Electronic Supporting Information (ESI ) SYNERGISTIC EFFECT IN THE OXIDATION OF BENZYL ALCOHOL USING CITRATE-STABILIZED GOLD

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1 Electronic Supporting Information (ESI ) SYNERGISTIC EFFECT IN THE OXIDATION OF BENZYL ALCOHOL USING CITRATE-STABILIZED GOLD BIMETALLIC NANOPARTICLES SUPPORTED ON ALUMINA Fernando Gómez-Villarraga*, Jörg Radnik, Andreas Martin and Angela Köckritz Leibniz-Institut für Katalyse e.v. an der Universität Rostock, Albert-Einstein-Str. 29a, Rostock, Germany. *To whom correspondence should be addressed: ferchogomezv@gmail.com; Tel:

2 Table of Contents Tables: Table S1. Particle size, nominal and actual Au and Ag loadings of the alumina supported mixture of AuAg and Au nanoparticles. Table S2. Results of the benzyl alcohol oxidation with the supported catalysts using toluene as solvent. Table S3. The effect of time on the benzyl alcohol oxidation with AuPd/Alumina using toluene as solvent. Table S4. Catalytic results of recycled AuPd/Alumina in the benzyl alcohol oxidation using toluene as solvent. Table S5. Results of the solvent-free oxidation of benzyl alcohol with the supported catalysts. Figures: Figure S1. Synthetic procedure of the alumina supported mixture of AuAg and gold nanoparticles. Figure S2. Representative HAADF-TEM images and particle size distribution of the alumina supported mixture of AuAg and Au nanoparticles. Figure S3. Representative HAADF-TEM image and the corresponding EDX spectra of the alumina supported mixture of AuAg and Au nanoparticles. Figure S4. Representative HAADF-TEM image and the corresponding EDX spectra of the AuPd/Alumina catalyst. Figure S5. Representative HAADF-TEM image and the corresponding EDX spectra of the AuPt/Alumina catalyst. Figure S6. Representative HAADF-TEM image and the corresponding EDX spectrum of the AuCu/Alumina catalyst. Figure S7. Representative HAADF-TEM image and the corresponding EDX spectra of the AuAg/Alumina catalyst. Figure S8. XPS spectrum and representative regions of the AuPd/Alumina catalyst. Figure S9. XPS spectrum and representative regions of the AuPt/Alumina catalyst.

3 Figure S10. XPS spectrum and representative regions of the AuCu/Alumina catalyst. Figure S11. XPS spectrum and representative regions of the AuAg/Alumina catalyst. Figure S12. XPS spectrum and representative regions of the Pd/Alumina catalyst. Figure S13. Stacked X-ray diffraction pattern of AuM/Alumina (M = Pd, Pt, Cu, Ag) catalysts and alumina. Figure S14. Stacked X-ray diffraction pattern of M/Alumina (M = Au, Pd) catalysts and alumina. Figure S15. XPS spectrum and representative regions of the recycled AuPd/Alumina catalyst. Additional Information: AI1. Catalysts Preparation, AuM/Alumina (M = Cu, Pd). AI2. Catalyst Preparation, AuPt/Alumina. AI3. Catalyst Preparation, AuAg/Alumina. AI4. Catalyst Preparation, Au/Alumina. AI5. Catalyst Preparation, Pd/Alumina. AI6. Derivatization of the catalytic reaction samples. AI7. Experimental procedure of the alumina supported mixture of AuAg and Au nanoparticles (sequential reduction method, AuAg/Alumina-Au/Alumina). Bibliography

4 AI1. Catalysts Preparation, AuM/Alumina (M = Cu, Pd). The gold, copper and palladium salts were reduced similarly to the methods in ref. [1] and [2], the catalysts were prepared using a modified procedure (in situ immobilization) previously reported in the literature.[3] Alumina powder (7.750 g) (Puralox TH 100/150) was suspended in 410 ml of deionised water. An aqueous solution (30 ml) of tetrachloroauric acid trihydrate, HAuCl 4 3H 2O, (155 mg, mmol) was added dropwise. Then, an aqueous solution (30 ml) of copper sulfate pentahydrate, CuSO 4 5H 2O, (98 mg, mmol) or sodium tetrachloropalladate, Na 2PdCl 4, (116 mg, mmol) according to the desired system was subsequently added drop-by-drop and the ph of the suspension was preadjusted to 7 by adding solid potassium carbonate, K 2CO 3. After stirring for 1 h at 60 C, an aqueous solution (30 ml) of trisodium citrate dihydrate, Na 3C 6H 5O 7 2H 2O, (464 mg, 1.58 mmol) and tannic acid, C 76H 52O 46, (11 mg, 6x10-3 mmol) at 60 C was added all at once into the above mixture and the suspension was further stirred at 60 C for 30 min. The solid was separated from the liquid by centrifugation, washed with deionised water and then dried at a rotary evaporator. Subsequently, the sample was calcined in air at 200 C for 3 h (heating rate = 1 C/min). AI2. Catalyst Preparation, AuPt/Alumina. The gold and platinum salts were reduced similarly to the methods in ref. [4] and [5], the catalyst was prepared using a modified procedure (in situ immobilization) previously reported in the literature.[3] Alumina powder (7.750 g) (Puralox TH 100/150) was suspended in 410 ml of deionised water. An aqueous solution (20 ml) of tetrachloroauric acid trihydrate, HAuCl 4 3H 2O, (155 mg, mmol) was added dropwise. Then, an aqueous solution (20 ml) of sodium hexachloroplatinate hexahydrate, Na 2PtCl 6 6H 2O, (221 mg, mmol) was subsequently added drop-by-drop. After stirring for 1 h at room temperature an aqueous solution (20 ml) of trisodium citrate dihydrate, Na 3C 6H 5O 7 2H 2O, (464 mg, 1.58 mmol) was added all at once into the above mixture and the suspension was stirred for 10 min. Afterwards, a freshly prepared ice-cold aqueous solution (30 ml) of sodium borohydride, NaBH 4, (149 mg, 3.94 mmol) was added all at once and the mixture was further stirred for 30 min at room temperature. The solid was separated from the liquid by centrifugation, washed with deionised

5 water and then dried at a rotary evaporator. Subsequently, the sample was calcined in air at 200 C for 3 h (heating rate = 1 C/min). AI3. Catalyst Preparation, AuAg/Alumina. The gold and silver salts were reduced similarly to the methods in ref. [1] and [6]. An aqueous solution (30 ml) of silver nitrate, AgNO 3, (67 mg, mmol) was added to 410 ml of deionised water. The solution was heated under stirring in the dark. After boiling had commenced, an aqueous solution (30 ml) of trisodium citrate dihydrate, Na 3C 6H 5O 7 2H 2O, (464 mg, 1.58 mmol) and tannic acid, C 76H 52O 46, (11 mg, 6x10-3 mmol) was added all at once into the above solution and it was stirred for 30 min at boiling temperature. An aqueous solution (30 ml) of tetrachloroauric acid trihydrate, HAuCl 4 3H 2O, (155 mg, mmol) was added all at once and the colloidal mixture was further stirred for 30 min at boiling temperature. The colloidal mixture was cooled down to room temperature and alumina powder (7.750 g) (Puralox TH 100/150) was added and the suspensión was stirred for 1h. After impregnation, the solvent was removed on the rotary evaporator and the dried solid was stored overnight. The next day, the solid was washed with deionised water, separated from the liquid by centrifugation, and then dried at a rotary evaporator. Subsequently, the sample was calcined in air at 200 C for 3 h (heating rate = 1 C/min). AI4. Catalyst Preparation, Au/Alumina. The catalyst was prepared using a modified procedure previously reported in the literature.[7] Alumina powder (7.750 g) (Puralox TH 100/150) was suspended in 410 ml of deionised water at 70 C. An aqueous solution (60 ml) of tetrachloroauric acid trihydrate, HAuCl 4 3H 2O, (155 mg, mmol) was added dropwise, along with a 0.1M NaOH solution to adjust the ph to 7. After stirring the mixture for 1 h at 70 C and cooling it down to room temperature, an aqueous solution (30 ml) of trisodium citrate dihydrate, Na 3C 6H 5O 7 2H 2O, (464 mg, 1.58 mmol) was added all at once, and the suspension was further stirred at room temperature for 1 h. The solid was separated from the liquid

6 by centrifugation, washed with deionised water and then dried at a rotary evaporator. Subsequently, the sample was calcined in air at 200 C for 3 h (heating rate = 1 C/min). AI5. Catalyst Preparation, Pd/Alumina. The palladium salt was reduced similarly to the method in ref. [8] and the catalyst was prepared using a modified procedure (in situ immobilization) previously reported in the literature.[3] Alumina powder (7.750 g) (Puralox TH 100/150) was suspended in 410 ml of deionised water. An aqueous solution (40 ml) of sodium tetrachloropalladate, Na 2PdCl 4, (214 mg, mmol) was added dropwise. After stirring at room temperature for 1 h, an aqueous solution (20 ml) of trisodium citrate dihydrate, Na 3C 6H 5O 7 2H 2O, (464 mg, 1.58 mmol) was added all at once into the above mixture and the suspension was stirred for 10 min. Afterwards, a freshly prepared ice-cold aqueous solution (30 ml) of sodium borohydride, NaBH 4, (149 mg, 3.94 mmol) was added all at once and the mixture was further stirred at room temperature for 30 min. The solid was separated from the liquid by centrifugation, washed with deionised water and then dried at a rotary evaporator. Subsequently, the sample was calcined in air at 200 C for 3 h (heating rate = 1 C/min). AI6. Derivatization of the catalytic reaction samples. 0,5 ml (toluene or NaOH aqueous solution as solvent) or one milliliter (solvent-free) of sample was filled in a heart shaped flask. Then, the solvent was carefully evaporated under reduced pressure (NaOH aqueous solution as solvent or solvent-free). After adding the internal standard (diethylene glycol di-n-butyl ether, 100 L, c = 100 g/l, solvent = toluene (toluene as solvent), solvent = MTBE (NaOH aqueous solution as solvent or solvent-free)), the sample was silylated for 1 h at 80 C using silylating mixture Fluka II according to Horning (250 L). After derivatization the sample was filled up to 1 ml with toluene (toluene as solvent) or MTBE (NaOH aqueous solution as solvent or solventfree) in a volumetric flask.

7 AI7. Experimental procedure of the alumina supported mixture of AuAg and Au nanoparticles (sequential reduction method, AuAg/Alumina-Au/Alumina). Figure S1. Synthetic procedure of the alumina supported mixture of AuAg and gold nanoparticles. H AuCl 4 Alumina H 2 O, NaOH Na citrate Calcination H 2 O, Na citrate Tannic acid AgNO 3 Calcination Spontaneous alloying The silver salt was reduced similarly to the method in ref. [6]. The previously obtained Au/Alumina catalyst (experimental section, Au/Alumina catalyst) was redispersed in 410 ml of deionised water. An aqueous solution (60 ml) of silver nitrate, AgNO 3, (67 mg, mmol) was subsequently added drop-by-drop. After stirring for 30 min at room temperature in the dark the mixture was heated. After boiling had commenced, an aqueous solution (30 ml) of trisodium citrate dihydrate, Na 3C 6H 5O 7 2H 2O, (464 mg, 1.58 mmol) and tannic acid, C 76H 52O 46, (11 mg, 6x10-3 mmol) was added all at once into the above mixture and the suspension was further stirred for 30 min at boiling temperature. The solid was separated from the liquid by centrifugation, washed with deionised water and then dried at a rotary evaporator. Subsequently, the sample was calcined in air at 200 C for 3 h (heating rate = 1 C/min).

8 Figure S2. Representative HAADF-TEM images and particle size distribution of the alumina supported mixture of AuAg and Au nanoparticles D = 2.2(0.7) nm Frequency (%) Particle size (nm) Table S1. Particle size, nominal and actual Au and Ag loadings of the alumina supported mixture of AuAg and Au nanoparticles. Catalyst a AuAg/Alumina- Au/Alumina (1:1) Particle size (nm) b Nominal metal loading (wt%) c Actual metal loading (wt. %) d Actual molar ratio Au M Au M (Au:M) 2.2(0.7) (1:1.2) a Catalyst type (and nominal molar ratio between both metals in parentheses). b The average size (and standard deviation in parentheses). c Percentage calculated on the basis of the support weight. d Percentage calculated on the basis of the final catalyst weight (determined by ICP).

9 Figure S3. Representative HAADF-TEM image and the corresponding EDX spectra of the alumina supported mixture of AuAg and Au nanoparticles AgMz CKa CrLl OKa AlKa CuKa 120 CrLa Counts CuLl CuLa SiKa AuMz AuMa AuMb AuMr AgLa AgLb AgLb2 CrKesc CrKa CrKb AuLl CuKb kev AuLa

10 Figure S4. Representative HAADF-TEM image and the corresponding EDX spectra of the AuPd/Alumina catalyst Counts CKa OKa PdMz CuLl CuLa SiKa AuMz AlKa AuMa AuMb PdLl PdLa PdLb PdLr CuKa AuLl CuKb AuLa kev Counts CKa OKa PdMz CuLl CuLa SiKa AuMz AlKa AuMa AuMb PdLl PdLa PdLb PdLr CuKa AuLl CuKb AuLa kev

11 Figure S5. Representative HAADF-TEM image and the corresponding EDX spectra of the AuPt/Alumina catalyst Counts CKa OKa CuLl CuLa AlKa PtMa PtMb PtMz AuMz PtM1 CuKa AuLl PtMr PtLl CuKb PtLa AuLa kev Counts CKa OKa CuLl CuLa AuMz AlKa PtMb PtMa PtMz PtMr PtM1 CuKa PtLl AuLl CuKb PtLa AuLa kev

12 Counts CKa OKa CuLl CuLa PtMz AlKa AuMz PtMb PtMa PtMr PtM1 CuKa PtLl AuLl CuKb PtLa AuLa kev

13 Figure S6. Representative HAADF-TEM image and the corresponding EDX spectrum of the AuCu/Alumina catalyst Counts CKa NiLl NiLa CuLl OKa CuLa AlKa AuMz AuMa AuMb SiKa AuMr NiKesc NiKa CuKa NiKb AuLl CuKb AuLa kev

14 Figure S7. Representative HAADF-TEM image and the corresponding EDX spectra of the AuAg/Alumina catalyst CuKa Counts AuMa AuMb AgMz CKa OKa CuLl CuLa AuMz AlKa AuMr AgLa AgLb AgLb kev AuLl CuKb AuLa

15 Figure S8. XPS spectrum and representative regions of the AuPd/Alumina catalyst. AuPd/Alumina Pd 3d O 1s Al 2p C 1s

16 Figure S9. XPS spectrum and representative regions of the AuPt/Alumina catalyst. AuPt/Alumina Pt 4f O 1s Au 4f C 1s

17 Au 4d

18 Figure S10. XPS spectrum and representative regions of the AuCu/Alumina catalyst. AuCu/Alumina Cu 2p O 1s Al 2p C 1s

19 Figure S11. XPS spectrum and representative regions of the AuAg/Alumina catalyst. AuAg/Alumina Ag 3d O 1s Au 4f C 1s

20 Al 2p

21 Figure S12. XPS spectrum and representative regions of the Pd/Alumina catalyst. Pd/Alumina Pd 3d O 1s Al 2p C 1s

22 Intensity / a.u. Intensity / a.u. Figure S13. Stacked X-ray diffraction pattern of AuM/Alumina (M = Pd, Pt, Cu, Ag) catalysts and alumina Alumina AuPd/Alumina AuPt/Alumina AuCu/Alumina AuAg/Alumina q / degree Figure S14. Stacked X-ray diffraction pattern of M/Alumina (M = Au, Pd) catalysts and alumina Alumina Au/Alumina Pd/lumina q / degree

23 Table S2. Results of the benzyl alcohol oxidation with the supported catalysts using toluene as solvent. Entry Catalyst Conversion Selectivity (%) Yield of TOF (mol mol -1 of BA (%) BZ BZA BB BZ (%) h -1 ) a 1 AuPd/Alumina b AuPd/Alumina c 100 d 3 AuPt/Alumina 43 >99 0 trace AuCu/Alumina AuAg/Alumina Au/Alumina Pd/Alumina 76 >99 0 trace Alumina Reaction conditions: 3.8 mmol benzyl alcohol, 0.5% mol catalyst (both metals basis -bimetallic-, metal basis -monometallic-), toluene (20 ml), 80 C, 10 bar O 2, 2h, 1000 rpm. a Rate of formation of benzaldehyde per mol (bimetallic: gold and the second metal, monometallic: metal) per hour. b 20 ml H 2O as solvent and 3.8 mmol NaOH. c Yield of benzoic acid. d Rate of formation of benzoic acid per mol (gold and palladium) per hour. Table S3. The effect of time on the benzyl alcohol oxidation with AuPd/Alumina using toluene as solvent. Entry Time (h) Conversion Selectivity (%) Yield of TOF (mol mol -1 of BA (%) BZ BZA BB BZ (%) h -1 ) a trace Reaction conditions: 7.6 mmol benzyl alcohol, 0.5% mol AuPd/Alumina catalyst (both metals basis), toluene (40 ml), 80 C, 10 bar O 2, 1000 rpm. a Rate of formation of benzaldehyde per mol (gold and palladium) per hour.

24 Table S4. Catalytic results of recycled AuPd/Alumina in the benzyl alcohol oxidation using toluene as solvent. Entry Cycle Conversion Selectivity (%) Yield of TOF (mol mol -1 of BA (%) BZ BZA BB BZ (%) h -1 ) a 1 Fresh run run run run Reaction conditions: 3.8 mmol benzyl alcohol, 0.5% mol AuPd/Alumina catalyst (both metals basis), toluene (20 ml), 80 C, 10 bar O 2, 2h, 1000 rpm. a Rate of formation of benzaldehyde per mol (gold and palladium) per hour.

25 Figure S15. XPS spectrum and representative regions of the recycled AuPd/Alumina catalyst. Recycled AuPd/Alumina Pd 3d O 1s Al 2p C 1s

26 Table S5. Results of the solvent-free oxidation of benzyl alcohol with the supported catalysts. Entry Catalyst Conversion Selectivity(%) Yield of TOF (mol mol -1 of BA (%) BZ BZA BB T BZ (%) h -1 ) a 1 AuPd/Alumina AuPt/Alumina AuCu/Alumina AuAg/Alumina Au/Alumina Pd/Alumina Alumina Reaction conditions: 19.1 mmol benzyl alcohol, 0.02% mol catalyst (both metals basis -bimetallic-, metal basis -monometallic-), 80 C; pressure of, 10 bar O 2, 5h, 1000 rpm. a Rate of formation of benzaldehyde per mol (bimetallic: gold and the second metal, monometallic: metal) per hour. Bibliography [1] A. Alshammari, A. Köckritz, V. N. Kalevaru, A. Bagabas and A. Martin, Open J. Phys. Chem., 2012, 2, [2] L. Guczi, A. Beck, A. Horváth, Zs. Koppány, G. Stefler, K. Frey, I. Sajó, O. Geszti, D. Bazin and J. Lynch, J. Mol. Catal. A: Chem., 2003, , [3] C. H. Yang, G. Chen and L. Zhang, Res. Chem. Intermed., 2011, 37, [4] K. Jiang, D. A. Smith and A. Pinchuk, J. Phys. Chem. C, 2013, 117, [5] J. Zeng, J. Y. Lee and W. Zhou, Appl. Catal., A, 2006, 308, [6] N. G. Bastu s, F. Merkoc i, J. Piella and V. Puntes, Chem. Mater., 2014, 26, [7] H. Berndt, I. Pitsch, S. Evert, K. Struve, M.-M. Pohl, J. Radnik and A. Martin, Appl. Catal. A, 2003, 244, [8] Y.-H. Qin, Y.-B. Jia, Y. Jiang, D.-F. Niu, X.-S. Zhang, X.-G. Zhou, L. Niu and W.-K. Yuan, Int. J. Hydrogen Energy, 2012, 37,