Copper-based catalysts, processes for their preparation and use, and processes for the synthesis of methanol

Abstract

The present application relates to the field of catalyst, in particular to a copper-based catalyst and its preparation method and application and methanol synthesis method, the preparation method comprises the following steps: step a, co-precipitation method is used to prepare a catalyst precursor containing copper element, zinc element and aluminum element; step b, the catalyst precursor prepared in step a is treated in-situ under CO2 / CH4 atmosphere, the catalyst prepared by the method has good stability, and when the catalyst is used for methanol synthesis, the generation of high-grade alkanes causing wax deposition can be effectively inhibited from the source under the conditions of high Fe content or temperature sudden change, so that the stable operation of the catalyst is ensured.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to a copper-based catalyst, its preparation method and application, and a method for methanol synthesis. Background Technology

[0002] Methanol is an important C1 chemical product and raw material for deep processing. It can be used to manufacture a variety of organic products such as chloromethane, methylamine and dimethyl sulfate, and is also a raw material for pesticides (insecticides, acaricides) and pharmaceuticals.

[0003] Industrially, methanol production primarily utilizes the catalytic conversion of syngas, with copper-based catalysts being the most common. However, during methanol synthesis, side reactions lead to the formation of paraffin wax—a mixture of higher alkanes—to varying degrees. Paraffin formation is generally considered to be related to the bulk Fe content in the catalyst and the reaction temperature; higher Fe content and sudden temperature changes result in severe wax deposition. This paraffin formation causes wax buildup in the methanol synthesis cooling system, increasing system resistance and negatively impacting the heat exchange efficiency of the methanol synthesis cooler. This leads to decreased efficiency of the crude methanol separator, excessive methanol content in the circulating gas, and more severe side reactions, potentially even causing liquid slugging in the compressor.

[0004] Most existing technologies passively reduce the impact of wax buildup on methanol production by using online dewaxing methods. CN209721996U discloses a methanol synthesis system that can remove paraffin wax generated during the synthesis process. The cold-side outlet of the preheater is connected to the inlet of the dewaxing device. The dewaxing device includes a tower body with internal separation components. The inlet of the dewaxing device is located on the lower-middle part of the tower body sidewall near the separation components. A methanol gas outlet is located at the top of the tower body, connected to the inlet of a methanol water cooler. A steam inlet is also located at the top of the tower body. A methanol discharge outlet and a paraffin wax discharge outlet are located at the bottom of the tower body. The methanol discharge outlet is connected to the hot-side inlet of a plate heat exchanger. Liquid methanol is cooled by the plate heat exchanger and then enters a methanol expansion tank. The cooled methanol gas enters a methanol high-pressure separator. The liquid separated from the methanol high-pressure separator enters the methanol expansion tank, and the gas exiting from the top of the methanol high-pressure separator is compressed by a circulating compressor. This system effectively solves the problem of wax buildup on the inner walls of the water cooler and high-pressure separator, ensuring stable operation over long production cycles. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem that existing catalysts may generate higher alkanes due to high Fe content or sudden temperature changes, thereby affecting the stability of the catalyst. This invention provides a copper-based catalyst, its preparation method, its application, and a methanol synthesis method. This catalyst has the characteristics of good stability.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a copper-based catalyst, the method comprising:

[0007] Step a: Prepare catalyst precursors containing copper, zinc and aluminum by co-precipitation method;

[0008] Step b: Treat the catalyst precursor obtained in step a in situ under a CO2 / CH4 atmosphere.

[0009] A second aspect of the present invention provides a copper-based catalyst prepared by the preparation method described in the first aspect.

[0010] A third aspect of the present invention provides the application of the catalyst described in the second aspect in methanol synthesis.

[0011] A fourth aspect of the present invention provides a method for methanol synthesis, the method comprising: reacting a feedstock containing CO and H2 under the copper-based catalyst conditions described in the second aspect.

[0012] Through the above technical solution, the present invention has the following advantages:

[0013] The catalyst prepared by the method of this invention has good stability. When the catalyst of this invention is used in the synthesis of methanol, it can effectively inhibit the formation of higher alkanes that cause waxing at the source under conditions of high Fe content or sudden temperature changes, thereby ensuring the stable operation of the catalyst. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] This invention provides a method for preparing the catalyst described above, the method comprising:

[0016] Step a: Prepare catalyst precursors containing copper, zinc and aluminum by co-precipitation method;

[0017] Step b: Treat the catalyst precursor obtained in step a in situ under a CO2 / CH4 atmosphere.

[0018] The catalyst prepared by the method of this invention has good stability. When the catalyst of this invention is used in the synthesis of methanol, it can effectively inhibit the formation of higher alkanes that cause waxing at the source under conditions of high Fe content or sudden temperature changes, thereby ensuring the stable operation of the catalyst.

[0019] According to a preferred embodiment of the present invention, the volume concentration of carbon dioxide in the CO2 / CH4 atmosphere is 10-50%, and the volume concentration of methane is 50-90%.

[0020] According to a preferred embodiment of the present invention, the conditions for the in-situ treatment include: a volume hourly space velocity of 1000-2000 h⁻¹. -1 The temperature is 300-500℃ and the pressure is 0.1-5MPa.

[0021] According to a preferred embodiment of the present invention, the in-situ treatment is performed by at least one alternating CO2 / CH4 purging in opposite directions.

[0022] According to a preferred embodiment of the present invention, step a includes: adding an alkaline substance to a mixed solution containing copper, zinc and aluminum sources for co-precipitation to obtain a precipitate, and then washing, drying, calcining and shaping the precipitate.

[0023] According to a preferred embodiment of the present invention, the alkaline substance includes at least one selected from sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide; and / or

[0024] According to a preferred embodiment of the present invention, the coprecipitation conditions include: a temperature of 50-70°C and a system pH of 7-8.

[0025] In this invention, the copper source, zinc source, and aluminum source can be conventional choices in the art, corresponding to soluble compounds of each element.

[0026] In this invention, the alkaline substance is first prepared into a solution with a concentration of 0.5-2 mol / L and then added to the mixed solution.

[0027] In this invention, the conditions for washing, drying, calcining, and molding can be conventional techniques in the field. For example, the washing is performed by centrifugation with deionized water at room temperature, using 3-5 times the volume of the precipitate each time, and washing is performed 5-10 times in total. The drying temperature is 100-120℃, and the drying time is 2-5 hours. The calcination is carried out in an air atmosphere at a temperature of 300-500℃ for 1-2 hours.

[0028] According to a preferred embodiment of the present invention, the molar ratio of copper source, zinc source and aluminum source in the mixed solution is 2-8:2-5:1-3.

[0029] This invention provides a copper-based catalyst prepared by the preparation method described herein.

[0030] This invention provides an application of the catalyst described herein in methanol synthesis.

[0031] When the catalyst of this invention is used in the synthesis of methanol, it can effectively suppress the formation of higher alkanes that cause wax deposition at the source, even under conditions of high Fe content or sudden temperature changes, thereby ensuring the stable operation of the catalyst.

[0032] This invention provides a method for methanol synthesis, comprising: reacting a feedstock containing CO and H2 under the conditions of a copper-based catalyst as described in this invention.

[0033] According to a preferred embodiment of the present invention, the reaction conditions include: the raw material volume percentages are 13-15% CO, 3-5% CO2, and 65-70% H2; the balance is N2; and / or the raw material gas hourly space velocity is 10,000-100,000 h⁻¹. -1 ; and / or temperature 220-280℃; and / or pressure 3-8MPa. The reaction time depends on the specific operating conditions.

[0034] The present invention will be described in detail below through examples. In the following examples, the quantitative analysis of the products was performed using an Agilent 8890 gas chromatograph with three valves and five columns, equipped with one FID detector and one TCD detector. He was used as the carrier gas to analyze the hydrogen composition, and hydrogen was used as the carrier gas to analyze CO, CO2, N2, and CH4. FID analysis was used for hydrocarbons. The content and peak area correspondence of CO, CO2, N2, CH4, O2, N2, C2H6, and C2H4 were corrected using standard gases. Except for H2, whose fitting factor was >0.99, the fitting factors for the other gases were all >0.999. The Fe content of the catalyst was determined using inductively coupled atomic emission spectrometry (ICP-AES). Unless otherwise specified, all raw materials were commercially available products.

[0035] Example 1

[0036] The catalyst had a copper / zinc / aluminum molar ratio of 2:2:3, and the alkaline solution was a 0.5 mol / L sodium carbonate aqueous solution. A mixed solution of 2 mol / L copper, 2 mol / L zinc, and 3 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 50℃ and the pH value at 7, resulting in a precipitate. The precipitate was centrifuged and washed, with three times the volume of water used each time, for a total of five washes. The washed precipitate was then dried in a 100℃ drying oven for 5 hours, and then transferred to a muffle furnace for calcination in air at 300℃ for 2 hours. The calcined precipitate was then sheeted into φ5×5mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CO2 / CH4 atmosphere. The treatment conditions were: CO2 volume content of 10% (the balance being methane, the same below), and gas hourly space velocity (VHSV) of 1000 h⁻¹. -1The processing temperature and pressure were 500℃ and 5MPa, respectively. The processing sequence was as follows: CO2 / CH4 mixed gas was first fed from the top and discharged from the bottom, and the processing time was 2h. Then the process was adjusted to the mixed gas being fed from the bottom and discharged from the top, and the processing time was 0.5h, to obtain catalyst GX1.

[0037] Example 2

[0038] The catalyst had a copper / zinc / aluminum molar ratio of 2:4:3, and the alkaline solution was a 0.8 mol / L sodium bicarbonate aqueous solution. A mixed solution of 2 mol / L copper, 4 mol / L zinc, and 3 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5 L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 55 °C and the pH was 7, resulting in a precipitate. The precipitate was centrifuged and washed four times, each time with three times the volume of water. The washed precipitate was then dried in a 100 °C oven for 5 h, and then transferred to a muffle furnace for calcination in air at 350 °C for 2 h. The calcined precipitate was then sheeted into φ5×3 mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CO2 / CH4 atmosphere. The treatment conditions were: CO2 volume content of 15% and gas hourly space velocity of 1000 h⁻¹. -1 The processing temperature and pressure were 500℃ and 5MPa, respectively. The processing sequence was as follows: CO2 / CH4 mixed gas was first fed from the top and discharged from the bottom, and the processing time was 1 hour. Then the process was adjusted to the mixed gas being fed from the bottom and discharged from the top, and the processing time was 1 hour, to obtain catalyst GX2.

[0039] Example 3

[0040] The catalyst had a copper / zinc / aluminum molar ratio of 2:5:1, and the alkaline solution was a 1 mol / L potassium carbonate aqueous solution. A mixed solution of 2 mol / L copper, 5 mol / L zinc, and 1 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5 L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 60 °C and the pH was 7, resulting in a precipitate. The precipitate was centrifuged and washed four times with four times the volume of water each time. The washed precipitate was then dried in a 100 °C oven for 5 h, and then transferred to a muffle furnace for calcination in air at 400 °C for 2 h. The calcined precipitate was then sheeted into φ3×3 mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CO2 / CH4 atmosphere. The treatment conditions were: CO2 volume content 20% and gas hourly space velocity 1000 h⁻¹. -1 The processing temperature and pressure were 500℃ and 4MPa, respectively. The processing sequence was as follows: CO2 / CH4 mixed gas was first fed from the top and discharged from the bottom, and the processing time was 1.5h. Then the process was adjusted to the mixed gas being fed from the bottom and discharged from the top, and the processing time was 1h, to obtain catalyst GX3.

[0041] Example 4

[0042] The catalyst had a copper / zinc / aluminum molar ratio of 4:2:1, and the alkaline solution was a 1.5 mol / L potassium bicarbonate aqueous solution. A mixed solution of 4 mol / L copper, 2 mol / L zinc, and 1 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5 L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 65 °C and the pH at 7.5, resulting in a precipitate. The precipitate was centrifuged and washed five times, each time with four times the volume of water. The washed precipitate was then dried in a 120 °C oven for 3 h, and then transferred to a muffle furnace for calcination in air at 450 °C for 2 h. The calcined precipitate was then sheeted into φ5×5 mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CO2 / CH4 atmosphere. The treatment conditions were: CO2 volume content of 25% and gas hourly space velocity of 1000 h⁻¹. -1 The processing temperature and pressure were 500℃ and 4MPa, respectively. The processing sequence was as follows: CO2 / CH4 mixed gas was first fed from the top and discharged from the bottom, and the processing time was 2h. Then the process was adjusted to the mixed gas being fed from the bottom and discharged from the top, and the processing time was 1h, to obtain catalyst GX4.

[0043] Example 5

[0044] The catalyst had a copper / zinc / aluminum molar ratio of 6:3:1, and the alkaline solution was a 1.7 mol / L sodium hydroxide aqueous solution. A mixed solution of 6 mol / L copper, 3 mol / L zinc, and 1 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5 L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 70 °C and the pH at 7.5, resulting in a precipitate. The precipitate was centrifuged and washed four times with water (4 times the volume of the precipitate each time). The washed precipitate was then dried in a 120 °C oven for 3 h, and then transferred to a muffle furnace for calcination in air at 500 °C for 1 h. The calcined precipitate was then sheeted into φ5×5 mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CO2 / CH4 atmosphere. The treatment conditions were: CO2 volume content 30% and gas hourly space velocity (GHSV) 1500 h⁻¹. -1 The processing temperature and pressure were 400℃ and 3MPa, respectively. The processing sequence was as follows: CO2 / CH4 mixed gas was first fed from the top and discharged from the bottom, and the processing time was 2h. Then the process was adjusted to the mixed gas being fed from the bottom and discharged from the top, and the processing time was 1h, to obtain catalyst GX5.

[0045] Example 6

[0046] The catalyst had a copper / zinc / aluminum molar ratio of 8:2:2, and the alkaline solution was a 1.8 mol / L potassium hydroxide aqueous solution. A mixed solution of 8 mol / L copper, 2 mol / L zinc, and 2 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 70℃ and the pH at 8, resulting in a precipitate. The precipitate was centrifuged and washed five times with five times its volume of water each time. The washed precipitate was then dried in a 120℃ drying oven for 3 hours, and then transferred to a muffle furnace for calcination in air at 500℃ for 1 hour. The calcined precipitate was then sheeted into φ5×5mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CO2 / CH4 atmosphere. The treatment conditions were: CO2 volume content 40% and gas hourly space velocity 1500 h⁻¹. -1 The processing temperature and pressure were 400℃ and 3MPa, respectively. The processing sequence was as follows: CO2 / CH4 mixed gas was first fed from the top and discharged from the bottom, and the processing time was 2h. Then the process was adjusted to the mixed gas being fed from the bottom and discharged from the top, and the processing time was 1h, to obtain catalyst GX6.

[0047] Example 7

[0048] The catalyst had a copper / zinc / aluminum molar ratio of 8:5:3, and the alkaline solution was a 2 mol / L sodium hydroxide aqueous solution. A mixed solution of 8 mol / L copper, 5 mol / L zinc, and 3 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5 L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 70℃ and the pH at 8, resulting in a precipitate. The precipitate was centrifuged and washed five times with water (5 times the volume of the precipitate each time). The washed precipitate was then dried in a 120℃ drying oven for 2 hours, and then transferred to a muffle furnace for calcination in air at 500℃ for 1 hour. The calcined precipitate was then sheeted into φ5×5 mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CO2 / CH4 atmosphere. The treatment conditions were: CO2 volume content 50% and gas hourly space velocity 2000 h⁻¹. -1 The processing temperature and pressure were 300℃ and atmospheric pressure, respectively. The processing sequence was as follows: CO2 / CH4 mixed gas was first introduced from the top and discharged from the bottom, and the processing time was 2 hours. Then, the mixed gas was adjusted to be introduced from the bottom and discharged from the top, and the processing time was 1 hour, to obtain catalyst GX7.

[0049] Comparative Example 1

[0050] The catalyst had a copper / zinc / aluminum molar ratio of 8:5:3, and the alkaline solution was a 2 mol / L sodium hydroxide aqueous solution. A mixed solution of 8 mol / L copper, 5 mol / L zinc, and 3 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5 L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 70 °C and the pH value at 8, resulting in a precipitate. The precipitate was centrifuged and washed, with 5 times the volume of water used each time, for a total of 5 washes. The washed precipitate was then dried in a 120 °C drying oven for 2 h, and then transferred to a muffle furnace for calcination in air atmosphere at 500 °C for 1 h. The calcined precipitate was then sheeted into φ5×5 mm cylindrical pieces to obtain catalyst T1.

[0051] Comparative Example 2

[0052] The catalyst had a copper / zinc / aluminum molar ratio of 8:5:3, and the alkaline solution was a 2 mol / L sodium hydroxide aqueous solution. A mixed solution of 8 mol / L copper, 5 mol / L zinc, and 3 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5 L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 70℃ and the pH at 8, resulting in a precipitate. The precipitate was centrifuged and washed five times with five times its volume of water each time. The washed precipitate was then dried in a 120℃ drying oven for 2 hours, and then transferred to a muffle furnace for calcination in air at 500℃ for 1 hour. The calcined precipitate was then sheeted into φ5×5 mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CO2 atmosphere with a gas hourly space velocity of 2000 h⁻¹. -1 The processing temperature and pressure were 300℃ and atmospheric pressure, respectively. The processing sequence was as follows: first, the gas was fed from the top and discharged from the bottom, and the processing time was 2 hours. Then, the mixture was adjusted to be fed from the bottom and discharged from the top, and the processing time was 1 hour, to obtain catalyst T2.

[0053] Comparative Example 3

[0054] The catalyst had a copper / zinc / aluminum molar ratio of 8:5:3, and the alkaline solution was a 2 mol / L sodium hydroxide aqueous solution. A mixed solution of 8 mol / L copper, 5 mol / L zinc, and 3 mol / L aluminum nitrates was added concurrently with the alkaline solution to a 5 L neutralization tank containing 500 mL of deionized water. The neutralization temperature was controlled at 70℃ and the pH at 8, resulting in a precipitate. The precipitate was centrifuged and washed five times with five times its volume of water each time. The washed precipitate was then dried in a 120℃ drying oven for 2 hours, and then transferred to a muffle furnace for calcination in air at 500℃ for 1 hour. The calcined precipitate was then sheeted into φ5×5 mm cylindrical pieces and then treated in situ in a methanol synthesis reactor under a CH4 atmosphere with a gas hourly space velocity of 2000 h⁻¹. -1The processing temperature and pressure were 300℃ and atmospheric pressure, respectively. The processing sequence was as follows: first, the gas was fed from the top and discharged from the bottom, and the processing time was 2 hours. Then, the mixture was adjusted to be fed from the bottom and discharged from the top, and the processing time was 1 hour, to obtain catalyst T3.

[0055] Example 8

[0056] Methanol synthesis catalytic performance testing: The test was conducted in a fixed-bed tubular reactor (id = 30 mm) with a catalyst loading of 50 mL. The feed gas volume composition was CO / CO2 / H2 / N2 = 15%:3%:70%:12%; the feed gas space velocity was 10000 h⁻¹. -1 The reaction temperature was 230℃ and the pressure was 5MPa. Samples were taken for analysis after 2 hours of reaction.

[0057] Temperature change test: After performance testing, maintain the reaction pressure and lower the temperature to 200℃, then rapidly raise it to 280℃, stabilize for 2 hours, and then take samples for analysis. This result is the result after the temperature change.

[0058] Quantitative analysis of the products was performed using an Agilent 8890 gas chromatograph with three valves and five columns, equipped with one FID detector and one TCD detector. He was used as the carrier gas for hydrogen composition analysis, and hydrogen was used as the carrier gas for CO, CO2, N2, and CH4 analysis. FID analysis was used for hydrocarbons. For CO, CO2, N2, CH4, O2, N2, C2H6, and C2H4, the content and peak area correspondence were corrected using standard gases. The curve fitting factor was >0.999 for all gases except H2 (>0.99). The Fe content of the catalyst was determined using inductively coupled atomic emission spectrometry (ICP-AES). The test results are shown in Table 1.

[0059] Table 1

[0060]

[0061] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a copper-based catalyst, characterized in that, The preparation method includes: Step a: Prepare catalyst precursors containing copper, zinc and aluminum by co-precipitation method; Step b: Treat the catalyst precursor obtained in step a in situ under a CO2 / CH4 atmosphere; The CO2 / CH4 atmosphere has a carbon dioxide volume concentration of 10-50% and a methane volume concentration of 50-90%. The conditions for the in-situ treatment include: a volume hourly space velocity of 1000-2000 h⁻¹. -1 The temperature is 300-500℃ and the pressure is 0.1-5MPa.

2. The preparation method according to claim 1, wherein, The in-situ treatment method involves performing at least one alternating CO2 / CH4 purging in opposite directions.

3. The preparation method according to claim 1 or 2, wherein, Step a includes: adding an alkaline substance to a mixed solution containing copper, zinc and aluminum sources for co-precipitation to obtain a precipitate, which is then washed, dried, calcined and shaped.

4. The preparation method according to claim 3, wherein, The alkaline substance includes at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide; and / or The conditions for coprecipitation include: a temperature of 50-70℃ and a system pH of 7-8.

5. The preparation method according to claim 3, wherein, In the mixed solution, the molar ratio of copper source, zinc source and aluminum source, in terms of elements, is 2-8:2-5:1-3.

6. A copper-based catalyst prepared by the preparation method according to any one of claims 1-5.

7. The application of the copper-based catalyst according to claim 6 in methanol synthesis.

8. A method for synthesizing methanol, characterized in that, The method includes reacting a feedstock containing CO and H2 under the conditions of the copper-based catalyst as described in claim 6.

9. The method according to claim 8, wherein, The conditions for the reaction include: The raw material volume percentage is 13-15% CO, 3-5% CO2, 65-70% H2; the balance is N2; and / or Feed gas volume hourly space velocity 10,000-100,000 h⁻¹ -1 ; and / or Temperature 220-280℃; and / or Pressure 3-8MPa.

Images