Dataset for the synthesis and application of single-component heterogeneous catalysts based on zinc and tin for the cycloaddition of pure, diluted, and impure CO₂ to epoxides under mild conditions

Abstract

The cycloaddition of CO₂ to epoxides under mild conditions is a growing field of research and a viable strategy to recycle CO₂ in the form of cyclic carbonates as useful intermediates, solvents, and additives. This target requires readily accessible and recyclable catalysts whose synthesis does not involve expensive monomers, multistep procedures, coupling reagents, etc. Additionally, the catalysts should be active under atmospheric pressure and tolerate impurities such as methane and H₂S. In a recent manuscript (Rational engineering of single-component heterogeneous catalysts based on abundant metal centers for the mild conversion of pure and impure CO₂ to cyclic carbonates;Chemical Engineering Journal 422 (2021) 129930) we have developed strategies to prepare efficient heterogeneous catalysts for the cycloaddition reaction of CO₂ to epoxides. Such materials consist of dispersions of metal halides (ZnCl₂ or SnCl₄) on silica support that is further functionalized with ionic liquids bearing nucleophilic halide moieties for cooperative epoxide activation and ring-opening. Herein, we provide useful complementary data for the characterization of the prepared materials in the form of: SEM images of materials (SEM: scanning electron microscope), SEM-EDS images of materials (EDS: Energy-dispersive X-ray spectroscopy), TEM images of materials (TEM: transmission electron microscope); XPS (X-ray photoelectron spectroscopy) survey spectra of most active catalysts and related high-resolution spectra in spectral regions of interest, BET (Brunauer–Emmett–Teller) physisorption isotherms of materials, raw ¹H NMR spectra of catalytic reactions to verify the reproducibility of the reaction outcome and identify the reaction products.

Specifications Table

Subject	Chemical Engineering: Catalysis
Specific subject area	Inorganic Chemistry and Physical Characterization
Type of data	Table Image Figure
How data were acquired	SEM/EDS mappings were acquired on a JEOL JSM-7610F field emission scanning electron microscope equipped with an Oxford Instruments X-Max150 EDS. TEM images were acquired on a JEOL JEM-ARM 200F electron microscope equipped with Energy dispersive X-ray analyser (EDS) JEOL EX-37001. Images acquired by TEM Center Ver. 2.0.15.6527 and analysed by Gatan Digital Micrograph Ver. 3.22.1461.0 XPS survey spectra and high-resolution spectra were acquired on a JEOL JPS-9010MC spectrometer with SpectraSurf Ver. 1.9.3 acquisition and analysis software. BET physisorption isotherms were acquired on a BELSORP-Mini II analyser with BELSORP-mini Ver. 2.5.10 measuring software and BELMasterTM Version 6.3.2.1 analysing software 1H NMR spectra were acquired on a Bruker Avance III 600 MHz with Topspin 3.6.2 software
Data format	Raw Analyzed
Parameters for data collection	SEM/EDS – High resolution SEM mode; 1 kV electron acceleration, 11-1 mA filament current. EDS mode; 15 kV electron acceleration, 7-8 mA filament current. Chamber pressure = 2.0·10−5 Pa TEM – High resolution mode; 200 kV electron acceleration, 11-1 µA filament current. Chamber pressure = 2.0·10−5 Pa XPS – Mg Kα source (1253.6 eV) working at 12 kV and 25 mA. Chamber pressure = 10-8 Pa, temperature = 25°C. Energy pass = 50 eV, binding energy range = 0-1100 eV, steps = 1 eV BET – Measurement by N2 adsorption/desorption at -196°C NMR – 600 MHz Avance III NMR spectrometer operating at 25°C with 5 mm TCI CryoProbe Prodigy and z-gradients 1H frequency = 600.13 MHz
Description of data collection	SEM/EDS – Finely dispersed catalyst powders were deposited on carbon tape glued to Al stubs in a N2-filled glove box and transferred to the XPS instrument by a sealed sample holder for air sensitive samples. TEM – Catalyst powders were dispersed in dry dichloromethane and deposited by dipping on Cu TEM grids. Coated grids were kept under N2
	before plasma treated and loaded in the TEM pre-chamber. XPS – samples in the form of powder were deposited on carbon tape glued to the sample holder in a N2 filled glove box and transferred to the XPS instrument by a sealed manipulator for air sensitive samples. BET – Catalyst powders were filled to the sample tubes and pretreated at 100°C for 16 h under 10−2 kPa vacuum before measurement. NMR – All compounds were measured in CDCl3 at room temperature by adding a drop of crude reaction mixture to 0.7 mL CDCl3 in a standard NMR tube.
Data source location	Vidyasirimedhi Institute of Science and Technology (VISTEC), department of materials science engineering, school of molecular science engineering, 555 Moo 1, 21210, Payupnai, WangChan, Rayong, Thailand. (13.002395649932376, 101.44350075242147).
Data accessibility	https://data.mendeley.com/datasets/dx5zpgmwp6/3 (https://doi.org/10.17632/dx5zpgmwp6.3)
Related research article	O. Sodpiban, C. Phungpanya, S. Del Gobbo,* S. Arayachukiat, T. Piromchart and V. D'Elia* Rational engineering of single-component heterogeneous catalysts based on abundant metal centers for the mild conversion of pure and impure CO2 to cyclic carbonates Chemical Engineering Journal 422 (2021) 129930, DOI: 10.1016/j.cej.2021.129930

Value of the Data

• •These data are important for the complete characterization (electron microscopy, XPS and BET isotherms) of efficient catalytic materials for the cycloaddition of CO₂ to epoxides under mild conditions and for assessing (¹H NMR of crude catalytic reactions) the reproducibility of the catalytic reactions using the most efficient catalysts among the synthesized materials.
• •Researchers in materials science and catalysis can find the spectroscopic data, microscopic images, physicochemical characterization, and spectra of catalytic reactions helpful when characterizing comparable materials and applying them in catalytic cycloaddition reactions of epoxides.
• •Reported data can be used for the design of new catalysts based on co-immobilized metal centres and ionic liquids and for the interpretation of crude spectra of catalytic cycloaddition reactions involving epoxides.

1. Data Description

The data in this article refer to the materials in Table 1 that were prepared as catalysts for the cycloaddition of CO₂ to epoxides [1], [2], [3], [4], [5] and that are described in detail (including the structure of ionic liquids IL-I and IL-Br) in Rational engineering of single-component heterogeneous catalysts based on abundant metal centers for the mild conversion of pure and impure CO₂ to cyclic carbonates [6].

Table 1.

List of materials mentioned in this article.

Material	Brief description
tt-SiO2-150	Support
IL-I@SiO2	Ionic liquid IL-I (iodide anion) grafted on support
IL-Br@SiO2	Ionic liquid IL-Br (bromide anion) grafted on support
ZnCl2(0.36)-IL-I	Catalytic material based on ZnCl2 with IL-I
ZnCl2-0.45@SiO2	Precursor of ZnCl2(0.36)-IL-I prior to IL-I grafting
ZnCl2(1.99)-IL-I	Catalytic material based on ZnCl2 with IL-I
ZnCl2-2.26@SiO2	Precursor of ZnCl2(1.99)-IL-I prior to IL-I grafting
ZnCl2(3.29)-IL-I	Catalytic material based on ZnCl2 with IL-I
ZnCl2-4.23@SiO2	Precursor of ZnCl2(3.29)-IL-I prior to IL-I grafting
ZnCl2(5.62)-IL-I	Catalytic material based on ZnCl2 with IL-I
ZnCl2-7.89@SiO2	Precursor of ZnCl2(5.62)-IL-I prior to IL-I grafting
SnCl4(0.24)-IL-Br	Catalytic material based on SnCl4 with IL-Br
SnCl4-0.32@SiO2	Precursor of SnCl4(0.24)-IL-Br prior to IL-Br grafting
SnCl4(0.66)-IL-Br	Catalytic material based on SnCl4 with IL-Br
SnCl4-0.84@SiO2	Precursor of SnCl4(0.66)-IL-Br prior to IL-Br grafting
SnCl4(1.06)-IL-Br	Catalytic material based on SnCl4 with IL-Br
SnCl4-1.45@SiO2	Precursor of SnCl4(1.06)-IL-Br prior to IL-Br grafting
SnCl4(1.93)-IL-Br	Catalytic material based on SnCl4 with IL-Br
SnCl4-2.89@SiO2	Precursor of SnCl4(1.93)-IL-Br prior to IL-Br grafting

The SEM and TEM images of the tt-SiO_2-150 sample in Fig. 1 show the aggregated nature of the Aerosil fumed silica nanoparticles used as the support in this work and their morphology by using two different magnifications. The SEM images of IL-I@SiO₂ and IL-Br@SiO₂ in Fig. 2 show that the aggregated nature of the silica materials is preserved after grafting ionic liquids on the support. The SEM images of ZnCl₂-based catalysts in Fig. 3 and of SnCl₄-based catalysts in Fig. 4 show a clear effect of increasing metal and ionic liquid loadings on particles aggregation. The SEM-EDS images for ZnCl₂-based catalysts (Fig. 5, Fig. 6, Fig. 7) and SnCl₄-based catalysts (Fig. 8, Fig. 9, Fig. 10) show the uniform distribution of Zn, Cl, I elements (for ZnCl₂-based catalysts) and of Sn, Cl, Br elements (for Sn-based catalysts).

Fig. 1.

a.) SEM image, b.) TEM image at 100k magnifications and c.) TEM image at 500k magnifications of tt-SiO_2-150.

Fig. 2.

SEM images of a.) IL-I@SiO₂ and b.) IL-Br@SiO₂.

Fig. 3.

SEM images of a.) ZnCl₂(0.36)-IL-I, b.) ZnCl₂(3.29)-IL-I and c.) ZnCl₂(5.62)-IL-I.

Fig. 4.

SEM image of a.) SnCl₄(0.24)-IL-Br, b.) SnCl₄(1.06)-IL-Br and c.) SnCl₄(1.93)-IL-Br.

Fig. 5.

a.) EDS mapping and b-d.) dispersion of Zn, Cl and I elements for ZnCl₂(0.36)-IL-I.

Fig. 6.

a.) EDS mapping and b-d.) dispersion of Zn, Cl and I elements for ZnCl₂(3.29)-IL-I.

Fig. 7.

a.) EDS mapping and b-d.) dispersion of Zn, Cl and I elements for ZnCl₂(5.62)-IL-I.

Fig. 8.

a.) EDS mapping and b-d.) dispersion of Sn, Cl and Br elements for SnCl₄(0.24)-IL-Br.

Fig. 9.

a.) EDS mapping and b-d.) dispersion of Sn, Cl and Br elements for SnCl₄(1.06)-IL-Br.

Fig. 10.

a.) EDS mapping and b-d.) dispersion of Sn, Cl and Br elements for SnCl₄(1.93)-IL-Br.

The survey XPS spectrum of ZnCl₂-2.26@SiO₂ (Fig. 11) confirms the presence of relevant elements Zn and Cl from grafting of the ZnCl₂ precursor by ball milling. A high-resolution overview of all relevant spectral regions of this material (C 1s, O 1s, Zn 2p, Cl 2p, Si 2p) is provided in Fig. 12. The survey spectrum of SnCl₄-0.84@SiO₂ (Fig. 13) shows the presence of tin and chlorine elements from the SnCl₄ precursor grafted by impregnation with the relevant spectral regions (C 1S, O 1s, Si 2p, Sn 3d and Cl 2p) being displayed in high-resolution in Fig. 14. The survey XPS spectrum of ZnCl₂(1.99)-IL-I (Fig. 15) shows the presence of Zn, Cl, N, I elements from ZnCl₂ and IL-I with the relevant spectral regions (C 1s, N 1s, O 1s, Si 2p, Cl 2p, I 3d and Zn 2p) being provided in high-resolution in Fig. 16. This is also the case of SnCl₄(0.66)-IL-Br (See Fig. 17 for survey spectrum, Fig. 18 for the high-resolution spectra in the C 1s, N 1s, O 1s, Si 2p, Cl 2p, Br 3d and Sn 3d regions) showing the presence of characteristic elements Sn, Cl (from SnCl₄) and N, Br from IL-Br. The XPS spectra in Fig. 19, Fig. 20, Fig. 21, Fig. 22 refer to the spent materials ZnCl₂(1.99)-IL-I (Fig. 19 (survey), Fig. 20 (high-resolution in the C 1s, N 1s, O 1s, Si 2p, Cl 2p, I 3d and Zn 2p regions)) and SnCl₄(0.66)-IL-Br ((Fig. 21 (survey), Fig. 22 (high-resolution in the C 1s, N 1s, O 1s, Si 2p, Cl 2p, Br 3d and Sn 3d regions)) after five catalytic cycles with a CO₂ feed containing H₂S. These figures show the apparent absence of sulfur contaminant in the survey spectra and the presence of the same elements as in the pristine materials but with lower intensity in the case of halides (due to dehalogenation).

Fig. 11.

XPS survey spectrum of ZnCl₂-2.26@SiO₂ prepared by ball-milling of ZnCl₂ on tt-SiO_2-150.

Fig. 12.

High resolution XPS spectra of ZnCl₂-2.26@SiO₂ in the C 1s, O 1s, Zn 2p, Cl 2p and Si 2p spectral regions.

Fig. 13.

XPS survey spectrum of SnCl₄-0.84@SiO₂ prepared by impregnation of SnCl₄ on tt-SiO_2-150.

Fig. 14.

High resolution XPS spectra of SnCl₄-0.84@SiO₂ in the C 1S, O 1s, Si 2p, Sn 3d and Cl 2p spectral regions.

Fig. 15.

XPS survey spectrum of ZnCl₂(1.99)-IL-I produced by grafting IL-I on ZnCl₂-2.26@SiO₂.

Fig. 16.

High resolution XPS spectra of ZnCl₂(1.99)-IL-I in the C 1s, N 1s, O 1s, Si 2p, Cl 2p, I 3d and Zn 2p spectral regions.

Fig. 17.

XPS survey spectrum of SnCl₄(0.66)-IL-Br produced by the grafting of IL-Br on SnCl₄-0.84@SiO₂.

Fig. 18.

High resolution XPS spectra of SnCl₄(0.66)-IL-Br in the C 1s, N 1s, O 1s, Si 2p, Cl 2p, Br 3d and Sn 3d spectral regions.

Fig. 19.

XPS survey spectrum of spent ZnCl₂(1.99)-IL-I after five catalytic cycles.

Fig. 20.

High resolution XPS spectra of spent ZnCl₂(1.99)-IL-I in the C 1s, N 1s, O 1s, Si 2p, Cl 2p, I 3d and Zn 2p spectral regions.

Fig. 21.

XPS survey spectrum of spent SnCl₄(0.66)-IL-Br after five catalytic cycles.

Fig. 22.

High resolution XPS spectra of spent SnCl₄(0.66)-IL-Br in the C 1s, N 1s, O 1s, Si 2p, Cl 2p, Br 3d and Sn 3d spectral regions.

The BET adsorption/desorption isotherms in Fig. 23 are for the ZnCl₂-based catalytic materials and those in Fig. 24 for the SnCl₄-based catalytic materials. Such isotherms show the lack of porosity of these materials as expected given the non-porous nature of the support (See isotherm shown in Fig. 25 along with metal-free catalytic materials IL-I@SiO₂ and IL-Br@SiO₂).

Fig. 23.

BET adsorption/desorption isotherms of ZnCl₂-based materials (ZnCl₂(0.36)-IL-I, ZnCl₂(1.99)-IL-I, ZnCl₂(3.29)-IL-I, ZnCl₂(5.62)-IL-I) as indicated in the graphics.

Fig. 24.

BET adsorption/desorption isotherms of SnCl₄-based materials (SnCl₄(0.24)-IL-Br, SnCl₄(0.66)-IL-Br, SnCl₄(1.06)-IL-Br, SnCl₄(1.93)-IL-Br) as indicated in the graphics.

Fig. 25.

BET adsorption/desorption isotherms of materials prepared without metal halides (IL-I@SiO₂, IL-Br@SiO₂) and of the tt-SiO_2-150 support.

The ¹H NMR spectra of catalytic cycloaddition reactions carried out under different reaction conditions[6] in Fig. 26, Fig. 27, Fig. 28, Fig. 29, Fig. 30, Fig. 31, Fig. 32, Fig. 33, Fig. 34, Fig. 35, Fig. 36, Fig. 37, Fig. 38, Fig. 39, Fig. 40, Fig. 41, Fig. 42, Fig. 43, Fig. 44, Fig. 45, Fig. 46, Fig. 47, Fig. 48, Fig. 49, Fig. 50, Fig. 51, Fig. 52, Fig. 53, Fig. 54, Fig. 55, Fig. 56, Fig. 57, Fig. 58, Fig. 59, Fig. 60, Fig. 61, Fig. 62, Fig. 63 generally show the formation of signals relative to the cyclic carbonate products in the 4-5 ppm region and the disappearance of the signals relative to the epoxide substrates in the 2-3 ppm region [7], [8], [9]. These data are useful to estimate the conversion of epoxides and to calculate conversion values based on the integration of corresponding signals of products and epoxides [10], [11], [12]. These data generally confirm the complete or nearly complete conversion of epoxide substrates and the absence of evident reaction by-products and the reproducible application of the catalysts

Fig. 26.

¹H-NMR spectrum of the cycloaddition of CO₂ to propylene oxide using 2 mol% ZnCl₂(1.99)-IL-I at room temperature, 1 bar CO₂ for 24 h.

Fig. 27.

¹H-NMR spectrum of the cycloaddition of CO₂ to propylene oxide using 2 mol% SnCl₄(0.66)-IL-Br at room temperature, 1 bar CO₂ for 24 h.

Fig. 28.

¹H-NMR spectrum of the cycloaddition of CO₂ to 1-butene oxide using 2 mol% ZnCl₂(1.99)-IL-I at room temperature, 1 bar CO₂ for 24 h.

Fig. 29.

¹H-NMR spectrum of the cycloaddition of CO₂ to 1-butene oxide using 2 mol% SnCl₄(0.66)-IL-Br at room temperature, 1 bar CO₂ for 24 h.

Fig. 30.

¹H-NMR spectrum of the cycloaddition of CO₂ to 1-butene oxide using 2 mol% ZnCl₂(1.99)-IL-I at room temperature, 1 bar CO₂ for 12 h.

Fig. 31.

¹H-NMR spectrum of the cycloaddition of CO₂ to 1-butene oxide using 2 mol% SnCl₄(0.66)-IL-Br at room temperature, 1 bar CO₂ for 12 h.

Fig. 32.

¹H-NMR spectrum of the cycloaddition of CO₂ to 1-hexene oxide using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar CO₂ for 24 h.

Fig. 33.

¹H-NMR spectrum of the cycloaddition of CO₂ to 1-hexene oxide using 2 mol% SnCl₄(0.66)-IL-Br at room temperature, 1 bar CO₂ for 4 h.

Fig. 34.

¹H-NMR spectrum of the cycloaddition of CO₂ to epichlorohydrin using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar CO₂ for 24 h.

Fig. 35.

¹H-NMR spectrum of the cycloaddition of CO₂ to epichlorohydrin using 2 mol% SnCl₄(0.66)-IL-Br at room temperature, 1 bar CO₂ for 24 h.

Fig. 36.

¹H-NMR spectrum of the cycloaddition of CO₂ to styrene oxide using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar CO₂ for 24 h.

Fig. 37.

¹H-NMR spectrum of the cycloaddition of CO₂ to styrene oxide using 2 mol% SnCl₄(0.66)-IL-Br at 40°C, 1 bar CO₂ for 48 h.

Fig. 38.

¹H-NMR spectrum of the cycloaddition of CO₂ to furfuryl glycidyl ether using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar CO₂ for 24 h.

Fig. 39.

¹H-NMR spectrum of the cycloaddition of CO₂ to furfuryl glycidyl ether using 2 mol% SnCl₄(0.66)-IL-Br at 40°C, 1 bar CO₂ for 24 h.

Fig. 40.

¹H-NMR spectrum of the cycloaddition of CO₂ to furfuryl glycidyl ether using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar CO₂ for 12 h.

Fig. 41.

¹H-NMR spectrum of the cycloaddition of CO₂ to furfuryl glycidyl ether using 2 mol% SnCl₄(0.66)-IL-Br at 40°C, 1 bar CO₂ for 12 h.

Fig. 42.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar CO₂ for 24 h.

Fig. 43.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% SnCl₄(0.66)-IL-Br at 40°C, 1 bar CO₂ for 24 h.

Fig. 44.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar CO₂ for 12 h.

Fig. 45.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% SnCl₄(0.66)-IL-Br at 40°C, 1 bar CO₂ for 12 h.

Fig. 46.

¹H-NMR spectrum of the cycloaddition of CO₂ to epoxy cyclohexane using 2 mol% ZnCl₂(1.99)-IL-I at 100°C, 15 bar CO₂ for 48 h.

Fig. 47.

¹H-NMR spectrum of the cycloaddition of CO₂ to epoxy cyclohexane using 2 mol% SnCl₄(0.66)-IL-Br at 100°C, 15 bar CO₂ for 48 h.

Fig. 48.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar 50% CO₂ in N₂ for 24 h.

Fig. 49.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% SnCl₄(0.66)-IL-Br at 40°C, 1 bar 50% CO₂ in N₂ for 24 h.

Fig. 50.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% ZnCl₂(1.99)-IL-I at 40°C, 1 bar 20% CH₄ in CO₂ for 24 h.

Fig. 51.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% SnCl₄(0.66)-IL-Br at 40°C, 1 bar 20% CH₄ in CO₂ for 24 h.

Fig. 52.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 1 mol% ZnCl₂(1.99)-IL-I at 100°C, 10 bar CO₂ for 1 h.

Fig. 53.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 1 mol% ZnCl₂(1.99)-IL-I at 100°C, 20 bar CO₂ for 1 h.

Fig. 54.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 1 mol% ZnCl₂(1.99)-IL-I at 100°C, 30 bar CO₂ for 1 h.

Fig. 55.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 1 mol% SnCl₄(0.66)-IL-Br at 100°C, 10 bar CO₂ for 1 h.

Fig. 56.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 1 mol% SnCl₄(0.66)-IL-Br at 100°C, 20 bar CO₂ for 1 h.

Fig. 57.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 1 mol% SnCl₄(0.66)-IL-Br at 100°C, 30 bar CO₂ for 1 h.

Fig. 58.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% ZnCl₂(1.99)-IL-I at 60°C, 10 bar CO₂ for 1 h.

Fig. 59.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% ZnCl₂(1.99)-IL-I at 80°C, 10 bar CO₂ for 1 h.

Fig. 60.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% ZnCl₂(1.99)-IL-I at 100°C, 10 bar CO₂ for 1 h.

Fig. 61.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% SnCl₄(0.66)-IL-Br at 60°C, 10 bar CO₂ for 1 h.

Fig. 62.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% SnCl₄(0.66)-IL-Br at 80°C, 10 bar CO₂ for 1 h.

Fig. 63.

¹H-NMR spectrum of the cycloaddition of CO₂ to glycidyl methacrylate using 2 mol% SnCl₄(0.66)-IL-Br at 100°C, 10 bar CO₂ for 1 h.

Supplementary material includes the raw data for XPS spectra, BET physisorption experiments and ¹H NMR experiments.

2. Experimental Design, Materials and Methods

The preparation of all compounds in Table 1 and the experimental procedure for catalytic reactions is described in Rational engineering of single-component heterogeneous catalysts based on abundant metal centers for the mild conversion of pure and impure CO₂ to cyclic carbonates [6].

2.1. Scanning electron microscopy (SEM)

SEM images of materials were acquired by a JEOL JSM-7610F field emission scanning electron microscope equipped with an Oxford Instruments X-Max150 EDS. Samples were prepared by tapping adhesive carbon stabs on paper smeared with the catalyst powders. No sputtering metallization was used.

2.2. Transmission electron microscopy (TEM)

TEM images were obtained on a JEOL JEM-ARM 200F electron microscope. All samples were dispersed in dry dichloromethane and coated by three dipping/drying cycles on TEM grids (Ted Pella Ultrathin C Type-A 400 mesh, Cu). All samples were plasma-treated before the insertion in the microscope vacuum pre-chamber.

2.3. X-ray photoelectron spectroscopy (XPS)

X-ray photoelectron spectroscopy (XPS) was performed by a JEOL JPS-9010MC spectrometer utilizing a Mg Kα source (1253.6 eV) working at 12 kV and 25 mA. All XPS spectra were acquired under high vacuum (10^-8 Pa) at room temperature. All samples were prepared by compacting the catalysts powders on carbon tape (9 × 9 mm² area). The survey scans were acquired with a pass energy of 50 eV, a binding energy range of 0-1100 eV and steps of 1 eV. Spectral regions relative to specific elements of interest were acquired with high resolution by averaging over a large number of spectra in order to have a good signal to noise ratio. All binding energies were charge corrected by referencing to the carbon peak C 1s at 284.80 eV.

2.4. Brunauer-emmett-teller (BET) analysis

The surface areas of tt-SiO_2-150 support and of powder catalysts were measured using a BELSORP-mini II instrument (BEL Japan) via N₂ adsorption/desorption isotherm at liquid nitrogen temperature (-196°C). Prior to the measurement, the samples were added to the sample tubes and subsequently pretreated under vacuum (at 100°C for 16 h) by a BELPREP-vac II instrument (MicrotracBEL) to remove undesired moisture adsorbed on the surface. The surface area was calculated by BET method using a linearity range of the relative pressure (P/P₀) = 0.05-0.35.

2.5. Nuclear magnetic resonance (NMR) spectroscopy

All NMR spectra of catalytic reactions were collected using a 600 MHz Bruker Avance III NMR spectrometer operating at 25°C with 5 mm TCI CryoProbe Prodigy and z-gradients. All chemical shifts (δ ppm) were referenced to the internal standard tetramethyl silane (TMS; ¹H resonances appear at 0.00 ppm) present in CDCl₃. ¹H frequency = 600.13 MHz. To collect the crude reaction spectra, an aliquot of the reaction product was withdrawn and added into an NMR tube containing 0.7 mL CDCl₃.

CRediT Author Statement

Chalida Phungpanya: Investigation, data curation; Ounjit Sodpiban: Data curation, Investigation, Writing - Original draft preparation; Silvano Del Gobbo: Visualization, Investigation, Data curation; Sunatda Arayachukiat: Validation, Data curation; Taradon Pimochart: Validation, Supervision; Valerio D’ Elia: Supervision, data curation, Writing - reviewing & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships which have or could be perceived to have influenced the work reported in this article.