KR20000014416A - Metal oxide catalyst for oxidizing volatile organic compound - Google Patents

Abstract

PURPOSE: The catalyst for oxidizing volatile organic compound is provided to compound the stable and various catalyst ingredients. CONSTITUTION: The catalyst for oxidizing volatile organic compound is composed of: 0.5¯5.0 wt% of manganese; magnesium 1.0¯10.0 wt%; cobalt 0.5¯10.0 wt%; iron 0.1¯7.0 wt%; copper 1.0¯10.0 wt%; nickel 0.1¯10.0 wt%; chrome 0.1¯5.0 wt%; vanadium 0.5¯15.0 wt%; zinc 0.1¯10.0 wt%; molybdenum 0.5¯5.0 wt%; titanium 0.1¯5.0 wt%; tungsten 0.1¯5.0 wt%; bismuth 0.5¯10.0 wt%; zirconium 0.1¯5.0 wt%; antimony 0.1¯5.0 wt%; cesium 0.5¯5.0 wt%; lanthanum 1.0¯12.0 wt%; silver 0.5¯15.0 wt% to the weight of a catalyst.

Description

Metal Oxide Catalysts for Oxidizing Volatile Organic Compounds

The present invention relates to a catalyst used to remove volatile organic compounds by vapor phase catalytic oxidation of a gas containing volatile organic compounds and air or oxygen. More specifically, manganese, magnesium, cobalt, iron, copper, nickel, chromium, vanadium, zinc, molybdenum, titanium, tungsten, bismuth, zirconium, antimony, supported or unsupported on a carrier such as alumina, silica, and zirconium And a catalyst having high activity using silver together with one or two or more mixed metal oxides of compounds such as cesium and lanthanum, are used to remove organic compounds by oxidation of volatile organic compounds.

The performance of the catalyst used to oxidize volatile organic compounds is substantially determined by the activity. Activity may be expressed at temperatures at which the concentration of volatile organic compounds at the outlet of the reactor is less than 5% under certain constant conditions (eg pressure, gas amount and catalyst amount). In other words, the lower the temperature required to oxidize more than 95% of volatile organic compounds, the higher the activity. When the activity is reduced, the reaction is maintained at a higher temperature to oxidize the volatile organic compound, thereby maintaining the same activity, which shortens the life of the catalyst and causes a cost increase.

Volatile organic compounds are generic terms of hydrocarbon compounds and are classified into general hydrocarbons such as aromatic hydrocarbons and aliphatic hydrocarbons (paraffinic and olefinic), and heterogeneous hydrocarbons containing nitrogen, oxygen, and halogen elements (eg, aldehydes, ketones, etc.). Particularly, volatile organic compounds may be directly harmful to the environment and health as the compounds themselves, such as aromatic hydrocarbons and halogenated hydrocarbons, or may participate in photochemical reactions in the atmosphere, such as aliphatic hydrocarbons, to generate secondary pollutants such as photochemical oxides. Olefin hydrocarbon compounds are well known for their high photochemical reactivity. These volatile organic compounds contain extremely irritating and unpleasant odors even at low concentrations, and have a profound effect on human bodies and ecosystems.

Catalytic oxidation (catalytic incineration) of volatile organic compounds is very similar to high temperature oxidation. The volatile organic compound-containing gas is collected, preheated and mixed, and then burned at a high temperature in a combustion chamber filled with a catalyst to convert the volatile organic compound into carbon dioxide and water. However, because the catalyst in the combustion chamber lowers the activation energy required for the combustion of volatile organic compounds, it is at a lower temperature than thermal incineration, and the device size can be much smaller. Catalysts used in the catalytic oxidation of volatile organic compounds include precious metals such as platinum or palladium and manganese, magnesium, cobalt, iron, copper, nickel, chromium, vanadium, zinc, molybdenum, titanium, tungsten, bismuth, zirconium, antimony, cesium, Metal oxides such as one or two or more mixed oxides of compounds such as lanthanum. The average lifetime of the catalyst is about 2 to 5 years. After that, the catalytic performance decreases rapidly due to clogging of pores of the catalyst or aging by heat. As a method of mounting the catalyst in the combustion chamber, a particulate catalyst is charged or a honeycomb type catalyst support is impregnated with the catalyst. In catalytic oxidation, it is necessary to determine the optimum operating conditions of the process because the composition of the off-gas and the operating conditions have a great effect on its performance. Catalytic oxidation is not effective due to a sharp decrease in catalytic activity in the exhaust gas containing lead, arsenic, sulfur, antimony, mercury, zinc or other catalyst derivatives. As it can be discarded, it is used to treat exhaust gases with low concentration of volatile organic compounds. In order to maintain the catalytic activity well, the temperature and pressure between the catalyst layers must be continuously measured and monitored. The increase in temperature of the catalyst layer indicates the degree of oxidation of the volatile organic compound. If the temperature decreases, the oxidation of the volatile organic compound is incomplete. Since excessive heat inactivates the catalyst, the inlet temperature into the catalyst bed must be kept low enough to maintain the catalytic activity. Catalytic oxidation usually operates at an oxidation temperature in the range of 260 to 480 캜. The pressure drop of the catalyst layer also indicates the performance of the catalyst. When the pressure drop decreases, it means that the catalyst is released to the outside together with the exhaust gas. As a result, the ability to remove volatile organic compounds decreases. Therefore, in order to prolong the life of the catalyst, it is necessary to periodically remove the inert materials or fine particles on the catalyst. In order to clean the catalyst, air or steam is passed through the catalyst layer to remove fine particles from the catalyst, or volatile organic compounds that inhibit the catalytic activity by heating clean air above the operating temperature at the time of catalytic oxidation. Oxidize and clean the catalyst. Alternatively, the catalyst can be treated with an acid or basic solution to remove chemical inerts.

Catalytic oxidation of volatile organic compounds in the air is carried out in a reactant concentration lower than 1000 ppm and in a high excess oxygen atmosphere. Since oxidation is a very high exothermic reaction and industrially these reactions are carried out in high concentrations of reactants, these processes are net producers of heat. At low reactant concentrations the process is a net consumer of heat if the entire gas stream has to be heated to a higher temperature. And heating the entire gas stream to high temperatures (> 400 ° C.) to achieve high reaction rates is very expensive. As a result, it is more economical to carry out catalytic oxidation of trace amounts of volatile organic compounds if they are carried out at low temperatures. This requires a highly active and non-selective catalyst.

The metal oxide catalyst is composed of one or more mixed metal oxides of compounds such as manganese, magnesium, cobalt, iron, copper, nickel, chromium, vanadium, zinc, molybdenum, titanium, tungsten, bismuth, zirconium, antimony, cesium, and lanthanum. Mainly used. These oxides are less volatile organic compounds in oxidation activity than the supported precious metals. However, metal oxides are more resistant to catalyst poisons due to the high active surface area of metal oxides compared to noble metal catalysts.

Precious metal catalysts are mainly platinum, palladium, silver and gold. These precious metals are usually used by alloying with ruthenium, rhodium, osmium and iridium supported on oxide supports such as alumina, silica and zirconium. In practice, however, only platinum, palladium and alloys are used because the temperatures applied to most oxidation catalysts are the sintering and volatilization losses of metals and the irreversible reaction of other metals. And these precious metals have led to the need for inexpensive metal oxide catalysts as in the present invention due to their high cost.

The core of catalytic oxidation technology lies in catalysts. Currently used catalysts are noble metal catalysts such as platinum and palladium, which have a very high effect on the oxidation of volatile organic compounds, but the cost is very expensive and deactivation of catalysts by poisonous substances Since the phenomenon is clear, it is necessary to develop a metal oxide catalyst which has similar performance to a noble metal catalyst and has a relatively high resistance to poisoning substances and can be manufactured at a low price. However, since metal oxides have lower activity on volatile organic compounds than noble metals, the development of useful catalysts is not simple, and there are considerable difficulties in the search for desired catalysts and the characterization of them.

Catalysts used for the oxidation and removal of volatile organic compounds are very harsh. That is, the reaction conditions are very demanding, such as a wide reaction temperature range (room temperature to 700 ° C), extremely low concentrations of reactants (in ppm), high concentrations of coexisting gases (usually air and oxygen), large flow rates, and occasional variations in reaction conditions. In addition, in the case of the synthesis reaction, the reaction conditions may be adjusted to the developed catalyst, but in the case of oxidation removal of the volatile organic compound, the difficulty is further increased because the catalyst must be adapted to the conditions of the emission site of the volatile organic compound.

Therefore, the catalyst required to oxidatively remove volatile organic compounds should have a catalytic requirement that has a high degree of complete oxidation activity at low temperatures, a wide use temperature range, a strong catalyst poison, a long life, and a regeneration in a relatively easy manner. However, in the catalytic oxidation and removal of volatile organic compounds, noble metal catalysts such as platinum and palladium have high complete oxidation activity but have low resistance to poisoning substances, and therefore, there are many restrictions on use of poisonous substances contained in extremely small amounts of volatile organic compounds emitted. However, metal oxide catalysts have lower activity than noble metal catalysts, but are more stable against catalyst poisons due to the large active surface area of metal oxides, and have the advantage of complexing various catalyst components. Developed a metal oxide catalyst.

The present invention relates to a catalyst used to remove volatile organic compounds by vapor phase catalytic oxidation of a gas containing volatile organic compounds and air or oxygen, and replaces expensive supported noble metal catalysts on alumina, silica and zirconium carriers. Impregnating a small amount of silver with one or more mixed oxides of compounds such as manganese, magnesium, cobalt, iron, copper, nickel, chromium, vanadium, zinc, molybdenum, titanium, tungsten, bismuth, zirconium, antimony, cesium, and lanthanum It is characterized in that it is used to remove the organic compound by the oxidation reaction of the volatile organic compound by producing a catalyst showing a high activity.

Catalysts for volatile organic compound oxidation according to the present invention is one of compounds such as manganese, magnesium, cobalt, iron, copper, nickel, chromium, vanadium, zinc, molybdenum, titanium, tungsten, bismuth, zirconium, antimony, cesium, lanthanum or the like. A catalyst containing a small amount of silver in two or more mixed oxides is characterized in that it is prepared by being supported on a carrier such as alumina, silica and zirconium. It is known that the type of anion moiety combined with the metal compound does not significantly affect the performance of the catalyst. Examples include hydroxides, carbonates, bicarbonates, nitrites, nitrites, formates, acetates, acetates, oxalates, citrates and lactates. lactate, oxide, and the like, and examples of using halogenated compounds and sulfates.

The catalyst of the present invention is suitable to use at a reaction temperature of 150 ~ 400 ℃, can be used in the reaction pressure 0 ~ 40kg / ㎠G range, it is suitable to use in the range of 5,000 ~ 30,000㏄ / h.

When the present invention is described with reference to the embodiment applied to benzene oxidized at a relatively high temperature of the volatile organic compounds. However, the present invention is not limited only to the following examples.

Example 1

A solution in which 2.0 g of manganese nitride, 9.48 g of magnesium nitride, 4.69 g of lanthanum nitride, and 2.35 g of cobalt nitride was dissolved in distilled water was put in a vacuum rotary evaporator and impregnated in the gamma alumina carrier at 40 ° C. After the impregnation was completed, the catalyst was dried at 120 ° C. for at least 15 hours and then calcined at 800 ° C. 2 g of the prepared catalyst was charged in a Pyrex reactor having an internal diameter of 17 mm, and then a reaction mixture gas containing 500 ppm of benzene, 21 v% of oxygen and the rest of nitrogen was supplied at a rate of 20,000 hr ⁻¹ to obtain the results shown in Table 1.

Example 2

After lanthanum and cobalt were first immersed in the gamma alumina carrier, dried at 120 ° C. for at least 15 hours, and then reacted with benzene instead of benzene using the same catalyst and method as in Example 1 using a catalyst prepared by immersing manganese and magnesium. The results are shown in Table 1 below.

Example 3

Manganese and magnesium were first immersed in the gamma alumina carrier, followed by drying at 120 ° C. for at least 15 hours, and then reacting in the same manner as in Example 1 using a catalyst prepared by lanthanum and cobalt. Indicated.

division 100% inverted temperature Example 1 430 ℃ Example 2 430 ℃ Example 3 390 ℃

Example 4

A solution of 2.0 g of manganese nitride, 9.48 g of magnesium nitride, and 2.35 g of cobalt nitride was dissolved in distilled water, and placed in a vacuum rotary evaporator to impregnate the gamma alumina carrier at 40 ° C. After the impregnation was completed, the catalyst was dried at 120 ° C. for at least 15 hours and then calcined at 800 ° C. Table 2 shows the results of the reaction in the same manner as in Example 1 using the prepared catalyst.

Example 5-8

The results of the reaction in the same manner as in Example 1 using a catalyst prepared by varying the amount of lanthanum supported in the same manner as in Example 4 are shown in Table 2 below.

division La loading amount (g) 100% inverted temperature Example 4 0 390 ℃ Example 5 0.73 370 ℃ Example 6 0.97 370 ℃ Example 7 1.46 370 ℃ Example 8 2.92 390 ℃

Example 9

A solution in which 2.0 g of manganese nitride, 9.48 g of magnesium nitride, 2.35 g of cobalt nitride, and 3.13 g of lanthanum nitride was dissolved in distilled water was placed in a vacuum rotary evaporator and impregnated with a gamma alumina carrier at 40 ° C. After the impregnation was completed, the catalyst was dried at 120 ° C. for at least 15 hours and then calcined at 800 ° C. The prepared catalyst was reacted in the same manner as in Example 1.

Example 10-11

In the same manner as in Example 9, the reaction was carried out in the same manner as in Example 1 using a catalyst prepared by adding a loading amount of niobium differently, as shown in Table 3 below.

division Nb loading amount (g) 100% inverted temperature Example 9 0.0 370 ℃ Example 10 0.1 430 ℃ Example 11 0.5 510 ℃

Example 12-15

The results of the reaction in the same manner as in Example 1 using a catalyst prepared by adding different amounts of silver in the same manner as in Example 9 are shown in Table 4 below.

division Ag loading (g) 100% inverted temperature Example 12 0.1 390 ℃ Example 13 0.3 370 ℃ Example 14 0.5 350 ℃ Example 15 1.0 290 ℃

Example 16

The reaction was carried out in the same manner as in Example 1 using a catalyst prepared in the same manner as in Example 15 except for cobalt, and 100% complete conversion was performed at 290 ° C., and the activity was higher than that of the catalyst in which cobalt was present.

Example 17

A solution in which 2.0 g of manganese nitride, 9.39 g of magnesium nitride, 3.13 g of lanthanum nitride, 1.58 g of silver nitride, and 0.38 g of copper nitride was dissolved in distilled water was placed in a vacuum rotary evaporator and impregnated with a gamma alumina carrier at 40 ° C. After the impregnation was completed, the catalyst was dried at 120 ° C. for at least 15 hours and then calcined at 800 ° C. The result of the reaction in the same manner as in Example 1 using the prepared catalyst is shown in Table 5 below.

Example 18-19

The result of the reaction in the same manner as in Example 1 using a catalyst prepared by varying the supported amount of copper in the same manner as in Example 17 is shown in Table 5 below.

division Copper loading (g) 100% inverted temperature Example 17 0.1g 290 ℃ Example 18 0.5g 390 ℃ Example 19 1.0 g 310 ℃

Example 20

A solution of 2.0 g of manganese nitride, 9.39 g of magnesium nitride, 3.13 g of lanthanum nitride, and 1.58 g of silver nitride was dissolved in distilled water in a vacuum rotary evaporator and impregnated with a gamma alumina carrier at 40 ° C. After the impregnation was completed, the catalyst was dried at 120 ° C. for at least 15 hours and then calcined at 400 ° C. The results of the reaction in the same manner as in Example 1 using the prepared catalyst are shown in Table 6 below.

Example 21

A solution in which 0.56 g of manganese nitride, 2.64 g of magnesium nitride, 0.85 g of lanthanum nitride, and 0.44 g of silver nitride was dissolved in distilled water was put in a vacuum rotary evaporator and impregnated with a gamma alumina carrier at 40 ° C. After the impregnation was completed, the catalyst was dried at 120 ° C. for at least 15 hours and then calcined at 400 ° C. Table 7 shows the results of the reaction in the same manner as in Example 1 using the prepared catalyst.

Example 22

A solution obtained by dissolving 1.13 g of manganese nitride, 5.28 g of magnesium nitride, 1.76 g of lanthanum nitride, and 0.89 g of silver nitride in distilled water was placed in a vacuum rotary evaporator and impregnated with a gamma alumina carrier at 40 ° C. After the impregnation was completed, the catalyst was dried at 120 ° C. for at least 15 hours and then calcined at 400 ° C. Table 7 shows the results of the reaction in the same manner as in Example 1 using the prepared catalyst.

Example 23

A solution of 2.0 g of manganese nitride, 9.39 g of magnesium nitride, 3.13 g of lanthanum nitride, and 1.58 g of silver nitride was dissolved in distilled water in a vacuum rotary evaporator and impregnated with a gamma alumina carrier at 40 ° C. After the impregnation was completed, the catalyst was dried at 120 ° C. for at least 15 hours and then calcined at 400 ° C. Table 7 shows the results of the reaction in the same manner as in Example 1 using the prepared catalyst.

division Total metal loading (wt%) 100% inverted temperature Example 21 10 310 ℃ Example 22 20 270 ℃ Example 23 30 270 ℃

According to the present invention, the activity of the metal oxide catalyst is increased. That is, in the case of the catalyst according to the present invention, the oxidation temperature of the volatile organic compound can be lowered. This low temperature is very important because it can prevent the shortening of the catalyst life, maintain the safety of the catalytic oxidation device and the process of volatile organic compounds and reduce the cost of the catalyst.

Claims (3)

Metal oxide catalyst for oxidation of volatile organic compounds containing silver as one of the catalyst components in the metal oxide catalyst for oxidation of volatile organic compounds. The catalyst for oxidation of volatile organic compounds contains metal components such as manganese, magnesium, cobalt, iron, copper, nickel, chromium, vanadium, zinc, molybdenum, titanium, tungsten, bismuth, zirconium, antimony, cesium, and lanthanum as catalyst components. A metal oxide catalyst for oxidizing volatile organic compounds prepared by using one or two or more of the compounds and a compound containing silver in an amount required. In the catalyst according to claim 2, 0.5 to 5.0 w% of manganese, 1.0 to 10.0 w% of magnesium, 0.5 to 10.0 w% of cobalt, 0.1 to 7.0 w% of iron, 1.0 to 10.0 w% of copper, and 0.1 to 10.0 w of nickel %, Chromium 0.1-5.0w%, Vanadium 0.5-15.0w%, Zinc 0.1-10.0w%, Molybdenum 0.5-5.0w%, Titanium 0.1-5.0w%, Tungsten 0.1-5.0w%, Bismuth 0.5-10.0w% A catalyst for oxidizing volatile organic compounds containing 0.1 to 5.0 w% of zirconium, 0.1 to 5.0 w% of antimony, 0.5 to 5.0 w% of cesium, 1.0 to 12.0 w% of lanthanum, and 0.5 to 15.0 w% of silver.