阅读说明：本技术 一种邻苯二甲酸酐的制备方法 (Preparation method of phthalic anhydride ) 是由 刘玉芬 安欣 袁滨 师慧敏 张东顺 冯晔 张作峰 于 2018-08-31 设计创作，主要内容包括：本发明公开了一种用于制备邻苯二甲酸酐的催化剂,所述催化剂为四段床催化剂,自气体入口端至气体出口端依次为催化剂A、催化剂B、催化剂C和催化剂D,四种催化剂均包括载体以及负载在载体上的活性物质,活性物质包括V<Sub>2</Sub>O<Sub>5</Sub>、TiO<Sub>2</Sub>和助剂；催化剂A中活性物质与载体的质量比为11％-17％；催化剂B中活性物质与载体的质量比为10％-16％；催化剂C中活性物质与载体的质量比大于15％且小于或等于17％；催化剂D中活性物质与载体的质量比大于15％且小于或等于18％。本发明提供的催化剂具有高选择性和长寿命,苯酐收率高,性能稳定。(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 V 2 O 5 、TiO 2 And 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.)

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 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%.

2. The catalyst according to claim 1, wherein the promoter is selected from one or more of the following elements or compounds thereof: K. rb, Cs, Sb, Sn, Nb, P, Zr, Bi and Ag.

3. The catalyst according to claim 1 or 2,

the mass ratio of the active substance to the carrier in the catalyst A is 12-16%;

the mass ratio of the active substance to the carrier in the catalyst B is 11-15%;

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 18% or less.

4. The catalyst according to any one of claims 1 to 3,

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: 12.00-20.00wt％V₂O₅、3.00-6.00wt％Sb₂O₃、0.20-0.60wt％Nb₂O₅、0.10-0.50wt％P₂O₅And the balance of TiO₂。

5. The method according to any one of claims 1 to 4, wherein the TiO is selected from the group consisting of₂Is anatase type TiO₂The preferred specific surface area is 17m²/g-25m²Per g, pore diameter

6. A method of production according to any one of claims 1 to 5, characterized in that the support is an inert non-porous annular support, preferably selected from one or more of sintered talc, fused SiC, fused alumina, aluminium silicates, quartz, ceramics.

7. 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 6 to obtain phthalic anhydride.

8. The process of claim 7, 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.

9. The process of claim 7 or 8, 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.

10. The process of any one of claims 7 to 9, wherein the reactor is a fixed bed reactor.

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 inventionThe catalyst is a four-section bed catalyst, 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 catalyst A, the catalyst B, the catalyst C and the catalyst D 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%.

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

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. Compared with the catalyst A and the catalyst B, the catalyst C has the advantages that the oxidation activity is dominant, the selectivity is lower, and the purpose is to fully react a small amount of raw materials remained after the catalyst A and the catalyst B are catalytically oxidized, so that the emission of harmful gases is reduced. 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 by weightSurface area 20m²/g-25m²Per g, pore diameter of

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.