WO2008002197A1 - Chlorine producing method - Google Patents

Abstract

The inventive chlorine producing method consists in continuously supplying a gaseous mixture containing hydrogen chloride and oxygen at a pressure ranging from 1.1 to 5.0 bars, in transferring said gaseous mixture into a low-temperature plasma state in a flowing reaction area by the action of impulse electric charge, in oxidising hydrogen chloride by oxygen in the thus obtained low-temperature plasma, in removing the gaseous mixture containing the oxidation product from the reaction area, in condensing said mixture and in giving off a target product from the thus condensed water.

Description

 The method of producing chlorine

Technical field

The claimed invention relates to a method for producing chlorine in the gas-phase oxidation of hydrogen chloride.

State of the art

Currently, two methods for producing chlorine from hydrogen chloride are mainly used in industry - electrolysis of an aqueous solution of hydrogen chloride and various variants of its catalytic oxidation. When implementing a method based on the electrolysis of an aqueous solution of hydrogen chloride, large-sized, complex equipment and high energy costs are required. All known catalytic methods are implemented at high temperatures (of the order of 450-500 degrees C) and, accordingly, require large expenditures of thermal and electric energy, expensive catalysts, and complex equipment operating under severe conditions.

A known method of producing chlorine in the absence of a catalyst in the process of gas-phase oxidation of hydrogen chloride by atmospheric oxygen by continuously supplying a gaseous mixture containing hydrogen chloride and oxygen to the flowing reaction zone. The process of oxidation of hydrogen chloride with oxygen with the formation of the target product is carried out in the zone of electrical impulse discharges created at a voltage of 10-40 kV (RU, 1801943 Al, valid 15.03.1993, IPC: COlB 7/04). The specified method allows the oxidation process in the absence of a catalyst. However, under the conditions of this method, the generation of active particles and chemical transformations occur under the influence of an extremely short-term electric discharge, which leads, in particular, to the achieved insufficiently high conversion of hydrogen chloride, which is 25%, and in the best case is 74%, which makes the named method practically unsuitable for industrial use. Disclosure of invention

The basis of the claimed invention is the task of creating conditions for a stable and continuous process of oxidation of hydrogen chloride to create such a method for producing chlorine, which would increase the degree of conversion of hydrogen chloride with high technological stability of the feasibility of the method.

This problem is solved when creating a method for producing chlorine by continuously supplying a gaseous mixture containing hydrogen chloride and oxygen to a flowing reaction zone and oxidizing hydrogen chloride with oxygen to form the target product, in which, according to the invention, a gaseous mixture is supplied at a pressure of 1.1 to 5.0 bar and transfer the gaseous mixture to a state of low-temperature plasma by exposure to pulsed electric discharge and is carried out in an environment formed by a low-temperature LASMA oxidation of hydrogen chloride with oxygen, after which the gaseous mixture containing the oxidation product is withdrawn from the reaction zone is condensed and separated the desired product from the condensed water.

Thanks to the invention, it has become possible in a technologically stable process suitable for industrial applications to achieve almost 100% conversion of hydrogen chloride.

According to the invention, it is advisable to use a microsecond streamer discharge as a pulsed electric discharge, generated at an accelerating voltage of at least 150 kV, pulse energy of at least 1.25 J, pulse repetition rate of not more than 10 kHz, pulse duration of not more than 10 microseconds, discharge current at least 80 A, or use a flash corona discharge generated at an accelerating voltage of 10 kV to 150 kV, an energy per pulse of at least 1.25 J, a pulse repetition rate of not more than 10 kHz, a pulse duration of not more e 10 microseconds, a discharge current is not less than 10 mA, or as a pulsed electric discharge by using a discharge forming unfocused an electron beam with an accelerating voltage of 150 kV, an energy per pulse of 1.75 J, and a pulse repetition rate of not more than 25 kHz.

Further objectives and advantages of the claimed invention will become apparent from the following detailed description of the method for producing chlorine and specific examples of the implementation of this method.

The best embodiment of the invention

The method of producing chlorine, as claimed in the present invention, is based on the use of gaseous hydrogen chloride as a chlorine-containing raw material for the recovery of chlorine.

The inventive method for producing chlorine is that a gaseous mixture containing hydrogen chloride and oxygen is continuously fed at a pressure of from 1.1 to 5.0 bar into the flowing reaction zone.

In the reaction zone, the gaseous mixture is partially or completely converted to ionized gas, that is, it is converted to a low-temperature plasma by exposure to a pulsed electric discharge, for example, a microsecond streamer discharge, a discharge forming an unfocused electron beam, a flash corona discharge, a surface-barrier discharge, and smoldering discharge of atmospheric pressure.

To implement a pulsed electric discharge, an electric accelerating voltage of 10 kV to 200 kV is performed, the pulse energy is not less than 1.25 J, the pulse repetition rate is not more than 100 kHz, the pulse duration is not less than 100 nanoseconds, the discharge current is not less than 10 mA.

More specifically, in order to transfer the gaseous mixture to a state of low-temperature plasma, according to the invention, it is advisable to use a microsecond streamer discharge generated at an accelerating voltage of at least 150 kV, pulse energy of at least 1.25 J, pulse repetition rate of not more than 10 kHz, pulse duration of not less than 100 nanoseconds, discharge current of not less than 80 A. Or it is advisable to use a flash corona discharge formed at accelerating voltage from 10 kV to 150 kV, pulse energy not less than 1.25 J, pulse repetition rate not more than 10 kHz, pulse duration not more than 10 microseconds, discharge current not less than 10 mA.

It is also possible to use a discharge forming an unfocused electron beam at an accelerating voltage of 150 kV, an energy per pulse of 1.75 J, and a pulse repetition rate of not more than 25 kHz.

It is also advisable to use a surface-barrier discharge generated at an accelerating voltage of at least 150 kV, pulse energy of at least 1, 25 J, pulse repetition rate of not more than 10 kHz, pulse duration of not less than 100 nanoseconds, discharge current of not less than 80 A. It is also advisable to use a glow discharge of atmospheric pressure generated at an accelerating voltage of 10 kV to 50 kV, an energy per pulse of at least 1.25 J, a pulse repetition rate of not more than 10 kHz, a pulse duration of not more than 10 microseconds, and a discharge current of at least 10 mA.

In an environment of low-temperature plasma formed in the above manner, hydrogen chloride is oxidized with oxygen.

Thus, the formation of the target product occurs, in accordance with the inventive method, from a gaseous mixture in a state of low temperature plasma.

The gaseous mixture containing the oxidation product is continuously withdrawn from the reaction zone, condensed and the desired product is isolated from condensed water.

In accordance with the claimed method, the achievement of a technologically stable process suitable for industrial use and the achievement of almost 100% conversion of hydrogen chloride became possible when organizing the process of producing chlorine, mainly by a radical chain branched reaction mechanism. To implement such a reaction mechanism, high concentration of active centers, namely free radicals, ions, excited molecules and atoms, are created and maintained during the entire process of oxidation of gaseous hydrogen chloride with oxygen. In the environment of a low-temperature plasma formed in the inventive modes, according to the claimed method, the following factors are created for the action of hydrogen chloride gas: free electrons, ions, excited neutral molecules and electromagnetic radiation in a wide range.

Under the action of the claimed pulsed electrical discharges in a gaseous medium chemically active particles are generated - free radicals, ions, excited molecules. The result of this effect is also the excitation of vibrational, rotational and electronic levels of molecules and atoms of the medium.

The processes of dissociation, recombination, and redistribution of energy as a result of various types of interaction (collisions, absorption of radiation, reradiation) ultimately lead to the decomposition of hydrogen chloride and oxygen molecules, the formation of a high concentration of active centers and the formation of chlorine and water.

To implement the aforementioned pulsed electrical discharges, it is possible to use well-known equipment. For example, it is possible to use a plasma-chemical reactor, a generator of high-voltage pulses from nanosecond to microsecond duration, and a frequency electron accelerator can be used to output an unfocused electron beam into the gas medium.

Thanks to the claimed method, a high percentage conversion of the mixture to chlorine and water vapor is achieved. To suppress the hydrolysis of chlorine formed, the gas-vapor mixture is subjected to cooling in a condenser to 2-3 degrees. C. At the same time, the bulk of the water is separated.

Thus, the inventive method is feasible in the absence of catalysts, does not require the use of high temperatures - feasible at ambient temperature, has high reliability and consistently good technological performance.

For a better understanding of the present invention, the following examples of its specific implementation. Example 1

Hydrogen chloride in an amount of 5.15 kg / h and oxygen in an amount of 1.13 kg / h are sent to the preliminary mixing chamber at a temperature of 20 degrees C, after which it is continuously fed at a pressure of 1.2 bar into the reaction zone of the plasma chemical reactor.

In the reaction zone in the medium of the indicated gaseous mixture at an accelerating voltage of 200 kV, an energy of 1.75 J per pulse, and a pulse repetition rate of 25 kHz, an unfocused electron beam from the electron frequency accelerator assembled according to the thyratron-pulse transformer-semiconductor current chopper scheme is formed.

At a pressure of 1.2 bar, under the influence of an unfocused electron beam, the gaseous mixture completely turns into an ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water.

The composition of the reaction products: chlorine - 5.0 kg / h, water - 1.27 kg / h.

Example 2

Hydrogen chloride in an amount of 10.3 kg / h and oxygen in an amount of 2.26 kg / h are sent to the preliminary mixing chamber at a temperature of 20 degrees C, after which they are fed into the streamer discharge zone created in the generator of high-voltage pulses of nanosecond duration - operating voltage generator no less than 150 kV, pulse duration 500 nanoseconds.

Under the influence of the indicated streamer discharge, the gaseous mixture partially or completely turns into an ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zones are subjected to condensation in a capacitor-phase separator and the target product is isolated from condensed water.

The composition of the reaction products: chlorine - 10.0 kg / h, water - 2.54 kg / h.

Example 3

Hydrogen chloride in an amount of 5.15 kg / h and oxygen in an amount of 1.13 kg / h are fed into the pre-mixing chamber at a temperature of 20 degrees C. The formed reaction gaseous mixture is then continuously directed at a pressure of 1.2 bar through the annular collector to the reaction zone of the plasma chemical reactor into the zone of streamer discharges created by the high-voltage pulse generator at a discharge current of 80 A, voltage of 150 kV, pulse energy of 1.75 J, and repetition rate pulses up to 10 kHz.

In a flowing reaction zone at a pressure of 1.2 bar, the gaseous mixture is partially or completely converted to ionized gas, that is, the gaseous mixture is transferred to a low-temperature plasma state. Under the influence of the indicated streamer discharges, the gaseous mixture partially or completely turns into an ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water.

The composition of the reaction products: chlorine - 5.0 kg / h, water - 1.27 kg / h.

Example 4

Hydrogen chloride in an amount of 52.425 kg / h and oxygen in an amount of 11.475 kg / h are fed into the preliminary mixing chamber at a temperature of 20 degrees C. The resulting reaction gas mixture is then continuously fed through a ring manifold to a reaction zone at a pressure of 1.6 bar. plasma-chemical reactor into the zone of flare corona discharges created by a high-voltage pulse generator at a discharge current of 10 mA, voltage of 100 kV, pulse repetition rate up to 10 Hz, pulse duration not more than 10 microseconds.

In a flowing reaction zone at a pressure of 1.6 bar, the gaseous mixture is partially or completely converted to ionized gas, that is, the gaseous mixture is transferred to a low-temperature plasma state.

Under the influence of these flare corona discharges, the gaseous mixture partially or completely turns into an ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water. The composition of the reaction products: chlorine - 49.96 kg / h, water - 12.62 kg / h.

Example 5

Hydrogen chloride in an amount of 52.425 kg / h and oxygen in an amount of 11.475 kg / h are fed into the preliminary mixing chamber at a temperature of 20 degrees C. The formed reaction gaseous mixture is then continuously directed through a ring collector to a reaction zone of a plasma chemical reactor into a flash corona discharge zone created by a high-voltage pulse generator with a discharge current of 12 mA, voltage of 150 kV, and a pulse repetition rate of up to lkHz.

In a flowing reaction zone at a pressure of 4.8 bar, the gaseous mixture is completely converted to ionized gas, that is, the gaseous mixture is transferred to a low-temperature plasma state.

Under the influence of these flare corona discharges, the gaseous mixture is completely converted into ionized gas and acquires the state of a low-temperature plasma. In a medium of low temperature plasma, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water. The composition of the reaction products: chlorine - 48.76 kg / h, water - 11.22 kg / h.

Example 6

Hydrogen chloride in an amount of 5.15 kg / h and oxygen in an amount of 1.13 kg / h are sent to the preliminary mixing chamber at a temperature of 20 degrees. C, after which it is continuously fed at a pressure of 5.0 bar to the reaction zone of the plasma chemical reactor.

In the reaction zone in the environment of the indicated gaseous mixture at an accelerating voltage of 150 kV, an energy of 1.97 J per pulse, and a pulse repetition rate of 25 kHz, an unfocused electron beam from an electron frequency accelerator assembled according to the thyratron-pulse transformer-semiconductor current chopper scheme is formed.

At a pressure of 5.0 bar, under the influence of an unfocused electron beam, the gaseous mixture partially or completely turns into an ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water.

The composition of the reaction products: chlorine - 5.0 kg / h, water - 1.27 kg / h.

Example 7

Hydrogen chloride in the amount of 10.3 kg / h and oxygen in the amount of 2.26 kg / h are sent to the preliminary mixing chamber at a temperature of 20 degrees C, after which it is supplied at a speed of 100 m / s to the glow discharge zone created by the high-voltage pulse generator nanosecond duration - the operating voltage of the generator is at least 30 kV, the pulse duration is 500 nanoseconds. Under the influence of the indicated glow discharge, the gaseous mixture partially or completely turns into an ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water.

The composition of the reaction products: chlorine - 10.0 kg / h, water - 2.54 kg / h.

Example 8

Hydrogen chloride in an amount of 5.15 kg / h and oxygen in an amount of 1.13 kg / h are fed into the pre-mixing chamber at a temperature of 20 degrees C. The formed reaction gaseous mixture is then continuously directed at a pressure of 1.2 bar through the annular collector into the reaction zone of the plasma chemical reactor to the surface-barrier discharge zone created by the high-voltage pulse generator at a discharge current of 80 A, voltage of 50 kV, pulse energy of 1.75 J, pulse repetition rate up to 10 Hz.

In a flowing reaction zone at a pressure of 1.2 bar, the gaseous mixture is partially or completely converted to ionized gas, that is, the gaseous mixture is transferred to a low-temperature plasma state. Under the influence of the indicated surface-barrier discharge, the gaseous mixture partially or completely turns into an ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water.

The composition of the reaction products: chlorine - 5.0 kg / h, water - 1.27 kg / h. Example 9

Hydrogen chloride in an amount of 52.425 kg / h and oxygen in an amount of 11.475 kg / h are fed into the preliminary mixing chamber at a temperature of 20 degrees C. The formed reaction gaseous mixture is then continuously directed through a ring collector to a reaction zone of a plasma chemical reactor at a pressure of 1.6 bar into a zone of surface-barrier discharge created by a high-voltage pulse generator at a discharge current of 100 A, voltage of 50 kV, pulse repetition rate up to 10 Hz, pulse duration no less than 100 nanoseconds.

In a flowing reaction zone at a pressure of 1.6 bar, the gaseous mixture is partially or completely converted to ionized gas, that is, the gaseous mixture is transferred to a low-temperature plasma state.

Under the influence of the indicated surface-barrier discharge, the gaseous mixture partially or completely turns into an ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water. The composition of the reaction products: chlorine - 49.96 kg / h, water - 12.62 kg / h.

Example 10

Hydrogen chloride in an amount of 52.425 kg / h and oxygen in an amount of 11.475 kg / h are fed into the preliminary mixing chamber at a temperature of 20 degrees C. The formed reaction gaseous mixture is then continuously fed at a pressure of 4.8 bar at a speed of 200 m / s into the reaction zone of the plasma chemical reactor into the atmospheric pressure glow discharge zone created by the high-voltage pulse generator at a discharge current of 12 mA, voltage of 50 kV, and pulse repetition rate up to lkHz . In a flowing reaction zone at a pressure of 4.8 bar, the gaseous mixture is completely converted to ionized gas, that is, the gaseous mixture is transferred to a low-temperature plasma state.

Under the influence of these flare corona discharges, the gaseous mixture is completely converted into ionized gas and acquires the state of a low-temperature plasma. In a low-temperature plasma environment, hydrogen chloride is oxidized with oxygen, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, condensed in a condenser-phase separator, and the target product is isolated from condensed water. The composition of the reaction products: chlorine - 48.76 kg / h, water - 11.22 kg / h.

Industrial applicability

The invention will find application, in particular, in the disposal of abhase hydrogen chloride formed in organochlorine synthesis processes.

Claims

CLAIM 1. A method of producing chlorine by continuously supplying a gaseous mixture containing hydrogen chloride and oxygen to a flowing reaction zone and oxidizing hydrogen chloride with oxygen to form the target product, such as in a flowing reaction zone the gaseous mixture is supplied at a pressure of from 1.1 to 5.0 bar and the gaseous mixture is transferred to a state of low temperature plasma by exposure to pulsed electric discharge and oxidation of hydrogen chloride acid is carried out in the medium of the formed low temperature plasma hydrochloride, after which the gaseous mixture containing the oxidation product is removed from the reaction zone, subjected to condensation, and the target product is isolated from condensed water. 2. The method of producing chlorine according to claim 1, characterized in that a microsecond streamer discharge is used as a pulsed electric discharge, which is formed at an accelerating voltage of at least 150 kV, an energy of at least 1.25 J per pulse, and a pulse repetition rate of no more than 10 kHz , pulse duration not less than 10 microseconds, discharge current not less than 80 A. 3. The method of producing chlorine according to claim 1, characterized in that a flash corona discharge formed at an accelerating voltage of 10 kV to 150 kV, pulse energy of at least 1.25 J, and pulse repetition rate of not more than 10 kHz, pulse duration not more than 10 microseconds, discharge current not less than 10 mA. 4. The method of producing chlorine according to claim 1, characterized in that a pulse forming an unfocused electron beam at an accelerating voltage of 150 kV, an energy per pulse of 1.75 J, and a pulse repetition rate of not more than 25 kHz is used as a pulsed electric discharge. 5. The method of producing chlorine according to claim 1, characterized in that a surface-barrier discharge is used as a pulsed electric discharge, which is formed at an accelerating voltage of not more than 50 kV, pulse energy of not less than 1.25 J, pulse repetition rate of not more than 10 kHz, pulse duration not less than 100 nanoseconds, discharge current not less than 80 A. 6. The method of producing chlorine according to claim 1, characterized in that a atmospheric pressure glow discharge is used as a pulsed electric discharge, which is generated at an accelerating voltage of up to 50 kV, pulse energy of at least 1.25 J, and pulse repetition rate of not more than 10 kHz , pulse duration not more than 10 microseconds, discharge current not less than 10 mA.