Preparation method and application of chlorohydrin
Technical Field
The invention belongs to the field of chlorohydrins preparation, and particularly relates to a preparation method and application of chlorohydrins.
Background
The chlorohydrin process is one of industrially important processes for producing epoxides, such as the reaction of chlorine gas and propylene in water to produce an aqueous chloropropanol solution, which is directly contacted with lime milk to produce propylene oxide by saponification. At present, over 50 percent of propylene oxide products are industrially prepared and produced by a chlorohydrin method. The main reaction and the side reaction of chlorine and propylene in water to prepare the chloropropanol aqueous solution are as follows, and the main byproducts include dichloropropane, dichlorodiisopropyl ether, chloropropone and the like.
Main reaction:
Cl2+H2O→HClO+HCl (1)
side reaction:
the chlorohydrin method for preparing the epoxide has the advantages of mature process, high reaction yield, less side reaction and low equipment requirement. However, the existing process for preparing epoxide by chlorohydrin method has the defect of large amount of waste water, for example, when one ton of propylene oxide is produced by chlorohydrin method, the waste water containing 2-3 wt% of calcium chloride or sodium chloride is by-produced about 50t, and the waste water with low salt content and large amount needs to be discharged after biochemical treatment to reach the standard, so that the environmental protection pressure is large, and the industrial application of chlorohydrin method is limited.
Disclosure of Invention
The invention provides a preparation method of chlorohydrin, which comprises the following steps: reacting chlorine and olefin in a high-concentration salt water solution to obtain a chlorohydrin solution;
the salt content of the high-concentration saline solution is more than or equal to 10 wt%.
According to an embodiment of the invention, the salt content of the high strength brine solution is 10-50 wt%, more preferably 20-35 wt%, exemplary 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt% or any combination of any two of the above.
According to an embodiment of the present invention, the salt in the high-concentration brine solution is at least one of a chloride of a group I element and a chloride of a group II element. For example, the salt is at least one of sodium chloride, potassium chloride, magnesium chloride, and calcium chloride; more preferably, the salt is sodium chloride and/or calcium chloride.
According to an embodiment of the invention, the olefin is ethylene, propylene, chloropropene or butene.
According to an embodiment of the invention, the temperature of the reaction is 10-120 deg.C, such as 20-100 deg.C, such as 30-80 deg.C, more preferably 40-60 deg.C, and exemplary 30 deg.C, 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C, 80 deg.C.
According to an embodiment of the invention, the pressure of the reaction is 0.1-0.5MPa, such as 0.2-0.4MPa, exemplary 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5 MPa.
According to an embodiment of the invention, the molar ratio of the feed of chlorine to olefin is 1 (1.01-1.3), for example 1 (1.05-1.175), and as another example 1 (1.1-1.15).
According to an embodiment of the invention, the chlorohydrin solution has a concentration of chlorohydrin of 1.0 to 10.0 wt.%, preferably 2.0 to 5.0 wt.%, illustratively 2.0 wt.%, 2.45 wt.%, 3.0 wt.%, 3.3 wt.%, 4.0 wt.%, 4.5 wt.%, 5.0 wt.%.
According to an embodiment of the present invention, the aqueous solution of the salt with high concentration may be selected from a saponification waste liquid obtained by preparing an alkylene oxide from the chlorohydrin solution and an alkaline substance through a saponification reaction, separating the alkylene oxide, and then performing a pretreatment, which is prepared by a method known in the art (for example, dissolving the salt in water to form an aqueous solution of the salt with high concentration), or a saponification waste liquid obtained by preparing an alkylene oxide.
Preferably, the pre-treatment comprises at least one of filtration, neutralization and cooling.
Preferably, the alkaline substance is selected from at least one of alkaline substances containing group I elements and/or group II elements, such as hydroxides and/or basic salts thereof, for example, at least one of sodium hydroxide, calcium hydroxide, and sodium carbonate.
According to an embodiment of the present invention, the preparation process of the chlorohydrin may be performed in a chlorohydrination reaction apparatus known in the art.
The invention also provides a preparation method of the chlorohydrins and/or application of chlorohydrin solution prepared by the method in preparation of alkylene oxide.
The invention has the beneficial effects that:
chlorine and olefin are reacted in an aqueous solution of a salt having a concentration of 10 wt% or more to prepare a chlorohydrin solution, and chlorohydrination in a high-concentration aqueous solution of chloride ions is achieved. The chlorohydrin solution and alkali are subjected to saponification reaction to prepare epoxy alkane, and saponification waste liquid is remained after the epoxy alkane is separated; most of the saponified waste liquid is used as high-concentration salt water solution for chlorohydrination reaction, and the rest saponified waste liquid is concentrated and crystallized to obtain solid salt product, so that the discharge of salt-containing waste water is reduced and even eliminated, and the green production of preparing epoxy alkane by chlorohydrination is realized.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to specific embodiments. 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.
Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.
The analysis conditions for the products in the following examples are as follows:
an analytical instrument: agilent GC 7820; a chromatographic column: 30 m.times.530 μm.times.0.25 μm DB-FFAP; a detector: FID; sample inlet temperature: 225 ℃, detector temperature: and (3) temperature programming at 240 ℃: maintaining at 40 deg.C for 5min, 30 deg.C/min to 230 deg.C for 5min, H2:0.1Mpa,AIR:0.1Mpa,N2: 0.075Mpa, tail-blown: 0.1 MPa.
Example 1
The reaction device is a 1000ml four-neck round bottom glass flask, and is provided with mechanical stirring, the stirring speed is 100rpm, two bottom inserting tubes are respectively arranged in two bottle mouths, one bottom inserting tube is used for introducing chlorine, and the other bottom inserting tube is used for introducing propylene. 20 wt% of calcium chloride solution is respectively added into the two flasks, the total volume of the calcium chloride solution is 800ml, the reaction temperature is controlled by a hot water bath at 50 ℃, and the reaction flasks are wrapped by black plastic cloth to be protected from light.
Chlorine gas was introduced subsurface at a rate of 52ml/min (2.3mmol/min), and propylene was introduced subsurface at a rate of 62ml/min (2.7 mmol/h).
The gas phase is removed from the gas phase space of the reaction bottle and is absorbed by alkali liquor and ethyl acetate.
And analyzing the contents of chloropropanol and impurities in the reaction material, and analyzing the contents of propylene and impurities in the gas phase removed from the reaction bottle.
The comprehensive analysis was carried out after 200min of aeration reaction, and the results were as follows:
3.02 wt% of chloropropanol, 0.14 wt% of dichloropropane, 0.08 wt% of dichlorodiisopropyl ether and 0.010 wt% of chloropropone.
Examples 2 to 5
The reaction apparatus, the amount of charge, and the control conditions were the same as in example 1 except for the concentration of calcium chloride in the calcium chloride solution. After the reaction was carried out under aeration for 200min, the contents of chloropropanol and major impurities in the reaction solution were determined, and the results are shown in Table 1.
TABLE 1
Example 6
The reaction apparatus, the amount of feed and the control conditions were the same as in example 1, except that the added brine solution was a sodium chloride solution containing 21 wt% of sodium chloride. After the reaction solution is aerated for 200min, the contents of chloropropanol and main impurities in the reaction solution are measured, and the results are as follows:
3.12 percent of chloropropanol, 0.130 percent of dichloropropane, 0.085 percent of dichlorodiisopropyl ether and 0.015 percent of chloropropone.
Example 7
The reaction apparatus, the amount of feed and the control conditions were the same as in example 1, except that the reaction solution before the introduction of chlorine gas and propylene was a saponified waste solution. The saponified waste liquid was obtained by subjecting the 3.02 wt% chloropropanol aqueous solution obtained in example 1 and lime milk (calcium hydroxide emulsion) to saponification, separating propylene oxide from the saponified liquid, and was filtered to remove solid residues therefrom, and was analyzed to contain 18.5 wt% calcium chloride, 0.02 wt% calcium hydroxide, and 0.02 wt% propylene glycol (propylene oxide hydrolysate).
After the reaction is carried out for 200min by introducing gas, the contents of chloropropanol and main impurities in the reaction liquid are measured, and the results are as follows:
2.98 wt% of chloropropanol, 0.19 wt% of dichloropropane, 0.095 wt% of dichlorodiisopropyl ether, 0.013 wt% of chloropropone and no propylene glycol.
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.