A method for preparing a solid phosphoric acid catalyst
By improving the catalyst composition and activation process through preparation methods, the problem of catalyst durability and performance balance was solved, resulting in catalysts with high conversion rates and long lifespans, thereby reducing enterprise production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 李成生
- Filing Date
- 2026-02-28
- Publication Date
- 2026-06-19
AI Technical Summary
Existing solid phosphoric acid catalysts have poor durability during use, are prone to degradation, and it is difficult to balance catalytic performance with physical properties, resulting in low production efficiency and frequent reactor shutdowns for maintenance.
The catalyst is prepared by using polyphosphoric acid, boric acid and diatomaceous earth as the main components, through specific mixing, extrusion, drying, calcination and activation steps. Activation is carried out by a combination of rotary kiln and steam generator, and the ratio of water vapor and air is controlled to ensure the activity and strength of the catalyst.
The prepared catalyst has high conversion rate and long life, which can meet the production needs of enterprises, reduce equipment maintenance and catalyst replacement frequency, and improve production efficiency.
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Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a catalyst, and more particularly to a method for preparing a solid phosphoric acid catalyst. Background Technology
[0002] Solid phosphoric acid catalysts (SPACs) are among the most widely used catalysts in the petrochemical industry. They are extensively applied in reactions such as oligomerization, chelation, hydrocarbonation, and hydration of low-carbon olefins. In particular, they exhibit excellent catalytic activity for the alkylation of benzene and other aromatic hydrocarbons with olefins, as well as for the oligomerization or polymerization of olefins. The activation process is one of the necessary conditions for the catalyst to acquire activity. The activation process not only enables the catalyst to acquire activity but also gives it a better pore size distribution, thereby improving the selectivity of the target product.
[0003] However, existing catalysts are not particularly durable and may degrade over time (e.g., through passivation, disintegration, etc.). Furthermore, in many cases, catalytic performance must be balanced with the physical properties of the catalyst material. For example, increasing the amount of phosphoric acid improves catalytic performance but lacks the physical properties necessary for continued use. Using existing catalysts may require higher operating temperatures and lower reactor space velocities to maintain acceptable conversion levels. However, higher temperatures may lead to undesirable byproducts and increased catalyst coking, while slower flow rates may result in lower overall productivity. Consequently, existing catalysts also require relatively frequent reactor shutdowns for catalyst replacement, all of which contribute to a decrease in overall efficiency.
[0004] Therefore, there is still a need for more durable catalysts with improvements in one or more areas of activity, compressive strength, crystallinity, acidity (surface and / or overall), and porosity. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing a solid phosphoric acid catalyst. The catalyst provided by this method has the advantages of long life and high conversion rate, and is particularly suitable for different products, thereby solving the problems in the prior art.
[0006] The objective of this invention is achieved through the following technical solution: a method for preparing a solid phosphoric acid catalyst, characterized in that: the solid phosphoric acid catalyst comprises the following components in parts by mass: polyphosphoric acid 40-60; boric acid 22-25; diatomaceous earth 22-25; The preparation method includes the following steps: (1) Heat polyphosphoric acid to 100-135℃ and add boric acid to mix; (2) After adding diatomaceous earth and mixing and homogenizing, the mixture is extruded into strips using an extruder. (3) Dry the sample at 150-230℃ for 4-5 hours; (4) The dried sample is calcined at 400-600℃ for 5 hours to obtain the final product.
[0007] Further: The components include the following parts by mass: polyphosphoric acid 50; boric acid 22; diatomaceous earth 22.
[0008] Furthermore: drying is carried out in a drying chamber, and activation is carried out in a rotary kiln.
[0009] Furthermore, it also includes an activation step: (1) The activation device includes a rotary kiln and a steam generator. 8-15 lifting plates are evenly arranged inside the rotary kiln. The rotary kiln and the steam generator are connected by a steam pipe. (2) A steam conduit passes through the rotary kiln, and air enters the rotary kiln through the conduit. The steam flow rate is 30 to 100 moles per kilogram of catalyst. The molar ratio of air to steam is 0.5 to 2.0:1. (3) The temperature at both ends of the rotary kiln is 200℃~300℃, the temperature in the middle of the rotary kiln is 200℃~300℃, the feed temperature is 160℃~200℃, and the rotary kiln speed is 50~100r / min; (4) When activating, first stop the water vapor and keep the activation temperature and air flow rate for 20 to 50 minutes.
[0010] Furthermore: There are two sets of rotary kilns, the first set is 8m long and the second set is 4m long; the temperatures of the first set of rotary kilns from front to back are 100℃, 200℃, 300℃ and 400℃ respectively; the temperature of the second set of rotary kilns is 200℃.
[0011] The advantages and effects of this invention are: The catalyst provided by this invention has the effects of uniform free acid, high crush resistance, high lifespan and high conversion rate, overcoming the defects of previous activation processes where free acid could not be precisely controlled, the activation results were greatly deviated, and free acid and strength could not be taken into account at the same time.
[0012] The catalyst prepared by this invention has a lifespan that is particularly suitable for the actual production conditions of enterprises, making the maintenance of equipment consistent with the replacement cycle of the catalyst, thereby reducing the production costs of enterprises. Detailed Implementation
[0013] This invention discloses a method for preparing a solid phosphoric acid catalyst, wherein the solid phosphoric acid catalyst comprises the following components in parts by mass: polyphosphoric acid 40-60; boric acid 22-25; diatomaceous earth 22-25; Preferably, the components include the following parts by weight: 50 parts polyphosphoric acid; 22 parts boric acid; and 22 parts diatomaceous earth.
[0014] The preparation method includes the following steps: (1) Heat the polyphosphoric acid to 100-135℃ and add boric acid while stirring; (2) Continue to add diatomaceous earth and mix until it becomes muddy. Put it into an extruder and press it into strips. The strips are 5.5±0.3mm in diameter and 20-30mm in length. (3) Dry the sample at 150-230℃ for 4-5 hours; (4) The dried sample strips were calcined at 400-600℃ for 5 hours; (5) The calcined samples were activated in a rotary kiln at 100-400℃ for 4-5 hours.
[0015] Preferred: The activation step includes: (1) The activation device includes a rotary kiln and a steam generator. 8-15 lifting plates are evenly arranged inside the rotary kiln. The rotary kiln and the steam generator are connected by a steam pipe. (2) A steam conduit passes through the rotary kiln, and air enters the rotary kiln through the conduit. The steam flow rate is 30 to 100 moles per kilogram of catalyst. The molar ratio of air to steam is (0.5 to 2.0): 1. (3) The temperature at both ends of the rotary kiln is 200℃~300℃, the temperature in the middle of the rotary kiln is 200℃~300℃, the feed temperature is 160℃~200℃, and the rotary kiln speed is 50~100r / min; (4) When activating, first stop the water vapor and keep the activation temperature and air flow rate for 20 to 50 minutes.
[0016] Preferably, there are two sets of rotary kilns: the first set is 8m long, and the second set is 4m long. The temperatures of the first set of rotary kilns, from front to back, are 100℃, 200℃, 300℃, and 400℃, respectively; the temperature of the second set of rotary kilns is 200℃. This two-stage design allows for a larger molar amount of steam in the first stage, thereby improving activation efficiency. The second stage dries the activated catalyst, thoroughly removing any residual moisture from the first stage to ensure the overall moisture content is below 2%, meeting the requirements. Because the second stage is purely drying, the temperature can be significantly lower than the first stage. Therefore, this design ensures thorough activation while significantly reducing overall energy consumption.
[0017] The present invention will be further illustrated below through examples. Example 1
[0018] A method for preparing a solid phosphoric acid catalyst, comprising the following components in parts by mass: 50 parts polyphosphoric acid; 22 parts boric acid; and 22 parts diatomaceous earth.
[0019] The preparation method includes the following steps: (1) Mix polyphosphoric acid and boric acid and heat to 100°C; (2) After adding diatomaceous earth and mixing and homogenizing, the mixture is placed in an extruder and extruded into strips with a diameter of about 5 mm. (3) Dry the sample at 200℃ for 4.5 hours; (4) The dried sample was calcined at 500℃ for 5 hours; (5) Activate the roasted material to obtain the final product.
[0020] Conversion rate test: In the propylene oligomerization reaction, the catalyst prepared in this example is compared with a commercially available catalyst from a certain brand.
[0021] Catalyst product evaluation was conducted in a stationary reactor, a stainless steel tubular reactor, with 100 mL of catalyst. Propylene was used as the reactant, with a propylene concentration of 47% (mass), and the remainder being alkanes. The process conditions were: pressure 4.0 MPa, temperature 200 °C, and liquid hourly space velocity (LHSV) 2.0 hr. -1 The raw material contains 40-55% olefins and the remainder is alkanes. The olefins react with the catalyst to undergo oligomerization, and the gaseous stream is periodically introduced into an online gas chromatograph for analysis.
[0022] The analysis and calculation methods in the above reaction process involve taking samples of the reaction raw materials and tail gas after the reaction has stabilized for 12 hours. The mass percentage content of olefins and alkanes in the raw materials and tail gas is analyzed according to GB / T3392-91 (Determination of Hydrocarbon Impurities in Polymer Propylene by Gas Chromatography), and the olefin conversion rate is calculated. The olefin conversion rate is defined as follows: Olefin conversion rate = (Mass of converted olefins / Mass of feed olefins) * 100%; The catalyst prepared in Example 1 was tested, and the results showed a propylene conversion rate of 90%, a free acid content of 15.8% (P₂O₅ by mass), a moisture content of 2.0%, and a bulk density of 1.1 g / cm³. 3 Its strength is 150 N / cm.
[0023] Pilot-scale test: The catalyst prepared according to Example 1 was placed in a reactor. A feed containing 45 wt% propane and 55 wt% propylene was introduced at a rate of 3.1 h. -1 The linear space-time velocity (LHSV) passes through the catalyst bed. The temperature and pressure of the catalyst bed are maintained at 216 °C and 6 x 10⁻⁶. 6 The propylene conversion rate is shown in the table below (where week 0 is calculated after the reaction has stabilized).
[0024] Table 1 Running Time and Propylene Conversion Rate
[0025] As shown in the table above, the catalyst prepared by this invention has a service life of up to 24 weeks, with minimal passivation throughout the cycle, meeting the requirements for the entire usage period. For processing enterprises, a minor repair and a major equipment overhaul (maintenance) are required within a one-year production cycle, typically taking three months between the two maintenance operations, with an interval of four and a half months (approximately 18 weeks). The catalyst described in this invention exhibits a relatively stable catalytic effect (conversion rate) within a single production cycle, and decreases significantly after 20 weeks. Its lifespan perfectly meets the actual production conditions of enterprises, aligning equipment maintenance with catalyst replacement cycles and reducing production costs.
[0026] Comparison of reaction products: In the petroleum cracking process, the catalyst prepared in this example and a certain brand of catalyst were added. C9 (hydrocarbon compounds containing 9 carbon atoms) and C6 (hydrocarbon compounds containing 9 carbon atoms) were prepared respectively. 12 The results are shown in the table below. Note: Content refers to the conversion rate of the target product in the main product.
[0027] Table 2 Comparison of conversion rates of different target products
[0028] As can be seen from the table above, for different target products, the catalyst of this invention only needs to adjust the corresponding process conditions to achieve different target products. That is, the catalyst prepared by this method has good target properties and high directed yield. Hydrocarbon compounds with different numbers of carbon atoms can be directionally prepared through different process conditions.
Claims
1. A method for preparing a solid phosphoric acid catalyst, characterized in that: The solid phosphoric acid catalyst comprises the following components in parts by weight: polyphosphoric acid 40-60; boric acid 22-25; diatomaceous earth 22-25; The preparation method includes the following steps: (1) Heat polyphosphoric acid to 100-135℃, add boric acid and mix. (2) After adding diatomaceous earth and mixing and homogenizing, the mixture is extruded into strips using an extruder. (3) Dry the sample at 150-230℃ for 4-5 hours; (4) The dried sample strips were calcined at 400-600℃ for 5 hours; (5) Activate the calcined sample at 100-400℃ for 4-5 hours.
2. The method for preparing a solid phosphoric acid catalyst according to claim 1, characterized in that: The components include the following parts by weight: polyphosphoric acid 50; boric acid 22; diatomaceous earth 22.
3. The method for preparing a solid phosphoric acid catalyst according to claim 1 or 2, characterized in that: Activation is carried out in a rotary kiln.
4. The method for preparing a solid phosphoric acid catalyst according to claim 3, characterized in that: The activation step includes: (1) The activation device includes a rotary kiln and a steam generator. 8-15 lifting plates are evenly arranged inside the rotary kiln. The rotary kiln and the steam generator are connected by a steam pipe. (2) A steam conduit passes through the rotary kiln, and air enters the rotary kiln through the conduit. The steam flow rate is 30 to 100 moles per kilogram of catalyst. The molar ratio of air to steam is 0.5 to 2.0:
1. (3) The temperature at both ends of the rotary kiln is 200℃~300℃, the temperature in the middle of the rotary kiln is 200℃~300℃, the feed temperature is 160℃~200℃, and the rotary kiln speed is 50~100r / min; (4) When activating, first stop the water vapor and keep the activation temperature and air flow rate for 20 to 50 minutes.
5. The method for preparing a solid phosphoric acid catalyst according to claim 3, characterized in that: There are two sets of rotary kilns. The first set is 8m long and the second set is 4m long. The temperatures of the first set of rotary kilns are 100℃, 200℃, 300℃ and 400℃ from front to back. The temperature of the second set of rotary kilns is 200℃.