CN1108862C - Catalytic conversion method for flue gas purification - Google Patents

Abstract

The present invention relates to a compound oxide catalyst which can simultaneously eliminate oxynitride, sulfur oxide and carbon monoxide in smoke gas. The compound oxide catalyst is prepared from magnesium, aluminum and composite oxides containing at least one of transition metal elements and at least one of rare earth metal elements. The catalyst is made by calcining lamellar matters having hydrotalcite structure and containing Mg, Al and transition metal elements, and mixtures of rare earth hydrated oxide, and the catalyst can simultaneously eliminate oxynitride, sulfur oxide and carbon monoxide in smoke gas, and has excellent hydrothermal stability.

Description

Catalytic conversion method for flue gas purification

The invention relates to a catalytic conversion method which can simultaneously reduce the emission of nitrogen oxides, sulfur oxides and carbon monoxide in industrial flue gas, such as flue gas in an FCC regenerator of an oil refinery, coal-fired boiler flue gas or automobile exhaust.

Fluid Catalytic Cracking (FCC) is one of the main methods used by refineries to produce gasoline, diesel, etc. The FCC unit mainly includes a reactor and a regenerator; the raw oil is transported into the riser of the reactor, and is cracked into distillate oil by mixing and contacting with the FCC catalyst; at the same time, the catalyst is deactivated due to coke; the deactivated catalyst is passed through steam After extraction, it is sent to the regenerator for coke regeneration; the nitrogen compounds and sulfur compounds (from raw oil) in the coke are oxidized into nitrogen oxides (NOx) and sulfur oxides (SOx), and the hydrogen contained in the coke Generate water. The nitrogen oxides in the FCC regenerator flue gas are mainly nitric oxide (about 90 volume %), and contain a small amount of nitrogen dioxide. The FCC reactor temperature is generally in the range of 480-570°C, and the regenerator temperature is between 650-760°C. The concentration of nitrogen oxides in the regenerator is 50-500ppmv, and the concentration of carbon monoxide is affected by the operating conditions of the FCC. The carbon monoxide content is very high during incomplete combustion, and the concentration is very low during complete combustion with a combustion aid. However, even in the case of complete combustion, the dense bed of the regenerator still has a high concentration of carbon monoxide. Likewise, flue gases from coal-fired boilers and vehicle exhaust also contain significant amounts of nitrogen oxides, carbon monoxide, and/or sulfur oxides.

Nitrogen oxides can destroy the ozone layer, and nitrogen oxides and sulfur oxides can form acid rain, which seriously damages the earth's environment; carbon monoxide is also a major air pollutant. Therefore, it is of great significance to study the method of removing nitrogen oxides, sulfur oxides and carbon monoxide in flue gas to improve the living environment of human beings.

There are many patent reports on methods for reducing nitrogen oxide and carbon monoxide emissions in coal-fired boiler flue gas. For example, by injecting ammonia or low-carbon chain hydrocarbons into the flue gas; in the presence of oxygen, the nitrogen in the flue gas can be oxidized through the catalytic action of catalysts such as V ₂ O ₅ /TiO ₂ The matter is reduced to a very low level in the temperature range of 150-400 °C. However, these methods are generally not suitable for FCC units due to the high regeneration temperatures and other harsh operating conditions in FCC regenerators.

USP 4,973,399 and USP 4,980,052 describe a catalyst for reducing nitrogen oxide emissions from an FCC regenerator comprising a copper-exchanged molecular sieve and a titania or zirconia component. Under proper conditions, its nitrogen oxide removal rate can reach 79%.

The method proposed by USP5,085,762 is to use MCM-22 loaded with copper, cerium and titanium as a catalyst. The role of cerium and titanium is mainly to improve the hydrothermal stability of Cu/MCM-22. The catalyst after hydrothermal aging at 700℃ and 100% H ₂ O for 4 hours can remove 60% of nitrogen oxides in FCC regenerator flue gas.

USP 5,002,654 and USP 4,988,432 describe methods for reducing nitrogen oxide emissions in FCC regenerators using zinc oxide and antimony oxide catalysts, respectively. However, it is only suitable for FCC units that process raw oil with low sulfur content, low metal content, and medium nitrogen content.

USP 5,364,517 describes a method for reducing nitrogen oxide emissions in FCC regenerators using a mixed composition of copper-containing perovskite and spinel.

USP5,591,418 describes an adsorbent for removing sulfur oxides or nitrogen oxides in FCC flue gas and its preparation method; A solid solution of impurities in the single oxide such as alumina, and contains spinel crystallites and crystallites of trivalent metals, wherein the divalent metals are selected from magnesium, calcium, zinc, barium and strontium, and the trivalent metals are selected from Cerium, lanthanum, iron, chromium, vanadium and cobalt, in addition to oxides and anions of V, W or Mo; the preparation method is to prepare a mixture of oxides of divalent metals, aluminum and trivalent metals, and then Adsorb metavanadate ions or tungsten and molybdate ions in the solution, and then roast. The adsorbent is mainly used to remove sulfur oxides and convert nitrogen oxides into nitrogen.

USP3,835,031 is about adding metal oxides (CaO or MgO) of Group IIA to cracking catalysts to reduce the release of sulfur oxides, and successfully developed a desulfurization oxide additive in 1977, which is the earliest desulfurization oxide additives.

USP 4,071,436, 4,166,787, 4,243,556 introduced various Al ₂ O ₃ as desulfurization oxide additives.

USP4,469,589 uses CeO ₂ Mg-Al spinel as desulfurization oxide additive and used in industrial production.

USP4,963,520 introduces such a desulfurization oxide catalyst, the spinel with a magnesium-aluminum ratio of 0.77 and a particle size of about 65 μm is loaded with Ce, Pr, La, Fe, Mn, Co, V, Sn and other metals respectively or simultaneously Two kinds of metals, then the loaded spinel is mixed with industrial catalyst, used in the pilot plant to observe the desulfurization situation, the spinel accounts for 1.25% by weight of the mixed catalyst, the raw material sulfur content is 2% by weight, and the test conditions are : The reactor temperature is 537°C, the regenerator temperature is 693°C, the stripping section temperature is 499°C, the catalyst regeneration time is 30 minutes, the catalyst-oil ratio is 6, and the weight hourly space velocity is 10 hours ^-1 . , La, Fe, Mn, Co, V, and Sn spinels, the desulfurization efficiency of the fresh agent loaded with Ce is the highest at 83%, followed by 81% when loaded with V, but after two days of accelerated aging (simulated industrial conditions), the desulfurization and oxide removal efficiency decreased to below 50%. When loading two metals at the same time, the desulfurization and oxide removal efficiency of V/Ce/spinel was the highest (96% for fresh agent and 78% after aging), but due to V Poisoning effect on FCC catalyst, should not be used.

USP4,957,718 prepared perovskite-like minerals: MgMnO ₃ , La _0.8 Mg _0.2 MnO ₃ , La _0.2 Mg _0.8 MnO ₃ , La _0.8 Mg _0.2 CoO ₃ , La _0.5 Mg _0.5 CoO ₃ , La _0.8 Mg _0.3 FeO ₃ , respectively Its desulfurization performance was tested _, and the results showed that under the _condition of enriched oxygen, with the increase of the number of cycles, _the efficiency of trapping collection rate dropped from 96% to 32%).

USP5,057,205 uses magnesium-aluminum spinel as a desulfurization oxide additive, and is used as a metal passivation agent at the same time, which can be more effective for raw materials with high metal content. A solid solution composed of magnesium aluminum spinel and magnesium oxide, loaded with a certain amount of Ce or La, is a very effective desulfurization oxide additive and V-scavenger, and is beneficial to improve gasoline selectivity, reduce coke and hydrogen, and Ce , La is used to promote the conversion of SO ₂ to SO ₃ .

USP5,288,675 prepared non-spinel ternary oxides by co-precipitation method, mainly MgO/La ₂ O ₃ /Al ₂ O ₃ and MgO/RE ₂ O ₃ /Al ₂ O ₃ , and the test shows that this Composite oxides with non-spinel structure are superior to Mg/Al/spinel in trapping sulfur oxides

USP5,750,020 introduces a method for preparing a desulfurization oxide or nitrogen oxide catalyst. Firstly, the mixture of hydrotalcite and cerium oxide is prepared, and after roasting, metavanadate ions in the solution are adsorbed, and then roasted. The hydrothermal stability and oxidation resistance of the catalyst are not considered in the patent, and sulfur oxides and nitrogen oxides cannot be removed at the same time.

The method of reducing carbon monoxide in the regenerator flue gas is usually to add a carbon monoxide combustion accelerant. There are a large number of patent reports about carbon monoxide combustion accelerants.

USP 2,647,860 proposes to add 0.1-1% by weight of chromium oxide to the FCC catalyst to promote the conversion of carbon monoxide to carbon dioxide and prevent afterburning. USP3,788,977 suggests loading Pt on alumina as a matrix component or directly adding it to FCC catalysts to promote the complete combustion of carbon monoxide. USP4,251,395, USP4,265,787, USP4,008,568, USP4,072,600, USP4,093,535, USP4,159,239, etc. are all patents on the composition and application of carbon monoxide combustion accelerants. Although the use of carbon monoxide combustion accelerant can solve the problem of carbon monoxide release and post-combustion, it cannot solve the problem of nitrogen oxide emissions, and may even increase the emission of nitrogen oxides.

USP4,199,435 adopts the method of passivating the carbon monoxide combustion accelerant to reduce its impact on the generation of nitrogen oxides. The method is to put it at about 980°C before the combustion accelerant (0.2% by weight Pt/Al ₂ O ₃ ) is used. Hydrothermal aging under normal pressure for 96 hours before use. USP4,235,704 adopts the method of adding antimony or tin to passivate the carbon monoxide combustion accelerant, so as to achieve the purpose of reducing the emission of nitrogen oxides in the FCC regenerator. However, the method of passivating the combustion accelerant of carbon monoxide reduces the utilization efficiency of the accelerant, thereby increasing the emission of carbon monoxide.

In USP4,300,997 and USP4,350,615, it is proposed to use Pd-Ru as a carbon monoxide combustion aid. Compared with other combustion aids, this combustion aid can reduce the generation of nitrogen oxides in the FCC regenerator while promoting the combustion of carbon monoxide, but These catalysts using noble metals are relatively expensive.

There are also many patent reports on catalysts for removing nitrogen oxides in automobile exhaust, and most of these catalysts use noble metals as part of the active components.

The purpose of the present invention is to provide a flue gas purification catalytic conversion method capable of effectively removing nitrogen oxides, sulfur oxides and carbon monoxide simultaneously.

The mechanism of the present invention to catalyze the purification of flue gas is: utilize the characteristics of the coexistence of NOx and CO in the dense phase bed, use CO as the reducing agent of NOx, and simultaneously convert carbon monoxide and nitrogen oxides, and the catalyst used in the present invention can efficiently Convert SO ₂ into SO ₃ , and SO ₃ is adsorbed with magnesium in the catalyst to form sulfates, and then reduced under reducing conditions to effectively regenerate the catalyst. Transition metals and rare earths act synergistically, and the role of transition metals is mainly to convert CO and NOx; on the one hand, rare earths have a synergistic effect on Cu, making transition metals less likely to be poisoned by SOx, and on the other hand, they can convert _SO2 into _SO3 and be absorbed by Mg .

The catalytic conversion method provided by the present invention is to make flue gas containing nitric oxide, sulfur oxide and carbon monoxide contact with a specific catalyst in the range of 300-800°C, especially in the range of 400-750°C.

The catalyst for removing nitrogen oxides, sulfur oxides and carbon monoxide in flue gas used in the present invention is composed of composite oxides of magnesium, aluminum, at least one transition metal element and at least one rare earth metal element; its anhydrous chemical expression The formula is mMgO nAl ₂ O ₃ xMO _a/2 yRE ₂ O ₃ ; where M is one or two transition metal elements selected from the group consisting of Zn, Co, Ni, Cu, Fe, Cr Among them, Cu or Fe is preferred; RE is one of the rare earth metal elements including lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), or is based on La and/or Ce-based mixed rare earth elements, wherein La, Ce, or La and/or Ce-based mixed rare earth elements are preferred, more preferably La or Ce; a is the valence state of M (its value is 2 or 3); the value of m/n is greater than 2 to less than 30, preferably m/n=3-10; x/(m+n+x+y)=0.001-0.15, preferably 0.005-0.08 ; y/(m+n+x+y)=0.001-0.1, preferably 0.003-0.05.

The catalyst used in the present invention is prepared by calcining a mixture of layered substances containing Mg, Al and transition metal elements with a hydrotalcite structure and rare earth hydrated oxides. The conditions for the calcining are that the temperature is 300-1100 ° C. It is preferably 450-900°C, more preferably 500-800°C, and the firing time is 1-15 hours, preferably 2-10 hours.

The preparation method of the catalyst used in the present invention can be:

(1), according to the ratio required in the definition of catalyst of the present invention above, magnesium, aluminum, transition metals and rare earth metal salt compounds are dissolved in distilled water, so that the total concentration of metal ions is between 0.5-2.5M, preferably 1 -1.5M, to obtain a mixed solution of metal salt; the anion of said metal salt can be selected from sulfate ion, nitrate ion, carbonate ion, acetate ion, chloride ion, etc.; wherein preferred carbonate ion;

(2), prepare the mixed alkali solution of sodium carbonate and sodium hydroxide according to a certain ratio, the mol ratio of sodium carbonate and sodium hydroxide is 10-20: 1, preferably 12-18: 1;

(3), under stirring, add the mixed solution of said metal salt and said mixed alkaline solution into a certain amount of water at a certain speed respectively, the amount of said water is not particularly limited, and the mixed solution of said metal salt 0.2-2 times of the volume is advisable; the adding speed of the salt solution and the alkali solution is to control the pH of the mixed slurry between 7.5-13, preferably between 8.5-11 as the standard; the amount of the mixed alkali solution There are no special restrictions, and the pH of the slurry after mixing the two solutions is controlled at 7.5-13 as a standard; the temperature of the distilled water can be between room temperature and 110°C, preferably between 40-90°C;

(4), hydrothermally crystallize the slurry obtained in step (3), the crystallization temperature is between 25-110°C, preferably 40-90°C; the crystallization time is between 0.5-24 hours, preferably 1-8 between hours; then the crystallized product is filtered and washed, and the pH value of the washing solution should be close to 7 when the washing is completed; the obtained filter cake is dried in a conventional manner after washing;

(5), roasting the product obtained in step (4), the conditions for roasting are that the temperature is 300-1100°C, preferably 450-900°C, more preferably 500-800°C; the time is 1-15 hours, preferably 2-10 hours .

In addition to being introduced in the form of co-precipitation, the rare earth element can also be introduced by impregnation or as a carrier.

Fig. 1 is the X-ray diffraction pattern of the sample prepared in Example 1 after drying and before firing, wherein "o" is the diffraction peak of hydrotalcite, and "*" is the diffraction peak of _CeO2 .

Figure 2 is the X-ray diffraction pattern of catalyst A obtained after calcination in Example 1, wherein "*" is the peak of _CeO2 , and "v" is the peak of MgO.

The characteristic of the catalyst used in the present invention for removing nitrogen oxides, sulfur oxides and carbon monoxide in flue gas is that carbon monoxide in the flue gas can be used as a reducing agent during its use, and while nitrogen oxides are reduced to nitrogen , carbon monoxide is oxidized to carbon dioxide to achieve the purpose of simultaneously removing nitrogen oxides and carbon monoxide.

The catalyst used in the present invention is also characterized in that the catalyst has high catalytic activity to nitric oxide and carbon monoxide, and has hydrophilicity, that is to say, its catalytic activity is higher under high-temperature hydrothermal conditions. .

The catalytic conversion method provided by the invention has application prospects in reducing nitrogen oxides and carbon monoxide in automobile tail gas, coal-fired boiler flue gas and FCC regenerator flue gas.

The following examples will further illustrate the present invention. Wherein the surface area and pore volume of the catalyst are measured by GB/T5816-1995 standard method.

Example 1

This example illustrates the preparation of the catalyst used in the present invention.

Dissolve 25.9 grams of magnesium nitrate hexahydrate, 14.1 grams of aluminum nitrate nonahydrate, 2.25 grams of cerous nitrate hexahydrate, and 1.125 grams of copper acetate monohydrate in 100 ml of distilled water at 65°C as a salt solution; weigh 13.5 grams of hydroxide Dissolve sodium and 14.3 grams of sodium carbonate decahydrate in 100 ml of distilled water at 65°C as an alkali solution; place a beaker filled with 100 ml of distilled water in a constant temperature water bath at 65°C, and simultaneously mix the above salt solution and the above alkali under stirring The solution is dripped into the beaker, and the dripping speed of the two solutions is controlled so that the pH value of the solution is always around 9.5. After the two solutions were dropped, the resulting mixture was stirred for an additional 15 minutes, then left to age for 4 hours. Filter and wash with water until the pH of the washings is 7. The filter cake was dried at 120°C for 12 hours; the resulting product was then calcined at 750°C for 3 hours. The obtained catalyst was designated as catalyst A, and its specific surface area and pore volume were measured by nitrogen adsorption method. The composition and properties of Catalyst A are listed in Table 1.

Example 2

This example illustrates the preparation of the catalyst used in the present invention.

25.9 grams of magnesium nitrate hexahydrate, 14.1 grams of aluminum nitrate nonahydrate, 0.9 grams of cerous nitrate hexahydrate, and 1.125 grams of copper acetate monohydrate were dissolved in 100 milliliters of distilled water at 65° C. as a salt solution; then according to Example 1 Catalysts were prepared under the same conditions and steps. The obtained catalyst is designated as catalyst B, and its composition and properties are listed in Table 1.

Example 3

The present embodiment illustrates the preparation of the catalyst used in the present invention

25.9 grams of magnesium nitrate hexahydrate, 14.1 grams of aluminum nitrate nonahydrate, 0.3 gram of cerous nitrate hexahydrate, and 1.125 grams of copper acetate monohydrate were dissolved in 100 milliliters of distilled water at 65° C. as a salt solution; then according to Example 1 The same conditions and steps were used to prepare the catalyst, except that the calcination condition was 7 hours at 550°C. The obtained catalyst is designated as catalyst C, and its composition and properties are listed in Table 1.

Example 4

This example illustrates the preparation of the catalyst used in the present invention.

25.9 grams of magnesium nitrate hexahydrate, 14.1 grams of aluminum nitrate nonahydrate, 1.8 grams of cerous nitrate hexahydrate, and 1.8 grams of copper acetate monohydrate were dissolved in 100 milliliters of distilled water at 65° C. as a salt solution; then according to Example 1 Catalysts were prepared under the same conditions and steps. The obtained catalyst is designated as catalyst D, and its composition and properties are listed in Table 1.

Example 5

This example illustrates the preparation of the catalyst used in the present invention.

25.9 grams of magnesium nitrate hexahydrate, 14.1 grams of aluminum nitrate nonahydrate, 1.8 grams of cerous nitrate hexahydrate, and 1.125 grams of copper acetate monohydrate were dissolved in 100 milliliters of distilled water at 65°C as a salt solution; 1 Prepare the catalyst under the same conditions and steps, except that the calcination condition is 2 hours at 800°C. The obtained catalyst is designated as catalyst E, and its composition and properties are listed in Table 1.

Example 6

This example illustrates the preparation of the catalyst used in the present invention.

25.9 grams of magnesium nitrate hexahydrate, 14.1 grams of aluminum nitrate nonahydrate, 1.8 grams of cerous nitrate hexahydrate, and 0.563 grams of copper acetate monohydrate were dissolved in 100 milliliters of distilled water at 65° C. as a salt solution; then according to Example 1 Catalysts were prepared under the same conditions and steps. The obtained catalyst is designated as Catalyst F, and its composition and properties are listed in Table 1.

Table 1 Example number Catalyst number Composition, wt% Surface area ( ^m2 /g) Pore volume (ml/g) Na ₂ O MgO Al ₂ O ₃ CuO _CeO2 1 A 0.07 53.9 27.2 7.5 11.3 168 0.71 2 B 0.05 58.1 28.5 7.7 5.6 159 0.59 3 C 0.05 60.6 29.7 7.9 1.7 155 0.63 4 D. 0.03 52.9 26.8 11.4 8.8 178 0.90 5 E. 0.08 57.2 26.6 7.4 8.7 183 0.93 6 f 0.04 59.3 27.5 4.1 9.0 195 0.97

Example 7

This example illustrates the preparation of the catalyst used in the present invention.

25.9 grams of magnesium nitrate hexahydrate, 12.0 grams of aluminum nitrate nonahydrate, 2.44 grams of cerous nitrate hexahydrate, and 4.55 grams of ferric nitrate nonahydrate were dissolved in 100 milliliters of distilled water at 65° C. as a salt solution; then according to Example 1 Catalysts were prepared under the same conditions and procedures. The obtained catalyst is designated as catalyst G, and _{its composition} and properties are: _Na2O : 0.01% by weight, MgO: 54.1% by weight, _Al2O3 : 22.1% by weight, _CeO2 : 12.5% by weight, _Fe2O3 : 11.2% by weight %; specific surface: 141 m ² /g, pore volume: 0.54 ml/g.

Example 8

This example illustrates the preparation of the catalyst used in the present invention.

25.9 grams of magnesium nitrate hexahydrate, 12.0 grams of aluminum nitrate nonahydrate, 2.44 grams of cerous nitrate hexahydrate, and 3.35 grams of zinc nitrate hexahydrate were dissolved in 100 milliliters of distilled water at 65° C. as a salt solution; then according to Example 1 Catalysts were prepared under the same conditions and procedures. The obtained catalyst is denoted as catalyst H, and its composition and _properties are: _Na2O <0.01% by weight, MgO: 53.6% by weight, _Al2O3 : 21.4% by weight, _CeO2 : 12.8% by weight, ZnO: 12.1% by weight; Surface: 156 ^m2 /g, pore volume: 0.63 ml/g.

Example 9

This example illustrates the preparation of the catalyst used in the present invention.

25.9 grams of magnesium nitrate hexahydrate, 12.0 grams of aluminum nitrate nonahydrate, 2.44 grams of lanthanum nitrate hexahydrate, and 2.25 grams of copper acetate monohydrate were dissolved in 100 milliliters of distilled water at 65°C as a salt solution; Conditions and steps to prepare the catalyst. The obtained catalyst is designated as catalyst I, and its composition and properties are: _Na2O <0.01% _by weight, _{MgO: 54.1% by weight, Al2O3: 21.6% by weight, La2O3 : 12.3} % by weight, CuO: 12.0% by weight ; Specific surface: 171 m ² /g, pore volume: 0.65 ml/g.

Example 10

The present embodiment illustrates the preparation of the catalyst used in the present invention

Dissolve 28.8 grams of magnesium nitrate hexahydrate, 14.06 grams of aluminum nitrate nonahydrate and 2.25 grams of copper acetate monohydrate in 100 milliliters of distilled water at 65°C as a salt solution; weigh 13.5 grams of sodium hydroxide and 14.3 grams of sodium carbonate decahydrate to dissolve In 100 milliliters of distilled water at 65° C., as an alkaline solution; weigh 2.1 grams of bastnaesite (which consists of: La ₂ O ₃ 26% by weight, CeO ₂ 46.9% by weight, Nd ₂ O ₃ 7.0% by weight, Pr ₆ O ₁₁ 4.9%% by weight) is put into the beaker that fills 100 milliliters of distilled water, this beaker is placed in the constant temperature water bath of 65 ℃, under stirring simultaneously, above-mentioned salt solution and above-mentioned alkali solution are dripped in this beaker, control The dripping speed of the two solutions makes the pH value of the solution around 9.5 all the time. After the two solutions were dropped, the resulting mixture was stirred for an additional 15 minutes, then left to age for 4 hours. Filter and wash with water until the pH of the washings is 7. The filter cake was dried at 120°C for 12 hours; the resulting product was then calcined at 750°C for 3 hours. The obtained catalyst is designated as Catalyst J, and its composition and properties are listed as follows: Na ₂ O < 0.01 wt%, MgO 47.8 wt%, Al ₂ O ₃ 20.2 wt%, CuO 9.6 wt%, La ₂ O ₃ 5.8 wt%, CeO ₂ 10.5% by weight, Nd ₂ O ₃ 1.6% by weight, Pr ₆ O ₁₁ 1.1% by weight, specific surface: 162 m ² /g, pore volume: 0.59 ml/g.

Comparative example 1

This comparative example illustrates the preparation of a comparative catalyst that does not contain transition metals.

28.8 grams of magnesium nitrate hexahydrate, 13 grams of aluminum nitrate nonahydrate, and 1.25 grams of cerous nitrate hexahydrate were dissolved in 100 milliliters of distilled water at 65° C. as a salt solution; then the catalyst was prepared according to the same conditions and steps as in Example 1 . The obtained catalyst is denoted as Catalyst K, and its composition is _Na2O : 0.05% by weight, MgO: 59.8% by weight, _Al2O3 : 25% by weight _{, CeO2} : 15% by weight; specific surface area: 105 ^m2 /g, pore volume : 0.34ml/g.

Comparative example 2

This comparative example illustrates the preparation of a comparative catalyst containing no rare earth elements.

2.25 grams of copper acetate monohydrate, 25.9 grams of magnesium nitrate hexahydrate, and 14.06 grams of aluminum nitrate nonahydrate were dissolved in 100 milliliters of distilled water at 65° C. as a salt solution; then the catalyst was prepared according to the same conditions and steps as in Example 1. The obtained catalyst is denoted as catalyst L, and its _composition is _Na2O <0.01 wt%, MgO: 49.8 wt%, _Al2O3 : 29 wt%, CuO: 21 wt%; specific surface area: 161 ^m2 /g, pore volume : 0.76ml/g.

Example 11

This example illustrates the preparation of hydrothermally aged samples of catalysts used in the present invention.

Catalysts A and G were hydrothermally aged at 80°C and 100% water respectively; the aging time and properties of the aged products are shown in Table 2.

Table 2 catalyst Hydrothermal aging time, hours Sample number after aging Specific surface ^m2 /g Pore volume ml/g A 4 A-1 80 0.51 17 A-2 65 0.43 G 4 G-1 72 0.49 17 G-2 60 0.38

Example 12-23

These examples illustrate the effectiveness of the catalytic conversion of nitric oxide and carbon monoxide provided by the present invention.

The catalyst is preformed into particles of 350-800 micron particle size. Catalyst is packed in the fixed-bed reactor (reaction tube internal diameter is 6 millimeters), feed carrier gas (argon) and be heated to reaction temperature and purge half an hour, under the situation of keeping the total flow of gas constant (by adjusting The flow rate of the carrier gas is controlled), and the reaction gas is passed into it, and the concentration of nitrogen oxides is detected online by a QGS-08B infrared analyzer (commercial product of Beijing Analytical Instrument Factory Mahake Analytical Instrument Co., Ltd.), and the GC-8APT double-column double-column The gas path gas chromatography detects the concentration of carbon monoxide, nitrogen, oxygen, sulfur dioxide and carbon dioxide online. Gas flow was controlled by a Brooks mass flow controller. Said conversion rate is the conversion rate calculated by volume percent concentration. Reaction conditions:

Argon is used as the carrier gas, and the total gas flow rate is 400 standard cubic centimeters per minute

Reaction temperature: 720°C

Reaction pressure: normal pressure

Catalyst loading: 150 mg

Table 3 is the conversion rate of NO → N during different reaction conditions, including the following 4 kinds of reaction systems: Reaction system ₁ : feed gas includes NO, CO and Ar, and the concentration of nitric oxide (NO) is 600ppm (volume

Volume), carbon monoxide (CO) concentration is 1.4% (volume concentration), continuous ventilation for 1 hour

The conversion ratio of nitric oxide into nitrogen after 1 hour is expressed as R ₁ ; reaction system 2: feed O ₂ into system 1, the concentration of oxygen (O ₂ ) is 0.5% (volume concentration), R ₂

Represents the conversion rate that nitric oxide is converted into nitrogen after feeding _O2 for 1 hour; Reaction system 3: feed water vapor in system 2, water vapor content is 3% (volume concentration), R ₃ represents

Shows the conversion rate of nitric oxide into nitrogen after 1 _hour of passing _water vapor;

degrees), R ₄ represents the conversion rate of nitric oxide into nitrogen gas after SO ₂ is introduced for 1 hour; R ₅ represents the conversion rate of CO→CO ₂ under the conditions of reaction system 4.

table 3 Example catalyst R ₁ , % R ₂ , % R ₃ ,% R ₄ , % R ₅ ,% 12 A 100 97.8 97.2 95.6 100 13 B 100 96.2 96.5 92.9 100 14 C 100 95.5 94.1 89.2 100 15 D. 100 97.1 96.8 95.2 100 16 E. 100 96.1 96.1 94.9 100 17 f 100 94.6 95.1 94.6 100 18 G 100 94.2 92.5 82.8 100 19 h 91.2 89.6 79.8 69.5 89.7 20 I 100 90.5 87.4 82.9 100 twenty one J 97.3 85.7 72.6 21.2 75.7 twenty two K 94.3 74.2 76.1 11.4 75.7 twenty three L 70.1 48.5 85 20.7 73.8

Example 24-27

These examples illustrate the effect of the catalytic conversion method provided by the present invention on the nitric oxide removal performance.

Catalysts A-1, A-2, G-1 and G-2 were obtained from catalysts A and G according to Example 17 through aging at 800°C and 100% H ₂ O for 4 hours or 17 hours. The test and reaction conditions are the same as in Examples 12-23, and the test results are listed in Table 4.

Table 4 Example catalyst R ₁ ,% R ₂ ,% R ₃ , % R ₄ ,% R ₅ , % twenty four A-1 100 97.8 97.2 95.6 100 25 A-2 100 97.8 97.2 95.6 100 26 G-1 100 93.1 93.5 81.4 100 27 G-2 100 91.9 93.7 80.3 100

Example 28-40

This example illustrates the effect of the catalytic conversion method provided by the present invention in removing sulfur oxides.

表5 实施例 催化剂           硫氧化物吸附容量(％)     350℃     550℃     720℃     28     A     6.53     45.15     81.8     29     B     4.97     29.30     85.11     30     C     4.13     21.15     67.90     31     D     6.23     40.31     63.49     32     E     4.97     36.00     67.00     33     F     6.33     40.24     73.15     34     K     5.14     44.32     73.06     35     L     6.12     29.02     74.91     36     A-1     -     15.81     63.40     37     A-2     -     15.99     67.94 The performance of the catalyst for adsorbing SOx and the regeneration after adsorption were measured by thermogravimetry on a TA2100 thermal analyzer. The adsorption conditions are: SO ₂ (0.5%(V))+O ₂ +Ar, the total gas flow rate is 200 SCCM, the catalyst loading is 20 mg, and the adsorption temperature is 720°C. The catalyst after adsorbing SOx is reduced with hydrogen at the adsorption temperature, the reduction condition is: H ₂ (20%(V))+Ar, the total gas flow is 200SCCM, and the reduction temperature is 550°C. The adsorption capacity is expressed by SOx adsorption capacity, and the test results are listed in Table 5. The hydrogen reduction performance (i.e. the regeneration ability of the catalyst after adsorbing SOx) is expressed by _H2 reduction degree, and the test results are listed in Table 6.

table 5 Example catalyst Sulfur oxide adsorption capacity (%) 350°C 550°C 720°C 28 A 6.53 45.15 81.8 29 B 4.97 29.30 85.11 30 C 4.13 21.15 67.90 31 D. 6.23 40.31 63.49 32 E. 4.97 36.00 67.00 33 f 6.33 40.24 73.15 34 K 5.14 44.32 73.06 35 L 6.12 29.02 74.91 36 A-1 - 15.81 63.40 37 A-2 - 15.99 67.94

Table 6 instance number catalyst Hydrogen reduction degree (%) 350°C 550°C 720°C 38 A 13.29 63.42 96.54 39 K 9.52 45.24 90.05 40 L 9.97 59.67 97.22

Claims (9)

1, a kind of catalysis conversion method that removes nitrogen oxide in the flue gas, oxysulfide and carbon monoxide, it is characterized in that making flue gas to contact with a kind of catalyst of being made up of the composite oxides of magnesium, aluminium, at least a transition metal and at least a thulium down at 300～800 ℃, the anhydrous chemical expression of this catalyst is mMgOnAl ₂O ₃XMO _A/2YRE ₂O ₃Wherein M is a kind of in the transition metal that is selected from the group of being made up of Zn, Co, Ni, Cu, Fe, Cr or two kinds; RE comprises a kind of in the thulium of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), or based on the mixed rare-earth elements of La and/or Ce; A is the valence state (its value is 2 or 3) of M; The value of m/n is to less than 30 greater than 2; X/ (m+n+x+y)=0.001-0.15; Y/ (m+n+x+y)=0.001-0.1.

2,, it is characterized in that flue gas is 400～750 ℃ with the temperature that contacts of catalyst according to the catalysis conversion method of claim 1.

3,, it is characterized in that this catalyst is made through roasting by the mixture of bedded substance that contains Mg, Al and transition metal with hydrotalcite structure and rare earth hydrous oxide according to the catalysis conversion method of claim 1.

4, according to the catalysis conversion method of claim 3, wherein the condition of said roasting is that temperature is 450-900 ℃, and the time is 1-15 hour.

5, according to the catalysis conversion method of claim 4, wherein the condition of said roasting is that temperature is 500-800 ℃, and the time is 2-10 hour

6, according to the catalysis conversion method of claim 1, M wherein is Cu or Fe.

7, according to the catalysis conversion method of claim 1, RE wherein is La, Ce or based on the mixed rare-earth elements of La and/or Ce.

8, according to the catalysis conversion method of claim 7, RE wherein is La or Ce.

9, according to the catalysis conversion method of claim 1, m/n=3-10 wherein; X/ (m+n+x+y)=0.005-0.08; Y/ (m+n+x+y)=0.003-0.05.

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