Highly porous alumino-naphthalene dicarboxylic organic frameworks and their composites with nanostructured gold, methods of their production and use in the catalytic conversion of co2 to cyclic esters

Abstract

The subject of the present invention is a highly porous alumino-naphthalene dicarboxylic organic framework of molecular formula AI(C12H6O4) • X (CH3)2NHC(O)H • 3 H2O, where X denotes 0.22 or 0.25 and a composite of a highly porous alumino-naphthalene dicarboxylic organic framework defined above with nanostructural gold of molecular formula AI(C12H6O4) • Y (CH3)2NHC(O)H • Z S • 0.01 Au* 3 H2O where Y denotes 0.13 or 0.14, and Z denotes 0.05 or 0.1, and also the methods of their production and use in the catalytic conversion of CO2 to cyclic esters.

Description

[0001] HIGHLY POROUS ALUMINO-NAPHTHALENE DICARBOXYLIC ORGANIC FRAMEWORKS AND THEIR COMPOSITES WITH NANOSTRUCTURAL GOLD, METHODS OF THEIR PRODUCTION AND USE IN THE CATALYTIC CONVERSION OF CO2TO CYCLIC ESTERS

[0002] The present invention relates to highly porous alumino-naphthalene dicarboxylic organic frameworks and their composites with nanostructured gold, production methods and their use in the catalytic conversion of CO2to cyclic esters.

[0003] The subject of the invention are highly porous metal-organic framework (MOF) nanomaterials built from clusters of aluminium ions coordinatively linked to 1,4-naphthalenedicarboxylic acid and their composites with nanostructured gold (ultra-small nanoparticles with a diameter of 2 nm). The nanomaterials obtained according to the developed procedure are effective catalysts for the cycloaddition reaction of CO2to epoxides. Reactions were carried out with glycidol, epichlorohydrin, styrene oxide and propylene oxide as model epoxides. The processes proceed with 100% atomic efficiency, allowing the utilisation of waste CO2, and the resulting cyclic organic carbonates are useful products for many applications, including as electrolytes in lithium-ion batteries or polar high-boiling solvents for the pharmaceutical and cosmetic industries. Using the developed catalysts in the cycloaddition of CO2to epoxides allows industrially important products to be obtained with high yields and selectivity under relatively mild reaction conditions (90°C, 1 MPa CO2).

[0004] Increased CO2emissions from anthropogenic sources are one of the most important causes of climate change observed over the past few decades. The increase in the Earth's average temperature is referred as global warming and is associated with an increase in the concentration of greenhouse gases in the atmosphere. This phenomenon leads, among other things, to a decrease in the area of glaciers, previously unobserved long periods of drought over increasingly large areas, lowering groundwater levels and many other phenomena threatening life on Earth. Among greenhouse gases, carbon dioxide is the one that is emitted from anthropogenic sources in the greatest quantities. The combustion of fossil fuels, i.e. coal, lignite, natural gas, diesel, petrol and others derived from crude oil processing, causes annual emissions of CO2 estimated at 30 Gt (in 2022, it will reach 36.1±0.3Gt), which represents 70% of global emissions of this gas into the atmosphere.1, 2

[0005] The main emitters of CO2 are power plants, combined heat and power plants, cement factories, metal smelters and ammonia plants. The implementation in such plants of technologies to capture CO2 from flue gases and its utilisation, described by the abbreviation CCU (Carbon Capture and Utilisation), is considered to be one of the most appropriate strategies to reduce anthropogenic CO2 emissions.3Such a solution is environmentally beneficial and in line with the principles of a closed loop economy.4However, implementing this strategy faces many difficulties because while ways of capturing CO2 from flue gases and storing it are fairly well developed, its disposal into valuable products is a major challenge. This is due to the very high thermodynamic and kinetic stability of this chemical compound.5To activate CO2, reactive substrates must be used, i.e. epoxides, amines or hydrogen, which reduces thermodynamic limitations, and an efficient catalyst must be used to reduce the kinetic barrier. It is also usually necessary to provide energy during the process through heat, radiation or current flow.6

[0006] The coupling reaction between CO2 and epoxides leading to cyclic esters (the corresponding carbonates), also known as cycloaddition of CO2 to epoxides, proceeds with 100 % atomic efficiency, i.e. all atoms from the substrate molecules build up into the product molecules as a result of the reaction (Scheme 1).

[0007] Scheme 1 : Reaction scheme for the cycloaddition of CO2 to epoxides.

[0008] Cyclic organic esters (COEs) are a broad group of chemical compounds with many applications, used, among others, as electrolytes in lithium-ion batteries, polar high-boiling organic solvents, additives in cosmetic preparations, raw materials for polymers (polyurethanes, polycarbonates), and their annual production is several hundred thousand tonnes.5They are mostly liquids with high dielectric constants, low volatilities, are characterised by biocompatibility, good water solubility, are non-toxic, and biodegrade readily to safe compounds in the environment. COEs are therefore considered environmentally friendly 'green solvents'. The reaction to obtain COE as a result of CO2 cycloaddition to epoxides may be the basis for the development of new industrial technologies for their production based on the assumptions of sustainable development.7In contrast, current technologies for the production of these compounds are based on the use of highly toxic phosgene.2The cycloaddition of CO2 to epoxy ring requires the use of a catalyst to achieve satisfactory yields. The catalytic process can be carried out in a homogeneous or heterogeneous system. If the catalyst does not form a single phase with the reactants (heterogeneous system), it is easily separated after the reaction and reused. Therefore, the development of efficient heterogeneous catalysts is more desirable than homogeneous ones. Among heterogeneous catalysts for the cycloaddition reaction of CO2 to epoxides, MOF-type materials, i.e. those in which the metal ions form a 3D framework with organic linkers, are particularly promising. These are crystalline and porous materials that can strongly adsorb CO2 inside the pores, have active catalytic centres in their structure (metal ions exhibiting behaviour typical of Lewis acids) and can be used as reusable catalysts if they have sufficiently high stability. Most commonly, MOF-type catalysts are used in the cycloaddition of CO2 with a co-catalyst, which is most often a tetraalkylammonium halide, providing a nucleophilic agent (halide anion) to activate the CO2 and form a halo-alkoxy transition compound.8

[0009] In recent years, several scientific papers have been published showing that composite materials constructed from MOF-type materials with catalytically active agents immobilised in the pores allow better performance and / or selectivity to be obtained than when these materials are used separately.7Ding and Jiang in 2018 showed that the incorporation of poly(ionic liquid) constructed from imidazolium subunits into the structure of a MOF obtained from chromium(lll) salt and terephthalic acid (MIL-101) allows to obtain a heterogeneous, highly efficient and selective catalyst for the cycloaddition of CO2 to epoxides.9However, the procedure for obtaining such a heterogeneous catalyst requires a complex multi-step synthesis and many expensive chemicals, which may make it too expensive for use on a scale larger than the laboratory. Furthermore, due to the significant toxicity of chromium(lll) salts, obtaining this type of catalytic material on an industrial scale may pose environmental risks.

[0010] Baumick et al.10proposed the use of MOFs obtained from the cerium salt Ce3+and 1,4- naphthalenedicarboxylic acid (1,4-NDC) as catalysts in the cycloaddition of CO2 to epoxides. The authors showed that the presence of 4-aminotriazole or 5-aminotetrazole during the synthesis of MOFs results in the formation of a more ordered structure (mediators of crystallisation), and the heterogeneous catalyst obtained in this way is highly efficient in the catalytic conversion reaction of CO2 to cyclic esters. Cerium belongs to rare elements and its weight content in the Earth's crust is only 0.0004%, so the use of catalysts derived from its compounds on an industrial scale would be very expensive.

[0011] Few papers published to date have described the successful use of nanostructured gold as a catalyst in CO2 cycloaddition reactions to epoxides. Yang et al.11in 2021 showed that gold nanoclusters catalyse the cycloaddition of CO2 to propylene oxide with dimethylaminopyridine (DMAP) as a co-catalyst. However, it has been shown that CO2 adsorbs poorly on the surface of gold nanoclusters, so immobilising them in a material capable of capturing this compound may improve their catalytic activity in CO2 conversion.12

[0012] The aim of the invention was to develop efficient catalysts for the cycloaddition reaction of CO2 to epoxides. This objective has been achieved by highly porous alumino-naphthalene dicarboxylic organic frameworks and their composites with nanostructured gold.

[0013] Thus, the subject of the present invention is a highly porous alumino-naphthalene dicarboxylic organic framework of molecular formula

[0014] AI(Ci2H6O4) • X (CH3)2NHC(O)H • 3 H2O, where X denotes 0.22 or 0.25.

[0015] Preferably, the highly porous alumino-naphthalene dicarboxylic organic framework has a specific surface area, according to the BET model, of more than 700 m2 / g.

[0016] The subject of the present invention is also a composite of a highly porous alumino- naphthalene dicarboxylic organic framework defined above with nanostructural gold of molecular formula AI(CI2H6O4) • Y (CH3)2NHC(O)H • Z S • 0.01 Au* 3 H2O where Y denotes 0.13 or 0.14, and Z denotes 0.05 or 0.1.

[0017] Preferably, the composite of the highly porous alumino-naphthalene dicarboxylicorganic framework with nanostructural gold has a specific surface area according to the BET model of more than 400 m2 / g.

[0018] Another subject of the invention is a method for producing a highly porous alumino- naphthalene dicarboxylic organic framework as defined above, characterised in that it comprises steps in which

[0019] - AI(NO3)2KI9H2O, 4H-1,2,4-triazole-4-amine or 5-amino-1 H-tetrazole, 1,4- naphthalenedicarboxylic acid and dimethylformamide are mixed in a reaction vessel until all components are completely dissolved and a clear solution is obtained;

[0020] - the reaction mixture is heated at 110°C until a white precipitate is formed;

[0021] - the precipitate is filtrated from the reaction mixture, washed with methanol and dried under an argon atmosphere;

[0022] - the dried precipitate is shaken in anhydrous methanol, centrifuged and then heated at 165°C.

[0023] Preferably, AI(NO3)2KI9H2O, 4H-1,2,4-triazole-4-amine or 5-amino-1 H-tetrazole and 1,4- naphthalenedicarboxylic acid are mixed in a molar ratio of 0.25 : 0.2 : 0.4.

[0024] Preferably, heating at 110°C is carried out for 72 hours until a white precipitate is formed.

[0025] Preferably, heating at 165°C is carried out for 24 hours.

[0026] A further subject of the present invention is a method for producing a composite of the highly porous alumino-naphthalene dicarboxylic organic framework with nanostructured gold as defined above, characterised in that it comprises steps in which

[0027] - gold nanoparticles, AI(NO3)2KI9H2O, 4H-1,2,4-triazole-4-amine or 5-amino-1 H- tetrazole, 1,4-naphthalenedicarboxylic acid and dimethylformamide are mixed in a reaction vessel until all components are completely dissolved and a clear solution is obtained; - the reaction mixture is heated at 110°C until a precipitate is formed;

[0028] - the precipitate is filtrated from the reaction mixture, washed with methanol and dried under an argon atmosphere;

[0029] - the dried precipitate is shaken in anhydrous methanol, centrifuged and heated at 165°C.

[0030] Preferably, gold nanoparticles, AI(NO3)IKI9H2O, 4H-1,2,4-triazole-4-amine or 5-amino-1 H- tetrazole and 1,4-naphthalenedicarboxylic acid are mixed in a molar ratio of 0.05 : 0.25 : 0.2 : 0.4.

[0031] Preferably, heating at a temperature of 110°C until the precipitate is formed is carried out for 72 hours.

[0032] Preferably, heating at 165°C is carried out for 24 hours.

[0033] Preferably, the octadecanothiol-stabilised gold nanoparticles, which are added to the solution during crystallisation of the MOF, are produced by a method comprising steps in which

[0034] - an aqueous solution of HAuCL^SFhO is extracted with a solution of tetraoctylammonium bromide in toluene;

[0035] - 1 -octanethiol is added to the toluene layer, next a solution of NaBFU in methanol is added dropwise and the reaction mixture is stirred, followed by extraction with water;

[0036] - the toluene layer is concentrated, and cooled, ethanol is added to precipitate a black precipitate, after which the resulting precipitate is centrifuged and dried.

[0037] The subject of the invention is also the use of a highly porous alumino-naphthalene dicarboxylic organic framework, as defined above, or obtained by the method described above, as a catalyst in the conversion reaction of CO2 to cyclic esters.

[0038] The subject of the invention is also the use of a composite of a highly porous alumino- naphthalene dicarboxylic organic framework with nanostructured gold as described above, as a catalyst in the conversion reaction of CO2 to cyclic esters.

[0039] The objects of the present invention are illustrated in the figures, where: Fig. 1 shows a kit used in CO2 cycloaddition with a pressure reactor, magnetic stirrer and thermostated oil bath;

[0040] Fig. 2 shows the reaction scheme for the cycloaddition of COito glycidol;

[0041] Fig. 3 shows the N2 adsorption isotherms recorded at the temperature of 77 K for the four catalyst materials obtained in the sorption and desorption cycles;

[0042] Fig. 4 shows CO2 adsorption isotherms for the invented materials , recorded at the temperature of 273 K;

[0043] Fig. 5 shows SEM images obtained for the four catalytic materials produced;

[0044] Fig. 6 shows TEM images obtained for the developed MOF-type materials and for the composites with nanostructured gold (gold nanoparticles in the structure are marked with arrows).

[0045] Fig. 7 shows TGA curves recorded during heating to 1000°C of material samples under an inert gas (nitrogen) atmosphere at a heating rate of 10 K min-1.

[0046] The subject of the invention are highly porous nanomaterials with the structure of organometallic MOF-type frameworks in which the linker is 1,4-naphthalenedicarboxylic acid coordinated with aluminium ions (AI@NDC), and their composites with nanostructured gold AIAu@NDC. The nanomaterials obtained, according to the procedure of the invention, were used in the catalytic conversion of CO2 to cyclic esters. Reactions involving them proceed under mild conditions (90°C, 1 MPa CO2), with high yields and high selectivity. In the synthesis, 4-aminotriazole (4-Atrz) (AI4@NDC) or 5-aminotetrazole (5-Atz) (AI5@NDC) were used as mediators for the crystallisation of MOFs. In the preparation of AIAu@NDC, ultra-small gold nanoparticles (2 nm in diameter) were used, which were introduced during the growth process of organometallic frameworks (“bottle around the ship” strategy), and the resulting composites had a gold content of 0.8 % (by weight).

[0047] EXAMPLES

[0048] Materials

[0049] Aluminium nitrate(V) nonahydrate (AI(NO3)3*9H2O ACS reagent, 1398% (Merck), 1,4- naphthalenedicarboxylic acid (NDC), 98% (AmBeed), chloroauric acid trihydrate (HAuCU • 3HiO) ACS reagent, &49.0% Au basis (Merck), tetraoctylammonium bromide ([CH3 (CFh^NBr) TOAB, 98% (Merck), tetrabutylammonium bromide ([CH3 (CHz^pNBr) TBAB, 98% (Merck), sodium borohydride NaBFU, powder > 98% (Sigma Aldich), glycidol, (Gly) 96% (Thermo Scientific), epichlorohydrin (EPI), 99% (Thermo Scientific), styrene oxide (St-O) > 97% (Thermo Scientific), (+ / -) propylene oxide (Pr-O), > 99% (Thermo Scientific), dimethylformamide DMF (p.a.) Chemat, dichloromethane (DCM) p.a., Chemat, ethyl acetate p.a., Chemat, toluene (p.a.) Chemat, absolute ethanol (>99%) Chemat, 4H-1,2,4-triazol-4- amine, 95% (AmBeed), 5-amino-1 H-tetrazole, 95% (Angene), anisole anhydrous, 99.7%, (Merck), propylene carbonate, anhydrous 99.7%, Merck, 4-(Hydroxymethyl)-1,3-dioxolan-2- one, >98%, Merck, methanol anhydrous, 99% (Merck), , ultra-pure water was used in all experiments (resistivity 18 MQ • cm-1at temperature of 25°C).

[0050] Example 1

[0051] Synthesis of AI4@NDC / AI5@NDC

[0052] In a vial, 92.4 mg of Al (N 03)2^9 H2O (0.25 mmol), 16.8 mg (0.2 mmol) of 4-Atrz, (for AI4@NDC) or 17 mg (0.2 mmol) of 5-Atz (for AI5@NDC), 86.5 mg of 1,4- naphthalenedicarboxylic acid (1,4-NDC) (0.4 mmol) and 10 ml of DMF were mixed. The solution was stirred for 10 minutes on a magnetic stirrer (until all components were completely dissolved and a clear solution was obtained). The vial was placed in an oven and heated at 110°C for 72 h, after which time a white precipitate formed. The products were filtrated , washed with MeOH and allowed to dry under an argon atmosphere. After drying, the products were transferred to vials, 5 ml of anhydrous MeOH was added and shaken (100 rpm) for 24 h. After 24 h, the mixtures were centrifuged (1000 rpm, 10 min), solid materials were placed in an oven, and heated at the temperature of 165°C for 24 h. The products obtained were white, fine crystalline substances (the weight of the AI5@NDC product was 60 mg, and AI4@NDC was 55 mg).

[0053] Example 2

[0054] Synthesis of AuNPs

[0055] 1 -Octadecanethiol-stabilised gold nanoparticles (AuNPs) were prepared according to the procedure developed by Brust-Schiffrin13with the introduction of modifications enabling the production of the product in gram quantities. An aqueous solution of HAuCl4*3HiO (100 mg (5 mmol) in 120 ml of ultra-pure water was placed in a separatory funnel and extracted three times with a solution of TOAB in toluene (3x with a solution obtained by dissolving 1.53 g of TOAB in 180 ml). The toluene layer was dark orange after extraction; the aqueous layer was discarded. The organic (toluene) layer was transferred to a flask on a magnetic stirrer, the solution obtained by dissolving 400 mg of NaBFU in 100 ml of MeOH was slowly dropped into the flask. After adding a few drops of NaBFU, the solution turned black, 673 mg of 1- octadecanethiol in 25 ml of toluene was added, and the dropwise addition of the NaBFU solution was continued. The mixture was stirred with a magnetic stirrer for 20 h. The solution was then extracted twice with ultra-pure water (2x200 ml) to remove inorganic reactants, the aqueous layer was discarded, and the toluene solution was concentrated using a vaccum rotary evaporator to a volume of approximately 10 ml. To the concentrated mixture, 50 ml of cooled EtOH (96%) was added, resulting in a black precipitate. The precipitate was then centrifuged (15000 rpm, 5 min). The supernatant was discarded, and the precipitate was dried in a vacuum oven (40°C, 10 mbar, 24h). 1.0342 g of product was obtained.

[0056] Example 3

[0057] Synthesis of AI4Au@NDC / AI5Au@NDC

[0058] The composite materials’ syntheses were carried out by crystallising of MOFs’ in a solvent in which gold nanoparticles (AuNPs) had previously been dissolved. A method referred to in the literature as “bottle around the ship” was used.14

[0059] The vial contained 26 mg of AuNPs (0.05 mmol Au3+), 92.4 mg (0.25 mmol) of AI(NOs)3 •9HiO, 16.8 mg (0.2 mmol) of 4-Atrz, (for AI4@NDC) or 17 mg (0.2 mmol) of 5-Atz (for AI5@NDC), 86.5 mg of 1,4-naphthalenedicarboxylic acid (1,4-NDC) (0.4 mmol). The total was dissolved in 10 ml of DMF and placed on a magnetic stirrer for 10 minutes. After this time, the vial was placed in an oven at 110°C for 24h. Light beige crystals were obtained. The products were filtrated. After grinding, the crystals were washed with methanol and dried under an argon atmosphere. After drying, the products were transferred to vials, 5 ml of anhydrous MeOH was added and the mixture was shaken ( 100 rpm) for 24 h. Afterwards the mixtures were centrifuged (1000 rpm, 10 min), solids were placed in an oven, and heated at a temperature of 165°C for 24 h. 80 mg of AI5Au@NDC and 85 mg of AI4Au@NDC were obtained.

[0060] Example 4

[0061] Cycloaddition reaction of CO2to epoxides

[0062] Reactions were carried out in a 50 ml stainless steel pressure reactor equipped with a pressure gauge and gas introduction valves. The reactants were placed in a Teflon vessel embedded inside the reactor (Fig. 1), and carbon dioxide was introduced until a starting pressure of 1 MPa was reached.

[0063] Fig. 1 shows the kit used for CO2cycloaddition with a pressure reactor, magnetic stirrer and thermostated oil bath.

[0064] Reactions were carried out in two systems: in a solution obtained by dissolving all components in methylene chloride (DCM) in the following amounts: 10 mg of a catalyst (AI4@NDC / AI5@NDC / AI4Au@NDC / AI5Au@NDC), = 4 mmol of epoxide, 29 mg (0.09 mmol) of TBAB (co-catalyst), = 80 mg of anisole (internal standard for GC analysis) and 6 ml of DCM. In the second system, the reactions were carried out without solvent using selected epoxides on a larger scale: glycidol (15 mmol), epichlorohydrin (20 mmol). Reaction procedure: the catalyst was placed in a Teflon vessel, and a solution prepared by dissolving the co-catalyst, epoxide and anisole in DCM, or without this solvent for a larger scale, was added, then CO2was introduced until a final stable pressure of 1 MPa was reached. The reactor was placed in a thermostated oil bath on a magnetic stirrer (Fig. 1). The bath temperature was maintained at 90 ± 2°C. After a specific reaction time, the reactor was cooled, and the reaction slurry was mixed with 7 ml of ethyl acetate (this facilitated the separation of the catalyst from the postreaction mixture). The solution was then filtered using a syringe filter, or the catalyst was centrifuged (10 min, 10000 rpm) for these with recycling to subsequent catalytic cycles. The mixture obtained after catalyst removal was subjected to GC analysis using the internal standard method (using anisole as the reference).

[0065] Gas chromatographic GC analyses

[0066] GC analyses were performed using a Shimadzu GC2010 Plus chromatograph equipped with a capillary injection system and a flame ionisation detector (FID): HP-5 columns (30 m x 0.320 mm, 0.25 m, Agilent Technologies). Analysis conditions: nitrogen carrier gas (~80 kPa); split ratio: 50; inlet temperatures 250°C; temperature in detector 280°C.

[0067] Analyses by Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy SEM-EDS

[0068] SEM-EDS measurements were carried out using a JEOL-JSM-5600 microscope equipped with an OXFORD Link-ISIS-300 spectrometer. Samples for imaging were coated with a thin layer of Au-Pd alloy (1-2 nm) to increase its conductivity and thus to obtain better resolution of the images.

[0069] Porosity analyses using the BET method

[0070] Measurements were performed using a Micrometrics ASAP 2020 analyser, the samples were annealed at 200°C for 6h, and then the pressure was reduced to a final pressure of < 1 pm Hg. N2 adsorption measurements were performed at a temperature of 77 K and CO2 adsorption at a temperature of 273 K. The specific surface area value was counted using the Brunauer- Emmett-Teller (BET) method.

[0071] Thermogravi metric analyses (TGA)

[0072] TGA measurements were performed using TA Instruments Q50 V20.10 Build 36 (TA instruments) with a balance with an accuracy of ± 0.4%; minimum weight of 0.02 mg in an N2 atmosphere at a heating rate of 10 K min1.

[0073] NMR Spectroscopy

[0074] 1H NMR spectra were recorded for the catalyst samples after their decomposition in deuterated sulphuric acid(VI) (100%) and dissolved in deuterated dimethylsulphoxide (DMSO- d&) as a solvent using a Bruker Corporation 300MHz spectrometer.1H NMR chemical shifts in ppm were determined using tetramethylsilane as a standard.

[0075] A 3 mg sample of the catalyst was dissolved in 20 pl of D2SO4 (100% concentration), then 600 pl of DMSO-ds was added, and the mixture was sonicated for 10 minutes, after which1H NMR spectra were recorded.

[0076] Spectral range: -2 - 18 ppm, relaxation time: 5 s, number of scans: 32. Transmission Electron Microscopy (TEM)

[0077] TEM analyses were performed using a JEM 1400 JEOL Co. microscope (|EOL) at 120 kV. The samples were obtained by casting the DMF solutions (3 mg / ml) of materials onto a carbon- coated copper microgrids (200 mesh) and air-dried overnight.

[0078] Elemental analysis

[0079] Measurements were performed using an Elementar UNIcube (C,H,N,S content analyses were performed).

[0080] Compositional analyses using Inductively Coupled Plasma-Mass Spectrometry (ICP MS)

[0081] Measurements were performed using an ICP-MS spectrometer a NexION 300D (Perkin Elmer, USA) equipped with a quartz sputtering tank with a Meinhard nebuliser.

[0082] Catalytic test results

[0083] Scheme 2 shows the formulae of the epoxides tested in the CO2 cycloaddition reaction using the catalysts being the subject of the invention and the formulae of the cyclic carbonates obtained as a result of this reaction.

[0084]

[0085] Scheme 2. Formulae of the epoxides tested and the cyclic carbonates obtained from them.

[0086] Table 1 shows the epoxide conversions obtained, the yields for cyclic carbonates and the reaction conditions.

[0087] The use of catalysts according to the present invention in the CO2 cycloaddition reaction allowed obtaining products for all the epoxides tested (glycidol, epichlorohydrin, styrene oxide, propylene oxide) under mild reaction conditions (90°C, 1 MPa CO2).

[0088] The highest conversions and yields were obtained for the reaction to obtain glycerol carbonate (Gly-COs), slightly lower for the reaction with epichlorohydrin and much lower for the reactions with styrene oxide and propylene oxide. In the case of AI5@NDC, 100% of glycidol is converted after 4 h of the reaction; extending the reaction time to 22 h increases the reaction yield from 83.5% to 93.5%. This indicates an intermediate is obtained after 4 h of reaction, which can react to the desired product if the reaction time is extended. The introduction of gold nanoparticles into the AI5@NDC structure allows a higher yield of Gly-CO3to be obtained for a much shorter reaction run time.

[0089] Table 1

[0090] Results and reaction conditions for the cycloaddition reaction of COi to the epoxides tested (substrate and product structures shown in Scheme 2).a

[0091] Substrate Product Reaction Substrate Yield TON time conversion [%]

[0092] [h] [%]

[0093] AI5@NDC

[0094] Gly Gly-CO322 100 93.6 117

[0095] 4 100 83.5 99.6

[0096] 2 82.0 70.0 83.8

[0097] 18 90.8 90.8 62.9

[0098] EPI EPI-CO3 6 62.0 62.0 41.63

[0099] 2 22.4 22.4 15.26

[0100] Pr-O Pr-CO348 ND 18.5 14.1

[0101] St-O St-CO322 10.9 6.63 4.76

[0102] AI5Au@NDC

[0103] 18 100 87.8 101.7

[0104] Gly Gly-CO34 100 87.5 102.8

[0105] 2 91.0 89.3 103.6

[0106] EPI EPI-CO318 90.9 90.9 61.1

[0107] Pr-O Pr-CO322 ND 16.7 7.10

[0108] 48 ND 33.8 9.71

[0109] St-O St-CO322 19.5 15.6 11.2

[0110] AI4@NDC

[0111] 19 100 79.7 95.1 Gly Gly-CO34 91.4 77.0 112.4

[0112] 2 84.0 73.3 82.4

[0113] EPI EPI-CO3 2 22.4 22.4 15.26

[0114] 6 62.2 62.2 41.61

[0115] Pr-O Pr-CO348 ND 13.9 10.6

[0116] St-O St-CO322 27.7 26.6 15.03

[0117] AI4Au@NDC

[0118] Gly Gly-CO318 100 89 103.4

[0119] EPI EPI-CO318 94.2 94.2 65.14

[0120] Pr-O Pr-CO322 ND 5.2 2.33

[0121] St-O St-CO322 24.2 22.8 15.9aReaction conditions: 90°C, 1 MPa CO2, 6 ml of DCM, 10 mg of catalyst, 29 mg of TBAB (cocatalyst), ND - not determined due to the very high volatility of propylene oxide, it was not possible to determine its conversion using GC, TON - the turnover number determined as nProduct / ncataiyst (molar mass of catalyst calculated from the molecular formula presented in Table 2)-

[0122] After 2 h of the reaction, the conversion of glycidol is 91%, and the yield of the resulting Gly- CO3 is very similar at 89.3%, indicating that the nanostructured gold in the MOF structure allows for increased selectivity. In cycloaddition reactions with epichlorohydrin, the use of the developed catalysts allows to obtain 100% selectivity (no by-products were observed, the yield is equal to the conversion of the epoxide reacted). The presence of nanostructured gold increases the conversion of the substrate to a minimal extent.

[0123] Cycloadditions of CO2 to styrene oxide and propylene oxide occur with lower yields than for Gly and EPI, due to their lower reactivity due to the lack of electron-acceptor substituents in the molecule. For styrene oxide (St-O), the highest conversion and similar yield were obtained using AI4@NDC catalyst (after 22 h of reaction, the conversion was 27.7% and the yield 26.6%). The presence of nanostructured gold in the developed catalysts does not increase the yield of obtaining St-CO3. On the other hand, it significantly increases the yield of obtaining propylene carbonate (Pr-COs). In the presence of AI5@NDC, the yield of the cycloaddition of CO2 to propylene oxide (Pr-O) after 48h of reaction is 18.5%, while in the presence of AI5Au@NDC, the yield is almost twice as high (33.8%). Lower yields were obtained in the presence of AI4@NDC and AI4Au@NDC.

[0124] For the cycloaddition reaction of CO2 to glycidol leading to glycerol carbonate, an industrially attractive product, optimisation of the reaction conditions and tests to assess the possibility of multiple uses of the optimal catalyst among those developed (AI5@NDC) were performed. The results of the tests are shown in Fig. 2.

[0125] Fig. 2 shows the reaction scheme for the cycloaddition of CO2 to glycidol, (a) effect of temperature on the reaction occurring under the conditions described in the scheme, reaction time 1 h, AI5@NDC as catalyst, (b) results obtained in five catalytic cycles using AI5@NDC as catalyst returned to the next cycle from the previous one (reaction time 3 h, temp 90°C, 20 mg AI5@NDC).

[0126] 90°C has been chosen as the optimum reaction temperature for the cycloaddition of CO2 to epoxides in the presence of the developed catalysts because at the temperature of 70°C, the conversion of glycidol was three times lower after 1 h of reaction. Comparing 60% conversion of Gly with 80% at the temperature of 110°C, it is economically justifiable to use less energy to heat the mixture; the conversion at 90°C after 1 h of reaction is satisfactory.

[0127] Using the example of the AI5@NDC catalyst in the reaction to obtain Gly-COs, it has been shown that the developed catalytic materials can be successfully recovered from the reaction mixture and reused in the reaction. In five consecutive reactions with the recovered catalyst, no decrease in conversion and yield has been observed (Fig. 2b). The slight differences between cycle I, II and subsequent cycles are within the conversion and yield determination errors.

[0128] The observed differences in the activity of the developed catalytic materials in the reactions with the epoxides tested are due to differences in their morphology. Characterisation of the catalytic materials

[0129] Compositional Analysis (ICP MS, Elemental Analysis, SEM-EDS)

[0130] The percentage content of elements in the developed materials is shown in Table 2. The content of aluminium and gold was determined by ICP MS and SEM-EDS, and elemental analysis allowed the carbon, hydrogen, nitrogen, and sulphur contents of the materials obtained to be determined. SEM-EDS also allows the determination of nitrogen, carbon, and sulphur content, but the results of the elemental analysis are much more accurate, and these were used in the calculations that led to the empirical molecular formulae. For most of the elements analysed, the results from the different techniques are similar. The oxygen content was determined as the difference between the sum of the contents of all other elements in the sample.

[0131] 1H NMR spectroscopy

[0132] Analysis of the 1 H NMR spectra showed that the crystallisation mediators used (4- aminotriazole and 5-aminotetrazole) do not incorporate into the structure of the synthesised nanomaterials. Spectra were recorded for AI5@NDC and AI4@NDC after decomposition in D2SO4 and dissolution in d6-DMSO. The recorded spectra for both materials were the same in terms of both, namely signal positioning and signal integration.

[0133] AI5@NDC, AI4@NDC:

[0134] 1H NMR (300 MHz, d6-DMSO) 8 = 12.78 (s, COOH, 2H), 8.72-8.69 (m, CH, naphthalene ring 2H), 8.10 (s, CH, naphthalene ring with COOH, 2H), 7.67-7.64 (m, CH, naphthalene ring 2H), 3.54 (s, H2O), 3.35 (s, NH w (CH3)2NH), 3.20 (s, CH3, 6H)

[0135] Table 2

[0136] The elemental composition (expressed in % by weight) of the catalytic materials synthesised and the molecular (empirical) formulae proposed on this basis.

[0137] Al C N S H O Au

[0138] AI5@NDC

[0139] 8.65a50.1b0.99b- 3.96b36.3C

[0140] 8.04d54.5d2.24d35.2d Empirical Al (CI2H6O4) • 0.22 (CH3)2NHC(O)H • 3 H2O formula Al (NDC) • 0.22 (DMF) • 3 H2O

[0141] AI5Au@NDC

[0142] 8.57a50.8b0.61b0.57b3.97b35.5C0.82a

[0143] 8.33d57.5d1.64d0.71d30.9d1.17d

[0144] Empirical Al (CI2H6O4) • 0.14 (CH3)2NHC(O)H • 0.05 S • 0.01 Au* 3 H2O formula Al (NDC) • 0.14 (DMF) • 0.05 S • 0.01 Au • 3 H2O

[0145] AI4@NDC

[0146] 8.76a50.3b1.12b- 4.07b35.7C

[0147] 4.38d53.0d2.21d40.4d

[0148] Empirical Al (CI2H6O4) • 0.25 (CH3)2NHC(O)H • 3 H2O formula Al (NDC) • 0.25 (DMF) • 3 H2O

[0149] AI4Au@NDC

[0150] 7.08d59.5d1.73d1.09d27.5d0.59d

[0151] Empirical Al (CI2H6O4) • 0.13 (CH3)2NHC(O)H • 0.1 S • 0.01 Au* 3 H2O formula Al (NDC) • 0.13 (DMF) • 0.1 S • 0.01 Au • 3 H2O a ICP MS analysis;belemental analysis;ccalculated as difference of 100% - (Al%a+C%b+N%b+H%b);dSEM-EDS analysis, NDC=1,4-naphthalenedicarboxylic acid (deprotonated), DMF - dimethylformamide

[0152] AI5@NDC and AI4@NDC do not differ in elemental composition; the small differences are within the limits of measurement error. Slightly larger differences are observed between AI5Au@NDC and AI4Au@NDC, particularly concerning the content of sulphur (derived from the coating of gold nanoparticles), nitrogen and oxygen. However, the differences in the catalytic activity of these materials cannot be attributed solely to differences in elemental composition, as these are too small. The differences in catalytic activity are due to differences in their morphology (described later). Table 2 provides the empirical molecular formulae determined based on the elemental compositions determined. For all catalytic materials, in the formulae determined, there is 1 mole of ligand (NDC) per 1 mole of Al3+ions, which means that the structure of these materials contains aluminium ions partially coordinated with the ligand, thanks to which they exhibit the properties of strong Lewis acids, which is important for the cycloaddition reaction of CO2to epoxides. Based on the determined number of moles of carbon, nitrogen and oxygen atoms per 1 mole of aluminium ions, an empirical formula was proposed, where DMF stands for dimethylformamide. In all materials, 3 moles of water (hydration water) are coordinated per 1 mole of Al3+ions, and in composites, there is 0.01 mole of gold per 1 mole of Al3+ions.

[0153] Porosity analysis, N2and CO2adsorption isotherms

[0154] Fig. 3 shows the N2adsorption isotherms recorded at 77 K for the four catalytic materials obtained in sorption and desorption cycles. The shapes of the isotherms are similar for all the nanomaterials tested but, there are clear differences in the values of the volume of N2adsorbed, expressed per gram, which correspond to the differences in their catalytic activity. The course of isotherms for AI4@NDC and AI5@NDC differs, which is due to differences in the morphology of these materials. Significantly lower N2adsorption values are observed for their nanostructured gold composites (AI4@Au@NDC and AI5@Au@NDC). The course of the isothermal curves for all the nanomaterials obtained shows their high porosity.

[0155] Table 3 shows the specific surface areas determined from N2isotherms and the pore sizes determined according to the Brunauer-Emmett-Teller (BET) model. The pore size distribution curves were determined based on the Density Functional theory (DFT).

[0156] Table 3

[0157] Porosity characteristics of the obtained nanocatalysts according to the BET model, where SBET - specific surface area of the adsorbent according to the BET model, SDFT - pore surface area by the QSDFT method, Lo- average size of micropores according to Stoecklie, Eo - characteristic energy of adsorption (Dubinin).

[0158] Calculations based on N2adsorption-desorption curves at the temperature of 77 K. SBET [m2g’1] SDFT [m2g’1] Lo[nm] Eo[kJ mol’1]

[0159] AI5@NDC 736.5 834.9 0.61 29.02

[0160] AI4@NDC 741.3 827.6 0.72 26.38

[0161] AI5@Au@NDC 526.4 595.7 0.84 24.20

[0162] AI4@Au@NDC 421.0 463.5 1.05 21.70

[0163] The specific surface areas determined according to the BET model and the DFT theory are very large, with AI4@NDC having the highest porosity and AI4Au@NDC the lowest, the average pore size < 2nm, meaning that all the materials obtained are characterised by microporosity. Such a morphology increases the gas adsorption efficiency. The differences in the catalytic activity of the nanomaterials obtained are due to the differences in their morphology. The smallest pore size for AI5@NDC should allow more gas to penetrate per unit weight of material. CO2 penetration is crucial in the catalytic reactions tested. The CO2 adsorption isotherms determined for the tested materials recorded at 273 K are shown in Fig. 4.

[0164] CO2 adsorption by the tested materials increases rapidly with increasing pressure in the range of 50-800 mm Hg and is very high under normal pressure at the temperature of 273 K. AI5@NDC has the highest CO2 adsorption capacity among the materials obtained, while AI4@NDC has a lower capacity, which is in good agreement with their catalytic activity in CO2 cycloaddition reactions. Their nanostructured gold composites have a lower CO2 adsorption capacity. The increased catalytic activity of AI5Au@NDC relative to AI5@NDC in the CO2 cycloaddition reaction to propylene oxide is, therefore, not due to differences in the adsorption capacity of this gas but to the presence of gold nanoparticles in its structure. However, the higher activity of AI5Au@NDC compared to AI4Au@NDC in this reaction can be explained by its greater ability to adsorb CO2. Morphology analysis of nanomaterials using SEM and TEM

[0165] The microporous structure of the developed materials was confirmed using scanning electron microscopy (SEM).

[0166] Fig. 5 shows SEM images obtained for the four catalytic materials that were developed .

[0167] It can be concluded from the SEM images (Fig. 5) that AI5@NDC and AI4@NDC form nanocrystallites in the shape of cuboids and cubes with edges smaller than 150 nm in the case of Au5@NDC and smaller than 100 nm in the case of Au4@NDC. AI4@NDC is, therefore, more finely crystalline than AI5@NDC.

[0168] The free spaces between the crystallites, measuring < 2 nm, form a framework of micropores, making them highly gas adsorbents. AI5@NDC has a more homogeneous structure compared to AI4@NDC, so the distribution of micropores within this material is also more homogeneous, which is probably the main reason why it has the best catalytic properties.

[0169] Materials that crystallised in the presence of gold nanoparticles (AI5Au@NDC and AI4Au@NDC) have a different morphology from those that crystallised without gold nanoparticles (AI5@NDC and AI4@NDC).

[0170] Composite materials with nanostructured gold are made of nanoplatelets with a longer side of about 150 nm ,a shorter side of 100 nm, and a thickness of a few nanometres. These materials are less homogeneous than AI5@NDC and AI4@NDC. However, the distances between these nanoplatelets are similar to those between nanocrystallites in AI5@NDC and AI4@NDC. The nanostructured gold composite materials obtained have a microporous structure, which is consistent with the results obtained from the N2 adsorption isotherms determined for them (Table 3).

[0171] Fig. 6 shows selected TEM microscopy images with visible gold nanoparticles in the composite material.

[0172] Thermogravi metric analysis (TGA)

[0173] TG analyses allowed to assess the thermal stability of the obtained nanomaterials and to analyse the changes in their composition during heating. Fig. 7 shows TGA curves recorded during heating to 1000°C of material samples under an inert gas (nitrogen) atmosphere at a heating rate of 10 K min-1.

[0174] The TGA curves recorded for AI5@NDC and AI4@NDC show two weight losses: a small one in the range 150 - 200°C and a much larger one in the range 500 - 600°C. The first weight loss corresponds to the removal of DMF molecules from the crystal lattice, and the second to the thermal decomposition of the material. In both materials, the DMF content is similar (Table 2), so the first weight loss is the same (7 wt.%). The thermal decomposition of AI4@NDC starts at a slightly lower temperature than AI5@NDC and leads to a lower final weight (15% of the initial weight). The solid residue of TGA contains aluminium and carbon from decomposition.

[0175] The TGA curves for AI5Au@NDC and AI4Au@NDC are almost identical in terms of their course, thermal decomposition starting at a slightly lower temperature than for AI5Au@NDC and AI4Au@NDC.

[0176] TG analyses have shown high thermal stability of the developed catalysts; their thermal decomposition occurs at temperatures above 450°C.

[0177] Summary and advantages of the present invention

[0178] The invention relates to new materials for use as catalysts for the cycloaddition of CO2 to epoxides. The new materials of the invention have the structure of Metal-Organic Frameworks (MOFs) formed by clusters of aluminium ions with 1,4-naphthalenedicarboxylic acid. Four types of catalytic materials have been developed: 1) formed by crystallisation between an aluminium salt and 1,4-naphthalenedicarboxylic acid in the presence of 5-aminotetrazole (AI5@NDC)

[0179] 2) formed by crystallisation between an aluminium salt and 1,4-naphthalenedicarboxylic acid in the presence of 4-aminotriazole (AI4@NDC)

[0180] 3) formed by crystallisation between aluminium salt and 1,4-naphthalenedicarboxylic acid in the presence of 5-aminotetrazole and gold nanoparticles (AuNPs) coated with octadecanethiol (AI5Au@NDC)

[0181] 4) formed by crystallisation occurring between aluminium salt and 1,4- naphthalenedicarboxylic acid in the presence of 4-aminotriazole and gold nanoparticles (AuNPs) coated with octadecanethiol (AI4Au@NDC).

[0182] The method for obtaining catalytic materials, which is the subject of the present invention, is simple to carry out and uses commercially available chemical compounds. The obtained catalytic materials are highly porous, and their specific surface area calculated according to the BET model is from 421 m2g'1for AI4Au@NDC to 735 m2g'1for AI5@NDC. The obtained materials strongly adsorb CO2 which increases their efficiency as catalysts in the cycloaddition of this gas to epoxides. The use of the obtained catalytic materials in the CO2 cycloaddition reaction enables the reaction to be carried out under relatively mild conditions (90°C, 1 MPa CO2) and cyclic esters to be obtained in a short reaction time. Among the catalysts obtained, the highest catalytic activity in the reaction of CO2 cycloaddition to epoxides is demonstrated by AI5@NDC due to the highest porosity and CO2 adsorption capacity.

[0183] Among the epoxides investigated, the cycloaddition reaction of CO2 to glycidol leading to glycerol carbonate in the presence of AI5@NDC is the fastest (100 % substrate conversion after 3 h of reaction running with a yield of 83.5 %). The introduction of small amounts of nanostructured gold (<1 wt%) into the catalytic materials allowed the yield of propylene carbonate from propylene oxide, the least active epoxide among those tested, to be increased twofold. The obtained catalytic materials are thermally stable (decomposition above 450° C), they can be used repeatedly, and their activity does not deteriorate in subsequent catalytic cycles. The new catalytic materials obtained are safer for the environment and cheaper to obtain than those whose efficiency in the cycloaddition reaction of CO2 to epoxides has been reported so far in the literature.

[0184] Literature

[0185] 1. Liu, Z.; Deng, Z.; Davis, S.; Ciais, P. Nature Reviews Earth & Environment 2023, 4, (4), 205-206.

[0186] 2. Yan, T.; Liu, H.; Zeng, Z.; Pan, W. Journal of CO2 Utilization 2023, 68, 102355.

[0187] 3. Leung, D. Y.; Caramanna, G.; Maroto-Valer, M. M. Renewable and sustainable energy reviews 2014, 39, 426-443.

[0188] 4. Koci, V.; Rocha, J. L.; Zakuciova, K. In The concept of circular economy applied to CCS, waste and wastewater treatment technologies, Proceedings of the 5th Annual International Conference on Sustainable Energy and Environmental Sciences (SEES 2016), Global Science & Technology Forum (GSTF), Singapore, 2016; pp 22-23.

[0189] 5. Kamphuis, A. J.; Picchioni, F.; Pescarmona, P. P. Green Chem. 2019, 21, (3), 406-448.

[0190] 6. Alper, E.; Orhan, O. Y. Petroleum 2017, 3, (1), 109-126.

[0191] 7. Pescarmona, P. P. Current Opinion in Green and Sustainable Chemistry 2021, 29, 100457.

[0192] 8. Beyzavi, M. FL; Stephenson, C. J.; Liu, Y.; Karagiaridi, O.; Hupp, J. T.; Farha, O. K. Frontiers in Energy Research 2015, 2, 63.

[0193] 9. Ding, M.; Jiang, H.-L. ACS Catalysis 2018, 8, (4), 3194-3201.

[0194] 10. Das, S. K.; Chatterjee, S.; Bhunia, S.; Mondal, A.; Mitra, P.; Kumari, V.; Pradhan, A.; Bhaumik, A. Dalton Transactions 2017, 46, (40), 13783-13792.

[0195] 11. Yang, D.; Song, Y.; Yang, F.; Sun, Y.; Li, S.; Liu, X.; Zhu, Y.; Yang, Y. The Journal of chemical physics 2021 , 155, (5).

[0196] 12. Cai, X.; Li, G.; Hu, W.; Zhu, Y. ACS Catalysis 2022, 12, (17), 10638-10653.

[0197] 13. Brust, M.; Walker, M.; Bethell, D.; Schiffrin, D. J.; Whyman, R. J. Chem. Soc., Chem. Commun. 1994, (7), 801-802.

[0198] 14. Wang, Y.; Ling, L.; Zhang, W.; Guo, J.; Ding, K.; Duan, W.; Liu, B. Chem. Mater. 2019, 31, (22), 9546-9553.

Claims

Claims1. A highly porous alumino-naphthalene dicarboxylic organic framework of molecular formulaAI(CI2H6O4) • X (CH3)2NHC(O)H • 3 H2O, where X denotes 0.22 or 0.25.

2. The highly porous alumino-naphthalene dicarboxylic organic framework, according to claim 1, characterised in that it has a specific surface area according to the BET model of more than 700 m2 / g.

3. A composite of a highly porous alumino-naphthalene dicarboxylic organic framework defined in either of claim 1 or claim 2 with nanostructural gold of molecular formulaAI(CI2H6O4) • Y (CH3)2NHC(O)H • Z S • 0.01 Au • 3 H2O where Y denotes 0.13 or 0.14, Z denotes 0.05 or 0.1.

4. The composite of the highly porous alumino-naphthalene dicarboxyl organic framework defined in claim 1 or 2 with nanostructural gold according to claim 3, characterised in that it has a specific surface area according to the BET model of more than 400 m2 / g.

5. A method for producing a highly porous alumino-naphthalene dicarboxylic organic framework as defined in claim 1 or 2, characterised in that it comprises steps in which- AI(NO3)2*9H2O, 4H-1,2,4-triazole-4-amine or 5-amino-1 H-tetrazole, 1,4- naphthalenedicarboxylic acid and dimethylformamide are mixed in a reaction vessel until all components are completely dissolved and a clear solution is obtained;- the reaction mixture is heated at 110°C until a white precipitate is formed;- the precipitate is filtrated from the reaction mixture, washed with methanol and dried under an argon atmosphere;- the dried precipitate is shaken in anhydrous methanol, centrifuged and then heated at 165°C.

6. The method according to claim 5, characterised in that AI(NO3)IKI9H2O, 41-1-1,2,4- triazole-4-amine or 5-amino-1 H-tetrazole and 1,4-naphthalenedicarboxylic acid are mixed in a molar ratio of 0.25 : 0.2 : 0.4.

7. The method according to claim 5 or 6, characterised in that heating at a temperature of 110°C is carried out for 72 hours until a white precipitate is formed.

8. The method according to claim 5 or 6 or 7, characterised in that heating at 165°C is carried out for 24 hours.

9. A method for producing a composite of the highly porous alumino-naphthalene dicarboxylic organic framework with nanostructured gold as defined in claims 3 or 4, characterised in that it comprises steps in which- gold nanoparticles, AI(NO3)2^I9H2O, 4H-1,2,4-triazole-4-amine or 5-amino-1 H- tetrazole, 1,4-naphthalenedicarboxylic acid and dimethylformamide are mixed in a reaction vessel until all components are completely dissolved and a clear solution is obtained;- the reaction mixture is heated at 110°C until a precipitate is formed;- the precipitate is filtrated from the reaction mixture, washed with methanol and dried under an argon atmosphere;- the dried precipitate is shaken in anhydrous methanol, centrifuged and heated at 165°C.

10. The method according to claim 8, characterised in that gold nanoparticles, AI(NO3)2*9H2O, 4H-1,2,4-triazole-4-amine or 5-amino-1 H-tetrazole and 1,4- naphthalenedicarboxylic acid are mixed in a molar ratio of 0.05 : 0.25 : 0.2 : 0.4.

11. The method according to claim 8 or 10, characterised in that heating at a temperature of 110°C until the precipitate is formed is carried out for 72 hours.

12. The method according to claim 9 or 10 or 11, characterised in that heating at 165°C is carried out for 24 hours.

13. The method according to any one of claims 9-12, characterised in that the octadecanothiol-stabilised gold nanoparticles, which are added to the solution during crystallisation of the MOF, are produced by a method comprising steps in which- an aqueous solution of HAuCl4*3HiO is extracted with a solution of tetraoctylammonium bromide in toluene;- a solution of NaBFU in methanol is added dropwise to the toluene layer, and 1- octanethiol is added, the reaction mixture is stirred, followed by extraction with water;- the toluene layer is concentrated, and cooled ethanol is added to precipitate a black precipitate, after which the resulting precipitate is centrifuged and dried.

14. Use of a highly porous alumino-naphthalene dicarboxylic organic framework as defined in claims 1 or 2, or obtained by the method defined in claims 5-8, as a catalyst in the conversion reaction of CO2 to cyclic esters.

15. Use of a composite of a highly porous alumino-naphthalene dicarboxylic organic framework with nanostructured gold as defined in claims 3 or 4, or obtained by the method defined in claims 9-13, as a catalyst in the conversion reaction of CO2 to cyclic esters.

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