CN110872265B - Preparation method of phthalic anhydride - Google Patents

Preparation method of phthalic anhydride Download PDF

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CN110872265B
CN110872265B CN201811011986.7A CN201811011986A CN110872265B CN 110872265 B CN110872265 B CN 110872265B CN 201811011986 A CN201811011986 A CN 201811011986A CN 110872265 B CN110872265 B CN 110872265B
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catalyst
carrier
tio
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phthalic anhydride
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CN110872265A (en
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刘玉芬
安欣
袁滨
师慧敏
张东顺
冯晔
张作峰
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
    • C07D307/77—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom ortho- or peri-condensed with carbocyclic rings or ring systems
    • C07D307/87—Benzo [c] furans; Hydrogenated benzo [c] furans
    • C07D307/89—Benzo [c] furans; Hydrogenated benzo [c] furans with two oxygen atoms directly attached in positions 1 and 3
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/20—Vanadium, niobium or tantalum
    • B01J23/22—Vanadium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/14—Phosphorus; Compounds thereof
    • B01J27/186—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J27/195—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with vanadium, niobium or tantalum
    • B01J27/198—Vanadium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts

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Abstract

The invention discloses a catalyst for preparing phthalic anhydride, which is a four-section bed catalyst, wherein the catalyst A, the catalyst B, the catalyst C and the catalyst D are sequentially arranged from a gas inlet end to a gas outlet end, the four catalysts respectively comprise a carrier and active substances loaded on the carrier, and the active substances comprise V2O5、TiO2And an auxiliary agent; the mass ratio of the active substance to the carrier in the catalyst A is 11-17%; the mass ratio of the active substance to the carrier in the catalyst B is 10-16%; the mass ratio of the active substance to the carrier in the catalyst C is more than 15% and less than or equal to 17%; the mass ratio of the active material to the carrier in the catalyst D is more than 15% and less than or equal to 18%. The catalyst provided by the invention has the advantages of high selectivity, long service life, high yield of phthalic anhydride and stable performance.

Description

Preparation method of phthalic anhydride
Technical Field
The invention relates to a preparation method of phthalic anhydride.
Background
A V-Ti system catalyst is generally adopted in the method for preparing phthalic anhydride (phthalic anhydride) by catalytic oxidation in a fixed bed reactor after gasification of o-xylene serving as a raw material, and the catalyst comprises a carrier and an active component loaded on the carrier, wherein the active component is TiO2And V2O5Is a main active substance and is supplemented with a small amount of cocatalyst.
At present, the yield of phthalic anhydride in industrial application is 108-110% by using domestic catalysts. The yield of the imported catalyst sold in the market can reach 114%, but some domestic phthalic anhydride manufacturers reflect that the service life of the catalyst is only 1 year more, namely the activity of the catalyst is obviously reduced along with the prolonging of the start time, the yield of the phthalic anhydride is quickly reduced, the yield is reduced, the product impurities are gradually increased, and the production cost is undoubtedly increased for the factories. Therefore, in order to satisfy high demands of plants for economic efficiency and environmental friendliness, improvement of catalysts for preparing phthalic anhydride is required.
Disclosure of Invention
In order to solve the problem that the existing catalyst has the concentration of o-xylene of 100g/m3The invention provides a new method for preparing the catalyst of phthalic anhydride, which can be operated under a high load state, has high selectivity, high stability and long service life, the yield of phthalic anhydride reaches 115-116%, and the content of impurities in the phthalic anhydride product is low.
According to a first aspect of the present invention, there is provided a catalyst for producing phthalic anhydride, the catalyst being a four-stage bed catalyst, catalyst a, catalyst B, catalyst C and catalyst D being arranged in this order from a gas inlet end to a gas outlet end, each of catalyst a, catalyst B, catalyst C and catalyst D comprising a carrier and an active substance supported on the carrier, the active substance comprising V2O5、TiO2And an auxiliary agent;
the mass ratio of the active substance to the carrier in the catalyst A is 11-17%;
the mass ratio of the active substance to the carrier in the catalyst B is 10-16%;
the mass ratio of the active substance to the carrier in the catalyst C is more than 15% and less than or equal to 17%;
the mass ratio of the active material to the carrier in the catalyst D is more than 15% and less than or equal to 18%.
According to a preferred embodiment of the invention, the auxiliary agent is selected from one or more of the following elements or compounds thereof: K. rb, Cs, Sb, Sn, Nb, P, Zr, Bi and Ag, preferably, the auxiliary agent is selected from one or more of the following elements or compounds thereof: rb, Cs, Sb, Sn, Nb and P.
According to a preferred embodiment of the present invention, the mass ratio of the active substance to the carrier in the catalyst a may be 11%, 12%, 13%, 14%, 15%, 16%, 17% and any value therebetween, preferably 12% to 16%.
According to a preferred embodiment of the invention, the mass ratio of active substance to support in catalyst B may be 10%, 11%, 12%, 13%, 14%, 15%, 16% and any value therebetween, preferably 11% to 15%;
according to a preferred embodiment of the invention, the mass ratio of active substance to support in catalyst C may be 15.1%, 15.5%, 16%, 16.5%, 17% and any value in between, preferably greater than 15% and less than or equal to 17%;
according to a preferred embodiment of the invention, the mass ratio of active substance to support in catalyst D may be 15.1%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18% and any value therebetween, preferably greater than 15% and less than or equal to 18%.
According to a preferred embodiment of the present invention,
catalyst a comprises, based on the total mass of active species in catalyst a: 3.00-8.00 wt% V2O5、0.50-2.00wt％Sb2O3、0.20-0.70wt％Cs、0.05-0.40wt％Nb2O5And the balance of TiO2；
Catalyst B comprises, based on the total mass of active substances in catalyst B: 6.00-10.00 wt% V2O5、1.00-4.00wt％Sb2O3、0.10-0.40wt％Cs、0.20-0.50wt％Nb2O5And the balance of TiO2；
Catalyst C comprises, based on the total mass of active species in catalyst C: 8.00-15.00 wt% V2O5、2.00-5.00wt％Sb2O3、0.30-0.80wt％Nb2O5And the balance of TiO2；
Catalyst D comprises, based on the total mass of active species in catalyst D: 12.00-20.00 wt% V2O5、3.00-6.00wt％Sb2O3、0.20-0.60wt％Nb2O5、0.10-0.50wt％P2O5And the balance of TiO2。
According to a preferred embodiment of the invention, said TiO2Is anatase type TiO2The preferred specific surface area is 17m2/g-25m2Per g, pore diameter of
Figure BDA0001785321300000021
The medium and small pores account for 70 to 80 percent, the pore volume is 0.1 to 0.3ml/g, and the particle diameter is 0.1 to 0.4 mu m.
According to a preferred embodiment of the invention, the support is an inert non-porous annular support, preferably selected from one or more of sintered talc, fused SiC, fused alumina, aluminium silicate, quartz, ceramics.
According to a preferred embodiment of the present invention, the support used in catalyst a, catalyst B, catalyst C and catalyst D is the same.
The catalyst provided in the present invention can be prepared by methods known to those skilled in the art, for example, by the following method:
preparing an active substance or a precursor thereof into suspension slurry;
and spraying the suspension slurry to the carrier in a sugar coating pot at the temperature of 120-150 ℃ to load a certain amount of active substances on the carrier, thereby obtaining the catalysts at all sections.
According to the preferred embodiment of the invention, before the start-up, the prepared catalyst needs to be calcined for 4-12 hours at the temperature of 400-420 ℃ in an oxidizing atmosphere, namely, the catalyst is activated, and then the feeding operation is carried out.
According to still another aspect of the present invention, there is provided a process for producing phthalic anhydride, which comprises subjecting a mixed gas of o-xylene and an oxygen-containing gas to catalytic oxidation reaction in a reactor in contact with the above-mentioned catalyst to obtain phthalic anhydride.
In the reactor, catalyst a, catalyst B, catalyst C and catalyst D were packed in this order from the gas inlet end to the gas outlet end.
According to a preferred embodiment of the invention, the loading volume of catalyst a is 35% to 55% of the total catalyst loading volume;
the filling volume of the catalyst B accounts for 14-30% of the total filling volume of the catalyst;
the filling volume of the catalyst C accounts for 16-35% of the total filling volume of the catalyst;
the loading volume of catalyst D was 11% to 25% of the total catalyst loading volume.
According to a preferred embodiment of the invention, the loading volume of catalyst B is smaller than the loading volume of catalyst a and the loading volume of catalyst D is smaller than the loading volume of catalyst C.
According to a preferred embodiment of the invention, the reactor is a fixed bed reactor.
In a preferred embodiment of the invention, the cross-sectional area of each catalyst bed is the same, and the filling height of the catalyst A is 1.2-1.6 m;
the filling height of the catalyst B is 0.5-0.9 m;
the filling height of the catalyst C is 0.6-1.0 m;
the filling height of the catalyst D is 0.4-0.8 m;
the total loading height of each catalyst was 2.9-3.6 meters.
The catalytic selectivity of the catalyst provided by the invention from the catalyst A to the catalyst D is in a descending trend. Wherein, the catalyst A and the catalyst B have higher catalytic oxidation selectivity, and in the process of contacting reaction raw materials with the catalyst A and the catalyst B, the o-xylene is selectively oxidized into phthalic anhydride. Thus, the activity of catalyst A and catalyst B is relatively low in order to avoid deep oxidation of the feedstock to maleic anhydride, CO and CO2By-products, thereby ensuring high yield of the phthalic anhydride and high quality of the product. Catalyst C and catalyst D show oxidation activity mainly compared with catalyst A and catalyst B, and are selectedThe catalyst has low performance, and aims to carry out sufficient reaction on a small amount of raw materials left after the catalyst A and the catalyst B are subjected to catalytic oxidation so as to reduce the emission of harmful gases. According to the four-section bed catalyst, the conversion rate of the o-xylene after the reaction raw material is contacted with the catalyst A reaches 75-85%, the conversion rate of the o-xylene after the reaction raw material passes through the catalyst B reaches 85-95%, the conversion rate of the o-xylene after the reaction raw material passes through the catalyst C reaches 95-98%, and the conversion rate of the o-xylene after the reaction raw material passes through the catalyst D reaches 100%.
The catalyst provided by the invention is 100-105g/Nm3Has higher selectivity and stability, moderate catalyst activity, phthalic anhydride yield of 114-116%, impurity phthalide content as low as 0.01%, and catalyst life of more than 3 years to 4 years.
Detailed Description
The present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.
In the embodiment of the invention, the catalyst A, the catalyst B, the catalyst C and the catalyst D all use the same carrier, and the carrier is annular, and has phi (outer diameter) of 8.0mm, phi (inner diameter) of 5.0mm and height of 6.0 mm.
The titanium dioxide used in the examples of the present invention was anatase type having a specific surface area of 20m2/g-25m2Per g, pore diameter of
Figure BDA0001785321300000041
The medium and small pores account for 70 to 80 percent, the pore volume is 0.1 to 0.3ml/g, and the particle diameter is 0.1 to 0.4 mu m.
83.78g of vanadyl oxalate, 3.86g of cesium sulfate, 4.86g of niobium oxalate and 180ml of formamide are prepared as a transparent blue solution, which is then mixed with 712g of titanium dioxide and 6.81g of antimony trioxide and emulsified to form a suspension, and the suspension is sprayed on the carrier in a sugar-coated pan at 140 ℃. When the weight of the coating on the carrier is increased to 13 percent, the catalyst A1 is obtained. The same suspension slurry and spray coating method as used for catalyst A1 was used to obtain catalyst A2 when the weight of the coating on the support was increased to 15%. The same suspension slurry and spray coating method as used for catalyst A1 was used to obtain catalyst A3 when the weight of the coating on the support was increased to 17%.
98.45g of vanadyl oxalate, 2.05g of cesium sulfate, 3.73g of niobium oxalate and 180ml of formamide are prepared into a transparent blue solution, then 712g of titanium dioxide and 15.23g of antimony trioxide are mixed and emulsified into a suspension slurry, and the suspension is sprayed on the carrier in a sugar coating pan at 140 ℃. When the weight of the coating on the carrier is increased to 14 percent, the catalyst B1 is obtained. The same suspension slurry and spraying method as those of catalyst B1 were used to obtain catalyst B2 when the weight of the coating on the support was increased to 15%. The same suspension slurry and spraying method as those of catalyst B1 were used to obtain catalyst B3 when the weight of the coating on the support increased by 16%.
112.04g vanadyl oxalate, 8.10g niobium oxalate and 180ml formamide are prepared into a transparent blue solution, then 712g titanium dioxide and 21.60g antimony trioxide are mixed and emulsified into suspension liquid, and the suspension liquid is sprayed on the carrier in a sugar coating pan under the condition of 140 ℃. When the weight of the coating on the carrier is increased to 16 percent, the catalyst C1 is obtained. Using the same suspension slurry and spray coating method as for catalyst C1, catalyst C2 was obtained when the weight of the coating on the support had increased to 15%.
130.2g of vanadyl oxalate, 5.03g of niobium oxalate and 5.36g of ammonium dihydrogen phosphate 180ml of formamide are prepared into a transparent blue solution, then 712g of titanium dioxide and 25.92g of antimony trioxide are mixed and emulsified into a suspension slurry, and the suspension is sprayed on the carrier in a sugar coating pan at 140 ℃. When the weight of the coating on the carrier is increased to 17 percent, the catalyst D1 is obtained. Using the same suspension slurry and spray coating method as for catalyst D1, catalyst D2 was obtained when the weight of the coating on the support had increased to 15%.
98.45g of vanadyl oxalate, 2.05g of cesium sulfate, 3.73g of niobium oxalate, 2.82g of ammonium dihydrogen phosphate and 180ml of formamide are prepared into a transparent blue solution, then 712g of titanium dioxide and 15.23g of antimony trioxide are mixed and emulsified into a suspension slurry, and the suspension is sprayed on the carrier in a sugar-coated pan at 140 ℃. When the weight of the coating on the carrier is increased to 14 percent, the catalyst B4 is obtained.
112.04g of vanadyl oxalate, 8.10g of niobium oxalate, 3.19g of ammonium dihydrogen phosphate and 180ml of formamide are prepared into a transparent blue solution, then 712g of titanium dioxide and 21.60g of antimony trioxide are mixed and emulsified into a suspension slurry, and the suspension is sprayed on the carrier in a sugar-coated pan at 140 ℃. When the weight of the coating on the carrier is increased to 16 percent, the catalyst C3 is obtained.
The catalyst prepared above is filled in a single-tube reactor, and phthalic anhydride is prepared by taking o-xylene as a raw material. The reaction tube is made of boiler steel, the inner diameter of the reaction tube is 28mm, the tube length is 4000mm, and the filling height of the catalyst is 2800-3600 mm. The yield of phthalic anhydride is determined by collecting a gas sample from a sampling port near the outlet end of the reaction tube, condensing the gas sample and then performing chemical analysis. The outer layer of the reaction tube is provided with a circularly flowing molten salt as a heat exchange medium.
Example 1
Catalyst D1, catalyst C1, catalyst B1 and catalyst A1 were sequentially loaded into the four-stage bed reactor from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 900mm, 800mm and 1400mm, respectively. Air flow rate of 4Nm3H, o-xylene concentration 105g/Nm3The salt bath temperature was 353 ℃ and the yield of phthalic anhydride was 115%. The hot spot of the upper section of the catalyst bed layer is 440-450 ℃, the hot spot of the middle section is 410-430 ℃, the content of phthalide in the phthalic anhydride product is 0.01 percent, the loss rate of the phthalic anhydride yield per quarter is 0.2 percent, and the service life of the catalyst is 3.5 years.
Example 2
Catalyst D1, catalyst C1, catalyst B1 and catalyst A2 were loaded into the four-stage bed reactor in the order from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 900mm, 800mm and 1400 mm. Air flow rate of 4Nm3H, o-xylene concentration 100g/Nm3The salt bath temperature is 350.5 ℃, and the yield of the phthalic anhydride is 116 percent. The hot spot of the upper section of the catalyst bed layer is 440-448 ℃, the hot spot of the middle section is 400-420 ℃, and the content of phthalide in the end product is 0.01%. The yield of phthalic anhydride lost per quarter was 0.2%, and the catalyst had a life of 4 years.
Example 3
Catalyst D1, catalyst C1, catalyst B1 and catalyst A3 were sequentially loaded into the four-stage bed reactor from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 900mm, 800mm and 1400 mm. Air flow rate of 4Nm3H, o-xylene concentration 95g/Nm3The salt bath temperature is 350.8 ℃, and the yield of the phthalic anhydride is 115%. The hot spot at the upper section of the catalyst bed is 450-460 ℃, andthe hot spot is 400-420 ℃, and the content of phthalide in the terminal product is 0.01%. The yield of phthalic anhydride lost per quarter was 0.2%, and the catalyst life was 3.5 years.
Example 4
Catalyst D1, catalyst C1, catalyst B2 and catalyst A2 were sequentially loaded into the four-stage bed reactor from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 900mm, 800mm and 1400 mm. Air flow rate of 4Nm3H, o-xylene concentration 95g/Nm3The salt bath temperature was 352 ℃ and the yield of phthalic anhydride was 114%. The hot spot of the upper section of the catalyst is 440-450 ℃, the hot spot of the middle section of the catalyst is 410-430 ℃, and the content of phthalide in the terminal product is 0.02%. The yield of phthalic anhydride lost per quarter was 0.2%, and the catalyst life was 2.5 years.
Example 5
Catalyst D1, catalyst C1, catalyst B3 and catalyst A2 were sequentially loaded into the four-stage bed reactor from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 900mm, 800mm and 1400 mm. Air flow rate of 4Nm3H, o-xylene concentration 90g/Nm3The salt bath temperature is 358 ℃, and the yield of the phthalic anhydride is 114%. The hot spot of the upper section of the catalyst is 440-450 ℃, the hot spot of the middle section is 430-440 ℃, and the content of phthalide in the terminal product is 0.02%. The yield of phthalic anhydride lost per quarter was 0.2%, and the catalyst life was 2.5 years.
Example 6
Catalyst D1, catalyst C1, catalyst B1 and catalyst A2 were loaded into the four-stage bed reactor in the order from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 1000mm, 700mm and 1300 mm. Air flow rate of 4Nm3H, o-xylene concentration 100g/Nm3Salt bath temperature 351 ℃ and yield of phthalic anhydride 115%. The hot spot of the upper section of the catalyst is 440-450 ℃, the hot spot of the middle section of the catalyst is 410-425 ℃, and the content of phthalide in the terminal product is 0.01%. The yield of phthalic anhydride lost per quarter was 0.2%, and the catalyst life was 3.5 years.
Example 7
Catalyst D2, catalyst C1, catalyst B1 and catalyst A2 were sequentially loaded into a four-stage bed reactor from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 900mm,800mm and 1400 mm. Air flow rate of 4Nm3H, o-xylene concentration 100g/Nm3The salt bath temperature was 353 ℃ and the yield of phthalic anhydride was 114%. The hot spot of the upper section of the catalyst is 440-450 ℃, the hot spot of the middle section of the catalyst is 400-420 ℃, and the content of phthalide in the terminal product is 0.04%. The yield of phthalic anhydride lost per quarter was 0.2%, and the catalyst life was 2.5 years.
Example 8
Catalyst D1, catalyst C2, catalyst B1 and catalyst A2 were loaded into the four-stage bed reactor in the order from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 900mm, 800mm and 1400 mm. Air flow rate of 4Nm3H, o-xylene concentration 100g/Nm3The salt bath temperature is 350 ℃, and the yield of the phthalic anhydride is 114%. The hot spot of the upper section of the catalyst is 440-450 ℃, the hot spot of the middle section of the catalyst is 410-420 ℃, and the content of phthalide in the terminal product is 0.01%. The yield of phthalic anhydride lost per quarter was 0.2%, and the catalyst life was 2.5 years.
Example 9
Catalyst D1, catalyst C3, catalyst B4 and catalyst A2 were loaded into the four-stage bed reactor in the order from the gas outlet direction to the inlet direction, and the corresponding loading heights were 500mm, 900mm, 800mm and 1400 mm. Air flow rate of 4Nm3H, o-xylene concentration 80g/Nm3The salt bath temperature was 362 ℃ and the yield of phthalic anhydride was 112%. The hot spot of the upper section of the catalyst is 440-450 ℃, the hot spot of the middle section of the catalyst is 420-440 ℃, and the content of phthalide in the terminal product is 0.02%. In this case, the oxidation load is low, the yield of phthalic anhydride is low, by-products are many, and the catalyst life is 1.5 years.
When the ratio of active substance to support mass in catalyst B is higher than that of catalyst A (1-2 percentage points), the load is 105g/Nm3The yield of phthalic anhydride in the state is 115 percent; when the mass ratio of the active material to the carrier in the catalyst A is higher than that in the catalyst B (1-2 percentage points), the load is 100g/Nm3In this state, the yield of phthalic anhydride was 116%.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims (9)

1. The catalyst is a four-section bed catalyst, and comprises a catalyst A, a catalyst B, a catalyst C and a catalyst D in sequence from a gas inlet end to a gas outlet end, wherein the catalyst A, the catalyst B, the catalyst C and the catalyst D all comprise carriers and active substances loaded on the carriers, and the active substances comprise V2O5、TiO2And an auxiliary agent;
the mass ratio of the active substance to the carrier in the catalyst A is 13-15%;
the mass ratio of the active substance to the carrier in the catalyst B is 14 percent;
the mass ratio of the active substance to the carrier in the catalyst C is more than 15% and less than or equal to 17%;
the mass ratio of the active substance to the carrier in the catalyst D is more than 15% and less than or equal to 18%;
catalyst a comprises, based on the total mass of active species in catalyst a: 3.00-8.00 wt% V2O5、0.50-2.00wt％Sb2O3、0.20-0.70wt％Cs、0.05-0.40wt％Nb2O5And the balance of TiO2；
Catalyst B comprises, based on the total mass of active substances in catalyst B: 6.00-10.00 wt% V2O5、1.00-4.00wt％Sb2O3、0.10-0.40wt％Cs、0.20-0.50wt％Nb2O5And the balance of TiO2；
Catalyst C comprises, based on the total mass of active species in catalyst C: 8.00-15.00 wt% V2O5、2.00-5.00wt％Sb2O3、0.30-0.80wt％Nb2O5And the balance of TiO2；
Catalyst D comprises, based on the total mass of active species in catalyst D: 12.00-20.00 wt% V2O5、3.00-6.00wt％Sb2O3、0.20-0.60wt％Nb2O5、0.10-0.50wt％P2O5And the balance of TiO2。
2. The method of claim 1, wherein the TiO is selected from the group consisting of2Is anatase type TiO2。
3. The method of claim 1, wherein the TiO is selected from the group consisting of2Has a specific surface area of 17m2/g-25m2Per g, pore diameter
Figure FDA0003130194380000011
The medium and small pores account for 70 to 80 percent, the pore volume is 0.1 to 0.3ml/g, and the particle diameter is 0.1 to 0.4 mu m.
4. The production method according to any one of claims 1 to 3, wherein the support is an inert nonporous annular support.
5. A method of production according to any one of claims 1 to 3, characterised in that the support is selected from one or more of sintered talc, fused SiC, fused alumina, aluminium silicate, quartz, ceramics.
6. A process for producing phthalic anhydride, which comprises subjecting a mixed gas of o-xylene and an oxygen-containing gas to catalytic oxidation reaction in a reactor in contact with the catalyst according to any one of claims 1 to 5 to obtain phthalic anhydride.
7. The process of claim 6, wherein the loading volume of catalyst A is 35% to 55% of the total catalyst loading volume;
the filling volume of the catalyst B accounts for 14-30% of the total filling volume of the catalyst;
the filling volume of the catalyst C accounts for 16-35% of the total filling volume of the catalyst;
the loading volume of catalyst D was 11% to 25% of the total catalyst loading volume.
8. The process of claim 6 or 7, wherein the packing volume of catalyst B is less than the packing volume of catalyst A and the packing volume of catalyst D is less than the packing volume of catalyst C.
9. The process according to claim 6 or 7, characterized in that the reactor is a fixed bed reactor.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1580050A (en) * 2003-08-14 2005-02-16 中国石油化工股份有限公司 Method for preparing phthalic anhydride
CN101130535A (en) * 2006-08-25 2008-02-27 中国石油化工股份有限公司 Method for producing phthallic anhydride
CN101422727A (en) * 2007-10-31 2009-05-06 中国石油化工股份有限公司 Benzoic anhydride catalyst and preparation method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1580050A (en) * 2003-08-14 2005-02-16 中国石油化工股份有限公司 Method for preparing phthalic anhydride
CN101130535A (en) * 2006-08-25 2008-02-27 中国石油化工股份有限公司 Method for producing phthallic anhydride
CN101422727A (en) * 2007-10-31 2009-05-06 中国石油化工股份有限公司 Benzoic anhydride catalyst and preparation method thereof

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