CN108250161B - Process for the oxidation of allyl alcohol - Google Patents

Process for the oxidation of allyl alcohol Download PDF

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CN108250161B
CN108250161B CN201611235883.XA CN201611235883A CN108250161B CN 108250161 B CN108250161 B CN 108250161B CN 201611235883 A CN201611235883 A CN 201611235883A CN 108250161 B CN108250161 B CN 108250161B
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molecular sieve
titanium silicalite
silicalite molecular
titanium
catalyst bed
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CN108250161A (en
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史春风
林民
朱斌
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/02—Synthesis of the oxirane ring
    • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
    • 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
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/02—Synthesis of the oxirane ring
    • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
    • C07D301/12—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with hydrogen peroxide or inorganic peroxides or peracids
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/02—Synthesis of the oxirane ring
    • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
    • C07D301/14—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with organic peracids, or salts, anhydrides or esters thereof
    • C07D301/16—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with organic peracids, or salts, anhydrides or esters thereof formed in situ, e.g. from carboxylic acids and hydrogen peroxide
    • 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
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/14—After treatment, characterised by the effect to be obtained to alter the inside of the molecular sieve channels

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  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Catalysts (AREA)

Abstract

The invention relates to an allyl alcohol oxidation method, which comprises the following steps: under the condition of oxidation reaction, enabling reaction feed containing allyl alcohol, 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, wherein each catalyst bed layer is filled with at least one titanium silicalite molecular sieve, at least part of the titanium silicalite molecular sieve is a modified titanium silicalite molecular sieve, the modified titanium silicalite molecular sieve is a titanium silicalite molecular sieve 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. The method can prolong the one-way service life of the catalyst, and can stabilize the conversion rate of raw materials, the effective utilization rate of the oxidant and the selectivity of target oxidation products at higher levels even if the catalyst is continuously operated for a long period.

Description

Process for the oxidation of allyl alcohol
Technical Field
The invention relates to an allyl alcohol oxidation method.
Background
Epoxypropanol is also called glycidol, is an important fine chemical raw material, can be used as a stabilizer of natural oil and vinyl polymer, a demulsifier and a dyeing layering agent, can also be used for synthesizing intermediates of glycerol and glycidyl ether (amine and the like), and is widely used in the fields of chemical synthesis, medicines, fine chemical industry and the like.
The industrial production of the epoxypropanol mainly comprises two methods, namely a glycerol chlorohydrin method and an alcohol propylene method. The glycerol chlorohydrin method is prepared by reacting chloropropanediol in the presence of alkali, and has harsh reaction conditions and difficult subsequent separation. The allyl alcohol process generally employs epoxidation of hydrogen peroxide or peracetic acid with allyl alcohol to produce epoxypropanol. When peracetic acid is used as an epoxidizing agent, the reaction speed is high, glycidol acetate is easily generated by the reaction of epoxy propanol in a product and acetic acid, so that the distillation and separation are difficult, and the mixture of epoxy propanol and acetic acid can generate a strong exothermic reaction at room temperature to cause explosion, so that the method is difficult to apply industrially. In addition, hexavalent tungstate can be used as a catalyst to perform epoxidation reaction on allyl alcohol and an oxidant (such as hypochlorous acid or perchloric acid) to prepare epoxypropanol, but the process has great environmental pollution, and the catalyst used has low activity and is not reproducible.
Therefore, the exploration of a novel method for catalyzing and oxidizing the allyl alcohol, which has the advantages of high conversion rate of the allyl alcohol, good selectivity of the epoxypropanol, small pollution, environmental friendliness and simplicity, has very important practical significance.
Disclosure of Invention
The present invention has an object to provide a process for the oxidation of allyl alcohol, 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-cycle continuous operation.
In order to achieve the above object, the present invention provides an allyl alcohol oxidation method comprising: under the condition of oxidation reaction, enabling reaction feed containing allyl alcohol, 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, wherein n is an integer more than 2, and each catalyst bed layer is filled with at least one titanium silicalite molecular sieve; the titanium silicalite molecular sieve is at least partially a modified titanium silicalite molecular sieve, 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.
Preferably, the method further comprises introducing a second stream between at least one pair of adjacent catalyst beds from 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, based on the direction of flow of the reaction feed, 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 in which the superficial velocity of the reactant stream in the downstream catalyst bed is expressed as vmThe superficial velocity of the reactant stream in the upstream catalyst bed is denoted by vm-1Said second stream is introduced in an amount such that vm/vm-11.5-15, preferably such that vm/vm-12 to 10, more preferably such that vm/vm-1＝2-5。
Preferably, the second stream is at least one selected from the group consisting of an inactive gas, the effluent of the catalyst bed and the solvent; the effluent of the catalyst bed layer is effluent flowing out of at least one catalyst bed layer from the 1 st catalyst bed layer to the n catalyst bed layer;
preferably, the second stream is the effluent of the nth catalyst bed;
more preferably, the second stream is a stream remaining after separation of the target product from the effluent of the nth catalyst bed.
Preferably, in the modification treatment, the molar ratio of the titanium silicalite molecular sieve as the raw material to the peroxide is 1: (0.01-5), preferably 1: (0.05-3), more preferably 1: (0.1-2), the molar ratio of the peroxide to the nitric acid is 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), wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.
Preferably, the concentrations of the peroxide and the nitric acid in the modification liquid are each 0.1 to 50% by weight, preferably 0.5 to 25% by weight, and more preferably 5 to 15% by weight.
Preferably, in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification solution at a temperature of 10-350 ℃, preferably 20-300 ℃, more preferably 50-250 ℃, and even more preferably 60-200 ℃, the contact is carried out in a container with a pressure of 0-5MPa, the pressure is gauge pressure, and the duration of the contact is 1-10 hours, preferably 3-5 hours.
Preferably, the peroxide 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.
Preferably, in the modification treatment, the contact degree between the titanium silicalite molecular sieve as the raw material and the modification liquid is such that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm in the ultraviolet-visible spectrum is reduced by more than 2%, preferably by 2-30%, more preferably by 2.5-15%, further preferably by 3-10%, and still further preferably by 3-6% based on the titanium silicalite molecular sieve as the raw material; the pore volume of the modified titanium silicalite molecular sieve is reduced by more than 1%, preferably reduced by 1-20%, more preferably reduced by 1.5-10%, and further preferably reduced by 2-5%, and the pore volume is determined by a static nitrogen adsorption method.
Preferably, the titanium silicalite molecular sieve as the raw material is at least partially derived from a discharging agent of a regenerated reaction device, and the discharging agent of the regenerated reaction device is at least one selected from the group consisting of a discharging agent of a regenerated ammoximation reaction device, a discharging agent of a regenerated hydroxylation reaction device and a discharging agent of a regenerated epoxidation reaction device.
Preferably, the surface silicon-titanium ratio of the titanium-silicon molecular sieve is not lower than the bulk silicon-titanium ratio, 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;
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-titanium ratio to the bulk silicon-titanium ratio is 1.2-5;
further preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.5-4.5.
Preferably, the preparation step of the titanium silicalite molecular sieve comprises:
(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 inorganic 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 TiO2Counting as N when the alkali source template contains nitrogen elements, and counting as OH < - > when the alkali source template does not contain nitrogen elements;
(B) standing the dispersion liquid obtained in the step (A) at 15-60 ℃ for 6-24 hours;
(C) the dispersion obtained in the step (A) or the dispersion obtained in the step (B) is subjected to crystallization in a sealed reaction kettle in the order of stage (1), stage (2) and stage (3), the crystallization in the stage (1) is carried out at 80-150 ℃, preferably at 110-.
Preferably, the phases (1) and (3) satisfy one or both of the following conditions:
condition 1: the crystallization temperature of the stage (1) is lower than the crystallization temperature of the stage (3), preferably the crystallization temperature of the stage (1) is 10-50 ℃ lower than the crystallization temperature of the stage (3), more preferably 20-40 ℃ lower;
condition 2: the crystallization time of stage (1) is less than the crystallization time of stage (3), preferably the crystallization time of stage (1) is 5-24 hours, more preferably 6-12 hours shorter than the crystallization time of stage (3).
Preferably, 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 base, aliphatic amine and aliphatic alcohol amine, preferably quaternary ammonium base, and more preferably tetrapropyl ammonium hydroxide; the inorganic silicon source is silica gel and/or silica sol.
Preferably, the titanium silicalite molecular sieve filled in the 1 st catalyst bed layer is a modified hollow titanium silicalite molecular sieve, and the titanium silicalite molecular sieve filled in the 2 nd to the nth catalyst bed layers is a modified non-hollow titanium silicalite molecular sieve.
Preferably, the mass of the catalyst filled in the catalyst bed positioned at the downstream in any one pair of adjacent catalyst beds from the 1 st catalyst bed to the last n catalyst bed is represented as WmThe mass of catalyst packed in the upstream catalyst bed is denoted by Wm-1，Wm-1/WmIs 0.1 to 20, preferably 2 to 8, m is [2, n ]]Any integer within the interval.
Preferably, the oxidizing agent is at least one selected from the group consisting of hydrogen peroxide, t-butyl hydroperoxide, ethylbenzene hydroperoxide, cumene hydroperoxide, cyclohexyl hydroperoxide, peracetic acid and peroxopropionic acid, and the molar ratio of the allyl alcohol to the oxidizing agent is (0.1 to 20): 1, preferably (0.2-10): 1, more preferably (1-5): 1.
preferably, the solvent is at least one selected from the group consisting of water, C1-C6 alcohols, C3-C8 ketones, and C2-C6 nitriles; preferably, the solvent is at least one selected from the group consisting of water, methanol, ethanol, n-propanol, isopropanol, tert-butanol, isobutanol, acetone, butanone, and acetonitrile; further preferably, the solvent is water and/or methanol.
Preferably, the oxidation reaction conditions include: the temperature is 0-120 ℃, preferably 20-80 ℃, and more preferably 30-60 ℃; the pressure is 0-3MP, preferably 0.1-2.5MPa, and the pressure is gauge pressure.
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 disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. 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 allyl alcohol oxidation method, which comprises the following steps: under the condition of oxidation reaction, enabling reaction feed containing allyl alcohol, 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, wherein n is an integer more than 2, and each catalyst bed layer is filled with at least one titanium silicalite molecular sieve; the titanium silicalite molecular sieve is at least partially a modified titanium silicalite molecular sieve. The modified titanium silicalite molecular sieve is subjected to modification treatment. The modification treatment comprises mixing a titanium silicalite molecular sieve as a raw material with a solution containing nitric acid (i.e., HNO)3) And contacting with peroxide modifying liquid. 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. In the present invention, "at least one" means one or two or more; "optional" means optional and is to be understood as "with or without" and "including or not including". n isAn integer between 2 and 50, preferably an integer selected from between 2 and 20, more preferably an integer selected from between 2 and 10, even more preferably an integer selected from between 2 and 5, such as 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 allyl alcohol 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 material may also change as it flows through the different catalyst beds due to various factors (e.g., as a result of reactions occurring or the introduction of new material, such as the second stream), such that the reactant material flowing through the different catalyst beds will generally also be different (e.g., in terms of its composition or properties). 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 second stream 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) refers to the mass flow rate (in kg/s) of the reaction mass in the whole course of the passage of a catalyst bed per unit time and a certain 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 1Degree 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 second stream 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 stream 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-1Said second stream is introduced in an amount such that 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 hereinafter) or internals (e.g., fluid distributors, catalyst bed support members, heat exchangers, etc.) and the like may be provided as desired, thereby providing more flexibility in regulating the allyl alcohol 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 according to the present invention, the 1 st to nth catalyst beds are preferably fixed beds from the viewpoint of facilitating the implementation of the allyl alcohol oxidation reaction of the present invention.
According to the method of the present invention, all the titanium silicalite molecular sieves may be subjected to the modification treatment (i.e., the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves), or a part of the titanium silicalite molecular sieves may be subjected to the 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. Herein, if "modified titanium silicalite" is not specified, it is regarded as unmodified titanium silicalite by default.
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 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 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 (i.e. discharged titanium silicalite molecular sieves) are regenerated and then contacted with allyl alcohol 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 part of the titanium silicalite is preferably the discharging agent of the regenerated reaction device (except the allyl alcohol 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 titanium silicalite molecular sieve as the raw material is at least partially derived from the discharging agent of the regenerated reaction device, and the discharging agent of the regenerated reaction device is at least one selected from the group consisting of the discharging agent of the regenerated ammoximation reaction device, the discharging agent of the regenerated hydroxylation reaction device and the discharging agent of the regenerated epoxidation reaction device. Therefore, the single-pass service life of the catalyst can be further prolonged, and the selectivity of the epoxypropanol and the conversion rate of the allyl alcohol can be obviously improved.
According to the method of the invention, the titanium silicalite is a generic term for a class of zeolites in which a part of the silicon atoms in the lattice framework is 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 silicon isThe sub-sieve may be selected from a titanium silicalite molecular sieve of MFI structure (e.g., TS-1), a titanium silicalite molecular sieve of MEL structure (e.g., TS-2), a titanium silicalite molecular sieve of BEA structure (e.g., Ti-Beta), a titanium silicalite molecular sieve of MWW structure (e.g., Ti-MCM-22), a titanium silicalite molecular sieve of MOR structure (e.g., Ti-MOR), a titanium silicalite molecular sieve of TUN structure (e.g., Ti-TUN), a titanium silicalite molecular sieve of two-dimensional hexagonal structure (e.g., Ti-MCM-41, Ti-SBA-15), a titanium silicalite molecular sieve of other structure (e.g., Ti-ZSM-48), and the like. 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, the surface silicon-titanium ratio of the titanium-silicon molecular sieve is not lower than the bulk silicon-titanium ratio, so that the effective utilization rate of the oxidant can be further improved, and the one-way service life of the titanium-silicon 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 of the present invention, the step of preparing the titanium silicalite molecular sieve may comprise:
(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 inorganic 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 more than two of quaternary ammonium base, aliphatic amine and aliphatic alcohol amine. 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 BDA0001195290560000141
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, specific examples of which may include, but are not limited to, 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, an inorganic 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, the 1 st to the nth catalyst beds are respectively filled with at least one titanium silicalite molecular sieve and at least partially with modified titanium silicalite molecular sieves. 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 modified hollow titanium silicalite molecular sieve, and the titanium silicalite molecular sieve filled in the 2 nd to the nth catalyst bed layers is a modified non-hollow titanium silicalite molecular sieve. This can further retard the deactivation rate of the titanium silicalite molecular sieve. More preferably, the titanium silicalite molecular sieve filled in the 1 st catalyst bed layer is a modified hollow titanium silicalite molecular sieve TS-1, and the titanium silicalite molecular sieve filled in the 2 nd to nth catalyst bed layers is a modified non-hollow titanium silicalite molecular sieve 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, unless "hollow titanium silicalite" is specified, it is assumed that the titanium silicalite is not hollow.
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-1The mass of catalyst filled in the upstream catalyst bed layer of any one pair of adjacent catalyst bed layers from the 1 st catalyst bed layer to the n-th catalyst bed layermThe 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 allyl alcohol (fed as the reaction)Component) can be 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 the oxidation reaction of allyl alcohol, 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 is specified) comprises allyl alcohol, an oxidizing agent and optionally at least one solvent.
The oxidizing agent may be any of various commonly used substances capable of oxidizing allyl alcohol. 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 used may be selected according to the amount of allyl alcohol comprised by the reaction feed. Generally, in the reaction feed, the molar ratio of the allyl alcohol to the oxidant may be (0.1-20): 1. from the viewpoint of further improving the selectivity of the product, the molar ratio of the allyl alcohol 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. In the present invention, the kind of the solvent is not particularly limited, and the solvent may be any of various solvents commonly used in the oxidation reaction of allyl alcohol. Preferably, the solvent is at least one of water, C1-C6 alcohol, C3-C8 ketone and C2-C6 nitrile. Preferably, the solvent is at least one of C1-C6 alcohol, C3-C8 ketone and C2-C5 nitrile. More preferably, the solvent is at least one of water, methanol, ethanol, n-propanol, isopropanol, tert-butanol, isobutanol, acetone, butanone, and acetonitrile. Further preferably, the solvent is methanol and/or water.
The amount of the solvent used in the present invention is not particularly limited, and may be selected depending on the amounts of the allyl alcohol and the oxidizing agent. Generally, the molar ratio of the solvent to the allyl alcohol in the reaction feed may be (0.1-100): 1, preferably (0.2-80): 1.
when the conditions of the oxidation reaction are sufficient to oxidize allyl alcohol to epoxypropanol 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 epoxypropanol. 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 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 of the invention, a reaction discharge containing epoxypropanol is obtained through the allyl alcohol oxidation reaction carried out in the 1 st to nth catalyst beds. 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 glycidol from the reaction discharge, obtaining an off-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.
According to the process of the present invention, by introducing the second stream 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 reaction mass flowing through all of the catalyst beds downstream of the separation, the superficial velocity of each reaction mass can be correspondingly increased to meet the aforementioned specification of the present invention. For example, where n is 2, by introducing the second stream into the separation between the 1 st and 2 nd catalyst beds, the overall throughput of the reactant passing 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 invention.
The present invention is not particularly limited as to the amount and manner of introduction of the second stream, 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 specifications of the present invention.
According to the method of the present invention, the second stream 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 can be used as the second stream without separation, or can be used as the second stream after the epoxypropanol is separated out. According to the process of the present invention, the second stream is more preferably the stream remaining after separation of the target product 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 second stream. If desired, the second stream may be pretreated by heat exchange (e.g., temperature reduction) or pressure application prior to introduction to 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 allyl alcohol, the effective utilization of the oxidizing agent, and the selectivity of epoxypropanol were calculated by the following formulas, respectively:
allyl alcohol conversion (%) × 100 [ (% by mole of allyl alcohol added-mole of unreacted allyl alcohol)/mole of allyl alcohol added ];
the effective utilization rate of the oxidant is ═ 100% of the molar amount of epoxypropanol produced by the reaction/(molar amount of the oxidant added-molar amount of the unreacted oxidant) ×;
the glycidol selectivity is ═ 100% by mole [ molar amount of glycidol produced by the reaction/(molar amount of allyl alcohol added-molar amount of unreacted allyl alcohol) ].
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, and the sample is put into a mortar and ground to the required value<300 meshes, tabletting and sampling.
Examples 1-12 are intended to illustrate the process of the invention.
Example 1
The catalyst used in this example was modified titanium silicalite TS-1, and the titanium silicalite TS-1 was prepared as described in Zeolite, 1992, Vol.12, page 943-950 by the following specific methods: 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 the prepared titanium silicalite TS-1 with HNO3(HNO3At a mass concentration of 10%) and hydrogen peroxide (mass of hydrogen peroxide)7.5%) of the aqueous solution, stirring the obtained mixture in a closed container at 70 ℃ for 5 hours to react, 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 silicalite 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, the molar ratio of hydrogen peroxide to nitric acid is 1: 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. Mixing the obtained modified 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 modified titanium silicalite TS-1 catalyst with the particle size of 500 microns (wherein the mass percentage of the modified 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 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.
Allyl alcohol, hydrogen 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, 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 the modified titanium silicalite molecular sieve. Wherein the mol ratio of the allyl alcohol to the hydrogen peroxide is 1: 1, the mol ratio of allyl alcohol 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 allyl alcohol 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. The liquid stream was distilled and the epoxypropanol was collected.
During the reaction, the composition of the reaction mixture output from the fixed bed reactor was monitored by gas chromatography, and the allyl alcohol conversion rate, the effective utilization rate of the oxidant, and the selectivity of epoxypropanol were calculated, and the reaction results are shown in table 1.
Example 2
The catalyst used in this example was a modified titanium silicalite TS-1, and the titanium silicalite TS-1 before modification was prepared by the following method.
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. The dispersion was sealed with a sealing film in a beaker, and then allowed to stand at room temperature (25 ℃ C., the same applies hereinafter) for 24 hours, followed by stirring at 35 ℃ for 2 hours with magnetic stirring to redisperse the dispersion. 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 with HNO3(HNO3At a mass concentration of 10%) and peroxyMixing aqueous solutions of hydrogen peroxide (the mass concentration of hydrogen peroxide is 7.5%), stirring and reacting the obtained mixture in a closed container at 70 ℃ for 5 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 silicalite 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, the molar ratio of hydrogen peroxide to nitric acid is 1: 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 3.8 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 2.3 percent. Mixing the obtained modified 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 modified titanium silicalite TS-1 catalyst with the particle size of 500 microns (wherein the mass percentage of the modified 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 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.
Allyl alcohol, hydrogen 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, 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 the modified titanium silicalite molecular sieve. Wherein the mol ratio of the allyl alcohol to the hydrogen peroxide is 1: 1, the mol ratio of allyl alcohol 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 allyl alcohol 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. The liquid stream was distilled and the epoxypropanol was collected.
During the reaction, the composition of the reaction mixture output from the fixed bed reactor was monitored by gas chromatography, and the allyl alcohol conversion rate, the effective utilization rate of the oxidant, and the selectivity of epoxypropanol were calculated, and the reaction results are shown in table 1.
Example 3
Allyl alcohol was oxidized in the same manner as in example 2, except that the crystallization temperature in the third stage was also 140 ℃ 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 4.21, and the content of titanium oxide is 3.1 wt%. The titanium silicalite TS-1 is modified according to the same method as in example 1, compared with the raw material titanium silicalite, the peak area of the absorption peak between 230-310nm in the UV-Vis spectrum of the obtained modified titanium silicalite is reduced by 4.3%, and the pore volume determined by the static nitrogen adsorption method is reduced by 4.1%. The reaction results are listed in table 1.
Example 4
Allyl alcohol 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 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 titanium silicalite TS-1 is modified according to the same method as in example 1, compared with the raw material titanium silicalite, the peak area of the absorption peak between 230-310nm in the UV-Vis spectrum of the obtained modified titanium silicalite is reduced by 4.6%, and the pore volume determined by the static nitrogen adsorption method is reduced by 2.8%. The reaction results are listed in table 1.
Example 5
Allyl alcohol was oxidized in the same manner as in example 2, except thatWhen the titanium silicalite TS-1 is used, the temperature is reduced to 70 ℃ and the temperature is kept for 2 hours in the second stage. 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 titanium silicalite TS-1 is modified according to the same method as in example 1, compared with the raw material titanium silicalite, the peak area of the absorption peak between 230-310nm in the UV-Vis spectrum of the obtained modified titanium silicalite is reduced by 3.2%, and the pore volume determined by the static nitrogen adsorption method is reduced by 2.5%. The reaction results are listed in table 1.
Example 6
Allyl alcohol 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. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite TS-1 prepared in the step (1) of the 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 content of titanium oxide is 3.5 percent by weight, and the surface silicon-titanium ratio/bulk silicon-titanium ratio is 1.18. The titanium silicalite TS-1 is modified according to the same method as in example 1, compared with the raw material titanium silicalite, the peak area of the absorption peak between 230-310nm in the UV-Vis spectrum of the obtained modified titanium silicalite is reduced by 3.9%, and the pore volume determined by the static nitrogen adsorption method is reduced by 3.6%. The reaction results are listed in table 1.
Example 7
Allyl alcohol was oxidized in the same manner as in example 1, except that in the modification treatment, the regenerated titanium silicalite TS-1 discharged from the cyclohexanone ammoximation reaction apparatus was used as the raw material (the titanium silicalite TS-1 was prepared in the same manner as in example 1, the discharged titanium silicalite TS-1 was calcined at 570 ℃ for 5 hours in the air atmosphere to regenerate it, the activity after regeneration was 35%, and the activity in 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.
Comparative example 1
The allyl alcohol is oxidized by adopting the same method as the example 1, except that the titanium silicalite TS-1 is not subjected to modification treatment, but the prepared titanium silicalite TS-1 raw powder is directly mixed with silica sol, a pore-forming agent (alkylphenol ethoxylates) and starch, a strip extruder is used for extruding strips, and then the titanium silicalite TS-1 catalyst with the particle size of 500 microns is prepared by pelletizing, drying and roasting (wherein the mass percentage content of the titanium silicalite is 85%). The reaction results are listed in table 1.
TABLE 1
Figure BDA0001195290560000301
Example 8
Allyl alcohol was oxidized in the same manner as in example 2, except that a second stream inlet and a liquid distributor were provided between the two catalyst beds, the liquid distributor being used to uniformly mix the second stream fed from the second stream inlet with the effluent of the first catalyst bed and then feed the mixture into the second catalyst bed. And carrying out flash separation on the reaction mixture output from the reactor, respectively collecting allyl alcohol, methanol, water and epoxy propanol, and outputting the epoxy propanol. The recovered allyl alcohol and methanol are mixed uniformly and heated to 30 ℃ as a second stream which is fed between the first catalyst bed and the second catalyst bed in such an amount that v is2/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. The reaction results are listed in table 2.
Example 9
The molecular sieve employed in this example was a hollow TS-1 titanium silicalite molecular sieve purchased from the north-Hunan Jian Ming Dynasty corporation under the designation HTS, and having a titanium oxide content of 2.5 wt.%. The hollow TS-1 titanium silicalite molecular sieve is modified according to the same method as that in the example 2, compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230-310nm in the UV-Vis spectrum of the obtained modified hollow TS-1 titanium silicalite molecular sieve is reduced by 4.3%, and the pore volume measured by a static nitrogen adsorption method is reduced by 3.7%. Mixing the obtained modified hollow TS-1 titanium silicalite molecular sieve 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 modified hollow TS-1 titanium silicalite molecular sieve catalyst with the particle size of 500 microns (wherein the mass percentage content of the modified titanium silicalite molecular sieve is 85%).
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 10 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 second stream inlet and a liquid distributor are arranged between the two catalyst bed layers, and the liquid distributor is used for uniformly mixing the second stream fed from the second stream inlet with the effluent of the first catalyst bed layer and then feeding the mixture into the second catalyst bed layer.
Allyl alcohol, hydrogen peroxide (provided in the form of 40 wt% of hydrogen peroxide) serving as an oxidant and acetone serving as a solvent are mixed to form a reaction raw material, ammonia water (with the concentration of 30 wt%) is added into the reaction raw material, the pH value of the reaction raw material is adjusted to 7.0, 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 modified titanium silicalite molecular sieve. Wherein the mol ratio of the allyl alcohol to the hydrogen peroxide is 1: 5, the mol ratio of allyl alcohol 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 allyl alcohol is 4.5h-1。
Flash separating the reaction mixture from the reactor, collecting allyl alcohol, water, acetone and epoxy propanol, and transferring epoxy propanolAnd (6) discharging. The recovered allyl alcohol and acetone are mixed uniformly and then directly (at 25 ℃) used as a second stream to be fed between the first catalyst bed layer and the second catalyst bed layer, and the feeding amount of the second stream is enabled to be 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 fixed bed reactor was monitored by gas chromatography, and the allyl alcohol conversion rate, the effective utilization rate of the oxidant, and the selectivity of epoxypropanol were calculated, and the reaction results are shown in table 2.
Example 10
Allyl alcohol was oxidized by the same method as in example 9, except that the hollow TS-1 titanium silicalite molecular sieve was modified by the following method under the condition that the loading of the first catalyst bed and the second catalyst bed were both kept unchanged; and the second catalyst bed is filled with the modified titanium silicalite TS-1 catalyst prepared in example 2.
Mixing hollow TS-1 titanium-silicon molecular sieve with HNO3(HNO3The mass concentration of the titanium dioxide solution 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 hollow TS-1 titanium silicalite molecular sieve. Wherein, the hollow TS-1 titanium silicalite molecular sieve is made of SiO2The molar ratio of the hollow TS-1 titanium silicalite molecular sieve to the hydrogen peroxide is 1: 0.4, the molar ratio of hydrogen peroxide to nitric acid is 1: 2.5. compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230-310nm in the UV-Vis spectrum of the obtained modified hollow TS-1 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 BDA0001195290560000321
Figure BDA0001195290560000331
Example 11
The titanium silicalite TS-1 used before modification in this example was prepared by the following method.
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, carrying out first-stage crystallization for 8h at 130 ℃, then cooling the mixture to 50 ℃, carrying out second-stage retention for 5h, continuing to carry out 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), taking out the obtained crystallized product, 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 with HNO3(HNO3At a mass concentration of 15%) and hydrogen peroxide (mass of hydrogen peroxide)8%) and 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 silicalite molecular sieve. Wherein, the titanium silicalite TS-1 is SiO2The molar ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 3, the molar ratio of hydrogen peroxide to nitric acid is 1: 3.5. 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. Mixing the obtained modified 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 content 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 the modified hollow TS-1 titanium silicalite molecular sieve catalyst (same as the example 9), the second catalyst bed layer is filled with the modified titanium silicalite molecular sieve TS-1 catalyst 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 9: 1, 900g and 100g respectively. And a second stream inlet and a liquid distributor are arranged between the two catalyst bed layers, and the liquid distributor is used for uniformly mixing the second stream fed from the second stream inlet with the effluent of the first catalyst bed layer and then feeding the mixture into the second catalyst bed layer.
Allyl alcohol, 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 modified titanium silicalite molecular sieve. Wherein the mol ratio of the allyl alcohol to the tert-butyl hydroperoxide is 1:0.5, the molar ratio of allyl alcohol to acetonitrile is 1: 100. 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 allyl alcohol is 20h-1。
And carrying out flash separation on the reaction mixture output from the reactor, respectively collecting acetonitrile, allyl alcohol and epoxy propanol, and outputting the epoxy propanol. The recovered allyl alcohol and acetonitrile are mixed uniformly and heated to 50 ℃ as a second stream which is fed between the first catalyst bed and the second catalyst bed in such an amount that v is2/v1＝8，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 fixed bed reactor was monitored by gas chromatography, and the allyl alcohol conversion, the effective utilization of the oxidant and the selectivity to epoxypropanol were calculated, and the reaction results are listed in table 3.
Example 12
The titanium silicalite TS-1 used before modification in this example was prepared by the following method.
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: 8: 30: 1800 Si source of 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, performing first-stage crystallization for 6h at 110 ℃, then cooling the mixture to 50 ℃, performing second-stage residence for 1h, continuously performing third-stage crystallization for 12h at 140 ℃ 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), and performing crystallization to obtain a productTaking out the product, directly drying the product at 110 ℃ for 2h without filtering and washing steps, and then roasting the product at 550 ℃ for 3h 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 with 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 SiO2The molar ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 5, the molar ratio of hydrogen peroxide to nitric acid is 1: 5. 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 3.8 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 4.1 percent. Mixing the obtained modified 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 content of the titanium silicalite is 85%).
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 modified hollow TS-1 titanium silicalite molecular sieve catalyst (same as the example 9), the second catalyst bed layer is filled with the modified 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 0.5: 1, 200g and 400g respectively. And a second stream inlet and a liquid distributor are arranged between the two catalyst bed layers, and the liquid distributor is used for uniformly mixing the second stream fed from the second stream inlet with the effluent of the first catalyst bed layer and then feeding the mixture into the second catalyst bed layer.
Allyl alcohol, cumene hydroperoxide as an oxidant and acetonitrile 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 modified titanium silicalite molecular sieve. Wherein the mol ratio of the allyl alcohol to the cumene hydroperoxide is 1: 15, the molar ratio of allyl alcohol to acetonitrile is 1: 0.1. 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 allyl alcohol is 1.5h-1。
And carrying out flash separation on the reaction mixture output from the reactor, respectively collecting acetonitrile, allyl alcohol and epoxy propanol, and outputting the epoxy propanol. The recovered allyl alcohol and acetonitrile are mixed uniformly and heated to 60 ℃ and fed between the first catalyst bed and the second catalyst bed as the second stream in such an amount that v is fed2/v1＝8，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 fixed bed reactor was monitored by gas chromatography, and the allyl alcohol conversion, the effective utilization of the oxidant and the selectivity to epoxypropanol were calculated, and the reaction results are listed in table 3.
TABLE 3
Figure BDA0001195290560000371
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 technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations 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 (63)

1. A process for the oxidation of allyl alcohol, the process comprising: under the condition of oxidation reaction, enabling reaction feed containing allyl alcohol, 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, wherein n is an integer more than 2, and each catalyst bed layer is filled with at least one titanium silicalite molecular sieve; at least part of the titanium silicalite molecular sieve is a modified titanium silicalite molecular sieve, 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;
introducing a second stream between at least one pair of adjacent catalyst beds from the 1 st catalyst bed to the n th catalyst bed during the reaction feed passes through the 1 st catalyst bed to the n th catalyst bed, so that the superficial velocity of the reactant stream in the downstream catalyst bed is higher than that in the upstream catalyst bed in the at least one pair of adjacent catalyst beds based on the flow direction of the reaction feed, and the superficial velocity of the reactant stream in the downstream catalyst bed in 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-1Said second stream is introduced in an amount such that vm/vm-1＝1.5-15；
In the modification treatment, the contact degree of the titanium silicalite molecular sieve as the raw material and the modification liquid is such 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 an ultraviolet-visible spectrum by taking the titanium silicalite molecular sieve as the raw material as a reference;
the pore volume of the modified titanium-silicon molecular sieve is reduced by 1-20%, and the pore volume is determined by adopting a static nitrogen adsorption method.
2. The method of claim 1, wherein the second stream is introduced in an amount such that vm/vm-1＝2-10。
3. The method of claim 2, wherein the second stream is introduced in an amount such that vm/vm-1＝2-5。
4. The method of claim 1, wherein the second stream is at least one selected from the group consisting of an inert gas, an effluent of a catalyst bed, and the solvent; the effluent of the catalyst bed is effluent flowing out of at least one catalyst bed from the 1 st catalyst bed to the n catalyst bed.
5. The method of claim 4, wherein the second stream is the effluent of the nth catalyst bed.
6. The process according to claim 5, wherein the second stream is a stream remaining after separating the target product from the effluent of the n-th 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 to the peroxide as the feedstock is 1: (0.05-3), wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.
9. The method of claim 8, wherein the molar ratio of the titanium silicalite molecular sieve to the peroxide as the feedstock is 1: (0.1-2), wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.
10. The process of claim 7, wherein the molar ratio of peroxide to nitric acid is 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 claim 17, wherein the duration of the contacting in the modification treatment is 3-5 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, ethylbenzene hydroperoxide, cumene hydroperoxide, cyclohexyl hydroperoxide, peroxyacetic acid and peroxypropionic 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 2-30% in the ultraviolet-visible spectrum based on the titanium silicalite molecular sieve as the raw material; the pore volume of the modified titanium silicalite molecular sieve is reduced by 1.5-10%, 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 2.5-15% 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 3-10% 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 3-6% in the uv-vis spectrum based on the titanium silicalite molecular sieve as the raw material.
27. The method of claim 23, wherein in the modification treatment, the titanium silicalite molecular sieve serving as the raw material is in contact with the modification solution to such an extent that the modified titanium silicalite molecular sieve has a pore volume, as measured by a static nitrogen adsorption method, reduced by 2 to 5% based on the titanium silicalite molecular sieve serving as the raw material.
28. The process of any one of claims 1 and 23 to 27, wherein the titanium silicalite molecular sieve as the feedstock is at least partially derived from a recycled reactor discharge agent, the recycled reactor discharge agent being at least one selected from the group consisting of a recycled ammoximation reactor discharge agent, a recycled hydroxylation reactor discharge agent, and a recycled epoxidation reactor discharge agent.
29. The process of claim 1, wherein the titanium silicalite molecular sieve has a surface silicon to titanium ratio not lower than a bulk silicon to titanium ratio, the silicon to titanium ratio being the molar ratio of silicon oxide to titanium oxide, the surface silicon to titanium ratio being determined by X-ray photoelectron spectroscopy, the bulk silicon to titanium ratio being determined by X-ray fluorescence spectroscopy.
30. A method as claimed in claim 29 wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.2 or greater.
31. The method of claim 30, wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.2-5.
32. The method of claim 31, wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.5-4.5.
33. The method of claim 29, wherein the step of preparing the titanium silicalite molecular sieve comprises:
(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 inorganic 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 as N when containing nitrogen element, and the alkali source template is counted as OH when not containing nitrogen element-Counting;
(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, the stage (3) is heated to the temperature of 120-phase and 200 ℃, and then the crystallization is carried out for 6-96 hours.
34. The method as claimed in claim 33, wherein the crystallization in stage (1) is at 110-140 ℃.
35. The method as claimed in claim 34, wherein the stage (1) is crystallized at 120-140 ℃.
36. The method as claimed in claim 35, wherein the stage (1) is crystallized at 130-140 ℃.
37. The process of claim 33, wherein stage (1) crystallizes for 6-8 hours.
38. The method of claim 33, wherein the temperature of stage (2) is reduced to no more than 50 ℃.
39. The process of claim 33, wherein the stage (2) residence time is from 1 to 5 hours.
40. The method as claimed in claim 33, wherein the temperature in stage (3) is raised to 140-180 ℃.
41. The method as claimed in claim 40, wherein the temperature in stage (3) is raised to 160-170 ℃.
42. The process of claim 33, wherein stage (3) crystallizes for 12-20 hours.
43. The method of any one of claims 33-42, wherein the stage (1) and the stage (3) satisfy one or both of the following conditions:
condition 1: the crystallization temperature of the stage (1) is lower than the crystallization temperature of the stage (3);
condition 2: the crystallization time of the stage (1) is less than the crystallization time of the stage (3).
44. The method of claim 43, wherein condition 1: the crystallization temperature of the stage (1) is 10-50 ℃ lower than that of the stage (3).
45. The method of claim 44, wherein condition 1: the crystallization temperature of the stage (1) is 20-40 ℃ lower than that of the stage (3).
46. The method of claim 43, wherein condition 2: the crystallization time of stage (1) is 5-24 hours shorter than the crystallization time of stage (3).
47. The method of claim 46, wherein condition 2: the crystallization time of stage (1) is 6-12 hours shorter than the crystallization time of stage (3).
48. The method of any one of claims 33 to 42, wherein the titanium source is an inorganic titanium salt selected from TiCl and/or an organic titanium ester4、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 base, aliphatic amine and aliphatic alcohol amine; the inorganic silicon source is silica gel and/or silica sol.
49. The method of claim 48, wherein the alkali-source templating agent is a quaternary ammonium base.
50. The method of claim 49, wherein the alkali-source templating agent is tetrapropylammonium hydroxide.
51. The method of claim 1, wherein the titanium silicalite molecular sieve packed in the 1 st catalyst bed layer is a modified hollow titanium silicalite molecular sieve, and the titanium silicalite molecular sieves packed in the 2 nd to nth catalyst bed layers are modified non-hollow titanium silicalite molecular sieves.
52. 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.
53. The method of claim 52, wherein Wm-1/WmIs 2-8.
54. The process of claim 1, wherein the oxidant is at least one selected from the group consisting of hydrogen peroxide, t-butyl hydroperoxide, ethylbenzene hydroperoxide, cumene hydroperoxide, cyclohexyl hydroperoxide, peracetic acid, and peroxopropionic acid, and the molar ratio of the allyl alcohol to the oxidant is (0.1-20): 1.
55. the process of claim 54, wherein the molar ratio of said allyl alcohol to said oxidizing agent is (0.2-10): 1.
56. the process of claim 55, wherein the molar ratio of said allyl alcohol to said oxidizing agent is (1-5): 1.
57. the method according to claim 1, wherein the solvent is at least one selected from the group consisting of water, C1-C6 alcohols, C3-C8 ketones, and C2-C6 nitriles.
58. The method according to claim 57, wherein the solvent is at least one selected from the group consisting of water, methanol, ethanol, n-propanol, isopropanol, tert-butanol, isobutanol, acetone, butanone, and acetonitrile.
59. The method of claim 58, wherein the solvent is water and/or methanol.
60. The method of claim 1, wherein the oxidation reaction conditions comprise: 0 to 120 ℃; the pressure is 0-3MPa, and the pressure is gauge pressure.
61. The method of claim 60, wherein the oxidation reaction conditions comprise: the temperature is 20-80 ℃.
62. The method of claim 61, wherein the oxidation reaction conditions comprise: the temperature is 30-60 ℃.
63. The method of claim 60, wherein the oxidation reaction conditions comprise: the pressure is 0.1-2.5 MPa.
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