A method for producing high quality pyrolysis feedstock

Abstract

The application discloses a method for preparing high-quality cracking material, which comprises the following steps: contacting C5 alkanes and hydrogen with a catalyst in a reactor, and reacting to obtain high-quality cracking material; the C5 alkanes are at least one selected from normal pentane and isopentane; the high-quality cracking material is at least one selected from ethane, propane, normal butane and normal pentane; the catalyst is composed of an acidic carrier and a noble metal active element and an auxiliary element supported on the surface of the acidic carrier; the noble metal active element is at least one selected from palladium and platinum; the auxiliary element is at least one selected from potassium and iron; in the catalyst, the mass ratio of the noble metal active element to the acidic carrier is 0.0001-0.005:1, and the mass ratio of the auxiliary element to the acidic carrier is 0.002-0.05:1.

Description

Technical Field

[0001] This application relates to a method for preparing high-quality pyrolysis feedstock, belonging to the field of chemical engineering. Background Technology

[0002] Ethylene, propylene, and butadiene produced by steam cracking are fundamental raw materials for the petrochemical industry, widely used in the production of synthetic materials such as plastics, rubber, and fibers. Ethylene is the most in-demand basic chemical raw material among these three olefins; 95% of the world's ethylene production is achieved through steam cracking, and China's domestic steam cracking capacity accounts for over 80% of the total ethylene production capacity. Steam cracking to produce ethylene is a non-catalytic thermal processing method, and the ethylene yield is determined by the overall composition of the feedstock. In China, the main feedstock for steam cracking units is naphtha, but the ethylene yield from naphtha cracking is typically only around 30%, far lower than that of ethane (approximately 80%) and propane (approximately 40%). C5 alkanes are an important component of naphtha; converting them first to ethane and propane before feeding them into the steam cracking unit can significantly improve the ethylene yield. Summary of the Invention

[0003] The purpose of this invention is to provide a catalyst for the precatalytic conversion of C5 alkanes to produce high-efficiency steam cracking feedstocks such as ethane and propane, and its applications. The catalyst features high catalytic activity, good selectivity, and resistance to deactivation.

[0004] According to one aspect of this application, a method for preparing high-quality pyrolysis feedstock is provided, characterized in that...

[0005] Includes the following steps:

[0006] In the reactor, C5 alkanes and hydrogen are brought into contact with the catalyst and reacted to obtain high-quality cracked feedstock;

[0007] The C5 alkane is selected from at least one of n-pentane and isopentane;

[0008] The high-quality pyrolysis feedstock is selected from at least one of ethane, propane, n-butane, and n-pentane;

[0009] The catalyst is composed of an acidic support and noble metal active elements and auxiliary elements supported on the surface of the acidic support.

[0010] The noble metal active element is selected from at least one of palladium and platinum;

[0011] The auxiliary element is selected from at least one of potassium and iron;

[0012] In the catalyst, the mass ratio of the noble metal active element to the acidic support is 0.0001 to 0.005:1, and the mass ratio of the auxiliary element to the acidic support is 0.002 to 0.05:1.

[0013] To achieve the modification of the acid properties of the molecular sieve to balance the cracking reaction and the hydrogen transfer reaction, the acid support is a modified molecular sieve;

[0014] The catalyst is obtained through the following steps:

[0015] (1) Mix the acidic support with an aqueous solution containing a precursor of noble metal active elements, and dry it to obtain the catalyst precursor.

[0016] (2) The catalyst precursor is mixed with an aqueous solution containing an auxiliary element precursor, dried (II), and calcined to obtain the catalyst.

[0017] The noble metal active element precursor is selected from at least one of palladium nitrate, palladium chloride, chloroplatinic acid, tetraammineplatinum chloride, platinum nitrate, and ammonium chloropalladate.

[0018] The temperature of the drying process I is 30–120°C;

[0019] The drying time for step I is 1 to 12 hours;

[0020] The auxiliary element precursor is selected from at least one of potassium nitrate and ferric sulfate;

[0021] The temperature of the drying II process is 30–120°C;

[0022] The drying time for step II is 1–12 hours;

[0023] The roasting temperature is 300–600°C;

[0024] The roasting time is 1 to 10 hours.

[0025] The acidic carrier is obtained through the following steps:

[0026] The molecular sieve was impregnated in a phosphoric acid solution, modified at room temperature, dried, calcined, and treated with steam to obtain the acidic support.

[0027] The molecular sieve is selected from at least one of SAPO-34 molecular sieve, Beta molecular sieve, MCM-41 molecular sieve, MOR molecular sieve, ZSM-22 molecular sieve and ZSM-5 type molecular sieve;

[0028] The phosphoric acid solution has a mass fraction of 1-10%;

[0029] The impregnation is an equal-volume impregnation;

[0030] The drying temperature is 90–120°C;

[0031] The drying time is 10–24 hours;

[0032] The calcination temperature is 300–600°C;

[0033] The calcination time is 1 to 10 hours;

[0034] The steam treatment time is 0.1 to 10 hours;

[0035] The mass ratio of water vapor to molecular sieve is 0.5 to 5:1.

[0036] The reactor is selected from at least one of a fixed-bed reactor, a moving-bed reactor, and a fluidized-bed reactor.

[0037] The catalyst is pre-reduced with hydrogen.

[0038] The volume hourly space velocity (VHSV) of the hydrogen pre-reduced hydrogen is 100–10000 h⁻¹. -1 ;

[0039] The temperature for hydrogen pre-reduction is 200–600°C;

[0040] The hydrogen pre-reduction time is 0.2 to 100 hours.

[0041] The mass hourly space velocity (MSV) of the C5 alkane is 0.1–10 h⁻¹. -1 ;

[0042] The molar ratio of hydrogen to C5 alkane is 0.2 to 10:1.

[0043] The reaction temperature is 250–500°C;

[0044] The reaction pressure is 0.1–10 MPa.

[0045] Specifically, it includes the following steps:

[0046] a) A certain concentration of phosphoric acid aqueous solution was dripped into the molecular sieve matrix in equal volumes, left to stand overnight at room temperature, dried at 120℃ for 12h, and finally calcined at 550℃ for 6h to obtain support A;

[0047] a) The molecular sieve parent material was immersed in a phosphoric acid solution and modified at room temperature. After the modification was completed, it was dried and calcined at 400-600℃ to obtain support A.

[0048] b) The carrier A obtained in step a) is loaded into a reaction tube and modified by steam heat treatment at 400-800°C to obtain the acidic carrier as described in claim 1.

[0049] c) Add the noble metal active component precursor to deionized water, stir thoroughly to dissolve, and prepare impregnation precursor solution a.

[0050] d) Add the impregnation precursor solution a obtained in step c) uniformly to the acidic support obtained in step b) until adsorption saturation, then let it stand at room temperature and dry.

[0051] e) Add the precursor of the auxiliary component to deionized water, stir thoroughly to dissolve, and prepare impregnation precursor solution b;

[0052] f) The impregnation precursor solution b obtained in step e) is uniformly added to the material obtained in step d) until adsorption saturation, allowed to stand at room temperature, and then dried. Then, it is calcined at 300–600°C to prepare the above-mentioned C5 alkane conversion catalyst.

[0053] The beneficial effects that this application can produce include:

[0054] (1) The noble metal active component in the catalyst provided by the present invention can efficiently catalyze the dehydrogenation of C5 alkanes;

[0055] (2) The acidic functional component in the catalyst provided by the present invention is modified by phosphoric acid treatment and hydrothermal treatment to make it have suitable acid density and acid strength, while inhibiting side reactions such as hydrogen transfer during the cracking process, and can efficiently catalyze the cracking of isopentane. In addition, phosphoric acid modification can enhance the hydrothermal stability of the molecular sieve and increase the selectivity of low carbon olefins.

[0056] (3) The catalyst provided by the present invention has the role of stabilizing the reaction intermediate. It plays a synergistic catalytic role with the noble metal active component and the acidic site in the support, which improves the reaction conversion rate and effectively inhibits the occurrence of side reactions.

[0057] (4) The catalyst preparation method provided by the present invention is simple, easy to operate, and has good repeatability, making it suitable for large-scale industrial production.

[0058] (5) The catalyst provided by the present invention can efficiently catalyze the C5 alkane conversion reaction, and has the characteristics of high catalytic activity, good selectivity and not easy deactivation. Detailed Implementation

[0059] The present invention will now be described in detail with reference to the embodiments, but the present invention is not limited to these embodiments.

[0060] Unless otherwise specified, all raw materials used in the examples are commercially available, and the instruments and equipment are configured with parameters recommended by the manufacturer.

[0061] Example 1: Preparation of Catalyst

[0062] An equal volume of 50g SAPO-34 molecular sieve matrix was impregnated with a 1% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120°C and calcined at 500°C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500°C. The mass ratio of steam to support was 2:1, and the steam treatment time was 3 hours, yielding the support.

[0063] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the required mass of the noble metal active component precursor and the auxiliary component precursor for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 0.20 wt%. First, a 0.50 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.20 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 500 °C to obtain catalyst 1. # .

[0064] Example 2: Preparation of Catalyst

[0065] An equal volume of 50g Beta molecular sieve matrix was impregnated with a 2% (w / w) phosphoric acid solution, left to stand overnight at room temperature, dried at 120℃, and calcined at 500℃. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500℃, with a steam-to-support mass ratio of 2:1 and a treatment time of 3 hours, yielding the support.

[0066] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the required mass of the noble metal active component precursor and the auxiliary component precursor for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 0.20 wt%. First, a 0.50 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.20 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 500 °C to obtain catalyst 2. # .

[0067] Example 3: Preparation of Catalyst

[0068] An equal volume of 50g MCM-41 molecular sieve matrix was impregnated with a 3% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120°C and calcined at 500°C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500°C. The mass ratio of steam to support was 2:1, and the steam treatment time was 3 hours, yielding the support.

[0069] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the mass of the noble metal active component precursor and the auxiliary component precursor required for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 0.20 wt%. First, a 0.50 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.20 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 500 °C to obtain catalyst 3. # .

[0070] Example 4: Preparation of Catalyst

[0071] An equal volume of 50g of MOR molecular sieve matrix was impregnated with a 3% (w / w) phosphoric acid solution, left to stand overnight at room temperature, dried at 120°C, and calcined at 500°C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500°C. The mass ratio of steam to support was 2:1, and the steam treatment time was 3 hours, yielding the support.

[0072] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the mass of the noble metal active component precursor and the auxiliary component precursor required for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 0.20 wt%. First, a 0.50 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.20 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 500 °C to obtain catalyst 4. # .

[0073] Example 5: Preparation of Catalyst

[0074] An equal volume of 50g ZSM-5 molecular sieve matrix was impregnated with a 5% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120℃ and calcined at 500℃. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500℃. The mass ratio of steam to support was 2:1, and the steam treatment time was 3 hours, yielding the support.

[0075] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading amounts of the noble metal active component and the auxiliary component, the required mass of the noble metal active component precursor and the auxiliary component precursor for preparing the impregnation precursor solution was calculated. The loading amount of the noble metal was 0.50 wt%, and the loading amount of the auxiliary component was 0.20 wt%. First, a 0.50 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.20 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 500 °C to obtain catalyst 5. # .

[0076] Example 6 Preparation of Catalyst

[0077] An equal volume of 50 g ZSM-5 molecular sieve matrix was impregnated with a 6% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120 °C and calcined at 500 °C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500 °C. The mass ratio of steam to support was 0.5:1, and the steam treatment time was 0.1 h, yielding the support.

[0078] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the required mass of the noble metal active component precursor and the auxiliary component precursor for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 0.20 wt%. First, a 0.50 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.20 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 500 °C to obtain catalyst 6. # .

[0079] Example 7 Preparation of Catalyst

[0080] An equal volume of 50 g ZSM-5 molecular sieve matrix was impregnated with a 6% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120 °C and calcined at 500 °C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500 °C. The mass ratio of steam to support was 0.5:1, and the steam treatment time was 0.1 h, yielding the support.

[0081] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the mass of the noble metal active component precursor and the auxiliary component precursor required for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 0.020 wt%. First, a 0.50 wt% platinum nitrate impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.020 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 500 °C to obtain catalyst 7. # .

[0082] Example 8 Preparation of Catalyst

[0083] An equal volume of 50 g ZSM-5 molecular sieve matrix was impregnated with a 6% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120 °C and calcined at 500 °C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500 °C. The mass ratio of steam to support was 0.5:1, and the steam treatment time was 0.1 h, yielding the support.

[0084] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the mass of the noble metal active component precursor and the auxiliary component precursor required for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 0.80 wt%. First, a 0.50 wt% platinum nitrate impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.80 wt% potassium nitrate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 600 °C to obtain catalyst 8. # .

[0085] Example 9 Preparation of Catalyst

[0086] An equal volume of 50 g ZSM-5 molecular sieve matrix was impregnated with a 6% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120 °C and calcined at 500 °C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500 °C. The mass ratio of steam to support was 0.5:1, and the steam treatment time was 0.1 h, yielding the support.

[0087] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading amounts of the noble metal active component and the auxiliary component, the required mass of the noble metal active component precursor and the auxiliary component precursor for preparing the impregnation precursor solution was calculated. The loading amount of the noble metal was 0.50 wt%, and the loading amount of the auxiliary component was 5 wt%. First, a 0.50 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 5 wt% potassium nitrate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 300 °C to obtain catalyst 9. # .

[0088] Example 10 Preparation of Catalyst

[0089] An equal volume of 50 g ZSM-5 molecular sieve matrix was impregnated with a 6% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120 °C and calcined at 500 °C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500 °C. The mass ratio of steam to support was 0.5:1, and the steam treatment time was 0.1 h, yielding the support.

[0090] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the mass of the noble metal active component precursor and the auxiliary component precursor required for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 3.00 wt%. First, a 0.50 wt% palladium chloride impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 3.00 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 400 °C to obtain catalyst 10. # .

[0091] Example 11 Preparation of Catalyst

[0092] An equal volume of 50 g ZSM-5 molecular sieve matrix was impregnated with a 6% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120 °C and calcined at 500 °C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500 °C. The mass ratio of steam to support was 0.5:1, and the steam treatment time was 0.1 h, yielding the support.

[0093] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the mass of the noble metal active component precursor and the auxiliary component precursor required for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 1.2 wt%. First, a 0.50 wt% palladium chloride impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 1.20 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 450 °C to obtain catalyst 11. # .

[0094] Example 12 Preparation of Catalyst

[0095] An equal volume of 50 g ZSM-5 molecular sieve matrix was impregnated with a 7% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120 °C and calcined at 500 °C. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 600 °C. The mass ratio of steam to support was 5:1, and the steam treatment time was 6 hours, yielding the support.

[0096] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the mass of the noble metal active component precursor and the auxiliary component precursor required for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.50 wt%, and the loading of the auxiliary component was 5 wt%. First, a 0.50 wt% palladium chloride impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 5.00 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 550 °C to obtain catalyst 12. # .

[0097] Example 13 Preparation of Catalyst

[0098] An 8% (w / w) phosphoric acid solution was used to impregnate 50g of ZSM-5 molecular sieve matrix with an equal volume. The mixture was left to stand overnight at room temperature, dried at 120℃, and calcined at 300℃. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500℃. The mass ratio of steam to support was 4:1, and the steam treatment time was 4 hours to obtain the support.

[0099] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the required mass of the noble metal active component precursor and the auxiliary component precursor for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 0.02 wt%, and the loading of the auxiliary component was 0.05 wt%. First, a 0.02 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 0.05 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 600 °C to obtain catalyst 13. # .

[0100] Example 14 Preparation of Catalyst

[0101] An equal volume of 50g ZSM-5 molecular sieve matrix was impregnated with a 9% (w / w) phosphoric acid solution and allowed to stand overnight at room temperature. The matrix was then dried at 120℃ and calcined at 400℃. The calcined sample was then placed in a quartz tube and subjected to steam heat treatment at 500℃. The mass ratio of steam to support was 0.5:1, and the steam treatment time was 1 hour, yielding the support.

[0102] The water absorption of the above-mentioned support was determined by saturated adsorption method. Then, based on the saturated water absorption and the target loading of the noble metal active component and the auxiliary component, the mass of the noble metal active component precursor and the auxiliary component precursor required for preparing the impregnation precursor solution was calculated. The loading of the noble metal was 1.00 wt%, and the loading of the auxiliary component was 1.20 wt%. First, a 1.00 wt% chloroplatinic acid impregnation precursor solution was uniformly added to the acidic support until adsorption saturation. Then, it was allowed to stand and dry overnight at room temperature, followed by drying at 120 °C. Subsequently, a 1.20 wt% ferric sulfate precursor solution was added to the above catalyst, allowed to stand overnight at room temperature, dried at 120 °C, and calcined at 300 °C to obtain catalyst 14. # .

[0103] Example 15 Comparative Example

[0104] Comparative catalyst 15 was prepared using unmodified hydrogen-form ZSM-5 (without phosphoric acid solution modification or steam heat treatment) as a support, following the catalyst preparation method described in Example 6. # .

[0105] Example 16 Evaluation of the isopentane cracking activity of the catalyst

[0106] The C5 alkane used in the catalyst evaluation was isopentane, for catalysts 1 prepared in Examples 1-15. # ~15 # The catalytic performance of isopentane conversion catalysts and comparative catalysts was evaluated using a fixed-bed reactor with an inner diameter of 9 mm and a catalyst loading of 2 mL. After reduction with hydrogen, the catalyst was reacted with a feedstock containing isopentane and hydrogen. The products were analyzed online using an Agilent 7890A chromatograph. Catalyst activity was evaluated based on indicators such as isopentane conversion and selectivity for high-quality cracked feedstock. The calculation methods for each indicator are as follows:

[0107]

[0108] isopentane 进 The mass flow rate (kg / h) of isopentane at the reactor inlet; isopentane 出 and (ethane + propane + n-butane + n-pentane) 出 These represent the mass flow rates (kg / h) of isopentane and low-carbon hydrocarbons at the reactor outlet, respectively. Experiment 1 # ~15 # The catalyst, catalyst pretreatment conditions, reaction conditions, and isopentane reactivity of the catalyst are shown in Table 1.

[0109] Table 1 Experiment 1 # ~15 # Pretreatment conditions, reaction conditions and catalyst activity

[0110]

[0111]

[0112]

[0113] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing high-quality pyrolysis feedstock, characterized in that, Includes the following steps: In the reactor, C5 alkanes and hydrogen are brought into contact with the catalyst and reacted to obtain high-quality cracked feedstock; The C5 alkane is selected from at least one of n-pentane and isopentane; The high-quality pyrolysis feedstock is selected from at least one of ethane, propane, n-butane, and n-pentane; The catalyst is composed of an acidic support and noble metal active elements and auxiliary elements supported on the surface of the acidic support. The noble metal active element is selected from at least one of palladium and platinum; The auxiliary element is selected from at least one of potassium and iron; In the catalyst, the mass ratio of the noble metal active element to the acidic support is 0.0001 to 0.005:1, and the mass ratio of the auxiliary element to the acidic support is 0.002 to 0.05:

1.

2. The method according to claim 1, characterized in that, The catalyst is obtained through the following steps: (1) Mix the acidic support with an aqueous solution containing a precursor of noble metal active elements, and dry it to obtain the catalyst precursor. (2) The catalyst precursor is mixed with an aqueous solution containing an auxiliary element precursor, dried (II), and calcined to obtain the catalyst.

3. The method according to claim 2, characterized in that, The noble metal active element precursor is selected from at least one of palladium nitrate, palladium chloride, chloroplatinic acid, tetraammineplatinum chloride, platinum nitrate, and ammonium chloropalladate. The temperature of the drying process is 30–120°C. The drying time for step I is 1 to 12 hours.

4. The method according to claim 2, characterized in that, The auxiliary element precursor is selected from at least one of potassium nitrate and ferric sulfate; The temperature of the drying II process is 30–120°C; The drying time for step II is 1–12 hours; The roasting temperature is 300–600°C; The roasting time is 1 to 10 hours.

5. The method according to claim 1, characterized in that, The acidic carrier is obtained through the following steps: The molecular sieve was impregnated in a phosphoric acid solution, modified at room temperature, dried, calcined, and treated with steam to obtain the acidic support.

6. The method according to claim 5, characterized in that, The molecular sieve is selected from at least one of SAPO-34 molecular sieve, Beta molecular sieve, MCM-41 molecular sieve, MOR molecular sieve, ZSM-22 molecular sieve and ZSM-5 type molecular sieve; The phosphoric acid solution has a mass fraction of 1-10%; The impregnation is an equal-volume impregnation; The drying temperature is 90–120°C; The drying time is 10–24 hours; The calcination temperature is 300–600°C; The calcination time is 1 to 10 hours; The steam treatment time is 0.1 to 10 hours; The mass ratio of water vapor to molecular sieve is 0.5 to 5:

1.

7. The method according to claim 1, characterized in that, The reactor is selected from at least one of a fixed-bed reactor, a moving-bed reactor, and a fluidized-bed reactor.

8. The method according to claim 1, characterized in that, The catalyst is pre-reduced with hydrogen. The volume hourly space velocity (VHSV) of the hydrogen pre-reduced hydrogen is 100–10000 h⁻¹. -1 ; The temperature for hydrogen pre-reduction is 200–600°C; The hydrogen pre-reduction time is 0.2 to 100 hours.

9. The method according to claim 1, characterized in that, The mass hourly space velocity (MSV) of the C5 alkane is 0.1–10 h⁻¹. -1 ; The molar ratio of hydrogen to C5 alkane is 0.2 to 10:

1.

10. The method according to claim 1, characterized in that, The reaction temperature is 250–500°C; The reaction pressure is 0.1–10 MPa.

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