Supporting Information. Visible Light Driven Selective Photocatalytic Hydrogenation of Cinnamaldehyde. over Au/SiC Catalysts

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1 Supporting Information Visible Light Driven Selective Photocatalytic Hydrogenation of Cinnamaldehyde over Au/SiC Catalysts Cai Hong Hao a,b, Xiao Ning Guo a *, Yung Tin Pan c, Shuai Chen a, Zhi Feng Jiao a,b, Hong Yang c * and Xiang Yun Guo a * a State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan , P. R. China b University of the Chinese Academy of Sciences, Beijing , P. R. China c Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana Champaign, 206 Roger Adams Laboratory, MC 712, 600 South Mathews Avuenue, Urbana, Illinois 61801, United States S1

2 Experimental Section Preparation of SiC support. SiC support was prepared using a xerogel method and subsequently carbonized through thermal reduction. In a typical synthesis, 6 g of phenolic resin (softening point: C) and 0.5 g of nickel(ii) nitrate hexahydrate (Ni(NO 3) 2 6H 2O, 99%, Aladdin) were dissolved in 18 ml of ethanol (absolute, AR grade, Sinopharm) and then mixed with 25 ml of tetraethoxysilane (TEOS, AR grade, Sinopharm) using a magnetic stirrer (LabDisc, ASONE) at 300 rpm for 30 min. The phenolic resin was made from formaldehyde (37%, Sinopharm) and phenol (99%, Aladdin). 25 ml of TEOS mixed with 0.5 ml of hydrochloric acid (HCl, 36%, Sinopharm) was then added dropwise into the above ethanolic solution within 20 min, and stirred for 24 h. After this initial hydrolysis step, 5 ml of hexamethylenetetramine (HMTA, 99%, Aladdin) aqueous solution (2.55mol/L) was added into the above mixture within 10 min for rapid gelation. The resulting mixture was then dried at 110 C for 12 h to obtain the xerogel. The xerogel (about 25 g) was placed in an alumina boat (6cm x 3.8cm x 2cm, Yinghui Alumina Porcelain Co. Ltd) and then transferred to an alumina tube furnace. Temperature of the furnace was rasied to 1000 C at a rate of 10 C/min under a flow of Ar gas (99.99%, Taiyuan Datong Public Industry Gas Co. Ltd, 40 ml/min), then to 1300 C at a rate of 2 C/min and finally maintained at this temperature for 5 h. After the temperature of furnace was cooled down to room temperature, the as prepared product containing SiC was collected. The raw product was heated in air at 700 C for additional 3 h to remove the residual carbon, and subsequently treated by nitric acid (HNO 3, 63%, Sinopharm) and hydrofluoric acid (HF, 40%, Sinopharm) to eliminate the S2

3 unreacted silica and other impurities (Caution: Take extreme precaution in handling HNO 3 and HF solutions). A light green powder was obtained after centrifugation at 5000 rpm for five times with distilled water (50 ml for each time). The synthetic detail was published elsewhere (Jin, G. Q.; Guo, X. Y. Micropor. Mesopor. Mat., 2003, 60, 207). BET specific surface area of this SiC powder was measured to be 50 m 2 /g based on N 2 adsorption desorption isotherm measurement (Micromeritics ASAP 2000 porosimeter). Preparation of 1 wt% Au/SiC catalysts. The SiC supported Au catalyst was prepared by a one step impregnation reduction method. The process began with adding 495 mg of SiC powder into 4.3 ml of chloroauric acid (HAuCl 4 4H 2O, 99.5%; Sinopharm) aqueous solution (2 mg/ml). After stirring for 30 min, 20 ml of lysine (99%, Aladdin) aqueous solution (0.53 mol/l) was added into the above mixture in 20 min. After stirring for another 30 min, 10 ml of NaBH 4 (98%, Aladdin) aqueous solution (0.35 mol/l) was added dropwise in 20 min, and 10 ml of 0.3 M HCl solution was then added dropwise to the above suspension. Finally, the mixture was left under ambient air condition for 24 h. The solid product was then separated, washed and dried to obtain Au/SiC catalyst with metal loading of 1wt% based on the amount of metal in the precursor. The exact loading of Au was determined to be 0.98wt% by inductively coupled plasma mass spectroscopy (ICP MS, Perkin Elmer ELAN 5000). Au/TiO 2, Au/Al 2O 3 Au/SiO 2, Pd/SiC and Pt/SiC catalysts were prepared at the same metal loading following the same procedures as those for Au/SiC, except the corresponding metal salt precursors and supports were used. S3

4 Charaterization. Microstructures of the catalysts were investigated by highresolution transmission electron microscope (HRTEM, JEM 2100F) at accelerating voltage of 200 kv. X ray photoelectron spectroscopy (XPS) was measured using Al K a (hk= ev) X ray line on a Kratos XSAM800 spectrometer. The crystalline phases were characterized by X ray diffractometer (XRD, Rigaku D Max/RB). Diffusive reflectance UV visible absorption spectra were measured with Al 2O 3 as the reference using a UV 3600 spectrophotometer (Shimadzu). Study of catalytic activity. The reactions were conducted under argon with a pressure of 1 atm. The reactant mixture consisted of 20 mg of KOH, 30 mg of Au/SiC catalyst, 10 ml of isopropyl alcohol (99.5%, Aladdin) and cinnamaldehyde (CAL, 99.5%, Aladdin, 0.2 ml or 1.6 mmol). The reaction temperature was set at 20 o C and controlled by a circulating water bath (RT4 circulator, ASONE). The mixture was stirred at 700 rpm using magnetic stirrer during the reaction and exposed to a Xenon lamp (PLS SXE300C/CUV, Beijing Perfect Light Scientific and Technical Co. Ltd) for 130 min, unless otherwise specified. Effect of wavelength of light on catalytic performance was investigated using various low pass optical filters to block off light below specific cutoff wavelengths. For instance, a filter with the cut off wavelength of 450 nm could block the light with wavelengths shorter than 450 nm (the reaction mixture was irradiated by light with wavelengths between 450 and 800 nm). During this process, the light intensity for the reaction remained unchanged. After reaction, 2 ml aliquots were collected, centrifuged, and then filtered through a Millipore filter (pore size: 0.22 μm) to remove the catalyst particles. The filtrates were analyzed by gas S4

5 chromatography mass spectrometry (GC MS, BRUKER SCION SQ 456 GC MS) to measure the concentration change of reactants and products. Quantitative analysis of specific analyte was detected by GC MS using the selected ion monitoring (SIM) mode. Conversions were calculated based on the amount of α,β unsaturated aldehydes (Aladdin). The turn over frequency (TOF) was calculated based on the following equation: TOF = Amount of α, β unsaturated aldehyde (mol) conversion (%) selectivity (%) Mass of Au/SiC (g) Au loading (%) reaction time (h) / M[Au] S5

6 Figures Figure S1. (A) XRD patterns and (B) X ray photoelectron spectroscopy of the 1 wt% Au/SiC catalyst. The 2θ peaks at 38.2, 44.4 and 64.5 can be indexed, respectively, to (111), (200) and (220) surfaces of face centered cubic phase Au. Other main diffraction peaks are from β SiC. Figure S2. TEM micrographs of (A) Au/Al 2O 3 and (B) Au/TiO 2 catalysts. The insets show the corresponding particle size distribution analysis of Au nanoparticles. S6

7 Figure S3. TEM micrographs of (A) Pd/SiC and (B) Pt/SiC catalysts. The insets show the corresponding particle size distribution analysis of metal nanoparticles. The average size of nanoparticles was 4.7 nm for Pd/SiC and 4.2 nm for Pt/SiC. Figure S4. (A) Recyclability in selective hydrogenation of CAL, (B) TEM micrograph and (C) XPS of the Au/SiC catalyst after five catalytic cycles. S7

8 Table S1. Summary of reaction conditions and catalytic activity of selective hydrogenation of CAL over various supported catalysts. Entry Reactant Catalyst T/ o C P(H2)/MPa TOF/h -1 Reference 1 Pt/ K-10 montmorillonite J. Catal. 1998, 179, Nanoporous Au 70 Et3SiH 0.7 Chem. Commun. 2014, 50, Pt/SiO Catal. Commun. 2012, 48, Ru/Y J. Mol. Catal. A: Chem. 2004, 217, Ru/carbon nanofiber J. Catal. 2003, 214, Au-Ir/TiO Catal. Commun. 2014, 54, Pt/3,3 thiodipropionic acid Catal. Commun. 2014, 43, Pd-Sn/C Catal. Commun. 2014, 43, Cu/meso-C Catal. Commun. 2012, 21, Pt/reduced graphene oxide RSC Adv. 2014, 4, Iron complexes Angew. Chem. Int. Ed. 2013, 52, Longer-chain fluorous carboxylic acid-modified FePt ACS Catal. 2015, 5, Pt3Co Angew. Chem. Int. Ed. 2012, 51, Ru/CNTs J. Catal. 2015, 329, Pt/graphene ChemCatChem 2014, 6, S8

9 16 Rh-Sn/SiO Top. Catal. 1998, 5, Pt/SiO J. Catal , Ru-Mg/AC App. Catal. A. 2001, 205, Au8Ag0.5/SBA J. Catal. 2015, 330, PtSn/TiO ml/min Phys. Chem. Chem. Phys. 2015, 17, Au/Fe3O J. Catal. 2011, 281, Au Appl. Catal. A 2009, 355, Au/meso-CeO Angew. Chem. Int. Ed. 2010, 49, Au/CeO (CO) 5.1 Chem. Commun. 2010, 46, Au/meso-CeO2 80 Air(HCOOK) 2 Chem. Eur. J. 2009, 15, S9

10 Ni2In/Al2O Chem. Mater. 2013, 25, Ni2In3/Al2O Ni2In3/Al2O S10

11 Table S2. Selective photocatalytic hydrogenation of CAL over different catalysts [a] Catalyst CAL conv. (%) COL select. (%) Au/SiC Au/TiO Au/Al 2O Au/SiO Pd/SiC Pt/SiC SiC TiO Al 2O Au nanoparticles [b] [a] Reaction conditions: 1.6 mmol of reactant, 30 mg of catalyst in 10 ml of isopropyl alcohol consisting of 20 mg of KOH. The reactions were conducted in an argon atmosphere at 20 ᵒC under Xe lamp irradiation (400 nm) with light intensity of 1.0 W cm 2. The reaction time was 130 min. [b] The amount of Au nanoparticles was ~ 2 mg. S11