Supporting Information Tandem Site and Size Controlled Pd Nanoparticles for the Directed Hydrogenation of Furfural Scott M. Rogers, 1,2 C. Richard. A. Catlow, 1,2,5 Carine E. Chan-Thaw, 3 Arunabhiram Chutia, 1,2 Nan Jian, 4 Richard E. Palmer, 4 Michal Perdjon, 1,2,5 Adam Thetford, 1,2 Nikolaos Dimitratos, 1,5 Alberto Villa, *1,3 and Peter P. Wells *1,2,6,7 1. UK Catalysis Hub, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxon, Didcot, OX11 0FA, UK. 2. Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK. 3. Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy. 4. Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. 5. Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK. 6. Diamond Light Source, Harwell Science and Innovation Campus, Chilton, Didcot, OX11 0DE, UK. 7. School of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, UK. Corresponding Authors: * Email: p.p.wells@soton.ac.uk, alberto.villa@unimi.it 1) Microwave plasma atomic emission spectroscopy (MP-AES) 1 wt. % Pd/TiO 2 was prepared by sol-immobilisation method. After immobilisation of metal on to the support, the catalyst was examined in MP-AES for the Pd metal weight loading. Pd standards were used for calibration and de-ionised water used as the blank sample. Pd concentrations (ppm) were obtained at two Pd wavelengths, 340.5 and 361.0 nm. Each sample was measured twice to ensure reliable results. Table S1 details the metal loading obtained for each sample, at the two different wavelengths. The average Pd loading is also documented for each catalyst. Table S1. MP-AES results of the sol-immobilised prepared 1 wt. % Pd/TiO 2 catalysts. Concentrations (ppm) at different Pd wavelengths (nm) 1 st repetition Concentrations (ppm) at different Pd wavelengths (nm) 2 nd repetition Pd 340.5 Pd 361.0 Pd 340.5 Pd 361.0 Average Pd wt. % PdA1 7.29 7.42 6.99 7.00 0.72 PdA2 7.39 7.39 7.16 7.12 0.72 PdB1 6.65 6.63 6.69 6.79 0.67 PdB2 8.72 8.80 8.85 8.87 0.88
2) TEM fresh Pd catalysts TEM images and Pd particle size distribution histograms for the 1 wt. % Pd/TiO 2 catalysts prepared at different temperatures, in different solvent environments (H 2O or H 2O/EtOH). Analysis was performed at the Research Complex at Harwell. Samples were examined using a JOEL JEM 2100 EM model.
Figure S1. Particle size distribution histograms of fresh 1 wt. % Pd/TiO 2 catalysts: A) PdA1, B) PdA2, C) PdA3, D) PdA4, E) PdB1, F) PdB2 and G) PdB3.
3) STEM HAADF microscopy of fresh Pd catalysts STEM HAADF images for PdA1 and PdB1 fresh catalysts. Analysis was performed at the Nanosclae Physics Research Laboratory at the University of Birmingham. Samples were examined using a JOEL JEM 2100F STEM model. Figure S2. STEM dark field images of fresh 1 wt. % Pd/TiO 2; A and B) PdA1, and C and D) PdB1.
4) EXAFS of fresh Pd catalyst EXAFS forward fourier transform indicating there is no bulk PdO present. XAFS studies were performed on the B18 beamline at the Diamond Light Source, Didcot, U.K. Figure S3. k 2 weighted forward Fourier Transform data for PdA1, Pd foil and PdO reference.
5) CO-adsorption using IR FTIR spectra of CO-adsorption studies performed on the fresh Pd/TiO 2 catalysts, prepared at different temperatures, in different solvent environments. The measurements were performed in transmission mode. Figure S4. FTIR spectra from CO-adsorption studies on different 1 wt. % Pd/TiO 2 catalysts.
6) Furfural hydrogenation testing at 25 C Table S2. Furfural hydrogenation activity and product selectivity of the different Pd/TiO 2 catalysts. Reaction performed at 25 C. Catalyst a Activity b Conv. (%) after 5h Furfuryl alcohol Tetrahydro Furfuryl alcohol Selectivity (%) c 2-methyl 2-methyl tetrahydro Ethers 1 2 A1 464 73 25 45 - - - 15 12 A2 240 51 28 16 - - - 50 3 A3 56 15 43 d 16 d - - - 40 d - A4 38 10 52 d 9 d - - - 38 d - B1 491 48 62 13 - - - 14 1 B2 568 71 43 45 - - - 9 1 B3 456 38 41 32 - - - 26 - a Reaction conditions: Furfural = 0.3 M; F/metal ratio=500 mol/mol, 25 C, 5 bar H2, solvent 2-propranol, b Converted mol (mol Pd) -1 h -1 calculated after 15 min of reaction, c selectivity calculated at 50% conversion, d selectivity calculated at 10% conversion. 7) Furfural hydrogenation testing at 50 C Table S3. Furfural hydrogenation activity and product selectivity of the different Pd/TiO 2 catalysts. Reaction performed at 50 C. Catalyst a Activity b Conv. (%) after 3h Furfuryl alcohol Tetrahydro Furfuryl alcohol Selectivity (%) c 2-methyl 2-methyl tetrahydro Furan Ethers 1 2 A1 620 87 48 39 - - - 5 - A2 321 58 65 25 - - - 5 - A3 67 22 76 20 - - - 3 - A4 43 13 78 15 - - - 6 - B1 470 79 67 19 - - - 13 - B2 223 63 65 24 - - - 2 - B3 196 40 55 30 - - - 2 - a Reaction conditions: Furfural = 0.3 M; F/metal ratio=500 mol/mol, 25 C, 5 bar H2, solvent 2-propranol, b Converted mol (mol Pd) -1 h -1 calculated after 15 min of reaction. c selectivity calculated at 50% conversion, d selectivity calculated at 10% conversion.
8) Furfural hydrogenation recycling studies performed at 25 C Table S4. Furfural hydrogenation recycling studies of PdA1 and PdB1 catalysts. Reactions performed at 25 C. PdA1 Run a Activity b Conv. (%) after 5h (25 C) & 3h (50 C) Furfuryl alcohol Tetrahydro Furfuryl alcohol Selectivity (%) c 2- methyl 2-methyl tetrahydro Furan Ethers 1 2 1 464 73 25 45 - - - 15 12 2 394 56 23 43 - - - 14 10 3 324 43 22 44 - - - 16 11 4 301 39 23 43 - - - 14 13 PdB1 1 491 48 62 13 - - - 14 1 2 450 41 63 12 - - - 13 2 3 420 35 67 10 - - - 12 2 4 356 30 69 9 - - - 13 3 5 361 31 70 8 15 2 a Reaction conditions: Furfural = 0.3 M; F/metal ratio=500 mol/mol, 5 bar H2, solvent 2-propranol, b Converted mol (mol Pd) -1 h -1 calculated after 15 min of reaction, c selectivity calculated at 50% conversion. 9) Furfural hydrogenation recycling studies performed at 50 C Table S5. Furfural hydrogenation recycling studies of Pd catalysts performed at 50 C. PdA1 Run a Activity b Conv. (%) after 5h (25 C) & 3h (50 C) Furfuryl alcohol Tetrahydro Furfuryl alcohol Selectivity (%) c 2- methyl 2-methyl tetrahydro Furan Ethers 1 2 1 620 87 48 39 - - - 5-2 580 75 52 36 - - - 6-3 564 72 51 35 - - - 6-4 541 68 53 34 - - - 5 - PdB1 1 471 79 67 19 - - - 13-2 465 75 68 18 - - - 12-3 402 61 70 15 - - - 14-4 403 59 72 13 - - - 15-5 397 60 73 12 16 a Reaction conditions: Furfural = 0.3 M; F/metal ratio=500 mol/mol, 5 bar H2, solvent 2-propranol, b Converted mol (mol Pd) -1 h -1 calculated after 15 min of reaction, c selectivity calculated at 50% conversion.
10) Time online furfural hydrogenation conversion profiles, performed at 25 C Furfural conversion profiles of all catalysts, in which the reaction was performed at 25 C. Reaction conditions: Furfural = 0.3 M; F/metal ratio=500 mol/mol, 5 bar H 2, solvent 2-propranol. Figure S5. Time online furfural hydrogenation conversion profiles using Pd/TiO 2 catalysts. Reaction performed at 25 C. 11) Time online furfural hydrogenation conversion profiles, performed at 50 C Furfural conversion profiles of all catalysts, in which the reaction was performed at 50 C. Reaction conditions: Furfural = 0.3 M; F/metal ratio=500 mol/mol, 5 bar H 2, solvent 2-propranol. Figure S6. Time online furfural hydrogenation conversion profiles using Pd/TiO 2 catalysts. Reaction performed at 50 C.
12) TEM of Pd catalysts used in furfural hydrogenation, reaction performed at 25 and 50 C. TEM and particle size distribution histograms of the Pd catalysts used in furfural hydrogenation at both 25 and 50 C.
Figure S7. Particle size distribution histograms of 1 wt. % Pd/TiO 2 catalysts used in the hydrogenation of furfural, performed at different temperatures: A) PdA1 25 C, B) PdA1 50 C, C) PdA2 25 C, D) PdA2 50 C, E) PdB1 25 C, F) PdB1 50 C, G) PdB2 25 C and H) PdB2 50 C.
13) STEM HAADF images of Pd catalysts after furfural hydrogenation, reaction performed at 25 C. STEM HAADF images for PdA1 and PdB1 catalysts after performing furfural hydrogenation at 25 C. Analysis was performed at the Nanosclae Physics Research Laboratory at the University of Birmingham. Samples were examined using a JOEL JEM 2100F STEM model. Figure S8. STEM HAADF images of Pd catalysts used in furfural hydrogenation: A) PdA1, B) PdA2, C) PdB1 and D) PdB2.
14) EXAFS of Pd catalysts before and after furfural hydrogenation at 25 C EXAFS forward fourier transform data and corresponding fit for PdA1 and PdB1 catalysts before and after testing in furfural hydrogenation, in which the reaction was performed at 25 C. XAFS studies were performed on the B18 beamline at the Diamond Light Source, Didcot, U.K. Figure S9. k 2 -weighted Forward fourier transform data and corresponding fit of the Pd catalysts after furfural hydrogenation. Table S6. 1 st shell EXAFS fitting parameters derived from the k 2 weighted Fourier transform for the Pd K edge EXAFS data for PdA1 and PdB1. Sample Abs Sc N R / Å 2σ 2 / Å 2 Ef / ev Rfactor Fresh PdA1 Pd O 1.2 (2) 1.970 (8) 0.004 (2) 6 0.005 Pd Pd 5.8 (4) 2.744 (2) 0.008 (0) Used PdA1 25 C Pd O 2.1 (4) 1.977 (8) 0.006 (3) 6 0.015 Pd Pd 4.0 (5) 2.772 (4) 0.008 (0) Fresh PdB1 Pd O 3.0 (3) 1.997 (5) 0.004 (1) 4 0.02 Pd Pd 1.7 (6) 2.746 (11) 0.008(3) Used PdB1 25 C Pd O 1.5 (4) 1.971 (11) 0.007 (4) 0 0.008 Pd Pd 5.7 (4) 2.762 (3) 0.008 (1)
15) Computational analysis Figure S10. (a) Initial and (b) final structure of Pd bulk with an interstitial C-atom. After structural relaxation C forms bonds with the nearby Pd atoms. The average distance of Pd around C atom is 2.855 Å. So the difference between the Pd-Pd distance in bulk Pd with and without C atom is 0.095 Å (=2.855Å-2.760Å). Figure S11. (a) Initial and (b) final structure of Pd(111) surface with an interstitial C-atom. After structural relaxation C forms bonds with the nearby Pd atoms. The difference between the Pd-Pd distance with and without interstitial C-atom is 0.057 Å (= 2.827 Å - 2.770Å). Table S7. Average C C, C=C, C O and C = O bond distances and CCCC torsional angle of furfural molecule on pristine Pd(111) and carbidized PdC(111) surfaces.
System Bond distances (Å) C-C C=C C-O C=O CCCC torsional angle ( ) Pristine Pd(111) Furfural on top of Pd 1.423 1.381 1.367 1.246 0.038 Furfural on bridge of Pd 1.421 1.381 1.369 1.254 0.033 Furfural on 3-fold HCP of Pd 1.447 1.442 1.398 1.286 1.072 Furfural parallel to the surface 1.460 1.440 1.401 1.274 0.973 PdC(111) Furfural parallel to the surface 1.444 1.410 1.385 1.302 3.902