An ionic liquid-modified porphyrin-based MOF material and its application in full-spectrum catalytic reduction of CO2.

Abstract

This invention discloses an ionic liquid-modified porphyrin-based MOF material and its application in full-spectrum catalytic reduction of CO2. The invention employs a hydrothermal method to synthesize an atomically dispersed Ni-anchored porphyrin-based MOF material. Its well-developed porous structure endows the catalyst with the ability to fill ionic liquids (ILs). Furthermore, the ordered structure of the MOF and the synergistic stabilization of C1 intermediates by ILs achieve full-spectrum catalytic deep reduction of CO2. The optimized ILs@Ni ADMS / PMOF, under a xenon lamp equipped with a 365, 420, and 765 nm bandpass filter, achieved ionic liquid-to-hydrogen (IPH) reductions of 12.83, 17.39, and 8.89 mmol / h, respectively. ‑1 g ‑1 The rate of C2H5OH formation is [not specified]. This invention provides an advanced strategy for regulating C1 stability and holds promise for achieving industrial-scale conversion from CO2 to C2H5OH through the design of fully solar-responsive photocatalysts.

Description

Technical Field

[0001] This invention belongs to the field of photocatalysis technology, specifically involving the synthesis of ILs@Ni ADMS / PMOF materials via a hydrothermal-vacuum impregnation method, which exhibit excellent full-spectrum catalytic reduction performance for CO2. This catalytic strategy provides new research ideas for the preparation of near-infrared photocatalysts and their application in the synthesis of C2H5OH, contributing to the development of the solar energy economy and the industrial-scale conversion of CO2 to C2H5OH. Background Technology

[0002] The near-infrared photoresponsive synthesis of C2H5OH, using CO2 and H2O as raw materials, is of great significance for the efficient utilization of solar energy. However, the mismatch between the energy and kinetic requirements of the C-C coupling step required for C2H5OH synthesis poses a significant challenge to near-infrared photocatalytic reduction of CO2. To date, numerous researchers have made significant efforts to efficiently prepare C2H5OH under ultraviolet and visible light irradiation. For example, the visible-light-responsive photocatalyst NiZrCu-BDC has shown promise in reducing CO2 to C2H5OH (36.62 μmol h⁻¹). −1 g −1 The ability of near-infrared light to form C-C bonds is well-known. Therefore, the utilization of near-infrared light has been a barrier to full-spectrum solar energy collection and conversion. Currently, near-infrared photoresponsive catalysts are almost entirely inorganic materials, such as black phosphorus (BP), plasmon metals, and their composites. Tetsuro et al. synthesized BP / CN and Au / La2Ti2O7 / BP, which exhibit excellent water-splitting performance under >420 and >780 nm light irradiation. In recent years, organometallic complexes have become another typical class of near-infrared photoredox catalysts, mainly used to form C-C and C-N bonds. However, the strong electronic localization of metal-ligand bonds usually confines the electronic excitation of these catalysts to high energies, meaning that using photons above 780 nm is challenging. For organic dyes, studies have shown that artificial supramolecular structures can generate several strongly absorbed exciton transitions with a redshift relative to the monomer. Therefore, ordered structures constructed from monomeric chromophores with delocalized electrons or excitons hold promise for changes in electronic structure and optical properties.

[0003] In this work, we propose a strategy for near-infrared driven CO2 reduction to C2H5OH using ILs-modified ordered PMOFs. It is important to note that no hole sacrificial agent was added during the performance evaluation of this photocatalytic CO2 reduction. ILs@NiADMS / PMOF exhibits record-breaking near-infrared catalytic performance, achieving a maximum C2H5OH yield of 8.89 mmol / h. −1 g −1Furthermore, the optimized reaction rates of the sample under ultraviolet and visible light irradiation were 12.83 and 17.39 mmol h⁻¹, respectively. −1 g −1 Transient absorption spectroscopy demonstrates that the Ni-N bond traps electrons through ligand-metal charge transfer, which favors obtaining long-lived excited-state electrons. Theoretical calculations show that ILs... * CH2OH and * CH3 exhibits a confinement effect, which further increases the formation rate of C2H5OH. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of photocatalytic CO2 reduction technology, such as limited near-infrared light energy utilization and slow C-C coupling kinetics, by providing a synthesis method for an ILs@Ni ADMS / PMOF catalyst. This synthesis method is simple, easy to implement, and low in cost, and can yield a full-spectrum responsive photocatalyst, providing a feasible solution for the development of novel near-infrared catalytic CO2 reduction technology. Under xenon lamps equipped with 365, 420, and 765 nm bandpass filters, the ILs@Ni ADMS / PMOF catalyst exhibited excellent C2H5OH synthesis capabilities, with rates of 12.83, 17.39, and 8.89 mmolh, respectively. −1 g −1 The reaction mechanism of full-spectrum catalytic reduction of CO2 to C2H5OH was revealed through a combination of theoretical calculations and experimental tests.

[0005] The technical solution of the present invention is as follows: A method for photocatalytic CO2 reduction to prepare C2H5OH in pure water using porphyrin MOF, wherein the porphyrin MOF includes three samples: a metal-free porphyrin MOF (PMOF), a metal-containing porphyrin MOF (Ni ADMS / PMOF), and an ILs-modified metal-containing porphyrin MOF (ILs@Ni ADMS / PMOF).

[0006] The following is a method for the catalytic reduction of CO2 to synthesize C2H5OH with a full-spectrum response: First, high-purity CO2 gas is introduced at a rate of 40 ml / min. −1 The catalyst was introduced into deionized water at a flow rate of [missing information - likely a specific flow rate or value]. After adsorption-desorption equilibrium was reached on the catalyst surface, the catalyst was irradiated with a lamp for 2 hours. Potential gases and liquids generated during the reaction were detected using gas chromatography and nuclear magnetic resonance (NMR) instruments. The detection and analysis results showed that ILs@Ni ADMS / PMOF exhibited record-breaking near-infrared catalytic performance, with a maximum C2H5OH yield of 8.89 mmol / h. −1 g −1Furthermore, under ultraviolet and visible light irradiation, the catalyst exhibited reaction rates of 12.83 and 17.39 mmol h⁻¹ for the production of ethanol, respectively. −1 g −1 Reaction conditions: 10–50 mg ILs-modified metalloporphyrin-based MOF catalyst, reaction temperature: 20 °C, no hole sacrificial agents.

[0007] The preparation method of the ILs@Ni ADMS / PMOF catalyst is as follows: 1) Synthesis of PMOF: Tetra(4-carboxyphenyl)porphyrin, benzoic acid and ZrCl4 were ultrasonically dispersed in DMF solvent; the dispersion was then subjected to hydrothermal reaction at 120 °C for 1080 min; the synthesized PMOF was washed three times with ethanol and then dried in a vacuum oven before use.

[0008] 2) Synthesis of Ni ADMS / PMOF: Under ultrasonication, the synthesized PMOF was first dispersed in DMF. Then, a DMF solution of NiCl2·6H2O was added to the dispersion system and ultrasonic mixing was continued. Subsequently, the mixture was subjected to hydrothermal reaction at 80 °C for 240 min. Finally, the obtained solid was washed and dried for later use.

[0009] 3) Synthesis of ILs@NiADMS / PMOF: Ni ADMS / PMOF was ultrasonically dispersed in acetonitrile, and then vacuum impregnated at 80 °C for 12 h to obtain the final photocatalyst ILs@NiADMS / PMOF.

[0010] The advantages of this invention are as follows: 1) The preparation methods of PMOF, Ni ADMS / PMOF, and ILs@NiADMS / PMOF obtained by this invention are simple and low in cost, and can obtain full-spectrum responsive catalysts under mild conditions, providing new ideas for the development of near-infrared photocatalysts.

[0011] 2) This catalyst exhibited excellent photocatalytic reduction performance of CO2. Under irradiation with a 300W Xe lamp equipped with 365, 420, and 765 nm bandpass filters, the rates of C2H5OH synthesis catalyzed by ILs@NiADMS / PMOF were 12.83, 17.39, and 8.89 mmol h⁻¹, respectively. −1 g −1 .

[0012] 3) Time-resolved transient absorption spectroscopy indicates that electrons rapidly transfer from the ligands to Ni, thereby increasing the excited-state electronic lifetime of NiADMS / PMOF and significantly promoting the formation of C2 products. Theoretical calculations show that the ILs filling the MOF channels have a significant impact on... *CH2OH and * The CH3 intermediate exhibits confinement effect and stability. * The ability of the CH2OH intermediate to couple Ni ADMS / PMOF promotes C−C coupling, thereby further improving the selectivity of ethanol.

[0013] 4) All the porphyrin-based MOF catalysts synthesized in this invention have high-efficiency charge separation capabilities and do not require the addition of any hole sacrificial agents in the photocatalytic reduction of CO2 performance evaluation test. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, some accompanying drawings are briefly described below. The drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0015] Figure 1 The image shows the transmission electron microscopy (TEM) spectrum of the ILs@Ni ADMS / PMOF catalyst prepared in Example 1.

[0016] Figure 2 The image shows the XPS spectrum of the ILs@Ni ADMS / PMOF catalyst prepared in Example 1.

[0017] Figure 3 The N2 adsorption-desorption isotherm of the ILs@Ni ADMS / PMOF catalyst prepared in Example 1.

[0018] Figure 4 The image shows the photocatalytic reduction performance of CO2 by the ILs@Ni ADMS / PMOF catalyst prepared in Example 1.

[0019] Figure 5 The time-resolved transient absorption and corresponding electron lifetime plots of the ILs@Ni ADMS / PMOF catalyst prepared in Example 1 under near-infrared light excitation.

[0020] Figure 6 The Gibbs free energy is the reaction of ILs@Ni ADMS / PMOF catalyzing the reduction of CO2 to C2H5OH in Example 1. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available. Example 1

[0023] A method for preparing an ILs@Ni ADMS / PMOF catalyst for the full-spectrum catalytic reduction of CO2 includes the following steps: 1) Synthesis of PMOF: 20 mg tetrakis(4-carboxyphenyl)porphyrin, 500 mg benzoic acid and 20 mg ZrCl4 were ultrasonically dispersed in 2 ml DMF solvent; then heated at 120 ℃ for 1080 min by hydrothermal method; finally, the synthesized PMOF was washed 3 times with ethanol and dried under vacuum for later use.

[0024] 2) First, 20 mg of PMOF was dispersed in 4 ml of DMF under ultrasonication. Then, a concentration of 20 mg / ml was added. −1 A DMF solution of nickel(II) hexahydrate was added to the above dispersion system and ultrasonically dispersed. The mixture was then reacted at 80 °C for 240 min. Finally, the sample was washed and vacuum dried to obtain Ni ADMS / PMOF.

[0025] 3) Synthesis of ILs@NiADMS / PMOF: 100 mg Ni ADMS / PMOF was dispersed in 40 ml acetonitrile under ultrasonication and impregnated in a vacuum oven at 80 °C for 12 h for further use.

[0026] The ILs@NiADMS / PMOF prepared according to the above method is applied to a full-spectrum responsive catalytic CO2 reduction reaction, including the following steps: 25 mg of ILs@NiADMS / PMOF catalyst was uniformly dispersed in 60 ml of water. After the CO2 adsorption-desorption equilibrium was reached on the catalyst surface (approximately 30 min), xenon lamp irradiation was performed for 2 h. A 300 W Xe lamp equipped with 365, 420, and 765 nm bandpass filters was used to simulate ultraviolet, visible, and near-infrared light sequentially. Gas chromatography and nuclear magnetic resonance (NMR) were used to detect possible products generated in the gas and liquid phases, and these were used to quantify the yield and selectivity.

[0027] The catalyst prepared in Example 1 was characterized as follows: Figure 1 Low-magnification transmission electron microscope image of ILs@Ni ADMS / PMOF. Figure 2 XPS spectrum of ILs@Ni ADMS / PMOF prepared in Example 1. Figure 3The N2 adsorption-desorption isotherm of the ILs@Ni ADMS / PMOF catalyst prepared in Example 1. Figure 4 The image shows the catalytic reduction performance of CO2 based on the full spectrum response of ILs@Ni ADMS / PMOF prepared in Example 1. Figure 5 Time-resolved transient absorption and electronic lifetime diagrams of ILs@Ni ADMS / PMOF prepared in Example 1 under near-infrared light excitation. Figure 6 The Gibbs free energy is the reaction of ILs@Ni ADMS / PMOF catalyzing the reduction of CO2 to C2H5OH in Example 1.

[0028] Depend on Figure 1 As can be seen from the TEM images, the morphology of ILs@Ni ADMS / PMOF is that of nanocubes with a size of less than 100 nm.

[0029] Figure 2 The results show that graphite N, pyridine N, pyrrole N and Ni-N exist in the Ni ADMS / PMOF-based catalyst, which confirms the formation of Ni-N bonds and maintains the stable structure belonging to PMOF after metallization and ILs modification.

[0030] The specific surface area of ​​the porphyrin-based catalyst was studied using N2 adsorption-desorption isotherms, and the results showed that... Figure 3 The results are presented in the figure. For PMOF, Ni ADMS / PMOF, and ILs@Ni ADMS / PMOF, similar type IV curves are observed, which is beneficial for ILs to fill the pores in the MOF structure. Compared to PMOF (1330.535 m), the results show a similar type IV curve. −2 g −1 The introduction of Ni and ILs both resulted in a lower specific surface area, which was 989.303 m². −2 g −1 77.100 m −2 g −1 This indicates that ILs do indeed fill the PMOF pores, which can improve the C1 intermediate environment and promote CO2 activation.

[0031] Depend on Figure 4 It can be seen that the formation rate of C2H5OH on Ni ADMS / PMOF reaches 15.46 mmol / h under visible light irradiation. −1 g −1 The efficiency was 2.47 times that of PMOF, demonstrating the crucial role of Ni as the active site. Furthermore, the C2H5OH formation rate catalyzed by ILs@NiADMS / PMOF increased by 130% (17.39 mmol h⁻¹) compared to NiADMS / PMOF. −1 g −1This indicates that Ni sites and ILs have a synergistic effect on CO2 reduction. Furthermore, the photocatalytic conversion of CO2 to C2 products under near-infrared light irradiation exhibits record-breaking catalytic performance, with a C2H5OH formation rate of 8.89 mmol / h. −1 g −1 .

[0032] Figure 5 The results show that, under 780 nm excitation, the TAS spectrum of PMOF exhibits a broad absorption band in the near-infrared region, due to rapid charge recombination of electrons and holes. Electrons decay over a period of 400 fs to 15 ps, while exhibiting the largest photoinduced absorption in the near-infrared region at 1150 nm, which is attributed to the singlet exciton absorption of PMOF.

[0033] We used Gibbs free energy calculations to reveal the mechanism of C2H5OH synthesis on ILs-modified Ni ADMS / PMOF. Figure 6 CO2 was initially reduced to * The COOH intermediate is spontaneous, and after the introduction of ILs... * CO and * The Gibbs free energy of CH2OH favors CO2 reduction, indicating that ILs can stabilize the C1 intermediate. Furthermore, compared to Ni-ADMS / PMOF, * CH3 to * The energy of the CH3CH2OH step is significantly reduced on the ILs@NiADMS / PMOF surface, and the energy barrier for C2H5OH desorption is also relatively low, which makes it easier for C2H5OH to be generated on the ILs@NiADMS / PMOF surface. Example 2-3

[0034] The catalysts used in the photocatalytic reduction of CO2 performance evaluation experiment mentioned in Example 1 were successively replaced with NiADMS / PMOF and PMOF. These two catalysts were synthesized using the same steps as the synthesis methods of PMOF and NiADMS / PMOF in Example 1, except that no ILs modifiers were added.

[0035] The above description is merely the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A porphyrin-based MOF catalyst for the full-spectrum catalytic reduction of CO2 to C2H5OH, characterized in that: The porphyrin-based MOF is a porous material composed of porphyrin ligands, Ni-N4 metal centers, and Zr cluster nodes.

2. The ILs-modified porphyrin-based MOF (ILs@NiADMS / PMOF) catalyst exhibits enhanced photocatalytic reduction performance of CO2, characterized by: The ILs@Ni ADMS / PMOF is filled with ILs in the MOF pore structure using a vacuum impregnation method.

3. The porphyrin-based MOF catalyst according to claim 1, characterized in that: The specific steps for preparing porphyrin-based MOF catalysts are as follows: 1) First, tetrakis(4-carboxyphenyl)porphyrin, benzoic acid, zirconium tetrachloride raw materials, and a small amount of deionized water as a conditioner were added to N,N-dimethylformamide (DMF) solvent and ultrasonically dispersed. Second, the uniformly dispersed mixture was transferred to a polytetrafluoroethylene-lined reactor and reacted at 120 °C for 1080 min. Finally, the obtained purple solid was washed with ethanol 3-4 times and dried under vacuum to obtain PMOF. 2) Add a DMF solution containing NiCl2·6H2O to DMF in which PMOF powder is dispersed, denoted as A; then hydrothermally heat A at 80℃ for 240 min; finally, wash the obtained solid with ethanol 3-4 times and dry it under vacuum to obtain Ni ADMS / PMOF.

4. The ILs@Ni ADMS / PMOF according to claim 2, characterized in that: The specific steps for preparing the ILs@Ni ADMS / PMOF catalyst are as follows: First, the Ni ADMS / PMOF described in claim 3 is ultrasonically dispersed in acetonitrile, and then impregnated under vacuum at 80 °C for 12 h to synthesize ILs@Ni ADMS / PMOF.

5. The porphyrin-based MOF catalyst according to claim 1, characterized in that: Under xenon lamps equipped with 365, 420, and 765 nm bandpass filters, the concentrations were 10.81, 15.46, and 8.01 mmol h, respectively. −1 g −1 The rate at which C2H5OH is generated.

6. The ILs@Ni ADMS / PMOF catalyst according to claim 2, characterized in that: Under xenon lamps equipped with 365, 420, and 765 nm bandpass filters, the ILs@Ni ADMS / PMOF catalyst exhibited excellent C2H5OH synthesis capabilities, with rates of 12.83, 17.39, and 8.89 mmol h⁻¹, respectively. −1 g −1 .

7. A method for the efficient synthesis of C2H5OH from CO2 via catalytic reduction with full-spectrum response, characterized in that: The method includes the following steps: The performance of CO2 reduction to C2H5OH was evaluated in a reactor with a quartz window using 300W Xe lamps equipped with 365, 420, and 765 nm bandpass filters to simulate ultraviolet, visible, and near-infrared light sequentially. First, high-purity CO2 (99.999%) was introduced at a rate of 40 ml / min. −1 The H2O dispersion containing a certain mass of catalyst was purged at a rate of 30 min, and then the CO2 rate was adjusted to 10 ml / min. −1 The CO2 was then reduced by photocatalysis, and the products were analyzed by gas chromatography and nuclear magnetic resonance.

8. The method for efficient photocatalytic reduction of CO2 to C2H5OH according to claim 7, characterized in that: The method described is a photocatalytic reduction performance test performed in the absence of any hole sacrificial agent.

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