Highly efficient nanocrystalline zirconosilicate catalysts for the aminolysis, alcoholysis, and hydroamination reactions

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1 Supporting Information for ighly efficient nanocrystalline zirconosilicate catalysts for the aminolysis, alcoholysis, and hydroamination reactions Rajkumar Kore, a Rajendra Srivastava, *a and Biswarup Satpati b a Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar , India b Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata , India 1

2 1. Materials Tetraethyl orthosilicate (TEOS, Aldrich, 98%), titanium (IV) butoxide (TBOT, Aldrich, 98%), zirconium (IV) isopropoxide (ZrIPO, Acros Organics, 70% solution in propanol), propyl triethoxy silane (PrTES, Aldrich, 97%) and tetrapropylammonium hydroxide (TPAO, Spectrochem Indian Pvt. Ltd., 20% aqueous solution) were used as received. Reactants used in the catalytic reactions were obtained from Aldrich. Solvents used in this study were procured from Merck India Pvt. Ltd. 2. Synthesis of nanocrystalline zeolites 2.1. Synthesis of nanocrstalline titanoslilicates In a typical synthesis, required amount of titanium (IV) butoxide (TBOT) was added to g of tetraethylorthosilicate (TEOS) and the resultant solution was stirred for 15 min under ambient condition until mixture becomes clear solution (Solution A). PrTES (2.48 g)/tpac (6.36 g) was mixed with TPAO (36.6 g) to form solution B. Solutions A was added slowly to the solution B, followed by 35.5 ml of 2 O and the resultant gel was further homogenized for 3 h under stirring. This mixture was transferred to a Teflon-lined stainless steel autoclave, and hydrothermally treated at 443 K for 4 days under static conditions. The final product was filtered, washed with distilled water, and dried at 373 K. The assynthesized material was calcined at 823 K for 15 h under air for surfactant removal. Ti containing nanocrystalline ZSM-5 prepared with PrTES is represented as Ti-Nano(PrTES)- ZSM-5 (y), whereas Ti containing nanocrystalline ZSM-5 prepared with TPAC is represented as Ti-Nano(TPAC)-ZSM-5 (y), where y = Si/M ratio Synthesis of nanocrstalline zirconoslilicates In a typical synthesis, required amount of zirconium (IV) isopropoxide (ZrIPO) was added to g of tetraethylorthosilicate (TEOS) and the resultant solution was stirred for 15 min under ambient condition until mixture becomes clear solution (Solution A). PrTES (1.74 g)/tpac (4.4 g) was mixed with TPAO (42.7 g) to form solution B. Solutions A was added slowly to the solution B, followed by 52 ml of 2 O and the resultant gel was further homogenized for 3 h under stirring. This mixture was transferred to a Teflon-lined stainless steel autoclave, and hydrothermally treated at 443 K for 5 days under static conditions. The final product was filtered, washed with distilled water, and dried at 373 K. The as-synthesized material was calcined at 823 K for 15 h under air for surfactant removal. Zr containing nanocrystalline ZSM-5 prepared with PrTES is represented as Zr- 2

3 Nano(PrTES)-ZSM-5 (y), whereas Zr containing nanocrystalline ZSM-5 prepared with TPAC is represented as Zr-Nano(TPAC)-ZSM-5 (y), where y = Si/M ratio. 3. Material characterization X-ray diffraction (XRD) patterns were recorded in the 2θ range of 5 60 with a scan speed of 2 /min on a PANalytical X PERT PRO diffractometer using Cu Kα radiation (λ= nm, 40 kv, 40 ma) and a proportional counter detector. Nitrogen adsorption measurements were performed at 77 K by Quantachrome Instruments Autosorb-IQ volumetric adsorption analyzer. Sample was out-gassed at 573 K for 3 h in the degas port of the adsorption apparatus. The specific surface area of zeolites was calculated from the adsorption data points obtained at P/P 0 between using the Brunauer-Emmett-Teller (BET) equation. The pore diameter was estimated using the Barret Joyner alenda (BJ) method. Scanning electron microscopy (SEM) measurements were carried out on a JEOL JSM-6610LV to investigate the morphology of the zeolites. The detailed TEM structural analysis of the developed morphologies were carried out using FEI, Tecnai G 2 F30, S-Twin microscope operating at 300 kv equipped with a GATAN Orius CCD camera. igh-angle annular dark field scanning transmission electron microscopy (AADF-STEM) employed here using the same microscope, which is equipped with a scanning unit and a AADF detector from Fischione (model 3000). The compositional analysis was performed by energy dispersive X- ray spectroscopy (EDS, EDAX Instruments) attachment on the Tecnai G 2 F30. Energyfiltered transmission electron microscopy (EFTEM) measurements were carried out using GIF Quantum SE (model 963). The sample was dispersed in ethanol using ultrasonic bath, mounted on a carbon coated Cu grid, dried, and used for TEM measurements. Acidity was examined by temperature-programmed desorption (TPD) with ammonia using a Quantachrome Autosorb-IQ. Before TPD experiments, catalyst was pre-treated in e (50 ml/min) at 873 K for 1 h. After cooling down to 343 K, a mixture of N 3 in e (10:90) was passed (75 ml/min) at 343 K for 1 h. Then, the sample was subsequently flushed by e stream (50 cm 3 /min) at 373 K for 1 h to remove physisorbed ammonia. The TPD experiments were carried out in the range of K at a heating rate of 10 K/min. The ammonia concentration in the effluent was monitored with a gold-plated, filament thermal conductivity detector. Fourier transform infrared (FTIR) spectra were recorded on a Bruker spectrophotometer in the region cm -1 (spectral resolution = 4 cm -1 ; number of scans = 200). Samples were prepared in the form of KBr pellets (1 wt.%). Diffuse reflectance 3

4 UV visible (DRUV vis) measurements were conducted using a Shimadzu UV-2550 spectrophotometer equipped with an integrating sphere attachment (ISR 2200). Spectral grade BaSO 4 was used as a reference material. 1 / 13 C NMR spectra were recorded on a JEOL (JNM-ECS400 Spectrometer; 400 Mz). 4. Procedure for catalytic reactions 4.1. Aminolysis of epoxides with amines A 50 ml round-bottomed flask was charged with epoxide and amine in equimolar quantities. A known amount of catalyst was added to the reaction mixture and reaction flask was placed in a temperature-controlled oil bath. The reaction flask was attached to a watercooled condenser. The reaction was conducted at a specific temperature for a desired period of time. The progress of the reaction was monitored by gas chromatograph as well as by NMR. Products were characterized by using various spectroscopic tools that matched well with the reported literature Alcoholysis of epoxide with methanol A 50 ml round-bottomed flask was charged with epoxide and alcohol (epoxide/alcohol = 1:30). A known amount of catalyst was added to the reaction mixture and reaction flask was placed in a temperature-controlled oil bath. The reaction flask was attached to a water-cooled condenser. The reaction was conducted at a specific temperature for a desired period of time. The progress of the reaction was monitored by gas chromatograph as well as by NMR. Products were characterized by using various spectroscopic tools that matched well with the reported literature ydroamination of activated olefins with amines A 50 ml round-bottomed flask was charged with methyl acrylate and amine in equimolar quantities. A known amount of catalyst was added to the reaction mixture and reaction flask was placed in a temperature-controlled oil bath. The reaction flask was attached to a water-cooled condenser. The reaction was conducted at a specific temperature for a desired period of time. The progress of the reaction was monitored by gas chromatograph as well as by NMR. Products were characterized by using various spectroscopic tools that matched well with the reported literature. 3 4

5 Average turnover frequency (TOF) for catalytic reaction was calculated by the following equation: Average TOF (h -1 ) = Moles of reactant converted per mole of active metal (Ti/Zr/Al) per hour Average TOF (or site-time-yield) was calculated based on a single conversion value at a particular reaction time. We took this conversion, divided by the time, and normalize by the number of sites to calculate Average TOF. In general, TOF is derived from a rate measurement, for example, the initial slope of the conversion vs. time curve, at low conversions. 5. Material characterization of nanocrystalline metallosilicates XRD: XRD pattern of materials are provided in Figure S1. N 2 -adsorption studies: The N 2 -adsoption isotherms for nanocrystalline ZSM-5 materials exhibited a typical type-iv isotherm similar to that of mesoporous materials (Figure S2). The major difference shown by nanocrystalline ZSM-5 isotherms to that of conventional ZSM-5 isotherm is a distinct increase of N 2 adsorption in the region 0.4<P/Po<0.9, which is interpreted as a capillary condensation in mesopore void spaces. The mesopores show a broad pore size distribution in the range of 5 50 nm. SEM: SEM investigations confirmed that capsule like morphology with a particle size of approximately 100 nm was obtained for Zr-ZSM-5 (50) (Figure S3). Nano-Zr(PrTES)-ZSM- 5 (50) exhibited irregular aggregated nanoparticle morphology, whereas Nano-Zr(TPAC)- ZSM-5 (50) showed aggregated compressed globular/capsule like morphology (Figure S3). Ti-ZSM-5 (50) exhibited irregular stone like morphology, whereas spherical/globular morphology was obtained for Nano-Ti(PrTES)-ZSM-5 (50)/Nano-Ti(TPAC)-ZSM-5 (50) (Figure S4). To obtain further in-depth information, TEM investigation was made for some selected samples. UV-visible study: Zr/Ti incorporated nanocrystalline ZSM-5 and conventional ZSM-5 materials with (Si/M = 50) exhibited an absorption band in the range of nm and a less distinguished overlapped absorption in the range of nm (Figure S5). UV absorption band in the range of nm is attributed to mono-atomically dispersed Ti 4+ /Zr 4+ ions in tetra-coordinated geometry, whereas the absorption in the range of

6 nm is corresponds to M(O)(OSi) 3 (M = Ti or Zr) structure. 4 All these absorption bands arise due to ligand-to-metal (O 2- M 4+ ) charger transfer transitions. The electronic transition for M(O)(OSi) 3 occurs at lower energy (at higher wavelength) than that of M(OSi) 4 due to differences in the electron donating capacities of O - and OSi - ligand groups (electron donating capacity of O - >OSi - ). ence, the energy gap between oxygen and M molecular orbitals is lower in the case of M(O)(OSi) 3 than that of M(OSi) 4. FT-IR investigation: Nanocrystalline ZSM-5 and conventional ZSM-5 materials exhibited several common IR peaks at 550 cm -1, 800 cm 1, 1100 cm 1, and 1230 cm 1 (Figure S6). 5 The absorption at 550 cm 1 is due to the pentasil framework vibration characteristic of MFI framework structure. The absorption peak at 800 cm 1 is due to Si O Si symmetric stretching, while absorption peaks at 1100 cm 1 and 1230 cm 1 are assigned to asymmetric stretching of Si O Si. It may be noted that no FT-IR signal was observed at 960 cm -1 for Si- ZSM-5 sample. owever, a sharp peak at 960 cm -1 in case of Ti containing ZSM-5 materials and a weak IR absorption at 960 cm -1 for Zr-containing ZSM-5 materials confirmed the incorporation of metal ions in the MFI framework and assigned to an asymmetric stretching mode of a [SiO 4 ] unit bonded to a M 4+ ion (O 3 Si O M) Monitoring the progress of the reaction with 1 NMR 1 NMR spectra of pure product and reaction mixture for the ring opening reaction of styrene oxide with aniline are shown in Figure S7. Since the electronic environment of attached to styrene oxide, product A, and product B (as shown in Figure S7) are different (attached to different neighbouring groups), therefore they exhibited different 1 signals in the NMR spectra. 1 in product B is attached to two polar groups (-N and O) and appeared at higher value compared to 1 in product A, which is attached to one polar group (-N). Similarly, 1 in product A appeared at higher value compared to 1 in reactant epoxide, which is attached to epoxide ring. Therefore, it was possible to monitor the progress of the reaction and calculate the yield of desired product using 1 NMR investigations. It was possible to monitor the progress of the ring opening reaction of styrene oxide with methanol and calculate the yield of β-alkoxy alcohols using 1 NMR investigations. 1 NMR of product C, E, and reaction mixture of styrene oxide and methanol is shown in Figure S8. 6

7 Furthermore, pure product F and reaction mixture of hydroamination reaction of methyl acrylate and aniline are provided in Figure S9. Table S1. Shift in the 2θ value w.r.t. parent ZSM-5, crystallite size and unit cell volume of the crystalline metallosilicate samples. Materials Unit cell edges (Ǻ) Unit cell Vol. a b c (Ǻ 3 ) Al-ZSM-5 (50) Zr-ZSM-5 (50) Zr-Nano(PrTES)-ZSM-5 (50) Zr-Nano(TPAC)-ZSM-5 (50) Ti-ZSM-5 (50) Ti-Nano(PrTES)-ZSM-5 (50) Ti-Nano(TPAC)-ZSM-5 (50)

8 Table S2. Influence of solvent on the ring opening reaction of styrene oxide with aniline over Zr-Nano(PrTES)-ZSM-5 (50). Solvent Styrene oxide Product (A/B) Average Conv. (%) Sel. (%) TOF (h -1 ) Nil 83 96/ Toluene 75 97/ C 2 Cl / CCl / CCl / C 3 CN 60 96/ Reaction conditions: Catalyst Zr-Nano(PrTES)-ZSM-5 (50) (25 mg), styrene oxide (5 mmol), amine (5 mmol), solvent (3 ml), reaction temperature (318 K), reaction time (5 min). [A] = 2-phenyl-2-(phenylamino)ethanol. [B] = 1-phenyl-2-(phenylamino)ethanol. Average TOF (h -1 ) = Turnover frequency [moles of epoxide converted per mole of active Zr per hour] 8

9 Table S3. Competitive adsorption of styrene oxide and methanol at Zr-Nano(PrTES)-ZSM-5 (50) and Al-ZSM-5 (50). Catalyst Amount adsorbed (mmol/g catalyst) Relative adsorption ratio: Average TOF Styrene oxide methanol epoxide/alcohol (h -1 ) Al-ZSM-5 (50) Zr-Nano(PrTES)-ZSM-5 (50) mg of Zr-Nano(PrTES)-ZSM-5 (50) was suspended for 5 min in (1 mmol) of styrene oxide and (10 mmol) of methanol dissolved in 5 ml of dichloromethane. The catalyst was, then, separated and the concentration of the substrate in the liquid portion was determined by gas chromatography. The amount adsorbed on the catalyst surface was determined by difference. Average TOF (h -1 ) = Turnover frequency [moles of epoxide converted per mole of active metal (Zr/Al) per hour] 9

10 Table S4. Ring opening reaction of styrene oxide in the absence of amine/alcohols over various zeolite catalysts. Catalyst Solvent Styrene oxide Conv. (%) a Product Sel. (%) [Phenyl acetaldehyde / 1-phenylethane-1,2-diol] Average TOF (h -1 ) Al-ZSM-5 (50) C 2 Cl /19 54 Zr-ZSM-5 (50) C 2 Cl /7 59 Zr-Nano(PrTES)-ZSM-5 (50) C 2 Cl /7 59 Zr-Nano(PrTES)-ZSM-5 (50) None /11 52 Zr-Nano(PrTES)-ZSM-5 (50) 2 O 80 32/ Reaction conditions: Catalyst (25 mg), styrene oxide (1 mmol), Solvent (2 ml), reaction temperature (323 K), reaction time (45 min). Average TOF (h -1 ) = Turnover frequency [moles of epoxide converted per mole of active metal (Zr/Al) per hour] 10

11 Table S5. Competitive adsorption of methyl acrylate and amines at Zr-Nano(PrTES)-ZSM-5 (50). Adsorbent Amount adsorbed mmol/g catalyst methyl acrylate amine Relative adsorption ratio: amine/methyl acrylate Average TOF (h -1 ) methyl acrylate + aniline a methyl acrylate + aniline b methyl acrylate + cyclohexyl amine a a 100 mg of Zr-Nano(PrTES)-ZSM-5 (50) was suspended for 5 min in equimolar amounts (2 mmol) of methyl acrylate and amine dissolved in 5 ml of dichloromethane. The catalyst was, then, separated and the concentration of the substrate in the liquid portion was determined by gas chromatography. The amount adsorbed on the catalyst surface was determined by difference. b 100 mg of Al-ZSM-5 (50) Average TOF (h -1 ) = Turnover frequency [moles of epoxide converted per mole of active metal (Zr/Al) per hour]. 11

12 Scheme S1. Mechanism for the ring opening of epoxide with amine/alcohol over metallosilcates. 12

13 Scheme S2. Mechanism for the hydroamination reaction of methyl acrylate and amine over metallosilcates. 13

14 Intensity (a.u.) Intensity (a.u.) Intensity (a.u.) Intensity (a.u.) (a) Zr-Nano(TPAC)-ZSM-5 (50) (011) (c) Zr-Nano(TPAC)-ZSM-5 (50) (020) (111) Zr-Nano(PrTES)-ZSM-5 (50) Zr-Nano(PrTES)-ZSM-5 (50) Zr-ZSM-5 (50) Zr-ZSM-5 (50) ZSM-5 ZSM (b) Ti-Nano(TPAC)-ZSM-5 (50) (d) Ti-Nano(TPAC)-ZSM-5 (50) Ti-Nano(PrTES)-ZSM-5 (50) Ti-Nano(PrTES)-ZSM-5 (50) Ti-ZSM-5 (50) Ti-ZSM-5 (50) ZSM-5 ZSM Figure S1. (a,b) XRD patterns of conventional and nanocrystalline ZSM-5 materials and (c,d) shift in 2 values in titanosilicates and zirconosilicate materials. 14

15 Adsorbed amount (ml/g) Adsorbed amount (ml/g) (a) (b) Ti-Nano(TPAC)-ZSM-5 (50) Ti-Nano(PrTES)-ZSM-5 (50) 0 Ti-ZSM-5 (50) Relative pressure (p/p 0 ) Zr-Nano(TPAC)-ZSM-5 (50) 50 Zr-Nano(PrTES)-ZSM-5 (50) 0 Zr-ZSM-5 (50) Relative pressure (p/p 0 ) Figure S2. N 2 -adsorption isotherms of various (a) titanosilicates and (b) zirconosilicate materials. The isotherms for Ti-Nano(TPAC)-ZSM-5 (50), Zr-Nano(PrTES)-ZSM-5 (50), and Zr-Nano(TPAC)-ZSM-5 (50) were vertically offset by 85, 30, and 95 ml/g, respectively. 15

16 Figure S3. SEM images of various zirconosilicates investigated in this study. 16

17 Figure S4. SEM images of various titanosilicates investigated in this study. 17

18 Absorbance (a.u) Absorbance (a.u) (a) (b) Zr-Nano(TPAC)-ZSM-5 (50) Ti-Nano(TPAC)-ZSM-5 (50) Zr-Nano(PrTES)-ZSM-5 (50) Ti-Nano(PrTES)-ZSM-5 (50) Ti-ZSM-5 (50) Zr-ZSM-5 (50) Wavelength (nm) Wavelength (nm) Figure S5. Diffuse reflectance UV visible spectra of (a) titanosilicates and (b) zirconosilicates prepared in this study. 18

19 % Transmittance (a.u.) % Transmittance (a.u.) (a) Ti-Nano(TPAC)-ZSM-5(50) 960 (b) Zr-Nano(TPAC)-ZSM-5(50) 960 Ti-Nano(PrTES)-ZSM-5(50) Zr-Nano(PrTES)-ZSM-5(50) Ti-ZSM-5 (50) Zr-ZSM-5(50) 800 ZSM ZSM Wavenumber (cm -1 ) Wavenumber (cm -1 ) Figure S6. FT-IR spectra of (a) titanosilicates and (b) zirconosilicates prepared in this study. 19

20 1 investigations to monitor the progress of the reaction pure product A Aminolysis reaction mixture Ph N Ph O Prod. B peak O Ph N Ph Prod. A peak Ph O Styrene oxide peak Chemical shift (ppm) Figure S7. 1 NMR spectra of the pure product A and reaction mixture of the ring opening of styrene oxide with aniline. 20

21 1 -NMR Spectra of Alcoholysis Reaction pure product C phenyl acetaldehyde a O Ph b Alcoholysis reaction mixture c O OC 3 Ph d b d Chemical shift (ppm) Figure S8. 1 NMR spectra of the product C, E and reaction mixture of the ring opening of styrene oxide with methanol. 21

22 pure product F d d 3 C O O c g N e O O f f g a c b ydroamination reaction mixture e Chemical shift (ppm) Figure S9. 1 NMR spectra of product F and reaction mixture of methylacrylate with aniline. References 1 (a) Kumar, A.; Srinivas, D. J. Catal. 2012, 293, ; (b) Matos, I.; Neves, P. D.; Castanheiro, J. E.; Perez-Mayoral, E.; Martin-Aranda, R.; Duran-Valle, C.; Vital, J.; Botelho Do Rego, A. M.; Fonseca, I. M. Appl. Catal. A: Gen. 2012, , Kahandal, S. S.; Kale, S. R.; Disale, S. T.; Jayaram, R. V. Catal. Sci. Technol. 2012, 2, Shanbhag, G. V.; Kumbar, S. M.; alligudi, S. B. J. Mol. Catal. A: Chem. 2008, 284, Ratnasamy P.; Srinivas D.; Knözinger. Adv. Catal. 2004, 48, Szostak, R. Molecular Sieves: Principles of Synthesis and Identification, Van Nostrand Reinhold, New York, 1989; pp