CN100446858C - A zirconium-based supported vanadium-phosphorus-oxygen catalyst and its preparation method and application - Google Patents

Abstract

A zirconium-based supported vanadium-phosphorus-oxygen catalyst, which is composed of a zirconium-based support material or a phosphoric acid-modified zirconium-based support material loaded with vanadium-phosphorus oxide, the zirconium-based support material is zirconia, and the loading capacity of the vanadium-phosphorus oxide is expressed as pyrophosphate oxygen Vanadium is preferably 25-46wt% of the total mass of the catalyst, wherein the atomic ratio of phosphorus to vanadium is 1.2, the specific surface area is about 21-29m²/g, and the supported vanadium phosphorus oxide is pyrophosphoric acid Vanadyl crystalline phase or amorphous phase, and contains a certain amount of vanadyl phosphate species. When it is used as a catalyst for maleic anhydride reaction by air oxidation of n-butane, its single-pass conversion rate is 38-89%, maleic anhydride selectivity is 29-69%, and the highest maleic anhydride yield is in the typical reaction temperature range of 380-420 °C. was 61.2%. The invention discloses its preparation method.

Description

A zirconium-based supported vanadium-phosphorus-oxygen catalyst and its preparation method and application

technical field

The invention relates to a supported vanadium phosphorus oxide catalyst and preparing maleic anhydride by catalytically oxidizing n-butane with air on the catalyst.

Background technique

Maleic anhydride, referred to as maleic anhydride, also known as maleic anhydride, is an important chemical raw material, which can be used in the production of unsaturated polyester resin, fumaric anhydride, lubricating oil additives, heat-resistant styrene resin and other fine chemical intermediates Body and specialty chemicals, and also raw materials for the production of high value-added fine chemicals such as 1,4-butanediol, tetrahydrofuran, γ-butyrolactone, etc., and its application range is still expanding [see Catal.Rev. - Sci. Eng., 27 (1985) 373 and Chem. Rev., 88 (1988) 50].

The early production method of maleic anhydride was prepared by selective oxidation of benzene using V ₂ O ₅ -MoO ₃ catalyst. Later, a production process route using 1-butene as a raw material was developed, but the catalytic activity of the original V ₂ O ₅ -MoO ₃ catalyst for the 1-butene reaction system was not ideal [see Hydrocarbon Process, 11 (1980) 149 ]. Later it was found that vanadium phosphorus composite oxide (VPO) can effectively catalyze the selective oxidation of n-butane to generate maleic anhydride [US Patent 3293268 (1966)]. However, due to the limited resources of butane at that time, the reaction process was not competitive in industry. Subsequently, due to the large-scale development of natural gas, butane has a rich source and its price is getting lower and lower. In addition, from the perspective of environmental protection, compared with the previously adopted benzene production process, the butane oxidation route also has obvious advantages. Therefore, developed countries such as Europe and the United States have gradually stopped the production route using benzene as the raw material and replaced it with the production route using butane as the raw material. 100% of the butane raw material has been used in the newly built reactors in western countries. In my country, the production process of maleic anhydride is still relatively backward, and the production route of benzene method is basically adopted, and the scale is relatively small and the output is low. With the rapid development of my country's national economy and the obvious increase in the demand for maleic anhydride, it is imperative to change the original backward production technology. Therefore, it is very necessary to strengthen scientific and technological research in this area and develop technologies with independent intellectual property rights.

For the reaction of catalyzing the selective oxidation of butane to maleic anhydride, many types of catalysts have been tried, but so far only VPO catalysts are the most effective for this reaction [see Catal.Rev.-Sci.Eng., 27 (1985) 373]. With a VPO catalyst, the products of this reaction are essentially carbon oxides (CO _x ), with the exception of maleic anhydride. The VPO catalysts currently used in industry are all unsupported, and their main component is vanadyl pyrophosphate [(VO) ₂ P ₂ O ₇ ]. Compared with unsupported catalysts, supported catalysts have several characteristics: ①It can increase the surface area/volume ratio of the active phase (active component); ②It can generally improve the mechanical strength of the catalyst; ③It can improve the heat and mass transfer of the catalyst. For this reason, many researchers have tried to prepare supported catalysts. The supports used include conventional SiO ₂ , TiO ₂ , Al ₂ O ₃ , SiC, Al-MCM-41, SBA-15, etc. However, the prepared supported The performance per unit mass of the catalyst is lower than that of the unsupported catalyst [see J.Phys.Chem.B, 101(1997) 6895; Appl.Catal.A, 135(1996) 231; Appl.Catal.A, 135 (1996) 209; React. Kinet. Catal. Lett., 32 (1986) 209; Catal. Lett., 28 (1994) 1; Catal. Lett., 76 (2001) 3; J. Catal., 238 (2006 )232]. The research results show that after the carrier is used, there will be an interaction between the carrier and the loaded VPO, and this interaction may inhibit the formation of the desired specific VPO phase, resulting in a decrease in catalytic performance. This indicates that the choice of support as well as the properties of the support itself are very important for the development of such supported catalysts. It has been found that when VPO is loaded onto a reducible carrier (such as TiO ₂ ) [see Appl.Catal.A, 135 (1996) 209; The interaction is stronger, and it is also easier to be reduced, so its catalytic activity is significantly improved but the selectivity is significantly reduced; and when VPO is loaded on a relatively inert carrier (such as SiO ₂ ), the distance between it and the carrier When the interaction is weak, the selectivity of the catalyst is improved but the activity is decreased. On the other hand, the research results also show that when the supported VPO catalyst is prepared by the impregnation method in water, there are more phosphates containing V ⁵⁺ in the sample, mainly α-VOPO ₄ and γ-VOPO ₄ . Butane conversion and maleic anhydride selectivity are all low on this type of supported catalyst, such as the butane conversion of the supported VPO catalyst prepared by aqueous phase impregnation method on conventional _SiO2 is about 50%, maleic anhydride selectivity is then low at 20% [see J. Phys. Chem. B, 101 (1997) 6895]. This suggests that improvements in catalyst preparation methods can also improve the performance of supported VPO catalysts.

Contents of the invention

The purpose of the present invention is to provide a better supported VPO catalyst, which is characterized by: 1. _ZrO is a class of multifunctional material, as catalyst carrier or carrier component, it is widely used in such as hydrocarbon selective reduction of nitrogen oxides (NO _x ) [see J.Catal.221(2004) 594], three-way catalyst [see Catal.Lett.72(2001) 39; J.Catal.221(2004) 148], methanol synthesis and decomposition [see J.Catal .178 (1998) 153; J.Catal.193 (2000) 207; Appl.Catal.A: Gen.171 (1998) 123], carbon monoxide hydrogenation [see Appl.Catal.A: Gen.213 (2001) 225 ], partial oxidation of methane [see Catal.Lett.51(1998) 163], steam reforming of methanol [see Catal.43(1988) 141; Catal.Today 51(1999) 521] and preparation of sulfated zirconia solid Strong acids [see J. Catal. 151 (1995) 364; J. Catal. 196 (2000) 104]. For the first time, the present invention adopts zirconia carrier material or phosphoric acid-modified zirconium-based carrier material; 2. adopt co-deposition method in organic phase to prepare supported catalyst, which can avoid generating more phosphate containing V ⁵⁺ ; 3. add Macromolecular organic matter makes the dispersion of supported vanadium phosphorus oxygen more uniform; ④The catalyst not only has high catalytic activity, but also can maintain a relatively ideal maleic anhydride selectivity, so it is a type of supported VPO catalyst with the highest yield of maleic anhydride so far.

Technical scheme of the present invention is as follows:

A zirconium-based supported vanadium-phosphorus-oxygen catalyst, which is composed of a zirconium-based support material or a phosphoric acid-modified zirconium-based support material loaded with vanadium-phosphorus oxide, the zirconium-based support material is zirconia, and the loading capacity of the vanadium-phosphorus oxide is expressed as pyrophosphate oxygen Vanadium is preferably 25-46wt% of the total mass of the catalyst, wherein the atomic ratio of phosphorus to vanadium is 1.2, the specific surface area is 21-29m ² /g, and the supported vanadium phosphorus oxide is vanadyl pyrophosphate crystal phase or amorphous Phase, and contains a certain amount of vanadyl phosphate species.

A method for preparing the supported vanadium phosphorus oxide catalyst of the present invention, which consists of the following steps:

A. Preparation of zirconium-based carrier:

A.1 Dissolve ZrOCl ₂ 8H ₂ O and CTAB (cetyltrimethylammonium bromide) in water at a mass ratio of 4 to 5:1, stir to obtain a clear solution, and continue at 70°C After stirring for 2 hours, slowly add NaOH solution with a concentration of 2mol/L dropwise to the solution to adjust the pH to 12-14 to obtain a white sol-gel.

A.2 Transfer the mixture to an autoclave and keep the temperature at 100°C for 48h, then cool it down to room temperature naturally, wash and filter the obtained white solid until the filtrate is neutral,

A.3 Dry the obtained white solid at 100°C first, then raise it from room temperature to 550°C at a rate of 1°C/min in an air atmosphere and keep the temperature at this temperature for 8 hours. This results in a zirconium-based support material, denoted ZrO ₂ .

B. Preparation of phosphoric acid-modified zirconium-based support material:

B.1 Dry the hydrothermally treated white solid obtained in step A.2 at 100°C, then treat it with H ₃ PO ₄ solution (0.5-1.5mol/L), add 20ml of H ₃ PO ₄ solution per gram of solid sample , stirred at constant temperature at 70°C for 12h, and then washed the treated sample several times until the filtrate was neutral. The calcination conditions are the same as step A.3, thus obtaining a phosphoric acid-modified zirconium-based support material, denoted as H ₃ PO ₄ -p-ZrO ₂ .

B.2 Treat the zirconium-based support material ZrO ₂ prepared in step A.3 with H ₃ PO ₄ solution (0.5-1.5 mol/L), and add 20 ml of H ₃ PO ₄ solution per gram of solid sample. Stir at constant temperature at 70°C for 12h, and then wash the treated sample several times until the filtrate is neutral. Dry the obtained sample, and the roasting conditions are the same as in step A.3. A phosphoric acid-modified zirconium-based support material is thus obtained, denoted as H ₃ PO ₄ —ZrO ₂ .

C. Preparation of zirconium-based supported vanadium phosphorus oxide catalyst

C.1 Mix vanadium pentoxide with isobutanol-benzyl alcohol mixed solvent, heat and reflux for 6 hours,

C.2 Add a certain amount of polyethylene glycol, and then add an appropriate amount of zirconium-based support (ZrO ₂ ) or phosphoric acid-modified zirconium-based support (H ₃ PO ₄ -p-ZrO ₂ or H ₃ PO ₄ -ZrO ₂ ), Continue to reflux for 0.5 hours,

C.3 Add phosphoric acid. The amount of phosphoric acid added is such that the atomic ratio of phosphorus to vanadium is 1.2:1.0. The added phosphoric acid can be 85% (m/m) phosphoric acid. Continue to reflux for 7 hours, and gradually turn blue during the reaction process. Precipitate out,

C.4 Cool the reaction mixture to room temperature, let it stand for 2 to 5 hours, filter, wash the filtrate several times with isobutanol and acetone, and heat the filtrate to 120°C in an air atmosphere to dry to obtain the zirconium-based support of the present invention Vanadium phosphorus oxygen catalyst precursor,

C.5 Activate at 400°C in the reaction mixture before use to obtain a fresh zirconium-based supported vanadium-phosphorus-oxygen catalyst of the present invention.

In the above-mentioned method for preparing a zirconium-based supported vanadium-phosphorus-oxygen catalyst, in step C.1, the isobutanol-benzyl alcohol mixed solvent is composed of 1 volume of isobutanol and 1 volume of benzyl alcohol.

In the above-mentioned method for preparing a zirconium-based supported vanadium-phosphorus-oxygen catalyst, in step C.2, the added polyethylene glycol is polyethylene glycol with a molecular weight of 2000 to 6000, and the amount of added polyethylene glycol is equal to The mass ratio of vanadium is 45.8:100-77.5:100.

The application of the supported vanadium-phosphorus-oxygen catalyst of the invention is as a catalyst for air oxidation of n-butane to prepare maleic anhydride. The specific surface area of the supported vanadium phosphorus oxygen catalyst of the invention is in the range of 23-36m ² /g. Observation by a transmission electron microscope revealed that the supported vanadium phosphorus oxides were relatively uniformly dispersed on the carrier material (see Figure 1). The catalyst preparation method is relatively simple. When it is used in the air oxidation of n-butane to prepare maleic anhydride, in the typical reaction temperature range of 380-420°C, the single-pass conversion rate is 38-89%, the maleic anhydride selectivity is 29-69%, and the highest maleic anhydride yield is 61.2 %.

Description of drawings

Figure 1 is the transmission electron micrograph of the catalyst: (a) overall view: (b): a single particle.

Figure 2 is an XRD pattern of a representative catalyst.

Detailed ways

The present invention is further illustrated by the following examples.

Example 1

Dissolve 5.00g ZrOCl ₂ ·8H ₂ O and 1.00g CTAB in water, stir to obtain a clear solution, continue stirring at 70°C for 2 hours, then slowly add 2mol/L NaOH solution to the solution dropwise, and adjust the pH≥ 12.00, a white sol-gel was obtained. The mixture was transferred to an autoclave and kept at 100 °C for 48 h, then cooled to room temperature naturally. The solid was filtered and washed until the pH of the filtrate was neutral. The resulting white solid was then dried at 100°C. The white solid was heated from room temperature to 550° C. at a rate of 1° C./min in the air and roasted at this temperature for 8 hours. Thus a zirconium-based support without phosphoric acid modification was obtained.

Weigh 2.4 grams of V ₂ O ₅ , place it in a mixed solution of isobutanol/benzyl alcohol (30ml/30ml), reflux at 140°C for 6 hours, add 1.1 grams of polyethylene glycol (PEG2000) with a molecular weight of 2000, and add 6.0 g of the above-prepared zirconium-based carrier ZrO ₂ was continued to reflux for 0.5 hour, and 2.2 ml of 85% H ₃ PO ₄ was added dropwise according to the atomic ratio of P/V=1.2/1.0. Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) From room temperature to 400°C at a rate of 2°C/min for in-situ activation for 15 hours, an activated fresh catalyst was obtained. The specific surface area is 25.6m ² /g, and the loaded VPO component is basically in an amorphous state.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 380°C, the space velocity is 1200h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 38.4%, the selectivity of maleic anhydride is 36.1%, and the yield of maleic anhydride is 13.8%.

Example 2:

Dissolve 4.00g ZrOCl ₂ 8H ₂ O and 1.00g CTAB in water, stir to obtain a clear solution, continue stirring at 70°C for 2 hours, then slowly add 2mol/L NaOH solution to the solution dropwise, and adjust the pH≥ 12.00, a white sol-gel was obtained. The mixture was transferred to an autoclave and kept at 100 °C for 48 h, then cooled to room temperature naturally. The solid was filtered and washed until the pH of the filtrate was neutral. Then dry the obtained white solid at 100°C, put it in 1mol/L H ₃ PO ₄ solution, add 20ml of H ₃ PO ₄ solution per gram of solid sample, stir at 70°C for 12h, and then treat The filtered and washed samples were dried at 100°C until the filtrate was neutral. In the air at a rate of 1 ° C / min from room temperature to 550 ° C and constant temperature roasting at this temperature for 8 hours. A phosphoric acid-modified zirconium-based support is thus obtained.

Weigh 0.8 g of V ₂ O ₅ , place it in a mixed solution of isobutanol/benzyl alcohol (10ml/10ml), reflux at 140°C for 6 hours, add 0.37 g of polyethylene glycol (PEG6000) with a molecular weight of 6000, and add 2.0 g of the phosphoric acid-modified zirconium-based support (H ₃ PO ₄ -p-ZrO ₂ ) prepared above, continued to reflux for 0.5 hours, and added dropwise 85% H ₃ PO according to the atomic ratio of P/V=1.2/1.0 ₄ 0.72ml. Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) In situ activation from room temperature to 400°C at a rate of 2°C/min for 15 hours, an activated fresh catalyst was obtained. The specific surface area is 24.2m ² /g, and the loaded VPO component is the vanadyl pyrophosphate crystal phase.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 400°C, the space velocity is 1200h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 89.1%, the selectivity of maleic anhydride is 68.8%, and the yield of maleic anhydride is 61.2%.

Example 3:

Dissolve 4.00g ZrOCl ₂ 8H ₂ O and 1.00g CTAB in water, stir to obtain a clear solution, continue stirring at 70°C for 2 hours, then slowly add 2mol/L NaOH solution to the solution dropwise, and adjust the pH≥ 12.00, a white sol-gel was obtained. The mixture was transferred to an autoclave and kept at 100 °C for 48 h, then cooled to room temperature naturally. The solid was filtered and washed until the pH of the filtrate was neutral. Then the obtained white solid was dried at 100° C., raised from room temperature to 550° C. in air at a rate of 1° C./min, and roasted at this temperature for 8 hours at a constant temperature. Put the calcined solid in 1mol/L H ₃ PO ₄ solution, add 20ml of H ₃ PO ₄ solution per gram of solid sample, stir at 70°C for 12 hours, then filter and wash the sample until the filtrate is neutral properties, dried at 100°C, and then calcined under the same conditions as above to obtain a phosphoric acid-modified zirconium-based support (H ₃ PO ₄ -ZrO ₂ ).

Weigh 0.8 g of V ₂ O ₅ , place it in a mixed solution of isobutanol/benzyl alcohol (10ml/10ml), reflux at 140°C for 6 hours, add 0.37 g of polyethylene glycol (PEG6000) with a molecular weight of 6000, and add 2.0 g of the phosphoric acid-modified zirconium-based carrier H ₃ PO ₄ -ZrO ₂ prepared above was refluxed for 0.5 hour, and 0.72 ml of 85% H ₃ PO ₄ was added dropwise at an atomic ratio of P/V=1.2/1.0. Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) In situ activation from room temperature to 400°C at a rate of 2°C/min for 15 hours, an activated fresh catalyst was obtained. The specific surface area is 22.8m ² /g, and the loaded VPO component is the vanadyl pyrophosphate crystal phase with low crystallinity.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 420°C, the space velocity is 1200h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 71.9%, the selectivity of maleic anhydride is 54.2%, and the yield of maleic anhydride is 39.0%.

Example 4:

Weigh 0.8 g of V ₂ O ₅ , place it in a mixture of isobutanol/benzyl alcohol (10ml/10ml), and reflux at 140°C for 6 hours, add 0.62 g of polyethylene glycol (PEG2000) with a molecular weight of 2000, and add 2.0 g of the phosphoric acid-modified zirconium-based carrier H ₃ PO ₄ -p-ZrO ₂ prepared in Example 2 was continued to reflux for 0.5 hour, and 0.72 ml of 85% H ₃ PO ₄ was added dropwise at an atomic ratio of P/V=1.2/1.0. Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) In situ activation from room temperature to 400°C at a rate of 2°C/min for 15 hours, an activated fresh catalyst was obtained. The specific surface area is 23.5m ² /g, and the loaded VPO component is the vanadyl pyrophosphate crystal phase.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 400°C, the space velocity is 1800h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 80.5%, the selectivity of maleic anhydride is 71.2%, and the yield of maleic anhydride is 57.3%.

Example 5:

Weigh 0.4 g of V ₂ O ₅ , place it in a mixed solution of isobutanol/benzyl alcohol (10ml/10ml), reflux at 140°C for 6 hours, add 0.37 g of polyethylene glycol (PEG6000) with a molecular weight of 6000, and add 2.0 g of the phosphoric acid-modified zirconium-based carrier H ₃ PO ₄ -p-ZrO ₂ prepared in Example 2 was continued to reflux for 0.5 hour, and 0.72 ml of 85% H ₃ PO ₄ was added dropwise at an atomic ratio of P/V=1.2/1.0. Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) In situ activation from room temperature to 400°C at a rate of 2°C/min for 15 hours, an activated fresh catalyst was obtained. The specific surface area is 28.6m ² /g, and the loaded VPO component is the vanadyl pyrophosphate crystal phase.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 400°C, the space velocity is 1200h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 58.7%, the selectivity of maleic anhydride is 58.5%, and the yield of maleic anhydride is 34.3%.

Embodiment 6:

Weigh 2.0 grams of V ₂ O ₅ , place it in a mixture of isobutanol/benzyl alcohol (20ml/20ml), reflux at 140°C for 6 hours, add 1.1 grams of polyethylene glycol (PEG6000) with a molecular weight of 6000, and add 4.0 g of the phosphoric acid-modified zirconium-based carrier H ₃ PO ₄ -p-ZrO ₂ prepared in Example 2 was continued to reflux for 0.5 hour, and 0.72 ml of 85% H ₃ PO ₄ was added dropwise at an atomic ratio of P/V=1.2/1.0. Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) In situ activation from room temperature to 400°C at a rate of 2°C/min for 15 hours, an activated fresh catalyst was obtained. The specific surface area is 20.5m ² /g, and the loaded VPO component is the vanadyl pyrophosphate crystal phase.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 400°C, the space velocity is 1200h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 78.3%, the selectivity of maleic anhydride is 58.7%, and the yield of maleic anhydride is 46.0%.

Embodiment 7:

Weigh 0.8 g of V ₂ O ₅ , place it in a mixed solution of isobutanol/benzyl alcohol (10ml/10ml), reflux at 140°C for 6 hours, add 0.37 g of polyethylene glycol (PEG6000) with a molecular weight of 6000, and add 2.0 g of the phosphoric acid-modified zirconium-based carrier H ₃ PO ₄ -p-ZrO ₂ prepared in Example 2 was continued to reflux for 0.5 hour, and 0.72 ml of 85% H ₃ PO ₄ was added dropwise at an atomic ratio of P/V=1.2/1.0. Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) In situ activation from room temperature to 400°C at a rate of 2°C/min for 15 hours, an activated fresh catalyst was obtained. The specific surface area is 24.2m ² /g, and the loaded VPO component is the vanadyl pyrophosphate crystal phase.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 400°C, the space velocity is 3000h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 60.2%, the selectivity of maleic anhydride is 70.7%, and the yield of maleic anhydride is 42.5%.

Embodiment 8:

Dissolve 4.00g ZrOCl ₂ 8H ₂ O and 1.00g CTAB in water, stir to obtain a clear solution, continue stirring at 70°C for 2 hours, then slowly add 2mol/L NaOH solution to the solution dropwise, and adjust the pH≥ 12.00, a white sol-gel was obtained. The mixture was transferred to an autoclave and kept at 100 °C for 48 h, then cooled to room temperature naturally. The solid was filtered and washed until the pH of the filtrate was neutral. Then dry the obtained white solid at 100°C, put it in 1.5mol/L H ₃ PO ₄ solution, add 20ml of H ₃ PO ₄ solution per gram of solid sample, stir at 70°C for 12h, and then put The treated samples were filtered and washed until the filtrate was neutral, and dried at 100°C. In the air at a rate of 1 ° C / min from room temperature to 550 ° C and constant temperature roasting at this temperature for 8 hours. A phosphoric acid-modified zirconium-based support is thus obtained.

Weigh 0.8 g of V ₂ O ₅ , place it in a mixed solution of isobutanol/benzyl alcohol (10ml/10ml), reflux at 140°C for 6 hours, add 0.37 g of polyethylene glycol (PEG6000) with a molecular weight of 6000, and add 2.0 g of the phosphoric acid-modified zirconium-based carrier H ₃ PO ₄ -p-ZrO ₂ prepared above, continued to reflux for 0.5 hour, and added 0.72 ml of 85% H ₃ PO ₄ dropwise at an atomic ratio of P/V=1.2/1.0. Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) In situ activation from room temperature to 400°C at a rate of 2°C/min for 15 hours, an activated fresh catalyst was obtained. The loaded VPO component is vanadyl pyrophosphate crystal phase.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 380°C, the space velocity is 1200h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 67.5%, the selectivity of maleic anhydride is 34.0%, and the yield of maleic anhydride is 22.9%.

Embodiment 9:

Dissolve 4.00g ZrOCl ₂ 8H ₂ O and 1.00g CTAB in water, stir to obtain a clear solution, continue stirring at 70°C for 2 hours, then slowly add 2mol/L NaOH solution to the solution dropwise, and adjust the pH≥ 12.00, a white sol-gel was obtained. The mixture was transferred to an autoclave and kept at 100 °C for 48 h, then cooled to room temperature naturally. The solid was filtered and washed until the pH of the filtrate was neutral. Then dry the obtained white solid at 100°C, put it in 0.5mol/L H ₃ PO ₄ solution, add 20ml of H ₃ PO ₄ solution per gram of solid sample, stir at 70°C for 12h, and then put The treated samples were filtered and washed until the filtrate was neutral, and dried at 100°C. In the air at a rate of 1 ° C / min from room temperature to 550 ° C and constant temperature roasting at this temperature for 8 hours. A phosphoric acid-modified zirconium-based support was thus obtained.

Weigh 1.6 grams of V ₂ O ₅ , place it in a mixture of isobutanol/benzyl alcohol (20ml/20ml), reflux at 140°C for 6 hours, add 1.1 grams of polyethylene glycol (PEG6000) with a molecular weight of 6000, and add 4.0 g of the precursor prepared above was modified with phosphoric acid on the zirconium-based carrier H ₃ PO ₄ -p-ZrO ₂ , and continued to reflux for 0.5 hours, and added dropwise 85% H ₃ PO ₄ 0.72 ml according to the atomic ratio of P/V=1.2/1.0 . Reflux was continued for 7 hours. Filter and dry to obtain a blue precipitate, which is dried in air at 120°C. The prepared catalyst precursor powder was pressed into tablets under a pressure of 0.5 MPa, crushed, and 40-60 mesh particle samples were sieved and mixed in a reaction atmosphere (C ₄ H ₁₀ /O ₂ /N ₂ =1.5/17.2/81.3) In situ activation from room temperature to 400°C at a rate of 2°C/min for 15 hours, an activated fresh catalyst was obtained. The loaded VPO component is the vanadyl pyrophosphate crystal phase with low crystallinity.

Weigh 0.5 g of the activated fresh catalyst and place it in a quartz reaction tube with an inner diameter of 0.8 cm to evaluate the catalytic performance. The reaction temperature is 380°C, the space velocity is 1200h ^-1 , and the raw material gas composition is C ₄ H ₁₀ /O ₂ /N ₂ = 1.5/17.2/81.3 (V/V). The reaction mixture is passed through the online gas phase According to chromatographic analysis, the conversion rate of n-butane is 78.3%, the selectivity of maleic anhydride is 58.7%, and the yield of maleic anhydride is 46.0%.

Claims (8)

1. A zirconium-based supported vanadium-phosphorus-oxygen catalyst is characterized in that: it is composed of a zirconium-based carrier material loaded vanadium-phosphorus oxide, the zirconium-based carrier material is zirconia, and the loading capacity of the vanadium-phosphorus oxide is calculated in vanadyl pyrophosphate It is 25-46wt% of the total mass of the catalyst, wherein the atomic ratio of phosphorus to vanadium is 1.2, the specific surface area is 21-29m ² /g, and the supported vanadium phosphorus oxide is vanadyl pyrophosphate crystal phase or amorphous phase, And contains vanadyl phosphate species. 2. The zirconium-based supported vanadium-phosphorus-oxygen catalyst according to claim 1, characterized in that: the zirconium-based carrier material is a phosphoric acid-modified zirconium-based carrier material. 3. a method for preparing the zirconium-based supported vanadium-phosphorus-oxygen catalyst claimed in claim 1, is characterized in that it is made up of the following steps: Step 1. vanadium pentoxide is mixed with isobutanol-benzyl alcohol mixed solvent, heated and refluxed for 6 hours, Step 2. Add polyethylene glycol, then add zirconium-based carrier, continue to reflux for 0.5 hours, Step 3. add phosphoric acid, the add-on of phosphoric acid is to make the atomic ratio of phosphorus and vanadium be 1.2: 1.0, continue to reflux 7 hours, have blue precipitation to separate out gradually in the reaction process, Step 4. Cool the reaction mixture to room temperature, let it stand for 2 to 5 hours, filter, wash the filtrate with isobutanol and acetone, and heat the filtrate to 120°C in an air atmosphere to dry to obtain the zirconium-based support Vanadium phosphorus oxygen catalyst precursor, Step 5. Activate the precursor of the zirconium-based supported vanadium-phosphorus-oxygen catalyst in the reaction mixture gas at 400° C. to obtain a fresh zirconium-based supported vanadium-phosphorus-oxygen catalyst. 4. the method for preparing zirconium-based loaded vanadium phosphorus oxygen catalyst according to claim 3 is characterized in that: in step 1, described isobutanol-benzyl alcohol mixed solvent is made of 1 part of volume of isobutanol and 1 part of volume benzyl alcohol mixture composition. 5. The method for preparing a zirconium-based supported vanadium-phosphorus-oxygen catalyst according to claim 3, characterized in that: in step 2, the polyethylene glycol added is polyethylene glycol with a molecular weight of 2000 to 6000, adding polyethylene glycol The mass ratio of ethylene glycol to vanadium pentoxide is 45.8:100-77.5:100. 6. The method for preparing a zirconium-based supported vanadium-phosphorus-oxygen catalyst according to claim 3, characterized in that: in step 2, the zirconium-based carrier is a phosphoric acid-modified zirconium-based carrier. 7. The method for preparing a zirconium-based supported vanadium-phosphorus-oxygen catalyst according to claim 3, characterized in that: in step 3, the added phosphoric acid is phosphoric acid with a concentration of 85% by mass. 8. The use of the zirconium-based supported vanadium-phosphorus-oxygen catalyst according to claim 1 is as a catalyzer for preparing maleic anhydride by air oxidation of n-butane.

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