CN106966872B - Aromatic oxidation method - Google Patents

Aromatic oxidation method Download PDF

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CN106966872B
CN106966872B CN201610019806.4A CN201610019806A CN106966872B CN 106966872 B CN106966872 B CN 106966872B CN 201610019806 A CN201610019806 A CN 201610019806A CN 106966872 B CN106966872 B CN 106966872B
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titanium silicalite
molecular sieve
titanium
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silicalite molecular
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CN106966872A (en
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林民
史春风
朱斌
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
    • C07C37/60—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by oxidation reactions introducing directly hydroxy groups on a =CH-group belonging to a six-membered aromatic ring with the aid of other oxidants than molecular oxygen or their mixtures with molecular oxygen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/89—Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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Abstract

The invention discloses an aromatic hydrocarbon oxidation method, which comprises the steps of enabling reaction feed containing at least one aromatic hydrocarbon, an oxidant and a solvent to sequentially flow through a 1 st catalyst bed layer to a last n catalyst bed layer under oxidation reaction conditions, wherein n is an integer more than 2, at least one titanium silicalite molecular sieve is filled in the catalyst bed layers, and the method also comprises the step of introducing at least one carrier fluid between at least one pair of adjacent catalyst bed layers between the 1 st catalyst bed layer and the n catalyst bed layer during the period that the reaction feed passes through the 1 st catalyst bed layer to the n catalyst bed layer, so that the apparent velocity of a reactant flow in a downstream catalyst bed layer is higher than that of a reactant flow in an upstream catalyst bed layer in the pair of adjacent catalyst bed layers by taking the flow direction of the reaction feed as a reference. The method can effectively prolong the one-way service life of the titanium-silicon molecular sieve and improve the effective utilization rate of the oxidant and the selectivity of the target product.

Description

Aromatic oxidation method
Technical Field
The invention relates to an aromatic oxidation method.
Background
Phenolic compounds are a substance that widely exists in nature and has important uses in industry. Anthocyanins, vanillin and catechols are well known as polyphenolic substances in nature. In the industrial field, phenols are important intermediates for synthesizing many organic compounds, and in addition, phenols also play a role as living body coloring agents, dyes and medicines. The importance and wide use of phenolic substances determines the importance of their synthesis. The currently used methods for preparing phenolic compounds mainly comprise aromatic hydrocarbon oxidation reaction, aryl thallium salt replacement hydrolysis, halogenated benzene hydrolysis, diazonium salt method and the like. The hydrolysis by using the halogenated benzene usually needs high temperature and high pressure and the presence of a catalyst; the diazo method is used for preparing phenols, so that a plurality of synthesis steps are required; although the reaction temperature is low and the rate is fast, the replacement hydrolysis of the aryl thallium salt uses toxic heavy metal thallium compound in the reaction, which is not suitable for mass promotion. In view of the above-mentioned circumstances, a new method for producing a phenol compound rapidly and efficiently has been developed, and many problems in the synthesis have been solved.
Phenol is an important bulk chemical raw material product in the current organic chemical industry, the world demand is over 66Mt in 2000, and the phenol is mainly used for preparing bisphenol A, phenolic resin, pharmaceutical intermediates and the like. In addition, phenol and its derivatives are used in the production of paints, dyes, explosives, petroleum additives, wood preservatives, and the like. The titanium silicalite molecular sieve is used as a catalyst to catalyze benzene oxidation to prepare phenol, the reaction condition is mild, the process is simple, and the environment is friendly. However, as the reaction time is prolonged, the catalytic activity of the titanium silicalite molecular sieve tends to be reduced, so that the selectivity of the target oxidation product is obviously reduced. When the reaction is carried out in a fixed bed reactor, the titanium silicalite molecular sieve needs to be regenerated in or out of the reactor due to the reduction of the catalytic activity of the titanium silicalite molecular sieve, so that the shutdown of the reactor is caused, the production efficiency is influenced, and the operation cost of the device is increased.
For the method for preparing phenol compounds by oxidizing aromatic hydrocarbon represented by the reaction of preparing phenol by oxidizing benzene with a titanium silicalite molecular sieve as a catalyst, how to prolong the one-way service life of the catalyst and reduce the regeneration frequency is one of the key links for improving the production efficiency and reducing the operation cost.
Disclosure of Invention
The object of the present invention is to provide an aromatic oxidation process which can prolong the one-way service life of a catalyst and stabilize the conversion of a raw material, the effective utilization rate of an oxidizing agent and the selectivity of a target oxidation product at high levels even in a long-period continuous operation.
In order to achieve the above object, the present invention provides an aromatic hydrocarbon oxidation method, which comprises making a reaction feed containing at least one aromatic hydrocarbon, an oxidant and optionally at least one solvent flow through a 1 st catalyst bed to a last n catalyst bed in sequence under oxidation reaction conditions, wherein n is an integer of more than 2, each catalyst bed is filled with at least one titanium-silicon molecular sieve, characterized in that during the reaction feed material passes through the 1 st catalyst bed layer to the n th catalyst bed layer, a carrier fluid is introduced between at least one pair of adjacent catalyst bed layers between the 1 st catalyst bed layer and the n th catalyst bed layer, so that the carrier fluid is introduced between the catalyst bed layers in a way that the flow direction of the reaction feed material is taken as a reference, in the at least one pair of adjacent catalyst beds, the superficial velocity of the reactant stream in the downstream catalyst bed is higher than the superficial velocity of the reactant stream in the upstream catalyst bed.
By adopting the technical scheme, the method can effectively prolong the one-way service life of the titanium silicalite molecular sieve, reduce the regeneration frequency of the titanium silicalite molecular sieve and prolong the total service life of the titanium silicalite molecular sieve.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is an XRD spectrum of a titanium silicalite TS-1 prepared in example 1 of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The invention provides an aromatic hydrocarbon oxidation method, which comprises the step of enabling reaction feed containing at least one aromatic hydrocarbon, an oxidant and at least one optional solvent to sequentially flow through a 1 st catalyst bed layer to a last n catalyst bed layer under the oxidation reaction condition, wherein n is an integer more than 2, and at least one titanium silicalite molecular sieve is filled in each catalyst bed layer. Herein, "at least one" means one or more than two; "optional" means optional and is to be understood as "with or without" and "including or not including".
In the present invention, n is an integer of 2 to 50, preferably an integer selected from 2 to 20, more preferably an integer selected from 2 to 10, and further preferably an integer selected from 2 to 5, for example 2.
In the present invention, the expression "the reaction feed flows through the 1 st to the n-th catalyst beds in sequence" means that the flow route of the reaction feed is formed from the 1 st catalyst bed to the n-th catalyst bed in sequence, but this does not mean that the reaction feed flows through the 1 st to the n-th catalyst beds without any change. In fact, since the catalyst enters the 1 st catalyst bed, the reaction feed (for example, in terms of its composition or properties) changes due to the occurrence of an aromatic oxidation reaction or the like, thereby losing its original composition or properties as a reaction raw material. In view of this, the reaction feed flowing through each catalyst bed is generally referred to as the reaction mass in the context of the present invention, in order to comply with the general understanding of the reaction feedstock by the skilled person. Moreover, the reactant materials may also change as they flow through the different catalyst beds due to various factors (e.g., due to reactions occurring or the introduction of new materials, such as carrier fluids), such that the reactant materials (e.g., in terms of their composition or behavior) flowing through the different catalyst beds are generally different. The present invention focuses on the superficial velocity of each reactant as it flows through its respective catalyst bed.
The method according to the present invention further comprises introducing a carrier fluid between at least one pair of adjacent catalyst beds between the 1 st to the n-th catalyst beds during the passage of the reaction feed through the 1 st to the n-th catalyst beds such that the superficial velocity of the reactant stream in the downstream catalyst bed is higher than the superficial velocity of the reactant stream in the upstream catalyst bed in the at least one pair of adjacent catalyst beds with respect to the flow direction of the reaction feed.
In the present invention, the apparent velocity (in kg/(m)2S) means passing a certain catalyst per unit timeThe mass flow (in kg/s) of the reaction mass throughout the catalyst bed and the cross-sectional area (in m) of the catalyst bed2Meter) of the measured values. For example, the superficial velocity of the reaction mass flowing through the catalyst bed 1 is v1Means the mass flow rate (in kg/s) of the reaction mass in the unit time passing through the 1 st catalyst bed and the cross-sectional area (in m) of the catalyst bed2Meter) of the measured values. Here, the "cross-sectional area" generally refers to an average cross-sectional area from the viewpoint of simplifying the description of the present invention. Furthermore, by "average cross-sectional area" is meant the total catalyst loading volume (in m) of the catalyst bed3In terms of m) to the length of the catalyst bed in the direction of flow of the reaction mass, as will be apparent to the skilled person. For a catalyst bed of equal diameter, the average cross-sectional area is the cross-sectional area. In addition, the present invention has no particular requirement on the superficial velocity (absolute value) of the reaction mass flowing through each catalyst bed, and those conventionally known in the art can be directly applied thereto, for example, the superficial velocity (absolute value) of the reaction mass flowing through the catalyst bed 1 may be generally in the range of 0.001 to 200kg/(m m.2S), but the range is not limited to these.
From the viewpoint of making the technical effect of the present invention more excellent, at least one carrier fluid is introduced between at least one pair of adjacent catalyst beds between the 1 st catalyst bed and the n-th catalyst bed so that the superficial velocity of the reactant flow in the downstream catalyst bed among the pair of adjacent catalyst beds is represented by vmThe superficial velocity of the reactant stream in the upstream catalyst bed is denoted by vm-1The carrier fluid is introduced in an amount vm/vm-11.5 to 15, more preferably vm/vm-12-10, more preferably vm/vm-12-5, m is [2, n ]]Any integer in the interval, namely any one integer selected from 2, 3, … and n; and, when n is 2, m is 2. For example, when m is 2, v is preferably2/v11.5 to 15, more preferably v2/v12-10, more preferably v2/v1＝2-5。
According to the process of the present invention, the 1 st to nth catalyst beds may all be arranged in the same reactor, constitute different reaction zones of the reactor, may be arranged in n reactors respectively, constitute n different reactors, or may be arranged in any combination of two or more (at most n-1) reactors, constitute a combination of multiple reaction zones and multiple reactors.
According to the method of the invention, the 1 st to the last nth catalyst beds can be continuously connected to form an integral catalyst bed, and a separation part can be arranged between any one or more pairs of adjacent catalyst beds to form a multi-stage catalyst bed. The partition may be the interior space of the reactor, in which case one or more non-catalyst beds (e.g., beds of non-activated packing as described below) or internals (e.g., fluid distributors, catalyst bed support members, heat exchangers, etc.) may be provided as desired, thereby providing more flexibility in the regulation of the aromatic oxidation reaction of the present invention.
According to the method of the present invention, the 1 st to the last n-th catalyst beds are connected in series in this order along the flow path of the reaction feed to form an upstream-downstream relationship, wherein the 1 st catalyst bed is located at the most upstream and the n-th catalyst bed is located at the most downstream. Nevertheless, some or all of the catalyst beds may be spatially arranged side by side, provided that it is ensured that the reaction feed flows through them one after the other.
According to the process of the present invention, each of the 1 st to nth catalyst beds may contain one or more catalyst beds. If a plurality of catalyst beds are contained, the catalyst beds may be connected in series, in parallel, or in a combination of series and parallel. For example, when the plurality of catalyst beds are divided into a plurality of groups, the catalyst beds in each group may be connected in series and/or in parallel, and the groups may be connected in series and/or in parallel.
In the process of the present invention, the 1 st to nth catalyst beds are preferably fixed beds from the viewpoint of facilitating the oxidation reaction of the aromatic hydrocarbon of the present invention.
According to the method of the invention, at least one titanium silicalite molecular sieve is filled in each of the 1 st to the n-th catalyst beds. Titanium silicalite is a generic term for a class of zeolites in which a portion of the silicon atoms in the lattice framework are replaced by titanium atoms, and can be represented by the formula xTiO2·SiO2And (4) showing. The content of titanium atoms in the titanium silicalite molecular sieve is not particularly limited in the invention, and can be selected conventionally in the field. Specifically, x may be 0.0001 to 0.05, preferably 0.01 to 0.03, more preferably 0.015 to 0.025.
The titanium silicalite molecular sieve can be common titanium silicalite molecular sieves with various topologies, such as: the titanium silicalite molecular sieve can be selected from titanium silicalite molecular sieve with MFI structure (such as TS-1), titanium silicalite molecular sieve with MEL structure (such as TS-2), titanium silicalite molecular sieve with BEA structure (such as Ti-Beta), titanium silicalite molecular sieve with MWW structure (such as Ti-MCM-22), titanium silicalite molecular sieve with MOR structure (such as Ti-MOR), titanium silicalite molecular sieve with TUN structure (such as Ti-TUN), titanium silicalite molecular sieve with two-dimensional hexagonal structure (such as Ti-MCM-41 and Ti-SBA-15), titanium silicalite molecular sieve with other structure (such as Ti-ZSM-48), etc. The titanium silicalite molecular sieve is preferably selected from a titanium silicalite molecular sieve with an MFI structure, a titanium silicalite molecular sieve with an MEL structure, a titanium silicalite molecular sieve with a two-dimensional hexagonal structure and a titanium silicalite molecular sieve with a BEA structure, and more preferably is a titanium silicalite molecular sieve with an MFI structure, such as a non-hollow titanium silicalite molecular sieve TS-1 and/or a hollow titanium silicalite molecular sieve TS-1. The hollow titanium silicalite TS-1 is a titanium silicalite with MFI structure, crystal grains of the titanium silicalite are of hollow structure, the radial length of a cavity part of the hollow structure is 5-300 nanometers, and the titanium silicalite is P/P at 25 DEG C0The benzene adsorption amount measured under the conditions of 0.10 and the adsorption time of 1 hour is at least 70 mg/g, and a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of the low-temperature nitrogen adsorption of the titanium silicalite molecular sieve. The hollow titanium silicalite TS-1 can be obtained commercially (e.g., HTS-brand molecular sieve commercially available from the shogaku corporation, Jian, Hunan), or can be prepared according to the method disclosed in CN 1132699C.
According to the method, at least part of the titanium silicalite molecular sieve is the titanium silicalite molecular sieve TS-1, and the surface silicon-titanium ratio of the titanium silicalite molecular sieve TS-1 is not lower than the bulk silicon-titanium ratio, so that the effective utilization rate of an oxidant can be further improved, and the one-way service life of the titanium silicalite molecular sieve can be further prolonged. Preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.2 or more. More preferably, the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.2 to 5. Further preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.5-4.5. Still more preferably, the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 2 to 3. The silicon-titanium ratio refers to the molar ratio of silicon oxide to titanium oxide, the surface silicon-titanium ratio is determined by adopting an X-ray photoelectron spectroscopy, and the bulk silicon-titanium ratio is determined by adopting an X-ray fluorescence spectroscopy.
According to the method, the titanium silicalite TS-1 is prepared by adopting a method comprising the following steps:
(A) dispersing an inorganic silicon source in an aqueous solution containing a titanium source and an alkali source template agent, and optionally supplementing water to obtain a dispersion liquid, wherein the ratio of the silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: (0.5-8): (5-30): (100-2000), the inorganic silicon source is SiO2The titanium source is calculated as TiO2The alkali source template is counted by OH < - > or N < - > (counted by N when the alkali source template contains nitrogen element; counted by OH < - > when the alkali source template does not contain nitrogen element);
(B) optionally, standing the dispersion at 15-60 ℃ for 6-24 h;
(C) and (3) sequentially carrying out stage (1), stage (2) and stage (3) crystallization on the dispersion liquid obtained in the step (A) or the dispersion liquid obtained in the step (B) in a sealed reaction kettle, wherein the stage (1) is crystallized for 6-72 hours at the temperature of 80-150 ℃, the stage (2) is cooled to the temperature of not higher than 70 ℃ and the retention time is at least 0.5 hour, and then the stage (3) is heated to the temperature of 120-200 ℃ for recrystallization for 6-96 hours.
The alkali source template can be various templates commonly used in the process of synthesizing the titanium silicalite molecular sieve, such as: the alkali source template agent can be one or two of quaternary ammonium base, aliphatic amine and aliphatic alcohol amineThe above. The quaternary ammonium base can be various organic quaternary ammonium bases, and the aliphatic amine can be various NH3In which at least one hydrogen is substituted with an aliphatic hydrocarbon group (e.g., an alkyl group), which may be a variety of NH3Wherein at least one hydrogen is substituted with a hydroxyl-containing aliphatic group (e.g., an alkyl group).
Specifically, the alkali source template may be one or more selected from the group consisting of a quaternary ammonium base represented by formula I, an aliphatic amine represented by formula II, and an aliphatic alcohol amine represented by formula III.
Figure BDA0000905742870000071
In the formula I, R1、R2、R3And R4Each C1-C4 alkyl group including C1-C4 linear alkyl group and C3-C4 branched alkyl group, R1、R2、R3And R4Specific examples of (a) may include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, or tert-butyl.
R5(NH2)n(formula II)
In the formula II, n is an integer of 1 or 2. When n is 1, R5Is C1-C6 alkyl, including C1-C6 straight chain alkyl and C3-C6 branched chain alkyl, specific examples of which may include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl or n-hexyl. When n is 2, R5Is C1-C6 alkylene, including C1-C6 linear alkylene and C3-C6 branched alkylene, specific examples of which may include, but are not limited to, methylene, ethylene, n-propylene, n-butylene, n-pentylene, or n-hexylene.
(HOR6)mNH(3-m)(formula III)
In the formula III, m is 1, 2 or 3. R6May be C1-C4 alkylene groups including C1-C4 linear alkylene groups and C3-C4 branched alkylene groups, and specific examples thereof may include, but are not limited toIn the methylene, ethylene, n-propylene and n-butylene groups.
Specific examples of the alkali-derived templating agent may include, but are not limited to: one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide (including various isomers of tetrapropylammonium hydroxide such as tetra-n-propylammonium hydroxide and tetraisopropylammonium hydroxide), tetrabutylammonium hydroxide (including various isomers of tetrabutylammonium hydroxide such as tetra-n-butylammonium hydroxide and tetraisobutylammonium hydroxide), ethylamine, n-propylamine, n-butylamine, di-n-propylamine, butanediamine, hexanediamine, monoethanolamine, diethanolamine, and triethanolamine. Preferably, the alkali source template is one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide. More preferably, the alkali-source templating agent is tetrapropylammonium hydroxide.
The titanium source may be an inorganic titanium salt and/or an organic titanate, preferably an organic titanate. The inorganic titanium salt may be TiCl4、Ti(SO4)2Or TiOCl2One or more than two of the above; the organic titanate may be of the formula R7 4TiO4A compound of wherein R7Is C1-C6 alkyl, preferably C2-C4 alkyl.
The inorganic silicon source can be silica gel and/or silica sol, and silica gel is preferred. SiO in the silica sol2The content of (b) may be 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more. In preparing the titanium silicalite molecular sieves according to this preferred embodiment, no source of organic silicon, such as organosilanes and organosiloxanes, is used.
In the dispersion, a silicon source: a titanium source: alkali source template agent: the molar ratio of water is preferably 100: (1-6): (8-25): (200-1500), more preferably 100: (2-5): (10-20): (400-1000).
The dispersion obtained in step (A) may be directly fed to step (C) for crystallization. Preferably, the dispersion obtained in step (A) is fed to step (B) and allowed to stand at a temperature of 15 to 60 ℃ for 6 to 24 hours. The step (B) between the step (A) and the step (C) can obviously improve the surface silicon-titanium ratio of the finally prepared titanium-silicon molecular sieve TS-1, so that the surface silicon-titanium ratio of the finally prepared titanium-silicon molecular sieve is not lower than the bulk silicon-titanium ratio, the catalytic performance of the finally prepared titanium-silicon molecular sieve can be obviously improved, the one-way service life of the finally prepared titanium-silicon molecular sieve is prolonged, and the effective utilization rate of an oxidant is improved. Generally, by placing step (B) between step (a) and step (C), the ratio of surface silicon to titanium to bulk silicon to titanium of the finally prepared titanium silicalite molecular sieve can be in the range of 1.2 to 5, preferably in the range of 1.5 to 4.5 (e.g., in the range of 2.5 to 4.5), more preferably in the range of 2 to 3. More preferably, the standing is carried out at a temperature of 20-50 deg.C, such as 25-45 deg.C.
In the step (B), the dispersion may be placed in a sealed container or may be placed in an open container and allowed to stand. Preferably, step (B) is carried out in a sealed vessel, so that introduction of external impurities into the dispersion during standing or volatilization loss of a part of the substance in the dispersion can be avoided.
After the standing in the step (B) is finished, the standing dispersion liquid can be directly sent into a reaction kettle for crystallization, or the standing dispersion liquid can be sent into the reaction kettle for crystallization after being redispersed, and preferably sent into the reaction kettle after being redispersed, so that the dispersion uniformity of the crystallized dispersion liquid can be further improved. The method of redispersion may be a conventional method such as one or a combination of two or more of stirring, sonication, and shaking. The duration of the redispersion is such that a homogeneous dispersion is formed from the dispersion on standing, and may generally be from 0.1 to 12 hours, for example from 0.5 to 2 hours. The redispersion can be carried out at ambient temperature, for example at a temperature of from 15 to 40 ℃.
In the step (C), the temperature increase rate and the temperature decrease rate for adjusting the temperature to each stage may be selected according to the type of the crystallization reactor specifically used, and are not particularly limited. In general, the rate of temperature increase to raise the temperature to the crystallization temperature of stage (1) may be from 0.1 to 20 deg.C/min, preferably from 0.1 to 10 deg.C/min, more preferably from 1 to 5 deg.C/min. The rate of temperature decrease from the stage (1) temperature to the stage (2) temperature may be from 1 to 50 deg.C/min, preferably from 2 to 20 deg.C/min, more preferably from 5 to 10 deg.C/min. The rate of temperature increase from the stage (2) temperature to the stage (3) crystallization temperature may be 1 to 50 ℃/min, preferably 2 to 40 ℃/min, more preferably 5 to 20 ℃/min.
In the step (C), the crystallization temperature in the stage (1) is preferably 110-. The crystallization time of stage (1) is preferably 6 to 24h, more preferably 6 to 8 h. The temperature of the stage (2) is preferably not higher than 50 ℃. The residence time of stage (2) is preferably at least 1h, more preferably from 1 to 5 h. The crystallization temperature of stage (3) is preferably 140-. The crystallization time of stage (3) is preferably 12-20 h.
In step (C), in a preferred embodiment, the crystallization temperature in stage (1) is lower than that in stage (3), so as to further improve the catalytic performance of the prepared titanium silicalite molecular sieve. Preferably, the crystallization temperature of stage (1) is 10-50 ℃ lower than the crystallization temperature of stage (3). More preferably, the crystallization temperature of stage (1) is 20-40 ℃ lower than the crystallization temperature of stage (3). In step (C), in another preferred embodiment, the crystallization time in stage (1) is shorter than that in stage (3), so as to further improve the catalytic performance of the finally prepared titanium silicalite molecular sieve. Preferably, the crystallization time of stage (1) is 5-24h shorter than the crystallization time of stage (3). More preferably, the crystallization time of stage (1) is 6-12h, such as 6-8h shorter than the crystallization time of stage (3). In step (C), these two preferred embodiments may be used alone or in combination, preferably in combination, that is, the crystallization temperature and crystallization time of stage (1) and stage (3) satisfy the requirements of these two preferred embodiments at the same time.
In step (C), in another preferred embodiment, the temperature of stage (2) is not higher than 50 ℃, and the residence time is at least 0.5h, such as 0.5-6h, so as to further improve the catalytic performance of the finally prepared titanium silicalite molecular sieve. Preferably, the residence time of stage (2) is at least 1h, such as 1-5 h. This preferred embodiment can be used separately from the two preferred embodiments described above, or in combination, preferably in combination, i.e. the crystallization temperature and crystallization time of stage (1) and stage (3) and the temperature and residence time of stage (2) simultaneously meet the requirements of the three preferred embodiments described above.
Conventional methods can be used to recover the titanium silicalite from the mixture crystallized in step (C). Specifically, after optionally filtering and washing the mixture obtained by crystallization in step (C), the solid matter may be dried and calcined to obtain the titanium silicalite molecular sieve. The drying and the firing may be performed under conventional conditions. Generally, the drying may be carried out at a temperature of from ambient temperature (e.g., 15 ℃) to 200 ℃. The drying may be carried out at ambient pressure (typically 1 atm), or under reduced pressure. The duration of the drying may be selected according to the temperature and pressure of the drying and the manner of the drying, and is not particularly limited. For example, when the drying is carried out at ambient pressure, the temperature is preferably 80 to 150 ℃, more preferably 100 ℃ to 120 ℃, and the duration of the drying is preferably 0.5 to 5 hours, more preferably 1 to 3 hours. The calcination may be carried out at a temperature of 300-800 ℃, preferably at a temperature of 500-700 ℃, more preferably at a temperature of 550-650 ℃, and even more preferably at a temperature of 550-600 ℃. The duration of the calcination may be selected according to the temperature at which the calcination is carried out, and may generally be 2 to 12 hours, preferably 2 to 5 hours. The calcination is preferably carried out in an air atmosphere.
According to the method of the present invention, at least part of the titanium silicalite molecular sieve is preferably a modified titanium silicalite molecular sieve, which can further improve the catalytic performance of the titanium silicalite molecular sieve. The modified titanium silicalite molecular sieve refers to a titanium silicalite molecular sieve subjected to modification treatment, and the titanium silicalite molecular sieve which is not subjected to modification treatment is an unmodified titanium silicalite molecular sieve. The modification treatment comprises the following steps: mixing Ti-Si molecular sieve with nitric acid (i.e. HNO)3) And at least one peroxide modifying solution. The titanium silicalite as a raw material is a titanium silicalite as a raw material for modification treatment, and may be a titanium silicalite which has not been subjected to the modification treatment or a titanium silicalite which has been subjected to the modification treatment but needs to be subjected to the modification treatment again.
According to the method of the present invention, all the titanium silicalite molecular sieves may be subjected to the above modification treatment (i.e., the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves), or some of the titanium silicalite molecular sieves may be subjected to the above modification treatment (i.e., the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves and unmodified titanium silicalite molecular sieves). Preferably, at least 50 wt% of the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves, more preferably at least 60 wt% of the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves, for example, the modified titanium silicalite molecular sieves may be present in an amount of 5 to 95 wt%, preferably 20 to 90 wt%, more preferably 40 to 80 wt%, based on the total amount of the titanium silicalite molecular sieves.
In the modification treatment, the peroxide may be selected from hydrogen peroxide, hydroperoxide and peracid. In the present invention, hydroperoxide means a substance obtained by substituting one hydrogen atom in a hydrogen peroxide molecule with an organic group, and peracid means an organic oxygen acid having an-O-bond in its molecular structure.
In the modification treatment, specific examples of the peroxide may include, but are not limited to: hydrogen peroxide, ethylbenzene hydroperoxide, tert-butyl hydroperoxide, cumene hydroperoxide, cyclohexyl hydroperoxide, peracetic acid and propionic acid. Preferably, the oxidizing agent is hydrogen peroxide. The hydrogen peroxide may be hydrogen peroxide in various forms commonly used in the art.
In the modification treatment, the molar ratio of the titanium silicalite molecular sieve as the raw material to the peroxide may be 1: (0.01-5), preferably 1: (0.05-3), more preferably 1: (0.1-2). The amount of nitric acid may be selected based on the amount of peroxide. Generally, the molar ratio of the peroxide to the nitric acid may be 1: (0.01-50), preferably 1: (0.1-20), more preferably 1: (0.2-10), more preferably 1: (0.5-5), particularly preferably 1: (0.6-3.5), such as 1: (0.7-1.2), wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.
In the modification liquid, the concentrations of the peroxide and the nitric acid may be 0.1 to 50% by weight, respectively. From the viewpoint of further improving the catalytic performance of the finally prepared modified titanium silicalite molecular sieve, it is preferably 0.5 to 25 wt%. More preferably, the concentrations of the peroxide and the nitric acid in the modification liquid are each 5 to 15% by weight.
The solvent of the modifying solution can be various common solvents capable of dissolving the nitric acid and the peroxide at the same time. Preferably, the solvent of the modifying solution is water.
In the modification treatment, the titanium silicalite molecular sieve as the raw material and the modification solution can be contacted at the temperature of 10-350 ℃. The contacting is preferably carried out at a temperature of 20 to 300 deg.c from the viewpoint of further improving the catalytic performance of the finally prepared modified titanium silicalite. More preferably, the contacting is carried out at a temperature of 50-250 ℃. Further preferably, the contacting is performed at a temperature of 60-200 ℃. Even more preferably, the contacting is carried out at a temperature of 70-150 ℃. The duration of the contact may be from 1 to 10h, preferably from 3 to 5 h. In the modification treatment, the pressure in the vessel in which the titanium silicalite molecular sieve as the raw material is brought into contact with the modification solution may be selected depending on the contact temperature, and may be either ambient pressure or pressurized. Generally, the pressure in the vessel in which the titanium silicalite molecular sieve as the raw material is contacted with the modifying liquid may be 0 to 5MPa, and the pressure is a gauge pressure. Preferably, the titanium silicalite molecular sieve as the raw material is contacted with the modifying liquid under the condition of pressurization. More preferably, the titanium silicalite molecular sieve as the raw material is contacted with the modifying liquid under autogenous pressure in a closed container.
In the modification treatment, the contact degree between the titanium silicalite molecular sieve as the raw material and the modification liquid is preferably such that, based on the titanium silicalite molecular sieve as the raw material, in an ultraviolet-visible spectrum, the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230 nm and 310nm is reduced by more than 2%, and the pore volume of the modified titanium silicalite molecular sieve is reduced by more than 1%. The peak area of the absorption peak of the modified titanium-silicon molecular sieve between 230-310nm is preferably reduced by 2-30%, more preferably reduced by 2.5-15%, still more preferably reduced by 3-10%, and still more preferably reduced by 3-6%. The pore volume of the modified titanium silicalite molecular sieve is preferably reduced by 1 to 20%, more preferably by 1.5 to 10%, and even more preferably by 2 to 5%. The pore volume is determined by a static nitrogen adsorption method.
In various industrial devices using titanium silicalite molecular sieves as catalysts, such as ammoximation reaction and epoxidation reaction devices, generally, after the devices operate for a period of time, the catalytic activity of the catalysts is reduced, and the catalysts need to be regenerated in or out of the devices, when satisfactory activity is difficult to obtain even if regeneration is carried out, the catalysts need to be unloaded from the devices (i.e. the catalysts need to be replaced), and the unloaded catalysts (i.e. unloading agents or waste catalysts) are generally piled up and buried, so that on one hand, precious land resources and storage space are occupied, on the other hand, the titanium silicalite molecular sieves are high in production cost, and are directly discarded without causing great waste. The discharging agents (namely, the discharged titanium silicalite molecular sieves) are regenerated and then contacted with aromatic hydrocarbon and an oxidant under the condition of oxidation reaction, so that better catalytic performance can be still obtained, and particularly higher effective utilization rate of the oxidant can be obtained. Therefore, according to the method of the present invention, at least a portion of the titanium silicalite is preferably the discharging agent of the regenerated reaction device (except the aromatic oxidation reaction device) using the titanium silicalite as the catalyst. The discharging agent may be discharged from various reaction apparatuses using a titanium silicalite as a catalyst, and may be discharged from an oxidation reaction apparatus, for example. Specifically, the discharging agent is a discharging agent of an ammoximation reaction device and/or a discharging agent of an epoxidation reaction device. More specifically, the discharging agent may be a discharging agent of a cyclohexanone ammoximation reaction apparatus and/or a discharging agent of a propylene epoxidation reaction apparatus.
The conditions for regenerating the discharging agent are not particularly limited, and may be appropriately selected depending on the source of the discharging agent, for example: high temperature calcination and/or solvent washing.
The activity of the regenerated discharging agent varies depending on its source. Generally, the activity of the regenerated discharging agent can be 5-95% of the activity of the titanium silicalite when fresh (i.e., the activity of fresh titanium silicalite). Preferably, the activity of the regenerated discharging agent can be 10-90% of the activity of the titanium silicalite molecular sieve in the fresh state, more preferably 30-50% of the activity in the fresh state, and even more preferably 35-45% of the activity in the fresh state. The activity of the fresh titanium silicalite molecular sieve is generally above 90%, usually above 95%.
The activity was determined by the following method: respectively using the regenerated discharging agent and the fresh titanium silicalite molecular sieve as catalysts of cyclohexanone ammoximation reaction, wherein the ammoximation reaction conditions are as follows: titanium silicalite molecular sieve, 36 wt% ammonia (as NH)3Calculated as H), 30 wt% of hydrogen peroxide (calculated as H)2O2Calculated by weight ratio of 1: 7.5: 10: 7.5: 10, reacting for 2h at 80 ℃ under atmospheric pressure. Respectively calculating the conversion rate of cyclohexanone when the regenerated discharging agent and the fresh titanium silicalite molecular sieve are used as catalysts, and respectively using the conversion rate as the activity of the regenerated discharging agent and the activity of the fresh titanium silicalite molecular sieve, wherein the conversion rate of the cyclohexanone is [ (the molar weight of the added cyclohexanone-the molar weight of the unreacted cyclohexanone)/the molar weight of the added cyclohexanone]×100％。
According to the method, the discharging agent can be used as a raw material of a modified titanium silicalite molecular sieve and can also be used as an unmodified titanium silicalite molecular sieve. Preferably, in the modification treatment, the titanium silicalite molecular sieve as the raw material is the discharging agent, so that the single-pass service life can be further prolonged, and the selectivity of phenol and the conversion rate of aromatic hydrocarbon can be obviously improved compared with the unmodified discharging agent.
According to the method of the invention, the 1 st to nth catalyst beds are respectively filled with at least one titanium silicalite molecular sieve. The types of the titanium silicalite molecular sieves filled in different catalyst bed layers can be the same or different. In addition, each catalyst bed layer can be filled with only one titanium silicalite molecular sieve, or can be filled with one or more than two titanium silicalite molecular sieves according to any required relative proportion.
Preferably, the titanium silicalite molecular sieve filled in the 1 st catalyst bed layer is a hollow titanium silicalite molecular sieve TS-1, and the titanium silicalite molecular sieves filled in the 2 nd to nth catalyst bed layers (i.e., the remaining catalyst bed layers) are titanium silicalite molecular sieves other than the hollow titanium silicalite molecular sieve TS-1, such as titanium silicalite molecular sieves selected from other MFI structures, so that the deactivation rate of the titanium silicalite molecular sieves can be further delayed. More preferably, the titanium silicalite molecular sieve filled in the 1 st catalyst bed layer is a hollow titanium silicalite molecular sieve TS-1, and the titanium silicalite molecular sieves filled in the 2 nd to nth catalyst bed layers are non-hollow titanium silicalite molecular sieves TS-1. Therefore, the deactivation speed of the titanium silicalite molecular sieve can be further delayed, the one-way service life of the titanium silicalite molecular sieve is prolonged, and the selectivity of a target oxidation product can be further improved. In this context, if "hollow titanium silicalite TS-1" is not specified, the default is non-hollow titanium silicalite TS-1.
According to the method of the present invention, the titanium silicalite molecular sieve is preferably a shaped titanium silicalite molecular sieve. The formed titanium silicalite molecular sieve generally contains a titanium silicalite molecular sieve as an active component and a carrier as a binder, wherein the content of the titanium silicalite molecular sieve can be selected conventionally. Generally, the content of the titanium silicalite molecular sieve can be 5 to 95 wt%, preferably 10 to 95 wt%, more preferably 70 to 90 wt% based on the total amount of the shaped titanium silicalite molecular sieve; the carrier may be contained in an amount of 5 to 95% by weight, preferably 5 to 90% by weight, more preferably 10 to 30% by weight. The support for the shaped titanium silicalite molecular sieve may be of conventional choice, such as alumina and/or silica. Methods of making the shaped titanium silicalite molecular sieves are well known in the art and will not be described in detail herein. The particle size of the shaped titanium silicalite molecular sieve is not particularly limited, and may be appropriately selected according to the specific shape. Generally, the average particle size of the shaped titanium silicalite molecular sieves may be in the range of from 4 to 10000 microns, preferably from 5 to 5000 microns, more preferably from 40 to 4000 microns, such as 100 and 2000 microns. The average particle size is a volume average particle size and can be measured by a laser particle sizer.
According to the method of the invention, the amount (mass) of the titanium silicalite molecular sieves filled in the 1 st to nth catalyst beds can be the same or different. According to one embodiment, m takes the interval [2, n ]]When an arbitrary integer is within, Wm-1/Wm0.1 to 20, Wm-1/WmPreferably 0.5 or more, more preferably 1 or more, and further preferably 2 or more. Here, Wm-1Any pair of adjacent catalyst beds from the 1 st catalyst bed to the n-th catalyst bedMass of catalyst packed in catalyst bed located upstream in catalyst bed, WmThe mass of the catalyst filled in the downstream catalyst bed in any one pair of adjacent catalyst beds from the 1 st catalyst bed to the n th catalyst bed. Wm-1/WmPreferably 15 or less, more preferably 10 or less. Even more preferably, Wm-1/WmIs 2-8. Wm-1And WmThe content of the titanium silicalite molecular sieve in the formed titanium silicalite molecular sieve is determined. In addition, the amount of the catalyst to be packed in each catalyst bed may be appropriately determined according to the need (e.g., production capacity), and is not particularly limited.
According to the method of the present invention, the total amount of the titanium silicalite molecular sieve (i.e., the total amount of the titanium silicalite molecular sieve catalyst loaded in the 1 st to nth catalyst beds) can be selected according to the specific treatment capacity of the system. Generally, the total amount of the catalyst is such that the weight hourly space velocity of the aromatic hydrocarbon (as a component of the reaction feed) may be in the range of from 0.05 to 100h-1Preferably 0.1 to 50h-1。
According to the method, the 1 st to nth catalyst beds can be further filled with inactive fillers according to requirements besides the titanium silicalite molecular sieves. The inactive filler may be packed in all of the 1 st to nth catalyst beds, or may be packed in one or more of the 1 st to nth catalyst beds. The amount of the catalyst in the catalyst bed layer can be adjusted by filling the inactive filler in the catalyst bed layer, so that the reaction speed can be adjusted. For a catalyst bed, the amount of inactive filler, when loaded, may be from 5 to 95 wt.%, relative to the total amount of catalyst and inactive filler loaded in the catalyst bed. Herein, the inactive filler means a filler having no or substantially no catalytic activity for aromatic oxidation reaction, which is conventionally known in the art, and specific examples thereof may include, but are not limited to: one or more than two of quartz sand, ceramic ring and ceramic fragment.
According to the invention, the reaction feed (in the present invention, the reaction mass immediately before entry into the 1 st catalyst bed) contains at least one aromatic hydrocarbon, an oxidant and optionally a solvent.
The oxidizing agent may be any of various substances commonly used to oxidize aromatic hydrocarbons. Preferably, the oxidizing agent is a peroxide, which may be selected from hydrogen peroxide, hydroperoxides and peracids. Specific examples of the peroxide may include, but are not limited to: hydrogen peroxide, tert-butyl hydroperoxide, cumene peroxide, ethylbenzene hydroperoxide, cyclohexyl hydroperoxide, peracetic acid and propionic acid peroxide. Preferably, the oxidizing agent is hydrogen peroxide, which further reduces the separation cost. The hydrogen peroxide may be hydrogen peroxide in various forms commonly used in the art. The oxidizing agent may be used alone or in combination of two or more.
The amount of the oxidant may be selected based on the amount of aromatic hydrocarbon contained in the reaction feed. Generally, the molar ratio of the aromatic hydrocarbon to the oxidant in the reaction feed may be (0.1 to 20): 1. from the viewpoint of further improving the selectivity of phenol, the molar ratio of the aromatic hydrocarbon to the oxidizing agent is preferably (0.2 to 10): 1, more preferably (1-5): 1.
according to the process of the present invention, the reaction feed may further contain a solvent in order to better control the reaction rate. The solvent used in the present invention is not particularly limited, and may be any of various solvents commonly used in oxidation reactions of aromatic hydrocarbons. Preferably, the solvent is at least one of water, C1-C10 alcohol, C3-C10 ketone, C2-C10 nitrile and C1-C6 carboxylic acid. Preferably, the solvent is one or more of C1-C6 alcohol, C3-C8 ketone and C2-C5 nitrile. More preferably, the solvent is one or more of methanol, ethanol, acetonitrile, n-propanol, isopropanol, tert-butanol, isobutanol, and acetone. Further preferably, the solvent is one or more of methanol, acetonitrile, acetone, and tert-butanol. These solvents may be used alone or in combination of two or more.
The amount of the solvent used in the present invention is not particularly limited, and may be selected according to the amounts of the aromatic hydrocarbon and the oxidizing agent. Generally, the molar ratio of the solvent to the aromatic hydrocarbon in the reaction feed may be (0.1 to 100): 1, preferably (0.2-80): 1.
when the oxidation reaction conditions are sufficient to oxidize the aromatic hydrocarbon to phenol according to the process of the present invention, the process of the present invention preferably further comprises feeding at least one basic substance into the liquid mixture in an amount such that the pH of the liquid mixture is in the range of 6 to 9, which further improves the selectivity to phenol. More preferably, the alkaline substance is added in an amount such that the pH of the liquid mixture is in the range of 6.5-8.5.
According to the method of the present invention, the aromatic hydrocarbon may be a substituted or unsubstituted monocyclic aromatic hydrocarbon or a substituted or unsubstituted polycyclic aromatic hydrocarbon, and the substituent may be at least one selected from alkyl, methoxy and haloalkyl, preferably a substituted or unsubstituted monocyclic aromatic hydrocarbon. These aromatic hydrocarbons may be used alone or in combination of two or more. Specifically, the aromatic hydrocarbon may be at least one selected from the group consisting of benzene, toluene, xylene, ethylbenzene, and cumene.
According to the method of the present invention, the oxidation reaction conditions in each catalyst bed may be the same or different (preferably the same), and each may include: the reaction pressure (in gauge pressure) is from 0 to 3MPa, preferably from 0.1 to 2.5MPa, and the reaction temperature is from 0 to 120 ℃ and preferably from 20 to 80 ℃ (for example from 30 to 60 ℃).
According to the method, the aromatic hydrocarbon oxidation reaction is carried out in the 1 st to nth catalyst beds, and the reaction discharge containing phenol is obtained. The reaction output here refers in particular to the reaction mass immediately after leaving the nth catalyst bed.
The process according to the invention optionally comprises a step of separating the phenol from the reaction output, obtaining a tail gas stream, if desired. Here, the off-gas stream may be present as a mixture containing unreacted reactants, reaction byproducts and solvent without further separation, or may be present as separate unreacted reactants, reaction byproducts and solvent after further separation, and these may be directly used as an off-gas stream without any purification treatment. As the separation method, those conventionally used in the art for this purpose can be directly applied without particular limitation. Furthermore, the separated unreacted reactants and solvent may be recycled as part of the reaction feed.
In accordance with the process of the present invention, by introducing a carrier fluid into the separation (as described above) between any one or more pairs of adjacent catalyst beds from among the 1 st to nth catalyst beds to increase the overall throughput of the reactant material through all of the catalyst beds downstream of the separation, the superficial velocity of each reactant material can be correspondingly increased to meet the aforementioned specifications of the present invention. For example, where n is 2, by introducing a carrier fluid into the separation between the 1 st catalyst bed and the 2 nd catalyst bed, the overall throughput of the reactant flowing through the 2 nd catalyst bed can be increased, thereby correspondingly increasing the superficial velocity of the reactant in the 2 nd catalyst bed to meet the foregoing specification of the present invention.
The present invention is not particularly limited as to the amount and manner of introduction of the carrier fluid, so long as it is capable of (1) uniformly mixing with the reaction mass exiting the catalyst bed immediately upstream of the partition, before, during or after entry into the catalyst bed immediately downstream of the partition, and (2) allowing the superficial velocity of each reaction mass to meet the aforementioned specification of the present invention.
According to the method of the present invention, the carrier fluid may be one or a combination of two or more of a solvent, an inert gas, and an effluent of the catalyst bed. The effluent of the catalyst bed refers to the effluent flowing out of one catalyst bed or a plurality of catalyst beds from the 1 st catalyst bed to the n-th catalyst bed, and preferably the effluent of the most downstream catalyst bed. The effluent of the catalyst bed layer can be directly used as a carrier fluid without separation, and can also be used as the carrier fluid after target phenol is separated. According to the process of the present invention, the carrier fluid is more preferably the stream remaining after separation of the target oxygenate from the effluent of the most downstream catalyst bed, such as the off-gas stream as described hereinbefore.
A fluid distributor or the like may be provided in the separation by any means known in the art, thereby facilitating uniform introduction of the carrier fluid. If desired, the carrier fluid may be pretreated by heat exchange (e.g., reduced temperature) or pressure prior to introduction into the separation.
The present invention will be described in detail with reference to examples, but the scope of the present invention is not limited thereto.
In the following examples and comparative examples, the reagents used were all commercially available reagents, and the pressure was gauge pressure.
In the following examples and comparative examples, the contents of the respective components in the obtained reaction liquid were analyzed by gas chromatography, and on the basis of which the conversion of aromatic hydrocarbons, the effective utilization of oxidizing agents, and the selectivity of phenols were calculated by the following formulas, respectively:
aromatic hydrocarbon conversion (%) × 100 [ (molar amount of added aromatic hydrocarbon-molar amount of unreacted aromatic hydrocarbon)/molar amount of added aromatic hydrocarbon ];
the effective oxidant utilization rate is ═ 100% of the molar amount of phenol produced by the reaction/(molar amount of oxidant added-molar amount of unreacted oxidant) ];
phenol selectivity ═ 100% by mole [ molar amount of phenol produced by the reaction/(molar amount of aromatic hydrocarbon added-molar amount of aromatic hydrocarbon unreacted) ].
In the following examples and comparative examples, the pore volume and the uv absorption peak of the ti-si molecular sieve before and after modification were characterized by static nitrogen adsorption and solid uv-vis diffuse reflectance spectroscopy, respectively. Wherein the static nitrogen adsorption was carried out on a static nitrogen adsorption apparatus model ASAP 2405 from Micromeritics, measured according to ASTM D4222-98. And (3) adsorbing nitrogen in a liquid nitrogen cold trap, keeping the titanium silicalite molecular sieve sample at 393K under the vacuum degree of 1.3kPa for 4h for degassing, and adsorbing nitrogen at 77K. Solid ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis) analysis is carried out on a SHIMADZU UV-3100 type ultraviolet-visible spectrometer, measurement is carried out at normal temperature and normal pressure, and the scanning wavelength range is 190 nm-800 nm. And (3) performing a powder tabletting method, roasting the sample, taking a certain amount of sample, putting the sample into a mortar, grinding the sample to be less than 300 meshes, and tabletting to prepare the sample.
In the following examples and comparative examples relating to regenerated discharge agent, the activity of titanium silicalite molecular sieves (including regenerants and fresheners) was determined using the following method:
mixing titanium-silicon molecular sieve with 36 wt% ammonia water (as NH)3Calculated as H), 30 wt% of hydrogen peroxide (calculated as H)2O2Calculated), tert-butanol and cyclohexanone in a weight ratio of 1: 7.5: 10: 7.5: 10 stirring and reacting for 2 hours at 80 ℃ under atmospheric pressure, filtering the reactants, analyzing the liquid phase by gas chromatography, calculating the conversion rate of cyclohexanone by adopting the following formula and using the conversion rate as the activity of the titanium silicalite molecular sieve,
conversion of cyclohexanone ═ molar amount of added cyclohexanone-molar amount of unreacted cyclohexanone)/molar amount of added cyclohexanone ] × 100%.
In the following examples and comparative examples including the step of preparing a titanium silicalite molecular sieve, X-ray diffraction analysis was performed on a Siemens D5005 type X-ray diffractometer, and the crystallinity of a sample relative to a reference sample was expressed as a ratio of the sum of diffraction intensities (peak heights) of five-finger diffraction characteristic peaks between 22.5 ° and 25.0 ° in 2 θ of the sample and the reference sample, test conditions were: CuK α radiation, 44 kv, 40 ma, scan speed 2 °/min. Fourier transform infrared spectrum analysis is performed on Nicolet 8210 type Fourier infrared spectrometer, KBr tablet is pressed, and resolution of infrared photometer is 4cm-1Test range 400cm-1～4000cm-1The number of times of accumulation is scanned 20 times. The silicon-titanium ratio is the molar ratio of silicon oxide to titanium oxide, the surface silicon-titanium ratio is measured by an X-ray photoelectron spectrometer with an instrument model PHI Quantera SXM (Scanning X-ray Microprobe), a monochromator is adopted, an Al anode target is selected, the energy resolution is 0.5eV, the sensitivity is 3M CPS, the incidence angle is 45 degrees, and the vacuum degree of an analysis chamber is 6.7 multiplied by 10- 8Pa; the bulk silicon-titanium ratio is measured by 3271E type X-ray fluorescence spectrometer of Japan science and electronics industries, rhodium target, excitation voltage of 50kV and excitation current of 50mA, the spectral line intensity of each element is detected by a scintillation counter and a proportional counter, a certain amount of sample is taken after the sample is roasted by a powder tabletting method,grinding in a mortar to<300 meshes, tabletting and sampling.
Examples 1-20 are intended to illustrate the process of the invention.
Example 1
The catalyst used in this example was titanium silicalite TS-1, prepared as described in Zeolite, 1992, Vol.12, pp 943-950, as follows.
At room temperature (20 ℃), 22.5g tetraethyl orthosilicate was mixed with 7.0g tetrapropylammonium hydroxide as a template, 59.8g distilled water was added, and after stirring and mixing, hydrolysis was performed at 60 ℃ for 1.0 hour under normal pressure to obtain a hydrolysis solution of tetraethyl orthosilicate. To the hydrolysis solution was slowly added a solution consisting of 1.1g tetrabutyl titanate and 5.0g anhydrous isopropanol with vigorous stirring, and the resulting mixture was stirred at 75 ℃ for 3h to give a clear and transparent colloid. Placing the colloid in a stainless steel sealed reaction kettle, and standing at a constant temperature of 170 ℃ for 36h to obtain a mixture of crystallized products. Filtering the obtained mixture, collecting the obtained solid matter, washing with water, drying at 110 ℃ for 60min, and then roasting at 500 ℃ for 6h to obtain the titanium silicalite TS-1 with the titanium oxide content of 2.8 wt%. The X-ray diffraction pattern (XRD pattern) is shown in figure 1, which shows that the TS-1 molecular sieve with MFI structure is obtained. Mixing raw powder of a titanium silicalite TS-1 with silica sol, a pore-forming agent (alkylphenol ethoxylates) and starch, extruding the mixture by using an extruder, and then carrying out granulation, drying and roasting to prepare the titanium silicalite TS-1 catalyst with the particle size of 500 microns (wherein the mass percentage of the titanium silicalite is 85%).
Filling a catalyst in an equal-diameter fixed bed reactor with the length-diameter ratio of 20 to form catalyst bed layers, wherein the number of the catalyst bed layers is 2, and the 2 catalyst bed layers are arranged in parallel at a distance of 10 cm; the mass of the catalyst filled in the two catalyst bed layers is the same, and is respectively 200 g; and a carrier fluid inlet and a liquid distributor are arranged between the two catalyst bed layers, and the liquid distributor is used for uniformly mixing the carrier fluid fed from the carrier fluid inlet with the effluent of the first catalyst bed layer and then feeding the mixture into the second catalyst bed layer.
Benzene is mixed withHydrogen peroxide (provided in the form of 30 wt% of hydrogen peroxide) serving as an oxidant and methanol serving as a solvent are mixed to form a reaction raw material, ammonia water (with the concentration of 25 wt%) is added into the reaction raw material, the pH value of the reaction raw material is adjusted to 6.8, and the reaction raw material is fed into a fixed bed reactor from the bottom and flows through a catalyst bed layer to be in contact reaction with a titanium silicalite molecular sieve. Wherein the molar ratio of benzene to hydrogen peroxide is 1: 1, the molar ratio of benzene to methanol is 1: 16. the temperature in the reactor is 30 ℃, the pressure in the fixed bed reactor is controlled to be 0.5MPa in the reaction process, and the weight hourly space velocity of the benzene is 5h-1。
The reaction mixture output from the reactor is subjected to flash evaporation and separated into a gas stream and a liquid stream. Wherein the gas stream is cooled to condense benzene for recovery of benzene; and distilling the liquid material flow, respectively collecting methanol, water and phenol, and outputting the phenol. The recovered benzene and methanol are uniformly mixed and heated to 30 ℃ to be used as a carrier fluid to be sent between a first catalyst bed layer and a second catalyst bed layer, and the sending amount of the carrier fluid is v2/v1＝2，v1Is the superficial velocity, v, of the reactant stream in the first catalyst bed2Is the superficial velocity of the reactant stream in the second catalyst bed.
During the reaction, the composition of the reaction mixture output from the second fixed bed reactor was monitored by gas chromatography, and the benzene conversion, the effective utilization of the oxidant and the phenol selectivity were calculated, with the reaction results listed in table 1.
Example 2
Benzene was oxidized in the same manner as in example 1, except that titanium silicalite TS-1 was used, which was prepared in the following manner.
Tetrabutyl titanate is firstly dissolved in an alkali source template tetrapropyl ammonium hydroxide aqueous solution, then silica gel (purchased from Qingdao silica gel factory) is added to obtain a dispersion liquid, and in the dispersion liquid, a silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: 4: 12: 400, the silicon source is SiO2The titanium source is calculated as TiO2The alkali source template is counted as N. Sealing the dispersion in a beaker with a sealing film, and standing at room temperature (25 deg.C or below)Same) was allowed to stand for 24h, followed by stirring for 2h at 35 ℃ using magnetic stirring to redisperse. Transferring the re-dispersed dispersion liquid into a sealed reaction kettle, carrying out first-stage crystallization for 6h at 140 ℃, then cooling the mixture to 30 ℃, carrying out second-stage retention for 2h, continuing to carry out third-stage crystallization for 12h at 170 ℃ in the sealed reaction kettle (wherein the heating rate from room temperature to the first-stage crystallization temperature is 2 ℃/min, the cooling rate from the first-stage crystallization temperature to the second-stage treatment temperature is 5 ℃/min, and the heating rate from the second-stage treatment temperature to the third-stage crystallization temperature is 10 ℃/min), taking out the obtained crystallized product, directly drying for 2h at 110 ℃, and then roasting for 3h at 550 ℃ to obtain the molecular sieve. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite TS-1 prepared in example 1, which shows that the obtained titanium silicalite TS-1 with an MFI structure; fourier transform infrared spectrogram at 960cm-1An absorption peak appears nearby, which indicates that titanium enters the molecular sieve framework, and in the titanium silicalite molecular sieve, the content of titanium oxide is 3.5 wt%, and the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.58 (in the titanium silicalite molecular sieve prepared in example 1, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 1.05). Mixing the prepared titanium silicalite TS-1 raw powder with silica sol, a pore-forming agent (alkylphenol ethoxylates) and starch, extruding the mixture by using an extruder, and then carrying out granulation, drying and roasting to prepare the titanium silicalite TS-1 catalyst with the particle size of 500 microns (wherein the mass percentage of the titanium silicalite is 85%).
The reaction results are listed in table 1.
Example 3
The benzene was reacted in the same manner as in example 2, except that the crystallization temperature in the third stage was also 140 ℃ in the preparation of the titanium silicalite TS-1. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite TS-1 prepared in example 1, which shows that the obtained TS-1 molecular sieve with MFI structure; in the Fourier transform infrared spectrum at 960cm-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 4.21, and the content of titanium oxide is 3.1 wt%. The reaction results are shown in the table1, listed in the table.
Example 4
Benzene was oxidized in the same manner as in example 2, except that the crystallization temperature in the first stage was 110 ℃ in the preparation of the titanium silicalite TS-1. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite TS-1 prepared in example 1, which shows that the obtained TS-1 molecular sieve with MFI structure; in the Fourier transform infrared spectrum at 960cm-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.37, and the content of titanium oxide is 3.2 wt%. The reaction results are listed in table 1.
Example 5
Benzene was oxidized in the same manner as in example 2, except that the first-stage crystallization time was 12 hours in the preparation of titanium silicalite TS-1. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite TS-1 prepared in example 1, which shows that the obtained TS-1 molecular sieve with MFI structure; in the Fourier transform infrared spectrum at 960cm-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 3.78, and the content of titanium oxide is 3.4 wt%. The reaction results are listed in table 1.
Example 6
Benzene was oxidized in the same manner as in example 2 except that in the second stage of the preparation of titanium silicalite TS-1, the temperature was reduced to 70 ℃ and the reaction was allowed to stand for 2 hours. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite TS-1 prepared in example 1, which shows that the obtained TS-1 molecular sieve with MFI structure; in the Fourier transform infrared spectrum at 960cm-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.75, and the content of titanium oxide is 3.1 wt%. The reaction results are listed in table 1.
Example 7
Benzene was oxidized in the same manner as in example 2, except that the aqueous dispersion was not allowed to stand at room temperature for 24 hours, but was directly fed into a reaction vessel for crystallization. XRD crystal phase diagram of the obtained sample and step (1) of example 1The prepared titanium silicalite TS-1 is consistent, which shows that the obtained titanium silicalite TS-1 with MFI structure; fourier transform infrared spectrogram at 960cm-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve, the content of titanium oxide is 3.5 percent by weight, and the surface silicon-titanium ratio/bulk silicon-titanium ratio is 1.18. The reaction results are listed in table 1.
Example 8
Benzene was oxidized in the same manner as in example 1, except that the titanium silicalite TS-1 was modified in the following manner before being used as a catalyst.
Mixing the titanium silicalite TS-1 prepared in the step (1) with HNO3(HNO3The mass concentration of the titanium dioxide is 10%) and hydrogen peroxide (the mass concentration of the hydrogen peroxide is 7.5%) are mixed, the obtained mixture is stirred and reacted for 5 hours in a closed container at 70 ℃, the temperature of the obtained reaction mixture is reduced to room temperature and then filtered, and the obtained solid-phase substance is dried to constant weight at 120 ℃ to obtain the modified titanium-silicon molecular sieve. Wherein, the titanium silicalite TS-1 is SiO2The molar ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 0.1. compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230 and 310nm in the UV-Vis spectrum of the obtained modified titanium silicalite molecular sieve is reduced by 3.5 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 2.6 percent. The reaction results are listed in table 1.
Example 9
Benzene was oxidized in the same manner as in example 8, except that in the modification treatment, as a raw material, a regenerated titanium silicalite TS-1 discharged from the cyclohexanone ammoximation reaction apparatus was used (the titanium silicalite TS-1 was prepared in the same manner as in example 1, the discharged titanium silicalite TS-1 was regenerated by calcining at a temperature of 570 ℃ for 5 hours in an air atmosphere, the activity after regeneration was 35%, and the activity when fresh was 96%). Compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230 and 310nm in the UV-Vis spectrum of the obtained modified titanium silicalite molecular sieve is reduced by 3.3 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 2.8 percent. The reaction results are listed in table 1.
Example 10
Benzene was oxidized in the same manner as in example 9 except that the regenerated titanium silicalite TS-1 discharged from the cyclohexanone ammoximation reaction apparatus as a raw material in example 9 was used as a catalyst. The reaction results are listed in table 1.
Comparative example 1
Benzene was oxidized in the same manner as in example 1 except that no carrier fluid was introduced between the first catalyst bed and the second catalyst bed. The reaction results are listed in table 1.
TABLE 1
Figure BDA0000905742870000261
Figure BDA0000905742870000271
Example 11
The catalyst used in this example was a hollow TS-1 titanium silicalite molecular sieve available from the north-Hunan Jian petrochemical Co., Ltd under the designation HTS, having a titanium oxide content of 2.5 wt.%.
Filling a catalyst in an equal-diameter fixed bed reactor with a length-diameter ratio of 15 to form catalyst bed layers, wherein the number of the catalyst bed layers is 2, and the 2 catalyst bed layers are arranged in parallel at a distance of 15 cm; the weight ratio of the filling amount of the first catalyst bed layer to the second catalyst bed layer is 2: 1, 500g and 250g respectively. And a carrier fluid inlet and a liquid distributor are arranged between the two catalyst bed layers, and the liquid distributor is used for uniformly mixing the carrier fluid fed from the carrier fluid inlet with the effluent of the first catalyst bed layer and then feeding the mixture into the second catalyst bed layer.
Benzene, hydrogen peroxide (supplied as 40 wt% hydrogen peroxide) as an oxidant and acetone as a solvent were mixed to form a reaction raw material, ammonia water (concentration: 30 wt%) was added to the reaction raw material, the pH of the reaction raw material was adjusted to 7.0, and the reaction raw material was fed from the bottom to a fixed bed to reactThe catalyst flows through the catalyst bed layer in the reactor to contact and react with the titanium silicalite molecular sieve. Wherein the molar ratio of benzene to hydrogen peroxide is 1: 0.5, the molar ratio of benzene to acetone is 1: 6. the temperature in the reactor is 35 ℃, the pressure in the fixed bed reactor is controlled to be 1.5MPa in the reaction process, and the weight hourly space velocity of the benzene is 4.5h-1。
The reaction mixture output from the reactor is subjected to flash evaporation and separated into a gas stream and a liquid stream. Condensing the benzene in the gas stream by reducing the temperature to recover the benzene; and distilling the liquid stream, respectively collecting water, acetone and phenol, and outputting the phenol. The recovered benzene and acetone are mixed uniformly and then directly (at 25 ℃) used as a carrier fluid to be sent between a first catalyst bed layer and a second catalyst bed layer, and the sending amount of the carrier fluid enables v2/v1＝5，v1Is the superficial velocity, v, of the reactant stream in the first catalyst bed2Is the superficial velocity of the reactant stream in the second catalyst bed.
During the reaction, the composition of the reaction mixture output from the second fixed bed reactor was monitored by gas chromatography, and the benzene conversion, the effective utilization of the oxidant and the phenol selectivity were calculated, with the reaction results listed in table 2.
Example 12
Benzene was oxidized by the same method as in example 11 except that the titanium silicalite TS-1 prepared by the method of example 1 was packed in the second catalyst bed under the same loading of the first and second catalyst beds as in example 11. The reaction results are listed in table 2.
Example 13
Benzene was oxidized by the same method as in example 11 except that the hollow TS-1 titanium silicalite molecular sieve was modified by the following method before being used as a catalyst under the condition that the loading of the first catalyst bed and the second catalyst bed were both kept constant; and the second catalyst bed was packed with the modified titanium silicalite TS-1 prepared in example 8.
Mixing hollow TS-1 titanium-silicon molecular sieve with HNO3(HNO3The mass concentration of the titanium dioxide is 10%) and hydrogen peroxide (the mass concentration of the hydrogen peroxide is 5%) are mixed, the obtained mixture is stirred and reacts for 4 hours in a closed container at the temperature of 120 ℃ under the self pressure, the temperature of the obtained reaction mixture is reduced to room temperature and then is filtered, and the obtained solid-phase substance is dried to constant weight at the temperature of 120 ℃ to obtain the modified titanium-silicon molecular sieve. Wherein the hollow titanium-silicon molecular sieve is made of SiO2The molar ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 0.4. compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230 and 310nm in the UV-Vis spectrum of the obtained modified titanium silicalite molecular sieve is reduced by 4.6 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 3.8 percent. The reaction results are listed in table 2.
TABLE 2
Figure BDA0000905742870000291
Example 14
The titanium silicalite TS-1 used in this example was prepared as follows.
Tetrabutyl titanate is firstly dissolved in an alkali source template tetrapropyl ammonium hydroxide aqueous solution, then silica gel (purchased from Qingdao silica gel factory) is added to obtain a dispersion liquid, and in the dispersion liquid, a silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: 2: 10: 600 silicon source of SiO2The titanium source is calculated as TiO2The alkali source template is counted as N. The dispersion was sealed with a sealing film in a beaker, and then allowed to stand at 40 ℃ for 10 hours, followed by stirring at 25 ℃ for 0.5 hour with magnetic stirring to redisperse the dispersion. Transferring the re-dispersed dispersion liquid into a sealed reaction kettle, performing first-stage crystallization for 8h at 130 ℃, then cooling the mixture to 50 ℃, performing second-stage retention for 5h, continuously performing third-stage crystallization for 16h at 170 ℃ in the sealed reaction kettle (wherein the heating rate from room temperature to the first-stage crystallization temperature is 1 ℃/min, the cooling rate from the first-stage crystallization temperature to the second-stage treatment temperature is 10 ℃/min, and the heating rate from the second-stage treatment temperature to the third-stage crystallization temperature is 20 ℃/min), and obtaining a crystallized productTaking out, directly drying at 120 ℃ for 3h without filtering and washing steps, and then roasting at 580 ℃ for 2h to obtain the molecular sieve. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite TS-1 prepared in example 1, which shows that the obtained titanium silicalite TS-1 with an MFI structure; fourier transform infrared spectrogram at 960cm-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.25, and the content of titanium oxide is 2.6 wt%. Mixing the prepared titanium silicalite TS-1 raw powder with silica sol, a pore-forming agent (alkylphenol ethoxylates) and starch, extruding the mixture by using an extruder, and then carrying out granulation, drying and roasting to prepare the titanium silicalite TS-1 catalyst with the particle size of 500 microns (wherein the mass percentage of the titanium silicalite is 85%).
Filling a catalyst in an equal-diameter fixed bed reactor with a length-diameter ratio of 50 to form catalyst bed layers, wherein the number of the catalyst bed layers is 2, and the 2 catalyst bed layers are arranged in parallel at a distance of 50 cm; the first catalyst bed layer is filled with a hollow titanium silicalite molecular sieve (same as the example 11), the second catalyst bed layer is filled with the titanium silicalite molecular sieve TS-1 prepared in the example, and the weight ratio of the filling amount of the first catalyst bed layer to the filling amount of the second catalyst bed layer is 8: 1, 800g and 100g respectively. And a carrier fluid inlet and a liquid distributor are arranged between the two catalyst bed layers, and the liquid distributor is used for uniformly mixing the carrier fluid fed from the carrier fluid inlet with the effluent of the first catalyst bed layer and then feeding the mixture into the second catalyst bed layer.
Benzene, tert-butyl hydroperoxide as an oxidant and acetonitrile as a solvent are mixed to form a reaction raw material, ammonia water (the concentration is 40 weight percent) is added into the reaction raw material, the pH value of the reaction raw material is adjusted to 6.9, and the reaction raw material is sent into a fixed bed reactor from the bottom and flows through a catalyst bed layer to be in contact reaction with a titanium silicalite molecular sieve. Wherein the molar ratio of benzene to tert-butyl hydroperoxide is 1: 1, the molar ratio of benzene to acetonitrile is 1: 8. the temperature in the reactor is 50 ℃, the pressure in the fixed bed reactor is controlled to be 2.0MPa in the reaction process, and the weight hourly space velocity of the benzene is 20h-1。
The reaction mixture output from the reactor is subjected to flash evaporation and separated into a gas stream and a liquid stream. Wherein the gas stream is cooled to condense benzene for recovery of benzene; and distilling the liquid stream, collecting acetonitrile and phenol respectively, and outputting the phenol. The recovered benzene and acetonitrile are uniformly mixed and heated to 50 ℃ to be used as a carrier fluid to be sent between a first catalyst bed layer and a second catalyst bed layer, and the sending amount of the carrier fluid is v2/v1＝3.5，v1Is the superficial velocity, v, of the reactant stream in the first catalyst bed2Is the superficial velocity of the reactant stream in the second catalyst bed.
During the reaction, the composition of the reaction mixture output from the second fixed bed reactor was monitored by gas chromatography and the benzene conversion, the effective utilization of the oxidant and the phenol selectivity were calculated, with the reaction results listed in table 3.
Example 15
Benzene was oxidized by the same method as in example 14, except that the first catalyst bed and the second catalyst bed were filled with regenerated titanium silicalite TS-1 discharged from the propylene epoxidation reaction apparatus (the titanium silicalite TS-1 was prepared by the same method as in example 14, the discharged titanium silicalite was regenerated by calcining at 580 ℃ for 3 hours in the air atmosphere, the activity after regeneration was 40%, and the activity when fresh was 95%). The reaction results are listed in table 3.
Example 16
Benzene was oxidized in the same manner as in example 15, except that the regenerated titanium silicalite TS-1 was modified in the following manner before being used as a catalyst.
With a catalyst containing HNO3(HNO315% by mass) and hydrogen peroxide (8% by mass), stirring the obtained mixture in a closed container at 150 ℃ for reaction for 3 hours, cooling the obtained reaction mixture to room temperature, filtering, and drying the obtained solid-phase substance at 120 ℃ to constant weight to obtain the modified titanium-silicon molecular sieve. Wherein, the titanium silicalite TS-1 is SiO2Titanium silicalite molecular sieves andthe molar ratio of hydrogen peroxide is 1: 2. compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230 and 310nm in the UV-Vis spectrum of the obtained modified titanium silicalite molecular sieve is reduced by 5.3 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 4.8 percent. The reaction results are listed in table 3.
Example 17
The titanium silicalite TS-1 used in this example was prepared as follows.
Tetrabutyl titanate is firstly dissolved in an alkali source template tetrapropyl ammonium hydroxide aqueous solution, then silica gel (purchased from Qingdao silica gel factory) is added to obtain a dispersion liquid, and in the dispersion liquid, a silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: 5: 18: 1000, silicon source is SiO2The titanium source is calculated as TiO2The alkali source template is counted as N. Sealing the dispersion liquid in a beaker by using a sealing film, and standing for 8 hours at 45 ℃; transferring the standing dispersion liquid into a sealed reaction kettle, carrying out first-stage crystallization for 6h at 140 ℃, then cooling the mixture to 40 ℃, carrying out second-stage retention for 1h, continuing to carry out third-stage crystallization for 12h at 160 ℃ in the sealed reaction kettle (wherein the heating rate from room temperature to the first-stage crystallization temperature is 5 ℃/min, the cooling rate from the first-stage crystallization temperature to the second-stage treatment temperature is 5 ℃/min, and the heating rate from the second-stage treatment temperature to the third-stage crystallization temperature is 5 ℃/min), taking out the obtained crystallized product, directly drying for 2h at 110 ℃, and then roasting for 3h at 550 ℃ to obtain the molecular sieve. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite TS-1 prepared in example 1, which shows that the obtained titanium silicalite TS-1 with an MFI structure; fourier transform infrared spectrogram at 960cm-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.71, and the content of titanium oxide is 4.3 wt%. Mixing the prepared titanium silicalite TS-1 raw powder with silica sol, a pore-forming agent (alkylphenol ethoxylates) and starch, extruding the mixture by using a strip extruder, and then carrying out particle cutting, drying and roasting to prepare the titanium silicalite TS-1 catalyst with the particle size of 500 microns (wherein the titanium silicalite TS-1 catalyst is prepared85% by mass).
Filling a catalyst in an equal-diameter fixed bed reactor with the length-diameter ratio of 5 to form catalyst bed layers, wherein the number of the catalyst bed layers is 2, and the 2 catalyst bed layers are arranged in parallel at a distance of 5 cm; the first catalyst bed layer is filled with a hollow titanium silicalite molecular sieve (same as the example 11), the second catalyst bed layer is filled with the titanium silicalite molecular sieve TS-1 prepared in the example 17, and the filling amount weight ratio of the first catalyst bed layer to the second catalyst bed layer is 4: 1, 800g and 200g respectively. And a carrier fluid inlet and a liquid distributor are arranged between the two catalyst bed layers, and the liquid distributor is used for uniformly mixing the carrier fluid fed from the carrier fluid inlet with the effluent of the first catalyst bed layer and then feeding the mixture into the second catalyst bed layer.
Benzene, cumene hydroperoxide as an oxidant and acetonitrile as a solvent are mixed to form a reaction raw material, ammonia water (the concentration is 25 weight percent) is added into the reaction raw material, the pH value of the reaction raw material is adjusted to 6.8, and the reaction raw material is sent into a fixed bed reactor from the bottom and flows through a catalyst bed layer to be in contact reaction with a titanium silicalite molecular sieve. Wherein the molar ratio of benzene to cumene hydroperoxide is 1: 1, the molar ratio of benzene to acetonitrile is 1: 6. the temperature in the reactor is 60 ℃, the pressure in the fixed bed reactor is controlled to be 1.8MPa in the reaction process, and the weight hourly space velocity of the benzene is 1.5h-1。
The reaction mixture output from the reactor is subjected to flash evaporation and separated into a gas stream and a liquid stream. Wherein the gas stream is cooled to condense benzene for recovery of benzene; and distilling the liquid stream, collecting acetonitrile and phenol respectively, and outputting the phenol. The recovered benzene and acetonitrile are uniformly mixed and heated to 60 ℃ to be used as a carrier fluid to be sent between a first catalyst bed layer and a second catalyst bed layer, and the sending amount of the carrier fluid is v2/v1＝4，v1Is the superficial velocity, v, of the reactant stream in the first catalyst bed2Is the superficial velocity of the reactant stream in the second catalyst bed.
During the reaction, the composition of the reaction mixture output from the second fixed bed reactor was monitored by gas chromatography and the benzene conversion, the effective utilization of the oxidant and the phenol selectivity were calculated, with the reaction results listed in table 3.
TABLE 3
Figure BDA0000905742870000331
Figure BDA0000905742870000341
Example 18
The same titanium silicalite TS-1 catalyst as in example 1 is adopted, and the catalyst is filled in an equal-diameter fixed bed reactor with the length-diameter ratio of 25 to form catalyst bed layers, wherein the number of the catalyst bed layers is 4, the 4 catalyst bed layers are arranged in parallel at equal intervals, and the interval is 10 cm; the mass of the catalyst filled in the four catalyst bed layers is the same and is respectively 200 g. And a carrier fluid inlet and a liquid distributor are respectively arranged among the first catalyst bed layer, the second catalyst bed layer, the third catalyst bed layer and the fourth catalyst bed layer, and the liquid distributor is used for uniformly mixing the carrier fluid fed from the carrier fluid inlet with the effluent of the first catalyst bed layer or the third catalyst bed layer and then feeding the mixture into the second catalyst bed layer or the fourth catalyst bed layer.
Benzene, hydrogen peroxide (provided in the form of 30 wt% hydrogen peroxide) as an oxidant and methanol as a solvent are mixed to form a reaction raw material, and the reaction raw material is fed into a fixed bed reactor from the bottom and flows through a catalyst bed layer to contact and react with a titanium silicalite molecular sieve. Wherein the molar ratio of benzene to hydrogen peroxide is 1: 1, the molar ratio of benzene to methanol is 1: 16. the temperature in the reactor is 30 ℃, the pressure in the fixed bed reactor is controlled to be 0.5MPa in the reaction process, and the weight hourly space velocity of the benzene is 5h-1。
The reaction mixture output from the reactor is subjected to flash evaporation and separated into a gas stream and a liquid stream. Wherein the gas stream is cooled to condense benzene for recovery of benzene; and distilling the liquid material flow, respectively collecting methanol, water and phenol, and outputting the phenol. The recovered benzene and methanol are mixed evenly and heated toFeeding the carrier fluid at 30 ℃ into the space between the first catalyst bed layer and the second catalyst bed layer and between the third catalyst bed layer and the fourth catalyst bed layer, wherein the feeding amount of the carrier fluid is such that v2/v1＝2，v4/v3＝2，v1Is the superficial velocity, v, of the reactant stream in the first catalyst bed2Is the superficial velocity, v, of the reactant stream in the second catalyst bed3Is the superficial velocity, v, of the reactant stream in the third catalyst bed4Is the superficial velocity of the reactant stream in the fourth catalyst bed.
During the reaction, the composition of the reaction mixture output from the fourth fixed bed reactor was monitored by gas chromatography, and the benzene conversion, the effective utilization of the oxidant and the phenol selectivity were calculated, with the reaction results listed in table 4.
Example 19
Benzene was oxidized in the same manner as in example 18 except that the first catalyst bed was packed with the hollow titanium silicalite as in example 11 and the second to fourth catalyst beds were packed with the titanium silicalite TS-1 prepared in example 14 under the condition that the packing amount of the four catalyst beds was kept constant. The reaction results are listed in table 4.
TABLE 4
Figure BDA0000905742870000351
Example 20
Toluene was oxidized in the same manner as in example 18. The reaction results are listed in table 5.
TABLE 5
Figure BDA0000905742870000352
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims (70)

1. A process for the oxidation of aromatic hydrocarbons, which process comprises passing a reaction feed comprising at least one aromatic hydrocarbon, an oxidant and optionally at least one solvent under oxidation reaction conditions through a 1 st catalyst bed to a final n th catalyst bed in sequence, n being an integer greater than 2, each of said catalyst beds being packed with at least one titanium silicalite, characterised in that during the passage of the reaction feed through the 1 st to the n th catalyst beds, a carrier fluid is introduced between at least one pair of adjacent catalyst beds between the 1 st to the n th catalyst beds such that, in the at least one pair of adjacent catalyst beds, the superficial velocity of the reactant stream in a downstream catalyst bed is higher than the superficial velocity of the reactant stream in an upstream catalyst bed, based on the direction of flow of the reaction feed; in the pair of adjacent catalyst beds, the superficial velocity of the reactant stream in the downstream catalyst bed is denoted by vmThe superficial velocity of the reactant stream in the upstream catalyst bed is denoted by vm-1The carrier fluid is introduced in an amount vm/vm-11.5-15; the carrier fluid is at least one selected from the group consisting of an inert gas, an effluent of the catalyst bed and the solvent; the titanium silicalite molecular sieve is at least partially modified, the modified titanium silicalite molecular sieve is subjected to modification treatment, and the modification treatment comprises the step of contacting the titanium silicalite molecular sieve serving as a raw material with a modification liquid containing nitric acid and peroxide。
2. The method of claim 1, wherein the carrier fluid is introduced in an amount such that vm/vm-1Is 2-10.
3. The method of claim 2, wherein the carrier fluid is introduced in an amount such that vm/vm-1Is 2-5.
4. The method of claim 1, wherein the effluent of the catalyst bed is an effluent from at least one of the 1 st to nth catalyst beds.
5. The method of claim 4, wherein the carrier fluid is the effluent of the nth catalyst bed.
6. The method of claim 4, wherein the carrier fluid is a stream remaining after separation of the target aromatic oxide from the effluent of the nth catalyst bed.
7. The method of claim 1, wherein the molar ratio of the titanium silicalite molecular sieve as the raw material to the peroxide in the modification treatment is 1: (0.01-5), the molar ratio of the peroxide to the nitric acid is 1: (0.01-50), wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.
8. The method of claim 7, wherein the molar ratio of the titanium silicalite molecular sieve as the raw material to the peroxide in the modification treatment is 1: (0.05-3).
9. The method of claim 8, wherein the molar ratio of the titanium silicalite molecular sieve as the raw material to the peroxide in the modification treatment is 1: (0.1-2).
10. A process according to any one of claims 7 to 9, wherein the molar ratio of peroxide to nitric acid is from 1: (0.1-20).
11. The process of claim 10, wherein the molar ratio of peroxide to nitric acid is 1: (0.2-10).
12. The process of claim 11, wherein the molar ratio of peroxide to nitric acid is 1: (0.5-5).
13. The process of claim 12, wherein the molar ratio of peroxide to nitric acid is 1: (0.6-3.5).
14. The method according to claim 1, wherein the concentrations of the peroxide and the nitric acid in the modification liquid are each 0.1 to 50% by weight.
15. The method according to claim 14, wherein the concentrations of the peroxide and the nitric acid in the modification liquid are each 0.5 to 25% by weight.
16. The method according to claim 15, wherein the concentrations of the peroxide and the nitric acid in the modification liquid are each 5 to 15% by weight.
17. The method of claim 1, wherein in the modification treatment, the titanium silicalite molecular sieves serving as the raw materials are contacted with the modification liquid at a temperature of 10-350 ℃, the contact is carried out in a container with a pressure of 0-5MPa, the pressure is gauge pressure, and the contact duration is 1-10 hours.
18. The method of claim 17, wherein in the modification treatment, the titanium silicalite molecular sieves serving as the raw material are contacted with the modification solution at a temperature of 20-300 ℃.
19. The method of claim 18, wherein in the modification treatment, the titanium silicalite molecular sieves serving as the raw material are contacted with the modification solution at a temperature of 50-250 ℃.
20. The method of claim 19, wherein in the modification treatment, the titanium silicalite molecular sieves serving as the raw material are contacted with the modification solution at a temperature of 60-200 ℃.
21. The method of any one of claims 17 to 20, wherein the duration of the contacting is 3 to 5 hours.
22. The method according to claim 1, wherein the peroxide is at least one selected from the group consisting of hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, ethylbenzene hydroperoxide, cyclohexyl hydroperoxide, peracetic acid and peroxopropionic acid.
23. The method as claimed in claim 1, wherein, in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification liquid to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by more than 2% in the ultraviolet-visible spectrum based on the titanium silicalite molecular sieve as the raw material; the pore volume of the modified titanium-silicon molecular sieve is reduced by more than 1%, and the pore volume is determined by adopting a static nitrogen adsorption method.
24. The method as claimed in claim 23, wherein in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification liquid to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by 2-30% in the uv-vis spectrum based on the titanium silicalite molecular sieve as the raw material.
25. The method as claimed in claim 24, wherein in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification liquid to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by 2.5-15% in the uv-vis spectrum based on the titanium silicalite molecular sieve as the raw material.
26. The method as claimed in claim 25, wherein in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification liquid to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by 3-10% in the uv-vis spectrum based on the titanium silicalite molecular sieve as the raw material.
27. The method as claimed in claim 26, wherein in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification liquid to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by 3-6% in the uv-vis spectrum based on the titanium silicalite molecular sieve as the raw material.
28. The method of any one of claims 23 to 27, wherein the modified titanium silicalite molecular sieve has a pore volume that is reduced by 1 to 20 percent, as measured by static nitrogen adsorption.
29. The process of claim 28, wherein the modified titanium silicalite molecular sieve has a pore volume reduction of 1.5 to 10%, as measured by static nitrogen adsorption.
30. The process of claim 29, wherein the modified titanium silicalite molecular sieve has a pore volume reduction of 2 to 5%, as measured by static nitrogen adsorption.
31. The process of claim 1, wherein the titanium silicalite molecular sieves are derived at least in part from a recycled reactor discharge agent selected from the group consisting of a recycled ammoximation reactor discharge agent and/or a recycled epoxidation reactor discharge agent.
32. The method of claim 1, wherein the titanium silicalite molecular sieve is at least partially a titanium silicalite TS-1, the titanium silicalite TS-1 has a surface silicon-to-titanium ratio not lower than a bulk silicon-to-titanium ratio, the silicon-to-titanium ratio is a molar ratio of silicon oxide to titanium oxide, the surface silicon-to-titanium ratio is determined by X-ray photoelectron spectroscopy, and the bulk silicon-to-titanium ratio is determined by X-ray fluorescence spectroscopy.
33. A method as claimed in claim 32 wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.2 or greater.
34. The method of claim 33, wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.2-5.
35. The method of claim 34, wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.5-4.5.
36. The method of any one of claims 32 to 35, wherein the titanium silicalite TS-1 is prepared by a method comprising:
(A) dispersing an inorganic silicon source in an aqueous solution containing a titanium source and an alkali source template agent, and optionally supplementing water to obtain a dispersion liquid, wherein the ratio of the silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: (0.5-8): (5-30): (100-2000), the inorganic silicon source is SiO2The titanium source is calculated as TiO2The alkali source template agent is calculated by OH < - > or N;
(B) standing the dispersion liquid obtained in the step (A) at 15-60 ℃ for 6-24 hours;
(C) and (3) sequentially carrying out stage (1), stage (2) and stage (3) crystallization on the dispersion liquid obtained in the step (A) or the dispersion liquid obtained in the step (B) in a sealed reaction kettle, wherein the stage (1) is crystallized for 6-72 hours at the temperature of 80-150 ℃, the stage (2) is cooled to the temperature of not higher than 70 ℃ and the retention time is at least 0.5 hour, and the stage (3) is heated to the temperature of 120-phase and 200 ℃ and then crystallized for 6-96 hours.
37. The method as claimed in claim 36, wherein in step (C), the crystallization temperature of the stage (1) is 110-140 ℃.
38. The method as claimed in claim 37, wherein in step (C), the crystallization temperature of the stage (1) is 120-140 ℃.
39. The method as claimed in claim 38, wherein in step (C), the crystallization temperature of the stage (1) is 130-140 ℃.
40. A process as claimed in any one of claims 36 to 39, wherein in step (C), the crystallization time of stage (1) is from 6 to 8 hours.
41. The process of claim 36, wherein in step (C), the residence time of stage (2) is 1-5 hours.
42. The method as claimed in claim 36, wherein in step (C), the temperature of the stage (3) is raised to 140-180 ℃.
43. The method as claimed in claim 42, wherein in step (C), the temperature of the stage (3) is raised to 160-170 ℃.
44. The process of claim 36, 42 or 43, wherein in step (C), the stage (3) recrystallizes for 12-20 hours.
45. The method of claim 36, wherein the phase (1) and the phase (3) satisfy one or both of the following conditions:
the condition 1 is: the crystallization temperature of the stage (1) is lower than the crystallization temperature of the stage (3);
the condition 2 is: the crystallization time of the stage (1) is less than the crystallization time of the stage (3).
46. The method of claim 45, wherein Condition 1 is: the crystallization temperature of the stage (1) is 10-50 ℃ lower than that of the stage (3).
47. The method of claim 46, wherein Condition 1 is: the crystallization temperature of the stage (1) is 20-40 ℃ lower than that of the stage (3).
48. The method according to any one of claims 45 to 47, wherein Condition 2 is: the crystallization time of stage (1) is 5-24 hours shorter than the crystallization time of stage (3).
49. The method of claim 48, wherein Condition 2 is: the crystallization time of stage (1) is 6-12 hours shorter than the crystallization time of stage (3).
50. The process according to claim 36, wherein the temperature of stage (2) is reduced to not more than 50 ℃ and the residence time is at least 1 hour.
51. The method of claim 36, wherein the titanium source is an inorganic titanium salt selected from TiCl and/or an organic titanate4、Ti(SO4)2And TiOCl2At least one of the organic titanates of the general formula R7 4TiO4A compound of formula (I), R7Is an alkyl group having 2 to 4 carbon atoms; the alkali source template agent is at least one selected from quaternary ammonium hydroxide, aliphatic amine and aliphatic alcohol amine; the inorganic silicon source is silica gel and/or silica sol.
52. The method of claim 51, wherein the alkali-source templating agent is a quaternary ammonium base.
53. The method of claim 52, wherein the base source templating agent is tetrapropylammonium hydroxide.
54. The method of claim 1, wherein the titanium silicalite molecular sieve packed in the 1 st catalyst bed layer is a hollow titanium silicalite molecular sieve TS-1, and the titanium silicalite molecular sieves packed in the 2 nd to nth catalyst bed layers are non-hollow titanium silicalite molecular sieve TS-1.
55. The method according to claim 1, wherein the mass of the catalyst packed in the downstream catalyst bed in any one pair of adjacent catalyst beds from the 1 st catalyst bed to the last n catalyst bed is represented by WmThe mass of catalyst packed in the upstream catalyst bed is denoted by Wm-1，Wm-1/WmIs 0.1-20, m is [2, n ]]Any integer within the interval.
56. The method of claim 55, wherein W ism-1/WmIs 2-8.
57. The process of claim 1, wherein the molar ratio of the aromatic hydrocarbon to the oxidant is (0.1-20): 1.
58. the process of claim 57, wherein the molar ratio of the aromatic hydrocarbon to the oxidant is (0.2-10): 1.
59. the process of claim 58, wherein the molar ratio of the aromatic hydrocarbon to the oxidant is (1-5): 1.
60. the method according to claim 1, wherein the oxidizing agent is at least one selected from the group consisting of hydrogen peroxide, t-butyl hydroperoxide, ethylbenzene hydroperoxide, cumene hydroperoxide, cyclohexyl hydroperoxide, peroxyacetic acid and peroxypropionic acid.
61. The method according to claim 1, wherein the solvent is at least one selected from the group consisting of water, C1-C10 alcohols, C3-C10 ketones, C2-C10 nitriles, and C1-C6 carboxylic acids.
62. The process of claim 61, wherein said solvent is at least one selected from the group consisting of C1-C6 alcohols, C3-C8 ketones, and C2-C5 nitriles.
63. The method according to claim 62, wherein the solvent is at least one selected from the group consisting of methanol, ethanol, acetonitrile, n-propanol, isopropanol, tert-butanol, isobutanol, and acetone.
64. The method of claim 63, wherein the solvent is at least one selected from methanol, acetonitrile, acetone, and tert-butanol.
65. The process of claim 1, further comprising feeding at least one alkaline material to the reaction feed in an amount such that the reaction feed has a pH in the range of 6 to 9.
66. The method according to claim 1, wherein the aromatic hydrocarbon is at least one selected from the group consisting of benzene, toluene, xylene, ethylbenzene, and cumene.
67. The method of claim 1, wherein the oxidation reaction conditions comprise: the temperature is 0-120 ℃; the pressure is 0-3MP, and the pressure is gauge pressure.
68. The method of claim 67, wherein the temperature of the oxidation reaction is 20-80 ℃.
69. The method of claim 68, wherein the temperature of the oxidation reaction is 30-60 ℃.
70. A process as claimed in any one of claims 67 to 69, in which the oxidation reaction is at a pressure in the range 0.1 to 2.5MPa, and the pressure is gauge pressure.
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CN101039893A (en) * 2004-11-12 2007-09-19 波利玛利欧洲股份公司 Continuous process for the preparation of phenol from benzene in a fixed bed reactor
CN104291352A (en) * 2014-09-30 2015-01-21 浙江大学 Method for preparing and modifying titanium silicalite molecular sieve catalyst and application of titanium silicalite molecular sieve catalyst in ketone oximation
CN104944441A (en) * 2014-03-31 2015-09-30 中国石油化工股份有限公司 Method for synthesizing titanium-silicon molecular sieve

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