KR20090026381A - Process for the chlorine by oxidation of hydrogen chloride - Google Patents

Abstract

A method for manufacturing chlorine is provided to maintain activity of a catalyst for a long reaction time. A method for manufacturing chlorine includes a step for dipping a cerium compound in a carrier and a step for oxidizing hydrogen chloride into gas containing oxygen by using the cerium compound as a catalyst. The cerium compound is a cerium oxide. The catalyst is made by oxidizing the cerium compound after dipping the cerium compound in the carrier. The rate of the carrier is 1~10 weight%. Size of the cerium compound is 100nm~100mum.

Description

Process for producing chlorine by low temperature catalytic oxidation of hydrogen chloride {Process for the Chlorine by Oxidation of Hydrogen Chloride}

The present invention relates to a method for producing chlorine by reacting a gas containing hydrogen chloride and oxygen under a cerium-based catalyst in the decomposition of hydrochloric acid to produce chlorine.

Chlorine is used in the manufacture of various compounds, and the demand is increasing, while the use of hydrochloric acid (liquid) or hydrogen chloride (gas) generated as a by-product of chlorination reaction is insufficient, so much effort and cost are required for disposal. This is happening, and production is also increasing. In Korea, most of hydrochloric acid and hydrogen chloride are produced and sold in aqueous solution (20% or 35% hydrochloric acid) except for the reaction of producing VCM by reacting hydrogen chloride with ethylene in an OxyChlorination reactor and discarded after neutralization treatment.

This treatment is not only an economic loss, but also an environmental problem. Therefore, converting and using hydrochloric acid, which is a by-product of a large amount in the chlorination industry, to chlorine with a high demand in Korea, can not only increase the production of chlorine without affecting the supply and demand of caustic soda produced during electrolysis, but also by-product hydrochloric acid. It is a way to proactively cope with the cost burden and environmental problems.

At home and abroad, a method for recovering chlorine from by-product hydrogen chloride has been studied for a long time as one of the effective methods to solve the imbalance between chlorine production and hydrogen chloride generation. Among them, the method of producing chlorine by catalytic oxidation method of hydrogen chloride was started by Deacon, and various methods applying this process have been studied, and some of them have been advanced to the practical stage. The core of the technology for producing chlorine from hydrogen chloride by oxidation is the selection and performance of catalysts.

The reaction for producing chlorine by oxidizing hydrogen chloride for the first time has been widely known from the name of the early inventors as "Deacon Process". The Deacon process, which is a catalytic oxidation method using CuCl ₂ as a catalyst, was not commercialized due to the problem of device design due to volatilization of catalyst components and the treatment of corrosive materials at high temperature due to the reaction temperature of 450 ~ 500 ° C. . Based on this process, various catalytic oxidation methods have been studied as follows. The MT-Chlor method is a method for producing chlorine using a chromium-silica fluid bed catalyst. The Kel-Chlor method is a method of producing chlorine by a non-contact oxidation method developed by Kellog, in which sulfuric acid is used as a circulating catalyst with nitrogen oxide as a catalyst. The Shell-Chlor method is an improvement of the catalytic oxidation method using the copper oxide catalyst invented by Deacon in 1868, and is a chlorine production method developed by Shell in the 1960s. Do.

Although several catalysts and processes have been reported to improve the copper catalyst, which is the Deacon catalyst (US Patent No. 2418930, US Patent No. 2418931, US Patent No. 4119705, Japanese Laid-Open Patent No. 53-125989, etc.) and the reaction temperature is 400 ° C. There was a limit above.

Iron-based catalysts have also been proposed (US Pat. No. 2577808), but also have a short lifespan due to high reaction temperatures of 400 ° C. or higher.

Although a chromium-based catalyst using chromium oxide as a catalyst to replace the copper-based or iron-based catalyst has been proposed (British Patent 676667), despite the high hydrogen chloride conversion of 60-75%, the chromium-based catalyst also has a reaction temperature of 400 ° C or higher. Due to the short life of the catalyst does not solve the problem.

The MT-Chlor catalyst of dichromium trioxide, collectively referred to as the MT-Chlor method, has been proposed (Japanese Patent Laid-Open Nos. 62-153103, 62-191403, 62-241805, 62-275001, Republic of Korea Patent Registration 10-0032752), chloride A dichromium trioxide catalyst with cerium added has been proposed (Korean Patent Laid-Open Patent Publication No. 1999-0000001), but it does not solve the activity and lifetime problems of the catalyst, and the production of the catalyst has a complicated problem.

Sumitomo's currently commercially reported method for producing chlorine by hydrogen chloride oxidation (Japanese Patent Laid-Open No. 95-119866, Japanese Patent Laid-Open No. 95-157959, Korean Patent No. 10-0424502) uses a highly active ruthenium oxide catalyst. To produce chlorine at a lower reaction temperature with a smaller amount of catalyst. The main focus of this technology is to use the ruthenium-based catalysts (ruthenium oxide, ruthenium complex oxide) in the oxidation process, and take advantage of the high activity of ruthenium to oxidize using a small amount of catalyst at a low temperature of 300 ° C. To react.

Mitsui Toaz Chemical also uses copper chloride, potassium chloride, chromium oxide, and ruthenium oxide as catalysts to make two reaction zones and a heat exchange system. The possibility of commercialization was mentioned by presenting in detail (US Patent Publication 94-278804, US Patent Publication 95-226090, US Patent Publication 95-228749, Korean Patent Publication 1996-0016957, International Patent Publication 88-00171, Korean Patent Publication 1988). -0701212).

However, the catalyst having low reaction temperature and being commercially available uses ruthenium, which is an expensive platinum group element, as a catalyst, and has a low temperature stability, causing an increase in the cost of producing chlorine, which is a barrier to commercialization.

In addition, most of the catalysts mentioned in the prior art show high activity at high temperatures, but show a phenomenon in which the performance of the catalyst decreases within several months during high temperature operation. The present invention is a more stable and durable in the reaction conditions as an oxidation reaction catalyst in the process of decomposing hydrogen chloride to produce chlorine in order to solve such a conventional problem, cerium is significantly cheaper than conventional platinum-based oxidation catalyst The present invention relates to a process using cerium oxide.

The present invention has a low reaction temperature in order to solve the above-mentioned problems of the prior art, high activity, high stability of the catalyst to maintain the activity of the catalyst even for a long reaction time, excellent economic efficiency of the chlorine using a new catalyst To provide a manufacturing method.

The present invention is characterized in that a cerium compound is used as a catalyst in a method of producing chlorine by oxidizing hydrogen chloride into an oxygen-containing gas.

The cerium compound is preferably cerium oxide, cerium complex oxide, or a mixture thereof, and the cerium compound is cerium acetate, cerium ammonium nitrate, cerium ammonium sulfate, cerium carbide, cerium carbonate, cerium chloride, cerium nitrate, cerium nitrate, cerium perchlorate, cerium sulfide, or mixtures thereof It is preferable.

The cerium compound is cerium acetate, cerium ammonium nitrate, cerium ammonium sulfate, cerium carbide, cerium carbonate, cerium chloride chloride), cerium nitrate, cerium perchlorate, cerium sulfide or an oxide of a mixture thereof.

The cerium compound is most preferably cerium oxide.

The catalyst is preferably prepared by supporting the cerium compound on a carrier or the catalyst is prepared by supporting the cerium compound on a carrier and then oxidizing the supported cerium compound.

The supporting ratio of the cerium compound to the carrier is preferably 1 to 10% by weight.

The cerium compound is preferably a particle having a size of 100nm to 100㎛.

The catalyst uses the cerium compound as the main catalyst, and may be used as a crude catalyst by using at least one metal selected from the platinum group or at least one metal compound selected from the platinum group. The crude catalyst is preferably 1 to 50% by weight based on the mass of the total catalyst.

Chlorine is produced at a temperature of 250 to 400 ° C. under the cerium-based catalyst (the catalyst using the cerium compound described above).

The cerium-based catalyst used in the chlorine production method of the present invention has a low reaction temperature of less than 400 ℃, high activity, high stability of the catalyst, the activity of the catalyst is maintained even for a long reaction time, and the economical advantages are excellent have.

The core of the present invention is to use a cerium compound as a catalyst in the process of producing chlorine by oxidizing hydrogen chloride into an oxygen-containing gas.

Hereinafter, the core idea of the present invention will be described in detail based on examples. At this time, if there is no other definition in the technical terms and scientific terms used, those having ordinary skill in the technical field to which the present invention has a meaning commonly understood, the following description may unnecessarily obscure the subject matter of the present invention. Descriptions of known functions and configurations are omitted.

The present invention relates to a catalyst that can be used economically in the commercialization reaction for producing chlorine by gas phase reaction of hydrogen chloride using a catalytic reactor, in particular, to suppress the reduction of catalyst activity due to a relatively exothermic reaction.

The reaction of the gaseous hydrogen chloride and oxygen in the catalytic reactor can be represented by the following reaction formula 1.

4HCl + O ₂ ↔ 2Cl ₂ + 2H ₂ O --------------------------- (1)

As shown in Scheme 1, the theoretical molar ratio is 1 mole of oxygen to 4 moles of hydrogen chloride, and since the reaction is exothermic, the production of chlorine at the lowest temperature at which the catalyst has satisfactory activity suppresses the catalyst damage. It is also economically advantageous.

The cerium compound is preferably cerium oxide, cerium complex oxide, or a mixture thereof, and the cerium compound is cerium acetate, cerium ammonium nitrate, cerium ammonium sulfate, cerium carbide, cerium carbonate, cerium chloride, cerium nitrate, cerium nitrate, cerium perchlorate, cerium sulfide, or mixtures thereof It is preferable.

The cerium compound is cerium acetate, cerium ammonium nitrate, cerium ammonium sulfate, cerium carbide, cerium carbide, cerium carbonate, cerium chloride , Cerium nitrate, cerium perchlorate, cerium sulfide, or an oxide of a mixture thereof.

The cerium compound is most preferably cerium oxide.

The cerium compound of the present invention can be prepared by a known method, or a commercially available cerium compound can also be used. As the method for preparing the cerium composite oxide, a coprecipitation method, a dispersion method (dispersion and heat treatment), an impregnation method, or the like may be used.

For use as a catalyst, the cerium compound may be prepared in the form of granules composed of particles having a size of 100 nm to 100 μm or granules of the above size, and filled in a reactor, and may be supported on a carrier.

When the cerium compound is cerium oxide or cerium complex oxide, the catalyst may be prepared by supporting the carrier, or when the cerium compound is not an oxide of cerium, the supported cerium compound is supported after supporting the cerium compound on the carrier. It may be prepared by oxidation. Preferably cerium acetate, cerium ammonium nitrate, cerium ammonium sulfate, cerium carbide, cerium carbonate, cerium chloride, Cerium nitrate, cerium perchlorate, cerium sulfide, or a mixture thereof is supported on a carrier and then oxidized to a temperature of 450 to 1300 ° C. in an oxygen-containing atmosphere to form a catalyst for cerium oxide. It is preferable to prepare.

The carrier may be a carrier used in the commercialization reaction for producing chlorine by gas phase reaction of hydrogen chloride, preferably titanium oxide, alumina, silica, zirconium oxide, zeolite, titanium composite oxide, zirconium composite oxide, aluminum Composite oxides and silicon composite oxides can be used.

Preferably, the carrier is formed with pores, and an impregnation method or an equilibrium adsorption method may be used as a method of supporting a cerium compound on the support.

The supporting ratio of the cerium compound to the carrier is preferably 1 to 10% by weight. This is the optimum condition for maintaining the activity of the catalyst while minimizing the reduction of the specific surface area of the carrier.

The cerium compound is preferably a particle having a size of 100nm to 100㎛. This is to maintain high temperature stability of the cerium compound, to prevent excessive overheating due to the exothermic reaction, which is a chlorine reaction, and to increase the surface area of the catalyst as much as possible to obtain a high conversion rate (chlorine production rate). The cerium compound having a size of 100 nm to 100 μm may be supported on a carrier, or the particles may be filled in a reaction tube and used as a catalyst.

The particle size control of the cerium compound may be controlled through pulverization and sieving of a commercially available cerium compound, and may be controlled by applying heat treatment temperature and time after synthesis, and by adjusting the synthesis condition itself.

As the catalyst, the cerium compound is used as the main catalyst, and at least one metal selected from the platinum group or a metal compound of the platinum group metal may be used as a crude catalyst. The crude catalyst is added to increase the activity of the cerium compound is preferably 1 to 50% by weight based on the mass of the total catalyst.

Under the cerium-based catalyst (catalyst using the above-described cerium compound) is characterized in that the chlorine is produced at a relatively low temperature of 250 to 400 ℃, preferably the chlorine is prepared at a temperature of 300 to 350 ℃ There is a characteristic.

(Example 1)

The reactor was a glass product having an inner diameter of 1 ", and the reactants, hydrogen chloride gas and oxygen gas, were supplied into the reactor at a molar ratio of 1: 1. The flow rates of the reactants were supplied at 25 ml / min, respectively, Cerium oxide having a particle size of 10 μm (Ceriun Oxide, manufactured by Hanwha Chemical, product number CED30S) was charged to a density of 0.4 g / cm ³ The length of the reactor was 20 cm, and the temperature of the reactor was maintained at 350 ° C. The gas (reactant) required for the reaction was supplied, and after 2 hours after the start of the reaction, the generated gas was collected and analyzed by Orsat method.

The length and reaction temperature of the reactor were the same as in Example 1 except 20 cm and 300 ° C. (Example 2), 30 cm and 350 ° C., 50 cm and 350 ° C. (Example 3), 100 cm and 350 ° C. (Example 4). The reaction was carried out.

The results after performing the reactions of Examples 1 to 4 are summarized in Table 1 below.

Conversion was calculated by comparing the amount of chlorine gas resulting from the amount of unreacted hydrogen chloride gas. At this time, the reaction conversion rate (%) = (amount of generated chlorine gas * 2) / (amount of hydrogen chloride gas before the reaction) * 100.

Table 1

(Example 5)

A 1 "inner diameter, 100 cm long reactor was charged with a cerium oxide of Example 1 at a density of 0.4 g / cm ^3. The catalyst was charged and the reactant hydrogen chloride gas and oxygen gas were fed into the reactor at a 1: 2 molar ratio. The flow rate of hydrogen chloride gas: oxygen gas supplied was 25:50 ml / min, and the reactor temperature was maintained at 350 ° C.

Hydrogen chloride gas: Same as Example 5 except that the flow rate of the oxygen gas and the temperature of the reactor were 17:34 ml / min and 300 ° C (Example 6), 17:34 ml / min and 350 ° C (Example 7) The reaction was carried out under conditions.

2 hours after the start of the reaction of Examples 5 to 7, the generated gas was collected and analyzed by the Orsat method, and the result of analyzing the gas collected after the reaction was summarized in Table 2 below.

Table 2

(Example 8)

Except that the temperature of the reactor was maintained at 400 ℃ reaction was carried out for 100 hours under the same conditions as in Example 5 to confirm the change in activity by analysis of the reaction gas (conversion rate of 2 hours 53.5%, conversion rate of 100 hours reaction) 52.7%), the X-ray diffraction analysis of the catalyst used after 100 hours of reaction with the unused catalyst is shown in FIG. As shown in FIG. 1, it was confirmed that the structure of the catalyst used during the reaction time of 100 hours at a high temperature of 400 ° C. was not changed.

Examples 1 to 8 are obtained by using only pure cerium oxide as a catalyst, the chlorine production method using the cerium-based catalyst of the present invention has a high conversion rate of 60% or more at a temperature of 400 ℃ or less, high temperature conditions of 400 ℃ In addition, the activity of the catalyst is not lowered, it can be seen that it maintains a stable structure, and with the activity and high temperature stability, it can be seen that there is an economic advantage because it does not use the platinum-based element.

As mentioned above, although preferred embodiment of this invention was described in detail with reference to an Example, this invention is not limited to the said embodiment, The person of ordinary skill in the art within the technical idea and the scope of the present invention is understood. Many variations and modifications are possible.

1 is an X-ray diffraction result of cerium oxide before and after the reaction of Example 8 of the present invention.

Claims (11)

A method of producing chlorine, wherein a cerium compound is used as a catalyst by oxidizing hydrogen chloride with an oxygen-containing gas to produce chlorine. The method of claim 1, The cerium compound is cerium oxide (Cerium Oxide) method for producing chlorine characterized in that. The method of claim 1, The cerium compound is cerium acetate, cerium ammonium nitrate, cerium ammonium sulfate, cerium carbide, cerium carbonate, cerium chloride, cerium chloride , Cerium nitrate, cerium perchlorate, cerium sulfide, or a mixture thereof. The method of claim 2, The cerium compound is cerium acetate, cerium ammonium nitrate, cerium ammonium sulfate, cerium carbide, cerium carbonate, cerium chloride ), Cerium nitrate, cerium perchlorate, cerium sulfide, or a mixture thereof. The method of claim 1, The catalyst is a method for producing chlorine, characterized in that prepared by supporting the cerium compound on a carrier. The method of claim 4, wherein The catalyst is prepared by oxidizing the supported cerium compound after the support of the cerium compound on a carrier. The method of claim 5, The support ratio of the cerium compound to the support is chlorine production method, characterized in that 1 to 10% by weight. The method of claim 1, The cerium compound is a method for producing chlorine, characterized in that the particles having a size of 100nm to 100㎛. The method of claim 1, The catalyst is a method for producing chlorine, characterized in that the cerium compound is used as the main catalyst, and at least one metal selected from the platinum group or at least one metal compound selected from the platinum group is used as a crude catalyst. The method of claim 9, The crude catalyst is a method for producing chlorine, characterized in that 1 to 50% by weight based on the mass of the total catalyst. The method according to any one of claims 1 to 10, Chlorine production method characterized in that the chlorine is produced at a temperature of 250 to 400 ℃.

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