A catalytic system for highly selective synthesis of ethanol by hydrogenation of CO, CO2 or CO / CO2 mixed gas

Abstract

The application discloses a catalytic system for high-selectivity synthesis of ethanol by hydrogenation of CO, CO2 or CO / CO2 mixed gas, and belongs to the field of CO and CO2 hydrogenation applications. The catalytic system comprises a heterogeneous catalyst and a homogeneous auxiliary agent. The catalytic system comprises a single-atom catalyst, an auxiliary agent and a solvent. The active component of the single-atom catalyst comprises at least one of Rh, Pd, Ir, Fe, Co, Ni and Cu. The auxiliary agent comprises LiI. The solvent comprises at least one of water and methanol. The heterogeneous and homogeneous dual-path synergistic catalytic system constructed by the application shows excellent reaction activity, ethanol selectivity and cycle stability. The application shows the potential to realize more excellent CO, CO2 or CO / CO2 mixed gas hydrogenation reaction performance by precisely designing and coupling the heterogeneous and homogeneous catalysis.

Description

Technical Field

[0001] This invention relates to a catalytic system for the highly selective synthesis of ethanol from CO, CO2, or a CO / CO2 mixture by hydrogenation, belonging to the field of CO and CO2 hydrogenation applications. Background Technology

[0002] Syngas, primarily composed of CO / CO2 and H2, plays a vital role in the chemical industry as a clean chemical feedstock. It is widely available and inexpensive, derived from substances such as coal, petroleum, and natural gas. Therefore, converting CO and CO2 into high-value chemicals through hydrogenation is of significant practical importance in mitigating their environmental harm.

[0003] As the most common C 2+ Ethanol, a chemical product, has wide applications in industry and daily life. It is an important precursor and solvent in the production of plastics, pharmaceuticals, and surfactants. Ethanol can also replace methanol as a non-toxic hydrogen source for fuel cells. Currently, ethanol is mainly produced through grain fermentation, a process that is not only energy-intensive but also competes with food resources. Directly producing ethanol from syngas is a simple, energy-efficient, and low-cost process that can alleviate carbon emission pressures and produce value-added chemicals, thus showing broad application prospects. However, in the field of syngas conversion research, the conversion of syngas into alcohols with two or more carbon atoms still requires further research and development. In most cases, ethanol production is very difficult, while methanol is a more readily available product. One key reason is the high CO bond energy (92.2 kJ / mol) of the CH3OH* intermediate, making it difficult for the CH3OH* intermediate to activate and dissociate to form CH4. x This is crucial for subsequent CC coupling hydrogenation with CO* to produce ethanol.

[0004] Currently, many heterogeneous catalysts have been developed for the hydrogenation of CO and CO2 to ethanol, including noble metal-based, Fischer-Tropsch-based, and multi-element composite catalysts. However, the reactivity and ethanol selectivity of these catalysts are still relatively poor. Summary of the Invention

[0005] [Technical Issues]

[0006] A catalytic system for the hydrogenation of CO, CO2, or a CO / CO2 mixture to synthesize ethanol is provided, which can improve the reaction activity of the catalyst and the selectivity of ethanol.

[0007] [Technical Concept]

[0008] This invention employs specific single-atom catalysts (Rh, Pd, Co, Cu, Fe, Ni, Ir single-atom catalysts), LiI as an auxiliary agent, and water or methanol as a solvent to efficiently synthesize ethanol through the synergistic catalytic hydrogenation of CO, CO2, or a CO / CO2 mixture via heterogeneous and homogeneous dual pathways. The reaction mechanism diagram is based on Rh1 / CeTiO2. x For example, Figure 1 As shown, LiI provides Lewis acidity of Li + And Lewis basic I - The synergistic effect of the catalyst modifies the adsorption and activation process of the reaction intermediate, which is beneficial to the formation of CH3* and its subsequent coupling with CO* to form ethanol, enhances the reaction activity and improves the ethanol selectivity, effectively inhibits the formation of by-products (such as methanol and CH4), and the catalytic system has excellent stability.

[0009] [Technical Solution]

[0010] On the one hand, a catalytic system for the highly selective synthesis of ethanol by hydrogenation of CO, CO2, or a CO / CO2 mixture is provided, comprising: a single-atom catalyst, an auxiliary agent, and a solvent; wherein: the active component of the single-atom catalyst includes at least one of Rh, Pd, Co, Cu, Fe, Ni, and Ir single-atom catalysts; the auxiliary agent is LiI; and the solvent includes at least one of water or methanol.

[0011] In some embodiments, the support for the single-atom catalyst comprises the composite oxide CeTiO₂. x At least one of the following: support, CeO2 support, nitrogen-doped carbon support, or nitrogen-phosphorus co-doped carbon support.

[0012] On the other hand, a method for highly selectively synthesizing ethanol by hydrogenation of CO, CO2, or a CO / CO2 mixture is provided, which employs the aforementioned catalytic system, and the method includes the following steps:

[0013] (1) The single-atom catalyst is activated and pretreated in a hydrogen or carbon monoxide atmosphere; the pressure of the activation and pretreatment is 0.1-3 MPa; the temperature of the activation and pretreatment is 200-600℃; and the time of the activation and pretreatment is 1-10 h.

[0014] (2) The single-atom catalyst, the auxiliary agent and the solvent obtained in step (1) are added to the reactor, the raw material gas is introduced, and the reaction temperature is adjusted to 180-350℃, the reaction pressure is 2-10MPa and the rotation speed is 100-800rpm to carry out the reaction.

[0015] In some embodiments, the raw material gas is a mixture of CO, CO2 and H2, wherein CO:(CO+CO2)=0~1, (CO+CO2) / H2=1:(0.1~8).

[0016] In some embodiments, the raw material gas is a mixture of CO, CO2 and H2, wherein CO:(CO+CO2)=0~1, (CO+CO2) / H2=1:(2~3).

[0017] In some embodiments, the reactor is a batch reactor, a fixed bed reactor, or a slurry bed reactor.

[0018] In some embodiments, the single-atom catalyst is Rh1 / CeTiO x .

[0019] In some embodiments, the ratio of the single-atom catalyst, the auxiliary agent, and the solvent is (10-50) mg: (0.1-10) mmol: (5-50) mL.

[0020] [Beneficial Effects]

[0021] (1) This invention creatively utilizes heterogeneous catalysis and homogeneous synergistic catalysis of specific single-atom catalysts (Rh, Pd, Co, Cu, Fe, Ni, Ir single-atom catalysts) and promoter LiI to regulate the activation and dissociation of intermediates. The catalytic system modified with homogeneous promoter LiI forms CH3I species that are more easily dissociated than methanol, increasing the amount of CH3I necessary for the formation of ethanol. x *Species supply. The catalytic system proposed in this invention achieves efficient hydrogenation synthesis of ethanol from CO, CO2, or a CO / CO2 mixture by introducing the homogeneous promoter LiI, and the catalytic system exhibits excellent stability.

[0022] (2) The homogeneous and heterogeneous dual-path synergistic catalytic strategy proposed in this invention effectively modulates the activation and dissociation capabilities of reaction intermediates, and enables the synthesis of ethanol and other C-type compounds through homogenization reactions of CO and / or CO2 and methanol. 2+ It exhibits excellent versatility in alcohols.

[0023] (3) The heterogeneous and homogeneous dual-path synergistic catalytic system constructed in this invention exhibits excellent reactivity, ethanol selectivity, and cycle stability. This invention, through precise design and coupling of heterogeneous and homogeneous catalysis, demonstrates the potential to achieve superior hydrogenation performance of CO, CO2, or CO / CO2 mixtures. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the reaction mechanism of the heterogeneous and homogeneous dual-pathway synergistic catalysis for the efficient synthesis of ethanol from CO, CO2 or CO / CO2 mixture by hydrogenation according to the present invention. Detailed Implementation

[0025] Catalyst performance evaluation was conducted in a batch reactor. The specific evaluation method was as follows: the catalyst underwent reduction pre-activation treatment. The pre-activation conditions were: high-purity hydrogen atmosphere, pressure 0.1 MPa, temperature 300℃, and time 1 h. After reduction, CO / H2, CO2 / H2, or CO / CO2 / H2 was introduced into the reactor to the specified pressure, and the reaction was initiated after reaching the specified temperature. The catalyst mass was 30 mg, the additive amount was 1 mmol, the solvent was water (20 mL), the rotation speed was 400 rpm, and the reaction time was specified. The gaseous products after the reaction were analyzed online by chromatography, and the liquid products were analyzed by nuclear magnetic resonance spectroscopy.

[0026] CO2 / CO conversion rate = (moles of CO2 / CO before reaction - moles of CO2 / CO after reaction) / moles of CO2 / CO before reaction × 100%;

[0027] Product selectivity = number of moles of product × number of carbon atoms in product molecule / (number of moles of CO2 / CO before reaction - number of moles of CO2 / CO after reaction) × 100%.

[0028] Preparation methods of single-atom catalysts involved in the examples and comparative examples:

[0029] Rh1 / CeTiO x Catalyst: Its preparation method is based on Example 1 of CN 115254100 A.

[0030] Rh1 / CeO2 catalyst: Its preparation method is based on Comparative Example 1 of CN 115254100 A.

[0031] Rh / CN catalyst: Its preparation method is based on Comparative Example 1 of CN 117181260 A.

[0032] Rh / CNP catalyst: Its preparation method is based on Example 1 of CN 117181260 A.

[0033] Pd1 / CeTiO x The preparation method is described in Example 8 of CN 115254100 A.

[0034] Co1 / CeTiO x Catalyst: Its preparation method is described in Example 11 of CN 115254100 A.

[0035] Cu1 / CeTiO x Catalyst: Its preparation method is described in Example 12 of CN 115254100 A.

[0036] Fe1 / CeTiOx Catalyst: Its preparation method is the same as that in Example 1 of CN 115254100 A, except that rhodium acetylacetone is replaced with an equimolar amount of ferric nitrate.

[0037] Ni1 / CeTiO x Catalyst: Its preparation method is described in Example 9 of CN 115254100 A.

[0038] Ir1 / CeTiO x Catalyst: Its preparation method is described in Example 10 of CN 115254100 A.

[0039] Catalyst systems for the hydrogenation of CO, CO2, or CO / CO2 mixtures to produce ethanol:

[0040] Example 1

[0041] The first step is to combine Rh1 / CeTiO x The catalyst was activated and pretreated in pure hydrogen at a pressure of 0.1 MPa, a temperature of 300 °C, and a time of 1 h.

[0042] The second step is to use 30 mg of activated pretreated Rh1 / CeTiO2. x The catalyst, 1 mmol LiI (auxiliary agent), and 20 mL water (solvent) were added to the reactor, and the feed gas (CO2:H2 volume ratio 1:3) was introduced. The reaction was carried out at 250 °C, 3 MPa, and 400 rpm for 5 h. The gaseous and liquid products after the reaction were analyzed, and the conversion rate and selectivity or distribution of each product were calculated. The results are shown in Table 1.

[0043] The catalyst was recovered after the reaction and labeled as run N (N being the number of cycles) for use in the next cycle test. The catalytic performance results of the catalyst are shown in Table 1.

[0044] After the reaction is complete, the reactor is cooled in an ice-water bath.

[0045] Example 2

[0046] The auxiliary agent in the second step of Example 1 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0047] Example 3

[0048] The catalyst in the first step of Example 1 was changed to Rh1 / CeO2 catalyst, while the remaining steps and operations remained unchanged. The performance of CO2 hydrogenation was evaluated in a batch reactor.

[0049] Example 4

[0050] The auxiliary agent in the second step of Example 3 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0051] Example 5

[0052] The catalyst in the first step of Example 1 was changed to an Rh / CN catalyst, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0053] Example 6

[0054] The auxiliary agent in the second step of Example 5 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0055] Example 7

[0056] The catalyst in the first step of Example 1 was changed to an Rh / CNP catalyst, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0057] Example 8

[0058] The auxiliary agent in the second step of Example 7 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0059] Example 9

[0060] The catalyst in the first step of Example 1 was changed to Pd1 / CeTiO2. x The catalyst, with the remaining steps and operations unchanged, was used to evaluate its CO2 hydrogenation performance in a batch reactor.

[0061] Example 10

[0062] The auxiliary agent in the second step of Example 9 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0063] Example 11

[0064] The catalyst in the first step of Example 1 was changed to Co1 / CeTiO2. x The catalyst, with the remaining steps and operations unchanged, was used to evaluate its CO2 hydrogenation performance in a batch reactor.

[0065] Example 12

[0066] The auxiliary agent in the second step of Example 11 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0067] Example 13

[0068] The catalyst in the first step of Example 1 was changed to Cu1 / CeTiO2. x The catalyst, with the remaining steps and operations unchanged, was used to evaluate its CO2 hydrogenation performance in a batch reactor.

[0069] Example 14

[0070] The auxiliary agent in the second step of Example 13 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0071] Example 15

[0072] The catalyst in the first step of Example 1 was changed to Fe1 / CeTiO. x The catalyst, with the remaining steps and operations unchanged, was used to evaluate its CO2 hydrogenation performance in a batch reactor.

[0073] Example 16

[0074] The auxiliary agent in the second step of Example 15 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0075] Example 17

[0076] The catalyst in the first step of Example 1 was changed to Ni1 / CeTiO. x The catalyst, with the remaining steps and operations unchanged, was used to evaluate its CO2 hydrogenation performance in a batch reactor.

[0077] Example 18

[0078] The auxiliary agent in the second step of Example 17 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0079] Example 19

[0080] The catalyst in the first step of Example 1 was changed to Ir1 / CeTiO. x The catalyst, with the remaining steps and operations unchanged, was used to evaluate its CO2 hydrogenation performance in a batch reactor.

[0081] Example 20

[0082] The auxiliary agent in the second step of Example 19 was removed, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0083] The above catalytic system was reacted, and the CO2 conversion rate and the selectivity or distribution of each product are shown in Table 1. The catalyst after the reaction was recovered and marked as run N (N is the number of cycles) for the next cycle test. The catalytic performance results of the catalyst are shown in Table 1.

[0084] Table 1 Performance of CO2 hydrogenation reaction under different catalytic systems

[0085]

[0086]

[0087] As can be seen from the results in Table 1, Example 1 used Rh1 / CeTiO2. x Using LiI as a catalyst, water as a promoter, and heterogeneous and homogeneous synergistic catalysis, the method of this invention exhibits high CO2 conversion (9.2%) and ethanol selectivity (99.5%) in the hydrogenation of CO2 to ethanol. Even after five cycles of testing, the catalyst maintains good catalytic performance (CO2 conversion 8.8%, ethanol selectivity 98.6%), demonstrating excellent catalytic stability. Furthermore, compared to single-atom catalyst systems, the addition of LiI as a promoter based on the strategy of this invention results in enhanced reactivity and ethanol selectivity on single-atom catalysts with metal (Rh, Pd, Co, Cu, Fe, Ni, Ir) active sites, indicating the universality of the strategy proposed in this invention.

[0088] Comparative Example 1

[0089] The auxiliary agent in the second step of Example 1 was changed to LiBr, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0090] Comparative Example 2

[0091] The auxiliary agent in the second step of Example 1 was changed to LiCl, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0092] Comparative Example 3

[0093] The auxiliary agent in the second step of Example 1 was changed to KI, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0094] Comparative Example 4

[0095] The auxiliary agent in the second step of Example 1 was changed to KCl, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0096] Comparative Example 5

[0097] The auxiliary agent in the second step of Example 1 was changed to KBr, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0098] Comparative Example 6

[0099] The auxiliary agent in the second step of Example 1 was changed to RuCl3, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0100] Comparative Example 7

[0101] The solvent in the second step of Example 1 was changed to N,N-dimethylformamide (DMF), while the other steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0102] Comparative Example 8

[0103] The solvent in the second step of Example 1 was changed to tetrahydrofuran (THF), while the other steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0104] Comparative Example 9

[0105] The solvent in the second step of Example 1 was changed to cyclohexane, while the other steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0106] Comparative Example 10

[0107] The solvent in the second step of Example 1 was changed to 1,3-dimethyl-2-imidazolinone (DMI), while the other steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0108] Comparative Example 11

[0109] The reaction temperature in the second step of Example 1 was changed to 150°C, while the other parameters remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0110] Comparative Example 12

[0111] The reaction pressure in the second step of Example 1 was changed to 1 MPa, while the other parameters remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0112] The above catalytic system was reacted, and the CO2 conversion rate and the selectivity or distribution of each product are shown in Table 2.

[0113] Table 2 Performance of CO2 hydrogenation reaction of different catalytic systems

[0114]

[0115] A comparison of Table 2 and Table 1 shows that, using the heterogeneous and homogeneous synergistic catalysis methods of this invention, the effects of CO2 hydrogenation to ethanol vary significantly depending on the catalyst, the additives, solvents, reaction temperatures, and reaction pressures employed. Example 1 used Rh1 / CeTiO2.x The optimal catalytic system for CO2 hydrogenation to ethanol production is characterized by using LiI as a catalyst, LiI as a promoter, and water as a solvent. Furthermore, when the reaction temperature is 250°C, the reaction pressure is 3 MPa, water is used as the solvent, and LiI is used as the homogeneous promoter, the combination of LiI and Rh1 / CeTiO2 exhibits the best performance. x The homogeneous / heterogeneous catalytic system composed of catalysts exhibits the best catalytic activity and ethanol selectivity.

[0116] Example 21

[0117] The water in the second step of Example 1 was replaced with methanol, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0118] Example 22

[0119] The reaction time in Example 21 was adjusted to 10 hours, while the other steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0120] Example 23

[0121] The reaction time in Example 21 was adjusted to 15 hours, while the other steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0122] Example 24

[0123] The reaction time in Example 21 was adjusted to 20 hours, while the remaining steps and operations remained unchanged. The CO2 hydrogenation performance was evaluated in a batch reactor.

[0124] The above catalytic system was reacted, and the results of ethanol yield and methanol conversion are shown in Table 3.

[0125] Table 3. Reactivity of CO2 hydrogenation with methanol as substrate at different reaction times.

[0126] 21 155.8 4.7 22 178.3 10.8 23 195.6 17.8 24 223.1 27.1

[0127] As shown in Table 3, when methanol is used as a substrate in the reaction, the ethanol yield increases significantly with increasing reaction time, and the methanol conversion also increases. This indicates that under a CO2 / H2 atmosphere, the LiI and Rh1 / CeTiO2 from Example 1 are effective. x The homogeneous / heterogeneous catalytic system composed of catalysts contains a reaction pathway for the carbonylation of methanol to form ethanol.

[0128] Example 25

[0129] The feed gas in the second step of Example 1 was changed to a CO:H2 volume ratio of 1:2, while the other steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0130] Example 26

[0131] The auxiliary agent in the second step of Example 25 was removed, while the remaining steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0132] Example 27

[0133] The feed gas in the second step of Example 3 was changed to a CO:H2 volume ratio of 1:2, while the other steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0134] Example 28

[0135] The auxiliary agent in the second step of Example 27 was removed, while the remaining steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0136] Example 29

[0137] The feed gas in the second step of Example 5 was changed to a CO:H2 volume ratio of 1:2, while the other steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0138] Example 30

[0139] The auxiliary agent in the second step of Example 29 was removed, while the remaining steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0140] Example 31

[0141] The feed gas in the second step of Example 7 was changed to a CO:H2 volume ratio of 1:2, while the other steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0142] Example 32

[0143] The auxiliary agent in the second step of Example 31 was removed, while the remaining steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0144] The above catalytic system was reacted, and the CO conversion rate and the selectivity or distribution of each product are shown in Table 4.

[0145] Table 4 Performance of CO hydrogenation reaction under different catalytic systems

[0146]

[0147] As can be seen from the results in Table 4, the method of heterogeneous and homogeneous synergistic catalysis proposed in this invention can significantly increase the CO conversion rate and ethanol selectivity in the CO hydrogenation reaction.

[0148] Example 33

[0149] In Example 25, the water in the second step was replaced with methanol, while the remaining steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0150] Example 34

[0151] The reaction time in Example 33 was adjusted to 10 h, while the other steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0152] Example 35

[0153] The reaction time in Example 33 was adjusted to 15 hours, while the other steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0154] Example 36

[0155] The reaction time in Example 33 was adjusted to 20 h, while the other steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0156] The above catalytic system was reacted, and the results of ethanol yield and methanol conversion are shown in Table 5.

[0157] Table 5. Reactivity of CO hydrogenation with methanol as substrate at different reaction times.

[0158] 33 130.0 3.9 34 156.4 9.5 35 177.8 16.2 36 199.9 24.3

[0159] As can be seen from the results in Table 5, when methanol is used as a substrate in the reaction, the ethanol yield increases significantly with the extension of reaction time, accompanied by the conversion of methanol. This indicates that there is also a reaction pathway for methanol carbonylation to form ethanol under a CO / H2 atmosphere.

[0160] Example 37

[0161] The feed gas in the second step of Example 1 was changed to a CO:CO2:H2 volume ratio of 1:4:14, while the other steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0162] Example 38

[0163] The auxiliary agent in the second step of Example 37 was removed, while the remaining steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0164] Example 39

[0165] The feed gas in the second step of Example 3 was changed to a CO:CO2:H2 volume ratio of 1:4:14, while the other steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0166] Example 40

[0167] The auxiliary agent in the second step of Example 39 was removed, while the remaining steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0168] Example 41

[0169] The feed gas in the second step of Example 5 was changed to a CO:CO2:H2 volume ratio of 1:4:14, while the other steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0170] Example 42

[0171] The auxiliary agent in the second step of Example 41 was removed, while the remaining steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0172] Example 43

[0173] The feed gas in the second step of Example 7 was changed to a CO:CO2:H2 volume ratio of 1:4:14, while the other steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0174] Example 44

[0175] The auxiliary agent in the second step of Example 43 was removed, while the remaining steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0176] The above catalytic system was reacted, and the results of CO and CO2 conversion rates and the selectivity or distribution of each product are shown in Table 6.

[0177] Table 6 Performance of CO / CO2 mixture hydrogenation reaction under different catalytic systems

[0178]

[0179] The results in Table 6 show that the heterogeneous and homogeneous synergistic catalysis method proposed in this invention can significantly promote the conversion of CO and CO2 in the hydrogenation reaction of CO / CO2 mixtures, while improving ethanol selectivity. Combined with the results in Tables 1 and 4, this demonstrates that the strategy proposed in this invention is universally applicable to the hydrogenation reactions of CO, CO2, and CO / CO2 mixtures.

[0180] Comparative Example 13

[0181] The feed gas in the second step of Example 1 was changed to a CO:CO2:H2 volume ratio of 1:1:5, while the other steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0182] Comparative Example 14

[0183] The feed gas in the second step of Example 1 was changed to a CO:CO2:H2 volume ratio of 4:1:11, while the other steps and operations remained unchanged. The performance of the CO / CO2 mixed gas hydrogenation was evaluated in a batch reactor.

[0184] The above catalytic system was reacted, and the results of CO and CO2 conversion rates and the selectivity or distribution of each product are shown in Table 7.

[0185] Table 7. Performance of the CO / CO2 mixed gas hydrogenation reaction of the catalytic system under different feed gas ratios.

[0186]

[0187] Comparing the results in Table 7 with those in Table 6, it can be seen that when CO:CO2:H2 = 1:4:14, LiI and Rh1 / CeTiO x The homogeneous / heterogeneous catalytic system composed of catalysts exhibits the best catalytic activity and ethanol selectivity.

[0188] Example 45

[0189] The water in step 2 of Example 37 was replaced with methanol, while the remaining steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0190] Example 46

[0191] The reaction time in Example 37 was adjusted to 10 hours, while the remaining steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0192] Example 47

[0193] The reaction time in Example 37 was adjusted to 15 hours, while the remaining steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0194] Example 48

[0195] The reaction time in Example 37 was adjusted to 20 hours, while the other steps and operations remained unchanged. The CO hydrogenation performance was evaluated in a batch reactor.

[0196] The above catalytic system was reacted, and the results of ethanol yield and methanol conversion are shown in Table 8.

[0197] Table 8. Reaction performance of CO / CO2 mixture hydrogenation with methanol as substrate at different reaction times.

[0198] 45 134.9 4.1 46 162.5 9.9 47 181.7 16.6 48 208.6 25.3

[0199] As shown in Table 8, when methanol is used as the substrate, the ethanol yield increases significantly with increasing reaction time, accompanied by methanol conversion. This indicates that a reaction pathway for methanol carbonylation to ethanol also exists under a CO / CO2 / / H2 mixed gas atmosphere. Combined with the results in Tables 3 and 5, this demonstrates that the homogeneous and heterogeneous synergistic catalytic system proposed in this invention has universal applicability to methanol carbonylation reactions under CO, CO2, and CO / CO2 mixed gas hydrogenation atmospheres.

[0200] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A catalytic system for the highly selective synthesis of ethanol by hydrogenation of CO, CO2, or a CO / CO2 mixture, characterized in that, include: Single-atom catalysts, auxiliaries, and solvents; among which: The active component of the single-atom catalyst includes at least one of Rh, Pd, Co, Cu, Fe, Ni, and Ir single-atom catalysts; The auxiliary agent is LiI; The solvent includes at least one of water or methanol; The support for the single-atom catalyst includes the composite oxide CeTiO. x At least one of the following: support, CeO2 support, nitrogen-doped carbon support, or nitrogen-phosphorus co-doped carbon support.

2. A method for the highly selective synthesis of ethanol by hydrogenation of CO, CO2, or a CO / CO2 mixture, characterized in that, Using the catalytic system of claim 1, the method comprises the following steps: (1) The single-atom catalyst is activated and pretreated in a hydrogen or carbon monoxide atmosphere; the pressure of the activation and pretreatment is 0.1~3 MPa; the temperature of the activation and pretreatment is 200~600 °C; and the time of the activation and pretreatment is 1~10 h. (2) The single-atom catalyst, the auxiliary agent and the solvent obtained in step (1) are added to the reactor, the raw material gas is introduced, and the reaction temperature is adjusted to 180~350 °C, the reaction pressure is 2~10 MPa and the rotation speed is 100~800 rpm to carry out the reaction.

3. The method according to claim 2, characterized in that, in, The raw material gas is a mixture of CO, CO2 and H2, wherein the volume ratio of CO:(CO+CO2) is 0~1 and the volume ratio of (CO+CO2) / H2 is 1:(0.1~8).

4. The method according to claim 3, characterized in that, in, The raw material gas is a mixture of CO, CO2 and H2, wherein the volume ratio of CO:(CO+CO2) is 0~1 and the volume ratio of (CO+CO2) / H2 is 1:(2~3).

5. The method according to claim 2, characterized in that, in, The reactor is either a batch reactor or a slurry bed reactor.

6. The method according to claim 2, characterized in that, in, The single-atom catalyst is Rh1 / CeTiO. x .

7. The method according to claim 2, characterized in that, in, The ratio of the amount of the single-atom catalyst, the auxiliary agent and the solvent is (10~50) mg: (0.1~10) mmol: (5~50) mL.

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