, the liquid hourly space velocity being 10 h -1 , the hydrogen hourly space velocity being 100 h -1 , and the conversion of α,α-dimethylbenzyl alcohol at the outlet of the reactor being 91.6%.

[0168] [Comparative Example 1]

[0169] A fixed bed reactor packed with unmodified alumina was passed through an aqueous solution containing 13% by weight of α,α-dimethylbenzyl alcohol and hydrogen, the pressure of the reactor being 1.5 MPa, the inlet temperature of the reactor being 160°C, the liquid hourly space velocity being 10 h-1 , the gas phase space velocity was 100 h -1 , the conversion of α,α-dimethylbenzyl alcohol at the reactor outlet was 67.4%.

[0170]

Comparative Example 2

[0171] A fixed bed reactor was packed with alumina particles, and deionized water was continuously fed under the same operating conditions as in Example 1 to produce modified alumina D1. The specific surface area of the modified alumina D1 was 108 m 2 / g, the pore volume was 0.43 cm 3 / g, and the average pore diameter was 15.6 nm. The ratio of the ammonia desorption peak area in the range of 290 to 440°C to the NH3desorption peak area in the range of 80 to 210°C in the ammonia-temperature programmed desorption spectrum of the modified alumina tested in the range of 50 to 600°C was 0.54.

[0172] Dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene

[0173] A fixed bed reactor packed with modified alumina D1 was fed with a solution containing 13% by weight of α,α-dimethylbenzyl alcohol and hydrogen, at a reactor pressure of 1.5 MPa, a reactor inlet temperature of 160°C, a liquid phase space velocity of 10 h -1 , and a gas phase space velocity of 100 h -1 , the conversion of α,α-dimethylbenzyl alcohol at the reactor outlet was 71.6%.

[0174]

Comparative Example 3

[0175] The procedure for preparing the modified alumina in Example 1 was repeated, except that the bed temperature was 120°C, to produce modified alumina D3. The specific surface area of the modified alumina D3 was 116 m 2 / g, the pore volume was 0.42 cm 3 / g, and the average pore diameter was 14.8 nm. The ratio of the ammonia desorption peak area in the range of 290 to 440°C to the NH3desorption peak area in the range of 80 to 210°C in the ammonia-temperature programmed desorption spectrum of the modified alumina tested in the range of 50 to 600°C was 0.42.

[0176] A fixed bed reactor packed with modified alumina 1 was fed with a solution containing 13% by weight of α,α-dimethylbenzyl alcohol and hydrogen, at a reactor pressure of 1.5 MPa, a reactor inlet temperature of 160°C, a liquid phase space velocity of 10 h -1 , and a gas phase space velocity of 100 h -1 , the conversion of α,α-dimethylbenzyl alcohol at the reactor outlet was 72.5%.

[0177] The present application is described in detail above with reference to specific embodiments and exemplary examples, but these are not to be understood as limiting the present application. It is understood by a person skilled in the art that various equivalent substitutions, modifications or improvements can be made to the technical solutions of the present application and the embodiments thereof without departing from the spirit and scope of the present application, and these all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims.

Claims

1. A modified alumina having a specific surface area of ​​80~160 m² 2 / g, pore volume 0.45~0.65cm³ 3 / g, with an average pore size of 9~16nm, the modified alumina is in the range of 50~600 o In the ammonia-temperature programmed desorption spectrum tested within the C range, 290~440 o The ammonia-desorption peak area in the C range and 80~210 o The area ratio of the NH3- desorption peaks in the C range is less than 0.

2.

2. The modified alumina according to claim 1, characterized in that, The modified alumina is alumina treated with an aqueous solution of an organic acid, wherein the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, phenol, tartaric acid, malic acid, succinic acid, citric acid, and oxalic acid.

3. A method for preparing modified alumina, used in the preparation of the modified alumina according to any one of claims 1 to 2, the method comprising: The modified alumina is obtained by mixing alumina with an aqueous solution of an organic acid and then treating the mixture at a temperature greater than 150°C. The organic acid is selected from one or more of formic acid, acetic acid, propionic acid, phenol, tartaric acid, malic acid, succinic acid, citric acid, and oxalic acid.

4. The preparation method according to claim 3, characterized in that, The pH of the organic acid aqueous solution is 1.5~6.

5. The preparation method according to claim 3, characterized in that, The pH of the organic acid aqueous solution is 2.5 to 4.

5.

6. The preparation method according to claim 3, characterized in that, The organic acid aqueous solution passes through the alumina bed at a space velocity of 2-10 h⁻¹. -1 .

7. The preparation method according to claim 3, characterized in that, The modified alumina contains auxiliary components.

8. The preparation method according to claim 7, characterized in that, The auxiliary component is at least one or two of phosphorus and silicon.

9. The preparation method according to claim 7, characterized in that, Based on the total weight of the modified alumina of 100wt%, the content of the auxiliary components is not less than 3wt%.

10. The preparation method according to claim 7, characterized in that, Based on the total weight of the modified alumina of 100wt%, the content of the auxiliary components is 4wt%~8wt%.

11. The preparation method according to any one of claims 3 to 10, characterized in that, The treatment is carried out at 180℃~350℃; and / or, The processing time is no less than 8 hours.

12. The preparation method according to claim 11, characterized in that, The processing time is 12~120h.

13. The preparation method according to claim 11, characterized in that, The treatment is carried out in a hydrogen atmosphere; and / or, Modified alumina is obtained by continuously passing an aqueous solution of organic acid through an alumina bed.

14. Modified alumina obtained by the preparation method according to any one of claims 3 to 13.

15. A dehydration catalyst comprising the modified alumina according to any one of claims 1 to 2 or the modified alumina obtained by the preparation method according to any one of claims 3 to 13.

16. The use of the modified alumina according to any one of claims 1 to 2, the modified alumina obtained by the preparation method according to any one of claims 3 to 13, or the dehydration catalyst according to claim 15 in the dehydration of α,α-dimethylbenzyl alcohol to α-methylstyrene or in the hydrogenolysis of α,α-dimethylbenzyl alcohol to cumene.

17. A method for the hydrogenolysis of α,α-dimethylbenzyl alcohol to produce cumene, comprising: (1) The material containing α,α-dimethylbenzyl alcohol is contacted with a catalyst under a hydrogen atmosphere or a protective atmosphere to obtain a mixture; (2) The mixture is contacted with a hydrogenation catalyst under a hydrogen atmosphere to obtain cumene; The catalyst used in step (1) is selected from the modified alumina according to any one of claims 1 to 2, the modified alumina obtained by the preparation method according to any one of claims 3 to 13, or the dehydration catalyst according to claim 15.

18. The method according to claim 17, characterized in that, Prior to step (2), water and hydrogen are separated from the mixture, or water and a protective atmosphere are separated from the mixture, and the oil phase is contacted with the hydrogenation catalyst; and / or, The hydrogenation catalyst includes a support, a metal component supported on the support, and optionally a co-metal component supported on the support.

19. The method according to claim 17 or 18, characterized in that, The reaction temperature in step (1) is 130~230℃. o C, the reaction pressure is 0.5~2.0 MPa; and / or, The liquid volume hourly space velocity (LHSV) in step (1) is 2-15 h. -1 The gas phase volume hourly space velocity is 50~200 h⁻¹. -1 ; and / or, The reaction temperature in step (2) is 50~100℃. o C, the reaction pressure is 0.3~1.0MPa.