Process for the conversion of synthesis gas

Abstract

The present application relates to the field of catalysis, in particular to a method for converting synthesis gas, which comprises: converting synthesis gas in the presence of a catalyst, wherein the catalyst contains, in parts by weight: component a, 20-50 parts, component a being selected from iron and / or iron oxide; component b, 5-20 parts, component b being selected from transition metal and / or transition metal oxide; component c, 1-10 parts, component c being selected from lanthanide metal and / or lanthanide metal oxide; component d, 0.5-5 parts, component d being selected from phosphorus and / or phosphorus oxide; component e, 20-75 parts, component e being selected from ZSM-5 type molecular sieve; wherein the amount of strong acid in the catalyst is 50-80% of the total acid amount, and the ratio of B acid amount to L acid amount is 20-50. The method for converting synthesis gas can significantly improve the selectivity of low-carbon olefins.

Description

Technical Field

[0001] This invention relates to the field of catalysis, and more specifically to a method for syngas conversion. Background Technology

[0002] Syngas, composed of carbon monoxide and hydrogen, is produced using natural gas, coal, and renewable resources. Under the action of a catalyst, this syngas is converted into low-carbon olefins. This method can replace the petrochemical route of producing low-carbon olefins through light hydrocarbon cracking, diversifying the production process and raw materials for low-carbon olefins. The catalyst for converting syngas into low-carbon olefins is mainly an iron-based composite catalyst. By adjusting the acidity and acid content of the catalyst, its performance can be improved, thereby increasing the selectivity for low-carbon olefins.

[0003] CN113631263A discloses a supported nanoparticle composition and precursor, its preparation method, and a syngas conversion method. A mixture of a long-chain hydrocarbon solvent, a long-chain organic acid, and one or more metal salts, optionally a sulfur or phosphorus promoter, is stepwise heated under an inert atmosphere to form a nanoparticle dispersion essentially composed of the promoter and mixed oxides of Fe and Mn, Co and Mn, or Fe, Cu, and Zn. The nanoparticle dispersion is then contacted with a support and a solid diluent to disperse the nanoparticles on the solid support, preparing a catalyst with the supported nanoparticle composition. Under Fischer-Tropsch synthesis conditions, syngas is converted to olefins. This catalyst preparation process is complex and not conducive to large-scale production. Even at a relatively high CO conversion rate of around 82%, the selectivity for low-carbon olefins is low, only around 30%. Summary of the Invention

[0004] To address the problem of low selectivity of low-carbon olefins in the syngas conversion to low-carbon olefins reaction in the prior art, the present invention provides a syngas conversion method that can improve the selectivity of low-carbon olefins in the syngas conversion to low-carbon olefins reaction.

[0005] To achieve the above objectives, the present invention provides a method for syngas conversion, the method comprising: performing a conversion reaction on syngas in the presence of a catalyst, wherein the catalyst contains, by weight:

[0006] Component a, 20 to 50 parts, wherein component a is selected from iron and / or iron oxides;

[0007] Component b, 5 to 20 parts, wherein component b is selected from transition metals and / or transition metal oxides;

[0008] Component c, 1 to 10 parts, wherein component c is selected from lanthanide metals and / or lanthanide metal oxides;

[0009] Component d, 0.5 to 5 parts, component d is selected from phosphorus and / or phosphorus oxides;

[0010] Component e, 20-75 parts, component e is selected from ZSM-5 type molecular sieve;

[0011] The catalyst contains 50-80% strong acid, and the ratio of Brønsted acid to Lewis acid is 20-50.

[0012] By adopting the above solution, the present invention has the following advantages:

[0013] This invention regulates the acidity of the molecular sieve by the combined action of phosphorus and / or phosphorus oxides with lanthanide metals and / or lanthanide metal oxides, and controls the amount of strong acid in the catalyst to account for 50-80% of the total acid amount, and the ratio of Brønsted acid to Lewis acid to Brønsted acid to be 20-50. When this catalyst is used for syngas conversion to prepare low-carbon olefins, the selectivity of the product low-carbon olefins can be significantly improved. 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 syngas conversion, the method comprising: carrying out a conversion reaction of syngas in the presence of a catalyst, wherein the catalyst contains, by weight:

[0016] Component a, 20 to 50 parts, wherein component a is selected from iron and / or iron oxides;

[0017] Component b, 5 to 20 parts, wherein component b is selected from transition metals and / or transition metal oxides;

[0018] Component c, 1 to 10 parts, wherein component c is selected from lanthanide metals and / or lanthanide metal oxides;

[0019] Component d, 0.5 to 5 parts, component d is selected from phosphorus and / or phosphorus oxides;

[0020] Component e, 20-75 parts, component e is selected from ZSM-5 type molecular sieve;

[0021] The catalyst contains 50-80% strong acid, and the ratio of Brønsted acid to Lewis acid is 20-50.

[0022] This invention regulates the acidity of the molecular sieve by the combined action of phosphorus and / or phosphorus oxides with lanthanide metals and / or lanthanide metal oxides, and controls the amount of strong acid in the catalyst to account for 50-80% of the total acid amount, and the ratio of Brønsted acid to Lewis acid to Brønsted acid to be 20-50. When this catalyst is used for syngas conversion to prepare low-carbon olefins, the selectivity of the product low-carbon olefins can be significantly improved.

[0023] According to a preferred embodiment of the present invention, in the catalyst, component a, 25-45 parts; component b, 8-18 parts; component c, 2-8 parts; component d, 1-4 parts; and component e, 25-70 parts. By adopting the aforementioned preferred embodiment, the selectivity of low-carbon olefins in the synthesis of low-carbon olefins from syngas can be further improved.

[0024] According to a preferred embodiment of the present invention, the catalyst contains 55-75% strong acid, and the ratio of Brønsted acid to Lewis acid is 25-45. By adopting the aforementioned preferred embodiment, the selectivity of low-carbon olefins in the synthesis of low-carbon olefins from syngas can be further improved.

[0025] In this invention, the lanthanide component c can be any conventional choice in the art, provided it achieves the objective of the invention. According to a preferred embodiment of the invention, the lanthanide component c is selected from at least one of Ce and Er. By employing the aforementioned preferred embodiment, the selectivity of low-carbon olefins in the synthesis of low-carbon olefins from syngas conversion can be further improved.

[0026] To further improve the selectivity of low-carbon olefins, according to a preferred embodiment of the present invention, the lanthanide metals are Ce and Er, and the molar ratio of Ce to Er is 0.5-3:1.

[0027] In this invention, as long as the objective of the invention is achieved, component a can be any conventional choice in the art. According to a preferred embodiment of the invention, component a is ferric oxide. By adopting the aforementioned preferred scheme, the selectivity of low-carbon olefins in the synthesis of low-carbon olefins from syngas conversion can be further improved.

[0028] In this invention, the transition metal of component b can be any conventional choice in the art, as long as it achieves the objective of the invention. According to a preferred embodiment of the invention, the transition metal of component b is selected from at least one of Cu and Zn. By adopting the aforementioned preferred embodiment, the selectivity of low-carbon olefins in the synthesis of low-carbon olefins from syngas conversion can be further improved.

[0029] In this invention, as long as the objective of the invention can be achieved, component d can be any conventional choice in the art. According to a preferred embodiment of the invention, component d is selected from phosphorus pentoxide. By adopting the aforementioned preferred scheme, the selectivity of low-carbon olefins in the synthesis of low-carbon olefins from syngas conversion can be further improved.

[0030] In this invention, as long as the objective of the invention is achieved, there are no particular requirements for the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve. According to a preferred embodiment of the invention, the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 50–300. By adopting the aforementioned preferred scheme, the selectivity of low-carbon olefins in the synthesis of low-carbon olefins from syngas conversion can be further improved.

[0031] In this invention, catalysts possessing the aforementioned characteristics can achieve the objectives of this invention. There are no particular requirements for the preparation method of the catalyst. According to a preferred embodiment of this invention, the preparation method of the catalyst includes:

[0032] I) Dissolve the soluble salt corresponding to component c) in water to prepare solution A;

[0033] II) Immerse solution A onto component e) to obtain mixture B;

[0034] III) Dry mixture B in air to obtain mixture C;

[0035] IV) Dissolve the soluble salt corresponding to component d) in water and add it to mixture C. Mix well, adjust the pH to 3-6, and react at 60-90℃ for 1-5 hours to obtain mixture D;

[0036] V) The mixture D is dried in air and calcined to obtain the mixture E;

[0037] VI) Dissolve the soluble salts corresponding to components a) and b) in water to prepare solution F;

[0038] VII) Solution F is impregnated onto mixture E to obtain mixture G;

[0039] VIII) The mixture G is dried in air and calcined to obtain the desired composite iron catalyst.

[0040] By employing the aforementioned preferred catalyst preparation method, the selectivity of low-carbon olefins in the catalyst used for syngas conversion to produce low-carbon olefins can be further improved.

[0041] In this invention, the calcination conditions in step V) can be conventionally chosen in the art. According to a preferred embodiment of the invention, the calcination conditions in step V) include: a calcination temperature of 300–450°C and a calcination time of 2–12 hours. By adopting the aforementioned preferred scheme, the selectivity of low-carbon olefins in the preparation of low-carbon olefins from syngas conversion can be further improved.

[0042] In this invention, the calcination conditions in step VIII) can be conventionally chosen in the art. According to a preferred embodiment of the invention, the calcination conditions in step VIII) include: a calcination temperature of 450–600°C and a calcination time of 1–6 hours. By adopting the aforementioned preferred scheme, the selectivity of low-carbon olefins in the preparation of low-carbon olefins from syngas conversion can be further improved.

[0043] According to a preferred embodiment of the present invention, the conditions for the conversion reaction in the syngas conversion include: a reaction temperature of 250–450°C, a reaction pressure of 0.5–6.0 MPa, and a syngas volume hourly space velocity of 500–12000 h⁻¹. -1 .

[0044] In this invention, in order to further improve the selectivity of low-carbon olefins in the conversion of syngas to low-carbon olefins, the molar ratio of CO to H2 in the syngas is 0.2 to 2.

[0045] Those skilled in the art will understand that the catalyst of the present invention preferably undergoes an online reduction process before being used in the reaction of syngas conversion to low-carbon olefins. Specific reduction conditions can be reasonably selected by those skilled in the art, for example, but not limited to, the following reduction conditions:

[0046] The reduction temperature is 350–650℃; the reducing agent is H2 and / or CO; the reduction pressure is atmospheric pressure to 3 MPa (gauge pressure); the volume hourly space velocity of the reducing agent is 500–10000 hr. -1 The restoration time is 2 to 48 hours.

[0047] The present invention will be further described below through specific embodiments. The scope of the present invention is not limited to the scope covered by the embodiments. The proportion of strong acid in the catalyst to the total acid content is measured using the NH3-TPD method; the ratio of Brønsted acid (B acid) to Lewis acid (L acid) in the catalyst is measured using the pyridine adsorption infrared acidic method. In this invention, the NH3 temperature-programmed desorption (NH3-TPD) experiment is performed on a PX 200A TPD / TPR instrument. The total acid content is calculated by fitting and peak-separating the obtained spectra. Acids with desorption temperatures of 100–250℃ are defined as weak acids, acids with desorption temperatures of 250–400℃ are defined as medium-strong acids, and acids with desorption temperatures of 400–550℃ are defined as strong acids. The proportion of strong acids is thus calculated. In this invention, the infrared spectroscopy determination of pyridine adsorption was performed using a BIO-RAD FTS 3000 infrared spectrometer (USA). The specific spectral acquisition method was as follows: approximately 10 mg of sample was weighed, pressed into a Φ15 mm circular sheet, placed in a quartz sample cell frame, and subjected to a vacuum of 4 × 10⁻⁶. -3 After dehydration at 400℃ for 2 hours under Torr (1 mmHg) conditions, the temperature was lowered to 200℃, followed by pyridine adsorption for 10 min, equilibration for 5 min, desorption under low vacuum for 10 min, and then under high vacuum for 30 min, followed by IR scanning. The difference spectrum before and after pyridine adsorption is the obtained pyridine adsorption-IR absorption spectrum, with the 1450 cm⁻¹ spectrum as an example. -1 This is considered a characteristic absorption peak for L-acids; 1540 cm⁻¹ -1 It is considered a characteristic absorption peak of Brønsted acid, while 1610 cm⁻¹ -1 This is considered to be a characteristic absorption peak shared by both L-acid and Brønsted acid. The calculation formula is: C(L-acid) = 1.42 * I(L) * R * R / W; C(Brønsted acid) = 1.88 * I(B) * R * R / W, where I(L) is the peak area of ​​L-acid, I(B) is the peak area of ​​Brønsted acid, R is the tablet diameter, and W is the tablet weight.

[0048] Example 1

[0049] 1. Catalyst Preparation

[0050] Weigh 2.9 parts by weight of cerium nitrate hexahydrate (Ce(NO3)3·6H2O) equivalent to CeO2 and 2.1 parts by weight of erbium nitrate pentahydrate (Er(NO3)3·5H2O) equivalent to Er2O3, wherein the molar ratio of Ce to Er is 1.5, and dissolve them in deionized water to prepare solution A; impregnate solution A on 44.0 parts by weight of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 150 to obtain mixture B; dry mixture B in air at 110°C to obtain mixture C; weigh 3.0 parts by weight of diammonium hydrogen phosphate ((NH4)2HPO4) equivalent to P2O5, dissolve it in deionized water, and add it to mixture C. The pH was adjusted to 5, and the mixture was reacted at 80℃ for 3 hours to obtain mixture D. Mixture D was dried in air at 110℃ and calcined at 400℃ for 6 hours to obtain mixture E. 35.0 parts by weight of ferric nitrate nonahydrate (molecular formula: Fe(NO3)3·9H2O) and 13.0 parts by weight of copper nitrate trihydrate (molecular formula: Cu(NO3)2·3H2O) were weighed and dissolved in 50.0 parts by weight of deionized water to prepare solution F. Solution F was impregnated onto mixture E to obtain mixture G. Mixture G was dried in air at 110℃ and calcined at 500℃ for 3 hours to obtain the desired catalyst.

[0051] The catalyst contained the following components: 35 parts by weight of Fe2O3, 13 parts by weight of CuO, 2.9 parts by weight of CeO2, 2.1 parts by weight of Er2O3, 3 parts by weight of P2O5, and 44 parts by weight of ZSM-5. The ratio of the strong acid content to the total acid content and the ratio of the Brønsted acid content to the Lewis acid content are shown in Table 1.

[0052] 2. Catalyst Evaluation

[0053] The evaluation criteria for catalysts are as follows:

[0054] The reaction conditions are:

[0055] φ10 mm fixed bed reactor

[0056] Reaction temperature 360℃

[0057] Reaction pressure 2.5 MPa

[0058] Catalyst loading volume 3ml

[0059] Volume hourly space velocity 4000 hV -1

[0060] The raw material ratio (moles) CO / H2 = 0.5.

[0061] The catalyst reduction conditions are:

[0062] Temperature 460℃

[0063] Pressure at normal pressure

[0064] Catalyst loading volume 3ml

[0065] Volume hourly space velocity 3000 hV -1

[0066] reducing gas H2

[0067] Restoration time is 24 hours.

[0068] The composition and evaluation results of the catalyst in this embodiment are listed in Table 1.

[0069] Example 2

[0070] Same as Example 1, except that 0.9 parts by weight of cerium nitrate hexahydrate equivalent to CeO2 were weighed, and the molar ratio of Ce to Er was 0.5; solution A was immersed in 45.0 parts by weight of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 50; and diammonium hydrogen phosphate equivalent to 4 parts by weight of P2O5 was weighed.

[0071] The ratio of strong acid content to total acid content in the catalyst, the ratio of B acid content to L acid content, the composition of the catalyst, and the evaluation results are listed in Table 1.

[0072] Example 3

[0073] Same as Example 1, except that 5.8 parts by weight of cerium nitrate hexahydrate equivalent to CeO2 were weighed, with a molar ratio of Ce to Er of 3; solution A was immersed in 43.1 parts by weight of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 300; and diammonium hydrogen phosphate equivalent to 1 part by weight of P2O5 was weighed.

[0074] The ratio of strong acid content to total acid content in the catalyst, the ratio of B acid content to L acid content, the composition of the catalyst, and the evaluation results are listed in Table 1.

[0075] Example 4

[0076] Same as Example 1, except that 5.8 parts by weight of cerium nitrate hexahydrate (molecular formula: Ce(NO3)3·6H2O) equivalent to CeO2 and 4.2 parts by weight of erbium nitrate pentahydrate (molecular formula: Er(NO3)3·5H2O) equivalent to Er2O3 were weighed, and solution A was immersed in 39.0 parts by weight of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 150.

[0077] The ratio of strong acid content to total acid content in the catalyst, the ratio of B acid content to L acid content, the composition of the catalyst, and the evaluation results are listed in Table 1.

[0078] Example 5

[0079] Same as Example 1, except that cerium nitrate hexahydrate was not added, and solution A was impregnated on 46.9 parts by weight of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 150.

[0080] The ratio of strong acid content to total acid content in the catalyst, the ratio of B acid content to L acid content, the composition of the catalyst, and the evaluation results are listed in Table 1.

[0081] Example 6

[0082] Same as Example 1, except that the SiO2 / Al2O3 molar ratio of ZSM-5 molecular sieve is 20.

[0083] The ratio of strong acid content to total acid content in the catalyst, the ratio of B acid content to L acid content, the composition of the catalyst, and the evaluation results are listed in Table 1.

[0084] Example 7

[0085] Weigh out 2.9 parts by weight of cerium nitrate hexahydrate (CeO2), 2.1 parts by weight of erbium nitrate pentahydrate (Er2O3), 3.0 parts by weight of diammonium hydrogen phosphate (P2O5), 35.0 parts by weight of ferric nitrate nonahydrate (Fe2O3), and 13.0 parts by weight of copper nitrate trihydrate (CuO) and dissolve them in water to prepare solution A. Mix thoroughly, adjust the pH to 5, and react at 80°C for 3 hours. Impregnate solution A onto 44.0 parts by weight of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 150 to obtain mixture B. Dry in air at 110°C and calcine at 500°C for 3 hours. After calcination, the desired catalyst is obtained.

[0086] Comparative Example 1

[0087] Catalyst preparation:

[0088] Weigh out 35.0 parts by weight of ferric nitrate nonahydrate (molecular formula: Fe(NO3)3·9H2O) equivalent to Fe2O3 and 13.0 parts by weight of copper nitrate trihydrate (molecular formula: Cu(NO3)2·3H2O) equivalent to CuO, and dissolve them in 50.0 parts by weight of deionized water to prepare solution F; impregnate solution F on 52.0 parts by weight of ZSM-5 molecular sieve with a SiO2 / Al2O3 molar ratio of 150 to obtain mixture G; dry mixture G in air at 110℃, calcine at 500℃ for 3 hours, and obtain the desired catalyst after calcine.

[0089] The catalyst contained the following components: 35 parts by weight of Fe2O3, 13 parts by weight of CuO, and 52 parts by weight of ZSM-5.

[0090] The catalyst evaluation was the same as in Example 1.

[0091] The ratio of strong acid content to total acid content in the catalyst, the ratio of B acid content to L acid content, the composition of the catalyst, and the evaluation results are listed in Table 1.

[0092] Table 1

[0093]

[0094] In summary, the method of the present invention can significantly improve the selectivity of low-carbon olefins in the reaction of syngas to low-carbon olefins.

[0095] 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 syngas conversion, characterized in that, The method includes: performing a conversion reaction on syngas in the presence of a catalyst, wherein the catalyst contains, by weight: Component a, 20 to 50 parts, wherein component a is selected from iron and / or iron oxides; Component b, 5 to 20 parts, wherein component b is selected from transition metals and / or transition metal oxides; Component c, 1 to 10 parts, wherein component c is selected from lanthanide metals and / or lanthanide metal oxides; Component d, 0.5 to 5 parts, component d is selected from phosphorus and / or phosphorus oxides; Component e, 20-75 parts, component e is selected from ZSM-5 type molecular sieve; The lanthanide metals are selected from at least one of Ce and Er, and the transition metals are selected from at least one of Cu and Zn; The catalyst contains 50-80% strong acid, and the ratio of Brønsted acid to Lewis acid is 20-50.

2. The method according to claim 1, wherein, In the catalyst, Component a, 25–45 parts; Component b, 8–18 parts; Component c, 2–10 parts; Component d, 1–4 parts; Component e, 25–70 parts.

3. The method according to claim 1, wherein, The catalyst contains 55-75% strong acid, and the ratio of Brønsted acid to Lewis acid is 25-45.

4. The method according to any one of claims 1-3, wherein, The lanthanide metals are Ce and Er, and the molar ratio of Ce to Er is 0.5-3:

1.

5. The method according to claim 1, wherein, Component a is ferric oxide; and / or Component d is selected from phosphorus pentoxide.

6. The method according to claim 1, wherein, The SiO2 / Al2O3 molar ratio of ZSM-5 molecular sieve is 20–300.

7. The method according to any one of claims 1-6, wherein, The method for preparing the catalyst includes: I) Dissolve the soluble salt corresponding to component c) in water to prepare solution A; II) Immerse solution A onto component e) to obtain mixture B; III) Dry mixture B in air to obtain mixture C; IV) Dissolve the soluble salt corresponding to component d) in water and add it to mixture C. Mix well, adjust the pH to 3-6, and react at 60-90℃ for 1-5 hours to obtain mixture D; V) The mixture D is dried in air and calcined to obtain the mixture E; VI) Dissolve the soluble salts corresponding to components a) and b) in water to prepare solution F; VII) Solution F is impregnated onto mixture E to obtain mixture G; VIII) The mixture G is dried in air and calcined to obtain the desired composite iron catalyst.

8. The method according to claim 7, wherein, The calcination conditions in step V) include: a calcination temperature of 300–450°C and a calcination time of 2–12 hours; The calcination conditions in step VIII) include: a calcination temperature of 450–600°C and a calcination time of 1–6 hours.

9. The method according to claim 7, wherein, The conditions for the conversion reaction include: a reaction temperature of 250–450 °C, a reaction pressure of 0.5–6.0 MPa, and a syngas volume hourly space velocity of 500–12000 h⁻¹. -1 .

10. The method according to any one of claims 1-6, wherein, The molar ratio of CO to H2 in the synthesis gas is 0.2-2.

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