CN112300046A - Purification method of tert-butyl hydroperoxide and recycling method of tert-butyl alcohol - Google Patents
Purification method of tert-butyl hydroperoxide and recycling method of tert-butyl alcohol Download PDFInfo
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Abstract
The invention also provides a recycling method of tert-butyl alcohol in the process of preparing propylene oxide by tert-butyl hydroperoxide oxidation, and the invention adopts an azeotropic distillation method to purify the tert-butyl hydroperoxide/tert-butyl alcohol mixed system containing water and other impurities. The tert-butyl alcohol which is a byproduct of the epoxidation reaction or the tert-butyl alcohol which is extracted from the top of the tert-butyl hydroperoxide/tert-butyl alcohol solution through azeotropic distillation and water removal tower and has high moisture content (for example, more than 500ppm) is subjected to water removal treatment through molecular sieve adsorption to obtain the tert-butyl alcohol with low moisture content (for example, less than 500ppm), and the tert-butyl alcohol can be circularly used for azeotropic distillation and water removal of the tert-butyl hydroperoxide/tert-butyl alcohol solution.
Description
Technical Field
The invention belongs to the technical field of tert-butyl alcohol and tert-butyl hydroperoxide, and particularly relates to a purification method of tert-butyl hydroperoxide and a recycling method of tert-butyl alcohol in a process of preparing propylene oxide from tert-butyl hydroperoxide by oxidizing propylene with tert-butyl hydroperoxide.
Background
The current methods for producing Propylene Oxide (PO) mainly include chlorohydrin method, ethylbenzene co-oxidation method, isobutane co-oxidation method, cumene peroxide method and direct oxidation method. The production of the propylene oxide by the isobutane co-oxidation method is to prepare tert-butyl hydroperoxide by the isobutane oxidation method, then prepare the propylene oxide by oxidizing propylene by the tert-butyl hydroperoxide, co-produce a byproduct methyl tert-butyl ether (MTBE) by a PO/MTBE method, and co-produce a byproduct tert-butyl alcohol (TBA) by a PO/TBA method. The oxidation of isobutane to prepare tert-butyl hydroperoxide is carried out by oxidizing oxygen and isobutane to obtain tert-butyl hydroperoxide and tert-butanol. After unreacted isobutane is separated out, the obtained tert-butyl hydroperoxide/tert-butanol solution is used as an oxidant for propylene epoxidation, and the specific reaction process is as follows:
however, in the production of t-butyl hydroperoxide by the isobutane oxidation method, a small amount of by-products such as water, acetone, methanol, isobutanol, and isobutyric acid are produced in addition to t-butanol, which is a main by-product. The tert-butyl hydroperoxide/tert-butyl alcohol solution is used as an oxidant and is subjected to epoxidation reaction with propylene under the catalysis of a catalyst to prepare propylene oxide, and water and acid impurities exist, so that the product propylene oxide can be promoted to generate side reactions such as ring opening decomposition and the like, and the selectivity of the epoxidation reaction is reduced. If the water content is higher, the catalyst can be separated out in the reaction system, so that the propylene epoxidation reaction can not be normally carried out, and the reaction conversion rate is greatly reduced.
Patent document US5104493 discloses that the concentration of tert-butyl hydroperoxide in the reaction liquid obtained by oxidizing isobutane is increased to 70% or more by means of high vacuum rectification under reduced pressure. The method has strict operation requirements, the vacuum degree and the tower temperature need to be controlled well in the operation process, otherwise, external air is easily introduced, a gas phase part enters an explosion interval, high safety risk exists, and the method has unobvious water and acid removal effects while concentrating the tert-butyl hydroperoxide.
Patent document US5093506 discloses the reduction of the acid number in a solution obtained by the rectification of a tert-butyl hydroperoxide/tert-butanol solution obtained by the oxidation of isobutane, followed by the addition of a certain amount of calcium oxide or calcium hydroxide. The calcium oxide and calcium hydroxide have poor solubility in the system, and the acid value can be effectively reduced only by heating and stirring for tens of hours, and the process can cause partial decomposition of the tert-butyl hydroperoxide. The method has unsatisfactory water and acid removing effects.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention also provides a method for purifying tert-butyl hydroperoxide, in particular a method for purifying a tert-butyl hydroperoxide/tert-butyl alcohol solution produced by oxidizing isobutane, wherein the tert-butyl hydroperoxide, in particular the tert-butyl hydroperoxide/tert-butyl alcohol solution, treated by the method can meet the requirements of the subsequent olefin epoxidation reaction process, and can ensure higher conversion rate of the olefin epoxidation reaction and better selectivity of the olefin epoxidation reaction. The method can remove acetone, methanol and other low-boiling-point impurities from the tert-butyl hydroperoxide, particularly tert-butyl hydroperoxide/tert-butyl alcohol solution, and simultaneously realize water removal and acid removal, and effectively avoid the explosion risks of the tert-butyl hydroperoxide in liquid phase and gas phase. The method has the characteristics of mild reaction conditions and simple equipment, and has good industrial application prospect.
The invention also provides a recycling method of tert-butyl alcohol in the process of preparing propylene oxide by tert-butyl hydroperoxide: subjecting the tert-butyl alcohol which is a byproduct of the epoxidation reaction to molecular sieve adsorption dehydration treatment to obtain the tert-butyl alcohol with low moisture content (for example, less than or equal to 500ppm), wherein the tert-butyl alcohol can be used as an entrainer for azeotropic distillation dehydration of tert-butyl hydroperoxide/tert-butyl alcohol solution produced by isobutanol oxidation; the tertiary butanol with high moisture content (for example, more than 500ppm) extracted from the top of the tertiary butyl hydroperoxide/tertiary butanol solution azeotropic distillation water removal tower is subjected to water removal treatment by molecular sieve adsorption to obtain the tertiary butanol with low moisture content (for example, less than or equal to 500ppm), and the tertiary butanol azeotropic distillation water removal method can be circularly used for azeotropic distillation water removal of the tertiary butyl hydroperoxide/tertiary butanol solution.
The purpose of the invention is realized by the following technical scheme:
a process for the purification of tert-butyl hydroperoxide, said process comprising the steps of:
(a) carrying out adsorption dehydration treatment on a mixed system containing tert-butyl alcohol by using a molecular sieve to obtain tert-butyl alcohol with the water content of less than or equal to 500 ppm;
(b) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, and rectifying in a rectifying tower;
(c) tertiary butyl alcohol, water and other impurities are extracted from the top of the rectifying tower, and a mixed system containing the tertiary butyl hydroperoxide and the tertiary butyl alcohol after concentration and purification is extracted from the tower bottom of the rectifying tower and is marked as a second mixed system.
In one embodiment of the present invention, in step (a), the content of impurity elements in the molecular sieve satisfies: the content of potassium is not higher than 1 wt%, the content of iron is not higher than 1 wt%, the content of sulfur is not higher than 0.5 wt%, and the content of nitrogen is not higher than 0.5 wt%.
In one embodiment of the present invention, in the step (a), the amount of the molecular sieve is 20 to 100 wt% based on the total mass of the mixed system containing t-butanol.
In one embodiment of the invention, in the step (a), the mixing system containing tert-butyl alcohol is tert-butyl alcohol obtained by oxidizing isobutane, which is obtained from the top of the azeotropic distillation water removal tower, tert-butyl alcohol obtained from the epoxidation reaction of propylene, or tert-butyl alcohol from other sources.
In one embodiment of the present invention, in step (a), the mixed system containing t-butanol may contain a small amount of t-butyl hydroperoxide, and the content of t-butyl hydroperoxide is not higher than 5 wt%.
In one embodiment of the present invention, in step (a), the mixed system containing t-butanol may contain small amounts of other impurities, such as acetone and methanol, wherein the content of acetone is 1.9 wt% or less and the content of methanol is 0.4 wt% or less.
In one embodiment of the present invention, in step (b), the first mixed system is derived from an isobutane oxidation reaction system, preferably a mixed system of tert-butyl hydroperoxide and tert-butyl alcohol derived from an isobutane oxidation reaction system and used for removing unreacted isobutane.
In one embodiment of the present invention, in the step (b), the first mixed system comprises the following components in parts by mass: the content of the tert-butyl hydroperoxide is less than or equal to 65 wt%; the content of tertiary butanol is more than or equal to 30 wt%; the content of water is less than or equal to 5 wt%; the acid value (calculated as acetic acid) is 0.4 to 1 wt.%.
In one embodiment of the present invention, in the step (b), the first mixed system further comprises impurities, the impurities comprise acetone and methanol, and the content of the impurities is 5 wt% or less.
In one embodiment of the present invention, in the step (b), the tertiary butanol having a moisture content of 500ppm or less is added in an amount of 10 to 50 wt% based on the total mass of the first mixed system.
In one scheme of the invention, in the step (b), the temperature of the bottom of the rectifying tower is 60-90 ℃, the temperature of the top of the rectifying tower is 25-50 ℃, the pressure of the top of the rectifying tower is 15-25kPa, and the reflux ratio of the top of the rectifying tower is 1-5: 1.
In one embodiment of the present invention, in the step (c), the impurities extracted from the top of the rectifying column are, for example, acetone and methanol, wherein the content of acetone is 1.9 wt% or less and the content of methanol is 0.4 wt% or less.
In one embodiment of the present invention, in the step (c), the content of the tert-butanol extracted from the top of the rectifying column is 90 wt% or more; the content of water extracted from the top of the rectifying tower is more than or equal to 0.1 wt%. Illustratively, the tertiary butanol content is 95 wt% or more and the water content is 0.6 wt% or more.
In one embodiment of the present invention, in step (c), the second mixed system comprises tert-butyl hydroperoxide, tert-butanol and water; wherein, the content of the tert-butyl hydroperoxide is 50 to 70 weight percent; the content of tertiary butanol is 30-50 wt%; the content of the water is 0.1-0.3 wt%.
In one embodiment of the present invention, in the step (c), the second mixed system further comprises acetone and methanol, wherein the content of acetone is 0.06 wt% or less, and the content of methanol is 0.1 wt% or less.
In one embodiment of the present invention, in step (c), the acid value (in terms of acetic acid) of the second mixed system is 0.4 to 1% by weight.
In one embodiment, the method specifically comprises the steps of:
(a) carrying out adsorption dehydration treatment on a mixed system containing tert-butyl alcohol by using a molecular sieve to obtain tert-butyl alcohol with the water content of less than or equal to 500 ppm;
(b) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system of tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, which is produced by oxidizing isobutane and is used for removing unreacted isobutane, and then feeding the mixture into a tert-butyl hydroperoxide concentration rectifying tower;
(c) tertiary butyl alcohol, water and impurities are extracted from the top of the rectifying tower, a purified mixed system containing tertiary butyl hydroperoxide and the tertiary butyl alcohol, namely a second mixed system, is extracted from the tower bottom of the rectifying tower, and the content of each substance in the second mixed system can meet the requirement of olefin epoxidation (such as propylene epoxidation), and cannot generate adverse effect on olefin epoxidation reaction.
The invention also provides a recycling method of tert-butyl alcohol in the process of preparing propylene oxide by tert-butyl hydroperoxide, which comprises the following steps:
(i) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, and rectifying in a rectifying tower;
(ii) collecting tert-butyl alcohol, water and other impurities at the top of the rectifying tower, and collecting a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol after concentration and purification at the tower bottom of the rectifying tower, and marking the mixed system as a second mixed system;
(iii) mixing the second mixed system, propylene and a catalyst to perform epoxidation reaction;
(iv) (iv) separating the mixed system after the reaction in the step (iii) to obtain a mixed system containing tert-butyl alcohol;
(v) and (3) carrying out molecular sieve adsorption dehydration treatment on the mixed system containing the tert-butyl alcohol in the step (iv) to obtain the tert-butyl alcohol with the moisture content of less than or equal to 500ppm, and circularly using the tert-butyl alcohol in the step (i).
In one aspect of the present invention, the method further comprises the steps of:
(vi) and (3) carrying out molecular sieve adsorption dewatering treatment on the mixed system containing the tert-butyl alcohol extracted from the tower top in the step (ii) to obtain the tert-butyl alcohol with the water content of less than or equal to 500ppm, and circularly using the tert-butyl alcohol in the step (i).
The invention has the beneficial effects that:
the invention provides a purification method of tert-butyl hydroperoxide. Compared with the prior art, the invention has the following advantages: the invention adopts an azeotropic distillation method to purify the tertiary butyl hydroperoxide/tertiary butanol mixed system containing water and other impurities. The invention adopts the molecular sieve to adsorb the tertiary butanol containing water and other impurities for water removal treatment, and has the characteristics of simple equipment, convenient operation, low cost and the like. After adsorption water removal, the obtained tert-butyl alcohol can be used for azeotropic distillation water removal of tert-butyl hydroperoxide/tert-butyl alcohol obtained by iso-butane oxidation. The azeotropic distillation has mild operation condition and high safety, and no additional component is introduced.
The invention also provides a recycling method of tert-butyl alcohol in the process of preparing propylene oxide by tert-butyl hydroperoxide and propylene oxide, which comprises the steps of carrying out adsorption water removal treatment on the tert-butyl alcohol which is a byproduct of epoxidation reaction or is extracted from the top of a tert-butyl hydroperoxide/tert-butyl alcohol solution azeotropic distillation water removal tower and has high moisture content (for example, more than 500ppm) to obtain the tert-butyl alcohol with low moisture content (for example, less than 500ppm), and recycling and sleeving the tert-butyl hydroperoxide/tert-butyl alcohol solution for azeotropic distillation water removal.
Drawings
FIG. 1 is a process flow diagram of the dehydration treatment of tertiary butanol by molecular sieve and the recycling of tertiary butanol according to a preferred embodiment of the present invention.
Reference numerals: 1. TBHP/TBA solution; 2. TBA/acetone/methanol/water; 3. TBHP/TBA; 4. a catalyst; 5. propylene; 6. TBA/PO/propylene; 7. PO/propylene; 8. TBA/heavies; 9. coarse TBA; 10. heavy components; 11. TBA; 12. a TBHP concentration tower; 13. a TBHP/TBA storage tank; 14. an epoxidation reaction system; 15. a TBA light component removal tower; 16. a TBA de-heavy tower; 17. TBA water removal tower (molecular sieve drying tower).
Detailed Description
< method for purifying t-butyl hydroperoxide >
As previously mentioned, the present invention provides a process for the purification of t-butyl hydroperoxide, said process comprising the steps of:
(a) carrying out adsorption dehydration treatment on a mixed system containing tert-butyl alcohol by using a molecular sieve to obtain tert-butyl alcohol with the water content of less than or equal to 500 ppm;
(b) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, and rectifying in a rectifying tower;
(c) tertiary butyl alcohol, water and other impurities are extracted from the top of the rectifying tower, and a mixed system containing the tertiary butyl hydroperoxide and the tertiary butyl alcohol after concentration and purification is extracted from the tower bottom of the rectifying tower and is marked as a second mixed system.
In one embodiment of the present invention, in step (a), the molecular sieve is an activated molecular sieve.
Wherein the temperature of the activation treatment is 200-500 ℃. The time of the activation treatment is 1 hour or more. The atmosphere of the activation treatment is air, nitrogen or other inert gases. The purpose of the activation treatment is to remove substances such as water and the like adsorbed in the cavity of the molecular sieve by heating, so that the molecular sieve has the best adsorption capacity.
In one embodiment of the invention, in step (a), the molecular sieve is a crystalline silicate or aluminosilicate formed from silicon-oxygen tetrahedra or aluminum-oxygen tetrahedra linked by oxygen bridges.
In one embodiment of the present invention, in step (a), the content of impurity elements in the molecular sieve satisfies: the content of potassium is not higher than 1 wt%, the content of iron is not higher than 1 wt%, the content of sulfur is not higher than 0.5 wt%, and the content of nitrogen is not higher than 0.5 wt%.
In one embodiment of the present invention, in step (a), the molecule is selected from at least one of the following molecular sieves: the molecular sieve comprises a 4A type molecular sieve, a 5A type molecular sieve, a 10X type molecular sieve, a 13X type molecular sieve and a Y type molecular sieve, wherein the content of impurity elements in the molecular sieve meets the following requirements: the content of potassium is not higher than 1 wt%, the content of iron is not higher than 1 wt%, the content of sulfur is not higher than 0.5 wt%, and the content of nitrogen is not higher than 0.5 wt%.
In one embodiment of the present invention, in the step (a), the amount of the molecular sieve is 20 to 100 wt% based on the total mass of the mixed system containing t-butanol.
In one embodiment of the invention, in the step (a), the mixing system containing tert-butyl alcohol is tert-butyl alcohol obtained by oxidizing isobutane, which is obtained from the top of the azeotropic distillation water removal tower, tert-butyl alcohol obtained from the epoxidation reaction of propylene, or tert-butyl alcohol from other sources.
In one embodiment of the present invention, in the step (a), the water content in the mixed system containing tert-butanol is not particularly limited, and may contain more water or less water, and from the viewpoint of economic utilization, it is preferable that the water content in the mixed system containing tert-butanol is not higher than 5 wt%, and if the water content in the mixed system containing tert-butanol to be treated is higher than 5 wt%, the water content therein may be removed by other means known in the art.
In one embodiment of the present invention, in step (a), the mixed system containing t-butanol may contain a small amount of t-butyl hydroperoxide, and the content of t-butyl hydroperoxide is not higher than 5 wt%.
In one embodiment of the present invention, in step (a), the mixed system containing t-butanol may contain small amounts of other impurities, such as acetone and methanol, wherein the content of acetone is 1.9 wt% or less and the content of methanol is 0.4 wt% or less.
In one embodiment of the present invention, in step (b), the first mixed system is derived from an isobutane oxidation reaction system, preferably a mixed system which is derived from an isobutane oxidation reaction system and removes (e.g. separates by rectification) unreacted isobutane from tert-butyl hydroperoxide and tert-butyl alcohol.
In one embodiment of the present invention, in the step (b), the first mixed system comprises the following components in parts by mass: the content of the tert-butyl hydroperoxide is less than or equal to 65 wt%; the content of tertiary butanol is more than or equal to 30 wt%; the content of water is less than or equal to 5 wt%; the acid value (calculated as acetic acid) is 0.4 to 1 wt.%.
Preferably, the content of tert-butyl hydroperoxide is 40-60 wt%; the content of tertiary butanol is 40-58 wt%; the water content is 0.2-1 wt%; the acid value (calculated as acetic acid) is 0.4 to 1 wt.%.
In one embodiment of the present invention, in the step (b), the first mixed system further comprises impurities, the impurities comprise acetone and methanol, and the content of the impurities is 5 wt% or less.
In one embodiment of the present invention, in the step (b), the rectifying tower is a concentration rectifying tower.
In one embodiment of the present invention, in the step (b), the tert-butanol having a moisture content of 500ppm or less may be added to the first mixed system before the first mixed system is added to the rectifying column, or may be added to the rectifying column separately from the first mixed system and mixed with the first mixed system in the rectifying column. For example, when t-butanol having a moisture content of 500ppm or less is fed to the rectifying column separately from the first mixed system, the inlet for t-butanol having a moisture content of 500ppm or less may be located below or above the inlet for the first mixed system.
In one embodiment of the present invention, in the step (b), the tertiary butanol having a moisture content of 500ppm or less is added in an amount of 10 to 50 wt%, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt% or 50 wt%, based on the total mass of the first mixed system.
In one scheme of the invention, in the step (b), the temperature of the bottom of the rectifying tower is 60-90 ℃, the temperature of the top of the rectifying tower is 25-50 ℃, the pressure of the top of the rectifying tower is 15-25kPa, and the reflux ratio of the top of the rectifying tower is 1-5: 1.
In one scheme of the invention, partial moisture and impurities in the first mixed system can be removed in the rectification process, and the concentration and purification of the tert-butyl hydroperoxide can be realized.
In one embodiment of the present invention, in the step (c), the impurities extracted from the top of the rectifying column are, for example, acetone and methanol, wherein the content of acetone is 1.9 wt% or less and the content of methanol is 0.4 wt% or less.
In one embodiment of the present invention, in the step (c), the content of the tert-butanol extracted from the top of the rectifying column is 90 wt% or more; the content of water extracted from the top of the rectifying tower is more than or equal to 0.1 wt%. Illustratively, the tertiary butanol content is 95 wt% or more and the water content is 0.6 wt% or more.
In one embodiment of the present invention, in step (c), the second mixed system comprises tert-butyl hydroperoxide, tert-butanol and water; wherein the content of tert-butyl hydroperoxide is 50-70 wt.%, for example 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.% or 70 wt.%; the content of tert-butanol is 30 to 50% by weight, for example 30, 35, 40, 45 or 50% by weight; the water content is 0.1-0.3 wt.%, for example 0.1 wt.%, 0.2 wt.% or 0.3 wt.%.
In one embodiment of the present invention, in the step (c), the second mixed system further comprises acetone and methanol, wherein the content of acetone is 0.06 wt% or less, and the content of methanol is 0.1 wt% or less.
In one embodiment of the present invention, in step (c), the acid value (in terms of acetic acid) of the second mixed system is 0.4 to 1% by weight.
In one embodiment of the present invention, in step (c), the contents of the components in the second mixed system can meet the requirements of olefin epoxidation (such as propylene epoxidation), and do not adversely affect the olefin epoxidation reaction.
In one embodiment, the method specifically comprises the steps of:
(a) carrying out adsorption dehydration treatment on a mixed system containing tert-butyl alcohol by using a molecular sieve to obtain tert-butyl alcohol with the water content of less than or equal to 500 ppm;
(b) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system of tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, which is produced by oxidizing isobutane and is used for removing unreacted isobutane, and then feeding the mixture into a tert-butyl hydroperoxide concentration rectifying tower;
(c) tertiary butyl alcohol, water and impurities are extracted from the top of the rectifying tower, a purified mixed system containing tertiary butyl hydroperoxide and the tertiary butyl alcohol, namely a second mixed system, is extracted from the tower bottom of the rectifying tower, and the content of each substance in the second mixed system can meet the requirement of olefin epoxidation (such as propylene epoxidation), and cannot generate adverse effect on olefin epoxidation reaction.
< method for recycling t-butyl alcohol in the process of preparing propylene oxide from t-butyl hydroperoxide
The invention also provides a recycling method of tert-butyl alcohol in the process of preparing propylene oxide by tert-butyl hydroperoxide, which comprises the following steps:
(i) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, and rectifying in a rectifying tower;
(ii) collecting tert-butyl alcohol, water and other impurities at the top of the rectifying tower, and collecting a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol after concentration and purification at the tower bottom of the rectifying tower, and marking the mixed system as a second mixed system;
(iii) mixing the second mixed system, propylene and a catalyst to perform epoxidation reaction;
(iv) (iv) separating the mixed system after the reaction in the step (iii) to obtain a mixed system containing tert-butyl alcohol;
(v) and (3) carrying out molecular sieve adsorption dehydration treatment on the mixed system containing the tert-butyl alcohol in the step (iv) to obtain the tert-butyl alcohol with the moisture content of less than or equal to 500ppm, and circularly using the tert-butyl alcohol in the step (i).
In one aspect of the present invention, the method further comprises the steps of:
(vi) and (3) carrying out molecular sieve adsorption dewatering treatment on the mixed system containing the tert-butyl alcohol extracted from the tower top in the step (ii) to obtain the tert-butyl alcohol with the water content of less than or equal to 500ppm, and circularly using the tert-butyl alcohol in the step (i).
According to the invention, the purified tert-butyl hydroperoxide/tert-butyl alcohol solution is introduced into an olefin epoxidation reaction system, so that higher olefin epoxidation reaction conversion rate and better olefin epoxidation reaction selectivity can be ensured. Meanwhile, the content of impurity elements in the molecular sieve is controlled in the purification process of the tert-butyl hydroperoxide/tert-butyl alcohol solution, so that the decomposition of the tert-butyl hydroperoxide and/or the precipitation and precipitation of the catalyst caused by the introduction of the impurity elements are avoided.
The method of the present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
In the present invention, the acid value, also called acid value, represents the number of grams of potassium hydroxide (KOH) required to neutralize 1g of substance. Acid number is a measure of the amount of free carboxylic acid groups in a compound or mixture.
In the invention, the high performance gas chromatography is used for detecting the tert-butyl hydroperoxide content before and after the reaction, the epoxypropane content after the reaction and the conversion rate X of the tert-butyl hydroperoxide after the reactionTBHPSelectivity to propylene oxide SPOThe calculation is performed as follows:
XTBHP(TBHP conversion/TBHP initial) 100%
SPO(amount of TBHP consumed/amount of TBHP converted to PO) 100%
The molecular sieves in the following examples are all commercial products, and are used after being heated and activated at 400 ℃ for 5 hours and then cooled to room temperature, so as to further remove moisture contained in the molecular sieves, and the content of impurity elements in the molecular sieves is tested by ICP-AES detection before use.
Example 1
A tert-butyl hydroperoxide/tert-butyl alcohol mixed solution system obtained by oxidation of isobutanol (the content of tert-butyl hydroperoxide is 53.71 wt%, the content of tert-butyl alcohol is 43.76 wt%, and the content of water is 0.46 wt%) is subjected to azeotropic rectification for removing water by using tert-butyl alcohol, 50kg of tert-butyl alcohol (the content of tert-butyl alcohol is 98.24 wt%, and the content of water is 1.15 wt%) extracted from the top of a tower is treated in an adsorption tower filled with 25kg of a 4A molecular sieve (the content of potassium in the 4A molecular sieve is less than 1 wt%, the content of iron is less than 1 wt%, the content of nitrogen is less than 0.5 wt%, and the content of sulfur is less than 0.5 wt%), the temperature of the adsorption tower is 25 ℃, the retention time is 1 hour, and the content of the obtained tert-butyl alcohol is 99.
55.88kg/h of a tert-butyl hydroperoxide/tert-butyl alcohol mixed solution mixed system (tert-butyl hydroperoxide content of TBHP53.85wt%, tert-butyl alcohol content of 43.72 wt%, water content of 0.49 wt%, acid value of 0.90 wt% (calculated as acetic acid)) for removing isobutane was fed into the rectifying tower through one feed pipe, and 11.00kg/h of tert-butyl alcohol (tert-butyl alcohol content of 99.13 wt%, water content of 0.03 wt%) treated by the 4A molecular sieve adsorption tower was fed into the rectifying tower through the other feed pipe. The temperature of the bottom of the column was maintained at 75 deg.C, the pressure at the top of the column was 22kPa, the temperature at the top of the column was 47.8 deg.C, and the reflux ratio was 3: 1. The flow rate of water/TBA taken out from the top of the column (tert-butanol content: 98.15 wt%, water content: 1.06 wt%) was 16.9 kg/h. The flow rate of TBHP/TBA taken out from the bottom of the column was 50.00kg/h, wherein the t-butyl hydroperoxide content was 60.15 wt%, the t-butyl alcohol content was 38.27 wt%, the water content was 0.10 wt%, and the acid value was 0.85 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 72.37%, and the PO selectivity is 91.28%.
Example 2
The procedure is otherwise the same as in example 1, except that the molecular sieve used is a type 5A molecular sieve (5A molecular sieve having less than 1 wt% potassium, less than 1 wt% iron, less than 0.5 wt% nitrogen, and less than 0.5 wt% sulfur), and after treatment the resulting tert-butanol content is 99.02 wt% and the water content is 0.04 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with tert-butyl alcohol (tert-butyl alcohol content: 99.02 wt%, water content: 0.04 wt%) treated in the 5A molecular sieve adsorption column to obtain a TBHP/TBA solution having a tert-butyl hydroperoxide content of 59.91 wt%, a tert-butyl alcohol content of 39.14 wt%, a water content of 0.11 wt%, and an acid value of 0.87 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 72.06%, and the PO selectivity is 90.97%.
Example 3
The procedure is otherwise as in example 1 except that the molecular sieve used is a 10X type molecular sieve (10X molecular sieve having less than 1 wt% potassium, less than 1 wt% iron, less than 0.5 wt% nitrogen, and less than 0.5 wt% sulfur), and after treatment the resulting tert-butanol content is 99.15 wt% and the water content is 0.03 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with tert-butyl alcohol (tert-butyl alcohol content: 99.15 wt%, water content: 0.03 wt%) treated in the 10X molecular sieve adsorption column to obtain a TBHP/TBA solution having a tert-butyl hydroperoxide content of 60.03 wt%, a tert-butyl alcohol content of 38.37 wt%, a water content of 0.10 wt%, and an acid value of 0.82 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 73.55%, and the PO selectivity is 91.36%.
Example 4
The procedure is otherwise the same as in example 1, except that the molecular sieve used is a 13X type molecular sieve (13X molecular sieve having less than 1 wt% potassium, less than 1 wt% iron, less than 0.5 wt% nitrogen, and less than 0.5 wt% sulfur), and after treatment the resulting tert-butanol content is 98.97 wt% and the water content is 0.04 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with tert-butyl alcohol (tert-butyl alcohol content: 98.97 wt%, water content: 0.04 wt%) treated in the 13X molecular sieve adsorption column to obtain a TBHP/TBA solution having a tert-butyl hydroperoxide content of 59.85 wt%, a tert-butyl alcohol content of 39.28 wt%, a water content of 0.11 wt%, and an acid value of 0.86 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 70.95%, and the PO selectivity is 90.68%.
Example 5
The procedure is otherwise as in example 1 except that the molecular sieve used is a Y-type molecular sieve (5A molecular sieve having less than 1 wt% potassium, less than 1 wt% iron, less than 0.5 wt% nitrogen, and less than 0.5 wt% sulfur), and the resulting tert-butanol has a 99.06 wt% water content after treatment.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with t-butanol (t-butanol content 99.06 wt%, water content 0.03 wt%) treated in the Y-type molecular sieve adsorption column to obtain a TBHP/TBA solution having a t-butyl hydroperoxide content of 60.04 wt%, a t-butanol content of 38.96 wt%, a water content of 0.11 wt%, and an acid value of 0.85 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 73.29%, and the PO selectivity is 91.75%.
Example 6
50kg of tertiary butanol (the content of the tertiary butanol is 99.53wt percent, the content of water is 0.28wt percent) obtained by rectifying and separating propylene epoxidation reaction liquid is treated in an adsorption tower filled with 25kg of 4A molecular sieve (the content of potassium in the 4A molecular sieve is less than 1wt percent, the content of iron is less than 1wt percent, the content of nitrogen is less than 0.5wt percent, and the content of sulfur is less than 0.5wt percent), the temperature of the adsorption tower is 25 ℃, the retention time is 1 hour, the content of the obtained tertiary butanol is 99.86wt percent, and the content of water is 0.02wt percent.
55.88kg/h of a tert-butyl hydroperoxide/tert-butyl alcohol mixed solution mixed system (tert-butyl hydroperoxide content of TBHP53.85wt%, tert-butyl alcohol content of 43.72 wt%, water content of 0.49 wt%, acid value of 0.90 wt% (calculated as acetic acid)) for removing isobutane was fed into the rectifying tower through one feed pipe, and 11.00kg/h of tert-butyl alcohol (tert-butyl alcohol content of 99.86 wt%, water content of 0.02 wt%) treated by the 4A molecular sieve adsorption tower was fed into the rectifying tower through the other feed pipe. The temperature of the bottom of the column was maintained at 75 deg.C, the pressure at the top of the column was 22kPa, the temperature at the top of the column was 47.8 deg.C, and the reflux ratio was 3: 1. The flow rate of the water/TBA material (t-butanol content: 98.21% by weight, water content: 0.98% by weight) taken out from the top of the column was 16.9 kg/h. The flow rate of TBHP/TBA taken out from the bottom of the column was 50.00kg/h, wherein the t-butyl hydroperoxide content was 60.15 wt%, the t-butyl alcohol content was 38.27 wt%, the water content was 0.10 wt%, and the acid value was 0.84 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 74.10%, and the PO selectivity is 92.79%.
Example 7
The procedure is otherwise as in example 6 except that the molecular sieve used is a 5A type molecular sieve (5A molecular sieve having less than 1 wt% potassium, less than 1 wt% iron, less than 0.5 wt% nitrogen, and less than 0.5 wt% sulfur), and after treatment the resulting tert-butanol content is 99.88 wt% and the water content is 0.03 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with tert-butyl alcohol (tert-butyl alcohol content: 99.88 wt%, water content: 0.03 wt%) treated in the 5A molecular sieve adsorption column to obtain a TBHP/TBA solution having a tert-butyl hydroperoxide content of 60.11 wt%, a tert-butyl alcohol content of 38.13 wt%, a water content of 0.10 wt%, and an acid value of 0.82 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 72.93%, and the PO selectivity is 92.10%.
Example 8
The procedure is otherwise as in example 6 except that the molecular sieve used is a 10X type molecular sieve (10X molecular sieve having less than 1 wt% potassium, less than 1 wt% iron, less than 0.5 wt% nitrogen, and less than 0.5 wt% sulfur), and the tert-butanol content after treatment is 99.82 wt% and the water content is 0.03 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with tert-butyl alcohol (tert-butyl alcohol content: 99.82 wt%, water content: 0.03 wt%) treated in the 10X molecular sieve adsorption column to obtain a TBHP/TBA solution having a tert-butyl hydroperoxide content of 59.92 wt%, a tert-butyl alcohol content of 38.64 wt%, a water content of 0.10 wt%, and an acid value of 0.85 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 71.94%, and the PO selectivity is 91.57%.
Example 9
The procedure is otherwise as in example 6 except that the molecular sieve used is a 13X type molecular sieve (13X molecular sieve having less than 1 wt% potassium, less than 1 wt% iron, less than 0.5 wt% nitrogen, and less than 0.5 wt% sulfur), and after treatment the resulting tert-butanol content is 99.90 wt% and the water content is 0.03 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with tert-butyl alcohol (tert-butyl alcohol content: 99.90 wt%, water content: 0.03 wt%) treated in the 13X molecular sieve adsorption column to obtain a TBHP/TBA solution having a tert-butyl hydroperoxide content of 60.05 wt%, a tert-butyl alcohol content of 38.33 wt%, a water content of 0.11 wt%, and an acid value of 0.87 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 72.66%, and the PO selectivity is 90.97%.
Example 10
The procedure is otherwise as in example 6 except that the molecular sieve used is a Y-type molecular sieve (Y molecular sieve having a potassium content of less than 1 wt%, an iron content of less than 1 wt%, a nitrogen content of less than 0.5 wt%, and a sulfur content of less than 0.5 wt%), and the process yields a tertiary butanol content of 99.87 wt% and a water content of 0.03 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with t-butanol (t-butanol content 99.87 wt%, water content 0.03 wt%) treated in the Y-type molecular sieve adsorption column to obtain a TBHP/TBA solution having a t-butyl hydroperoxide content of 60.23 wt%, a t-butanol content of 38.12 wt%, a water content of 0.10 wt%, and an acid value of 0.82 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 70.928%, and the PO selectivity is 92.43%.
Example 11
In example 1, 50kg of t-butanol (t-butanol content 98.15 wt%, water content 1.06 wt%) withdrawn from the top of the column was treated in an adsorption column containing 25kg of 4A molecular sieve (potassium content of 4A molecular sieve is less than 1 wt%, iron content is less than 1 wt%, nitrogen content is less than 0.5 wt%, and sulfur content is less than 0.5 wt%), at an adsorption column temperature of 25 ℃ for a retention time of 1 hour, and the t-butanol content was 99.17 wt% and the water content was 0.03 wt%.
55.88kg/h of a tert-butyl hydroperoxide/tert-butyl alcohol mixed solution mixed system (tert-butyl hydroperoxide content of TBHP53.85wt%, tert-butyl alcohol content of 43.72 wt%, water content of 0.49 wt%, acid value of 0.90 wt% (calculated as acetic acid)) for removing isobutane was fed into the rectifying tower through one feed pipe, and 11.00kg/h of tert-butyl alcohol (tert-butyl alcohol content of 99.17 wt%, water content of 0.03 wt%) treated by the 4A molecular sieve adsorption tower was fed into the rectifying tower through the other feed pipe. The temperature of the bottom of the column was maintained at 75 deg.C, the pressure at the top of the column was 22kPa, the temperature at the top of the column was 47.8 deg.C, and the reflux ratio was 3: 1. The flow rate of the water/TBA material (tert-butanol content 98.19 wt%, water content 1.14 wt%) taken out from the top of the column was 16.9 kg/h. The flow rate of TBHP/TBA taken out from the column bottom was 50.00kg/h, wherein the t-butyl hydroperoxide content was 60.03 wt%, the t-butyl alcohol content was 38.24 wt%, the water content was 0.11 wt%, and the acid value was 0.87 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 72.87%, and the PO selectivity is 91.03%.
Example 12
In example 6, 50kg of t-butanol (t-butanol content 98.21 wt%, water content 0.98 wt%) withdrawn from the top of the column was treated in an adsorption column containing 25kg of 4A molecular sieve (potassium content of 4A molecular sieve is less than 1 wt%, iron content is less than 1 wt%, nitrogen content is less than 0.5 wt%, and sulfur content is less than 0.5 wt%), at an adsorption column temperature of 25 ℃ for a retention time of 1 hour, and the t-butanol content was 99.13 wt% and the water content was 0.03 wt%.
55.88kg/h of a tert-butyl hydroperoxide/tert-butyl alcohol mixed solution mixed system (tert-butyl hydroperoxide content of TBHP53.85wt%, tert-butyl alcohol content of 43.72 wt%, water content of 0.49 wt%, acid value of 0.90 wt% (calculated as acetic acid)) for removing isobutane was fed into the rectifying tower through one feed pipe, and 11.00kg/h of tert-butyl alcohol (tert-butyl alcohol content of 99.13 wt%, water content of 0.03 wt%) treated by the 4A molecular sieve adsorption tower was fed into the rectifying tower through the other feed pipe. The temperature of the bottom of the column was maintained at 75 deg.C, the pressure at the top of the column was 22kPa, the temperature at the top of the column was 47.8 deg.C, and the reflux ratio was 3: 1. The flow rate of the water/TBA material (tert-butanol content 98.16 wt%, water content 1.07 wt%) taken out from the top of the column was 16.9 kg/h. The flow rate of TBHP/TBA taken out from the bottom of the column was 50.00kg/h, wherein the t-butyl hydroperoxide content was 60.11 wt%, the t-butyl alcohol content was 38.19 wt%, the water content was 0.10 wt%, and the acid value was 0.82 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method can be used for propylene epoxidation reaction for 15min, the TBHP conversion rate is 72.86%, and the PO selectivity is 91.16%.
Comparative example 1
The procedure is otherwise as in example 1 except that the type 3A molecular sieve is used (potassium content of 3A molecular sieve > 15 wt%, sulphur content > 0.5 wt%, nitrogen content > 0.5 wt%), the tert-butanol content after treatment is 99.07 wt% and the water content 0.04 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with tert-butyl alcohol (tert-butyl alcohol content: 99.07 wt%, water content: 0.04 wt%) treated in the 3A molecular sieve adsorption column to obtain a TBHP/TBA solution having a tert-butyl hydroperoxide content of 59.98 wt%, a tert-butyl alcohol content of 38.24 wt%, a water content of 0.11 wt%, and an acid value of 0.84 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method is used for propylene epoxidation, a small amount of ethylene glycol molybdenum is separated out in a reaction system as a catalyst, the reaction time is 15min, the TBHP conversion rate is 40.37%, and the PO selectivity is 80.26%.
And detecting the components of the precipitated precipitate, wherein the precipitated precipitate contains 22.18 percent of molybdenum, 4.17 percent of potassium, 0.04 percent of sulfur and 0.35 percent of nitrogen.
Comparative example 2
The procedure is otherwise as in example 1 except that the type 4A molecular sieve is used (4A molecular sieve having a potassium content of greater than 1 wt%, a sulfur content of greater than 0.5 wt%, and a nitrogen content of greater than 0.5 wt%), and the tert-butanol content after treatment is 99.18 wt% and the water content is 0.04 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with t-butanol (t-butanol content: 99.18 wt%, water content: 0.04 wt%) treated in the 4A molecular sieve adsorption column to obtain a TBHP/TBA solution having a t-butyl hydroperoxide content of 60.25 wt%, a t-butanol content of 38.07 wt%, a water content of 0.10 wt%, and an acid value of 0.82 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method is used for propylene epoxidation, a small amount of ethylene glycol molybdenum is separated out in a reaction system as a catalyst, the reaction is carried out for 15min, the TBHP conversion rate is 43.60%, and the PO selectivity is 82.18%.
And (3) carrying out component detection on the precipitated precipitate, wherein the precipitated precipitate contains 24.07 percent of molybdenum, 3.66 percent of potassium, 0.06 percent of sulfur and 0.29 percent of nitrogen.
Comparative example 3
The procedure is otherwise as in example 6 except that the type 3A molecular sieve is used (potassium content of 3A molecular sieve is greater than 15 wt%, sulfur content is greater than 0.5 wt%, nitrogen content is greater than 0.5 wt%), the tert-butanol content after treatment is 99.78 wt% and the water content is 0.03 wt%.
The TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with tert-butyl alcohol (tert-butyl alcohol content: 99.78 wt%, water content: 0.03 wt%) treated in the 3A molecular sieve adsorption column to obtain a TBHP/TBA solution having a tert-butyl hydroperoxide content of 60.01 wt%, a tert-butyl alcohol content of 38.17 wt%, a water content of 0.10 wt%, and an acid value of 0.83 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method is used for propylene epoxidation, a small amount of ethylene glycol molybdenum is separated out in a reaction system as a catalyst, the reaction is carried out for 15min, the TBHP conversion rate is 37.28%, and the PO selectivity is 83.04%.
And detecting the components of the precipitated precipitate, wherein the precipitated precipitate contains 25.26 percent of molybdenum, 3.04 percent of potassium, 0.06 percent of sulfur and 0.31 percent of nitrogen by weight.
Comparative example 4
The other operation was the same as example 6 except that the molecular sieve used was a type 4A molecular sieve (potassium content of 4A molecular sieve is more than 1 wt%, sulfur content is more than 0.5 wt%, nitrogen is more than 0.5 wt%), and TBHP/TBA solution obtained by oxidizing isobutane was subjected to azeotropic distillation dehydration with t-butanol treated in this type 4A molecular sieve adsorption column to obtain TBHP/TBA solution having a t-butyl hydroperoxide content of 60.08 wt%, a t-butanol content of 38.13 wt%, a water content of 0.11 wt%, and an acid value of 0.79 wt% (based on acetic acid).
The TBHP/TBA solution obtained by the method is used for propylene epoxidation, a small amount of ethylene glycol molybdenum is separated out in a reaction system as a catalyst, the reaction is carried out for 15min, the TBHP conversion rate is 52.43%, and the PO selectivity is 81.64%.
The precipitated precipitate was subjected to composition detection, and contained 22.91 wt% of molybdenum, 3.87 wt% of potassium, 0.04 wt% of sulfur and 0.33 wt% of nitrogen.
Comparative example 5
55.88kg/h of a tert-butyl hydroperoxide/tert-butanol mixed solution mixed system (tert-butyl hydroperoxide content of TBHP53.71wt%, tert-butanol content of 43.76 wt%, water content of 0.46 wt%, acid value of 0.87 wt% (calculated as acetic acid)) for isobutane removal was fed into the rectifying column through one feed pipe, and tert-butanol was not added to the other feed pipe. The temperature of the bottom of the column was maintained at 75 deg.C, the pressure at the top of the column was 22kPa, the temperature at the top of the column was 47.5 deg.C, and the reflux ratio was 3: 1. The flow rate of water/TBA taken out from the top of the column was 5.88 kg/h. The flow rate of TBHP/TBA taken out from the bottom of the column was 50.00kg/h, wherein the t-butyl hydroperoxide content was 60.02 wt%, the t-butyl alcohol content was 38.05 wt%, the water content was 0.36 wt%, and the acid value was 0.90 wt% (based on acetic acid). The water content in the tower bottom is improved by 0.26 wt% compared with that in the example 1 by adding no TBA material into the rectifying tower.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A process for the purification of tert-butyl hydroperoxide, said process comprising the steps of:
(a) carrying out adsorption dehydration treatment on a mixed system containing tert-butyl alcohol by using a molecular sieve to obtain tert-butyl alcohol with the water content of less than or equal to 500 ppm;
(b) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, and rectifying in a rectifying tower;
(c) tertiary butyl alcohol, water and other impurities are extracted from the top of the rectifying tower, and a mixed system containing the tertiary butyl hydroperoxide and the tertiary butyl alcohol after concentration and purification is extracted from the tower bottom of the rectifying tower and is marked as a second mixed system.
2. The method of claim 1, wherein in step (a), the content of impurity elements in the molecular sieve satisfies: the content of potassium is not higher than 1 wt%, the content of iron is not higher than 1 wt%, the content of sulfur is not higher than 0.5 wt%, and the content of nitrogen is not higher than 0.5 wt%.
Preferably, in the step (a), the amount of the molecular sieve is 20 to 100 wt% of the total mass of the mixed system containing t-butanol.
3. The method as claimed in claim 1 or 2, wherein in the step (a), the mixing system containing tert-butyl alcohol is tert-butyl hydroperoxide/tert-butyl alcohol solution obtained by oxidizing isobutane, tert-butyl alcohol is extracted from the top of a water column by azeotropic distillation, a byproduct obtained by propylene epoxidation reaction or tert-butyl alcohol from other sources.
Preferably, in the step (a), the mixed system containing tert-butyl alcohol may contain a small amount of tert-butyl hydroperoxide, and the content of tert-butyl hydroperoxide is not higher than 5 wt%.
Preferably, in step (a), the mixed system containing t-butanol may contain small amounts of other impurities, such as acetone and methanol, wherein the content of acetone is 1.9 wt% or less and the content of methanol is 0.4 wt% or less.
4. The method according to any one of claims 1 to 3, wherein in the step (b), the first mixed system is derived from an isobutane oxidation reaction system, preferably a mixed system of tert-butyl hydroperoxide and tert-butyl alcohol which is derived from the isobutane oxidation reaction system and is used for removing unreacted isobutane.
Preferably, in the step (b), the first mixed system comprises the following components in parts by mass: the content of the tert-butyl hydroperoxide is less than or equal to 65 wt%; the content of tertiary butanol is more than or equal to 30 wt%; the content of water is less than or equal to 5 wt%; the acid value (calculated as acetic acid) is 0.4 to 1 wt.%.
Preferably, in the step (b), the first mixed system further comprises impurities, the impurities comprise acetone and methanol, and the content of the impurities is less than or equal to 5 wt%.
5. The process according to any one of claims 1 to 4, wherein the tertiary butanol having a moisture content of 500ppm or less is added in an amount of 10 to 50 wt% based on the total mass of the first mixed system in step (b).
Preferably, in the step (b), the temperature of the bottom of the rectifying tower is 60-90 ℃, the temperature of the top of the rectifying tower is 25-50 ℃, the pressure of the top of the rectifying tower is 15-25kPa, and the reflux ratio of the top of the rectifying tower is 1-5: 1.
6. The process according to any one of claims 1 to 5, wherein in the step (c), the impurities such as acetone and methanol are extracted from the top of the rectifying column, wherein the content of acetone is 1.9 wt% or less, and the content of methanol is 0.4 wt% or less.
Preferably, in the step (c), the content of the tertiary butanol extracted from the top of the rectifying tower is more than or equal to 90 wt%; the content of water extracted from the top of the rectifying tower is more than or equal to 0.1 wt%. Illustratively, the tertiary butanol content is 95 wt% or more and the water content is 0.6 wt% or more.
7. The process of any one of claims 1-6, wherein in step (c), the second mixed system comprises t-butyl hydroperoxide, t-butanol, and water; wherein, the content of the tert-butyl hydroperoxide is 50 to 70 weight percent; the content of tertiary butanol is 30-50 wt%; the content of the water is 0.1-0.3 wt%.
Preferably, in the step (c), the second mixed system further comprises acetone and methanol, wherein the content of acetone is less than or equal to 0.06 wt%, and the content of methanol is less than or equal to 0.1 wt%.
In one embodiment of the present invention, in step (c), the acid value (in terms of acetic acid) of the second mixed system is 0.4 to 1% by weight.
8. The method according to any of claims 1-7, wherein the method comprises in particular the steps of:
(a) carrying out adsorption dehydration treatment on a mixed system containing tert-butyl alcohol by using a molecular sieve to obtain tert-butyl alcohol with the water content of less than or equal to 500 ppm;
(b) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system of tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, which is produced by oxidizing isobutane and is used for removing unreacted isobutane, and then feeding the mixture into a tert-butyl hydroperoxide concentration rectifying tower;
(c) tertiary butyl alcohol, water and impurities are extracted from the top of the rectifying tower, a purified mixed system containing tertiary butyl hydroperoxide and the tertiary butyl alcohol, namely a second mixed system, is extracted from the tower bottom of the rectifying tower, and the content of each substance in the second mixed system can meet the requirement of olefin epoxidation (such as propylene epoxidation), and cannot generate adverse effect on olefin epoxidation reaction.
9. A recycling method of tert-butyl alcohol in a process of preparing propylene oxide by tert-butyl hydroperoxide oxidation propylene, which comprises the following steps:
(i) adding tert-butyl alcohol with the moisture content of less than or equal to 500ppm into a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol, namely a first mixed system, and rectifying in a rectifying tower;
(ii) collecting tert-butyl alcohol, water and other impurities at the top of the rectifying tower, and collecting a mixed system containing tert-butyl hydroperoxide and tert-butyl alcohol after concentration and purification at the tower bottom of the rectifying tower, and marking the mixed system as a second mixed system;
(iii) mixing the second mixed system, propylene and a catalyst to perform epoxidation reaction;
(iv) (iv) separating the mixed system after the reaction in the step (iii) to obtain a mixed system containing tert-butyl alcohol;
(v) and (3) carrying out molecular sieve adsorption dehydration treatment on the mixed system containing the tert-butyl alcohol in the step (iv) to obtain the tert-butyl alcohol with the moisture content of less than or equal to 500ppm, and circularly using the tert-butyl alcohol in the step (i).
10. The method of claim 9, wherein the method further comprises the steps of:
(vi) and (3) carrying out molecular sieve adsorption dewatering treatment on the mixed system containing the tert-butyl alcohol extracted from the tower top in the step (ii) to obtain the tert-butyl alcohol with the water content of less than or equal to 500ppm, and circularly using the tert-butyl alcohol in the step (i).
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