Supporting Information Porous TiO 2 /Pt/TiO 2 Sandwich Catalyst for Highly Selective Semihydrogenation of Alkyne to Olefin Haojie Liang,, Bin Zhang *,, Huibin Ge,, Xiaomin Gu,, Shufang Zhang,, Yong Qin *, State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001,People s Republic of China. University of Chinese Academy of Sciences, Beijing, 100049,People s Republic of China. *Email: zhangbin2009@sxicc.ac.cn, qinyong@sxicc.ac.cn Experimental Section Synthesis of CNFs template. The CNFs templates were synthesized at 280 C by chemical vapor deposition using copper nanoparticles and acetylene as catalysts and a feed gas, respectively. Then the CNFs were carbonized at 900 C in Ar for 2 h. After that, the CNFs were treated by a HNO 3 aqueous solution (25 wt %) at 100 C for 4 h, followed by filtering, washing and drying at 120 C in sequence. Atomic Layer Deposition. ALD was performed at a home-made, hot-walled ALD machine. Ultrahigh purity N 2 (99.999%) was used as a carrier gas at a flow of 50 sccm and a pressure of 60 Pa. TiO 2 deposition was conducted at 150 C using titanium isopropoxide (Alfa Aesar, 97%, held at 80 C) and deionized water (room temperature) as precursors. The pulse, exposure, and purge time for titanium isopropoxide were 1, 8, and 20 s, and 0.1, 8, and 25 s for H 2 O, respectively. ALD of Pt nanoparticles was performed at 230 C using trimethyl(methylcyclopentadienyl)
platinum (Strem Chemicals, 99 %, held at 60 C) as precursor, and O 3 (5 sccm) as oxidizing reagent. The pulse, exposure, and purge time were 0.5, 10, and 20 s for Pt precursor, and 1, 10, and 20 s for O 3, respectively. Alucone deposition was conducted at150 C using trimethylaluminum (TMA, Alfa Aesar, 25 wt% in hexane) and ethylene glycol (held at 80 C) as precursors. The pulse, exposure, and purge time for TMA were 0.02, 8, and 25 s, and those for ethylene glycol were 1, 10, and 25 s, respectively. Synthesis of xtio 2 io 2 /npt/tio 2. All the xtio 2 /npt/tio 2 catalysts were prepared by ALD using CNFs as sacrificial templates (which could be removed easily and was suitable for ALD process 1-3 ). Typically, xtio 2 /npt/tio 2 was prepared by sequential deposition of 300 cycles TiO 2, n cycles Pt and x cycles TiO 2 on CNFs, followed by calcination in air at 500 C for 2 h. The whole process is illustrated in Figure 1A. Synthesis of 100Al 2 O 3 /Pt/TiO 2. 100Al 2 O 3 /Pt/TiO 2 was prepared by sequential deposition of 300 cycles TiO 2, 20 cycles Pt and 100 cycles alucone on CNFs, followed by calcination in air at 500 C for 2 h. Synthesis of 50TiO 2 /50Al 2 O 3 /Pt/TiO 2. 50TiO 2 /50Al 2 O 3 /Pt/TiO 2 was prepared by sequential deposition of 300 cycles TiO 2, 20 cycles Pt, 50 cycles alucone and 50 cycles TiO 2 on CNFs, followed by calcination in air at 500 C for 2 h. Characterization and Equipment. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) were conducted using a FEI Tecnai G2 F20 S-Twin instrument. The textural characterization of the catalysts was based on the nitrogen adsorption isotherm, determined at the normal boiling point of N2 ( 196 C) with a Micromeritics ASAP 2500 instruments. Each sample was degassed under vacuum at 90 C for 1 h and 350 C for 8 h prior to the measurement. X-ray powder diffraction
(XRD) analysis was carried out on a Bruker D2 PHASER X-ray powder diffractometer, with Cu Kα radiation (λ = 0.154 nm) operated at 40 kv. The content of Pt in catalysts was determined by inductively coupled plasma optical emission spectrometry (ICP- OES, Thermo icap 6300, U.S.A.). X-ray photoelectron spectroscopy (XPS) was performed on a Kratos AXIS ULTRA DLD system. Before XPS test, all the samples were in situ treated with H 2 /N 2 at 80 C for 1 h. Pt L3-edge X-ray absorption fine spectra (XAFS) were performed on the BL14W1 beamline at the Shanghai Synchrotron Radiation Facility (SSRF), Shanghai Institute of Applied Physics (SINAP), China, operated at 3.5 GeV with injection currents of 140 210 ma. 4 A Si(111) double-crystal monochromator was used to reduce the harmonic component of the monochrome beam. Pt foil and PtO 2 were used as reference samples and measured in the transmission mode, and xtio 2 /Pt/TiO 2 samples were measured in fluorescence mode. Hydrogen chemisorption was conducted from a Xianquan TP- 5080 multifunctional atomic adsorption instrument. Same treatment was practiced as XPS pretreatment before hydrogen pulse adsorption and XAFS analysis. Catalytic performance. The tandem ammonia borane decomposition and phenylacetylene hydrogenation was carried out in a 50 ml 3 mouth flask with a stirring speed of 400 rpm. In a typical run, 0.18 mmol phenylacetylene, 10 mg catalyst, and 8 ml ethanol were mixed into the flask under magnetic stirring at 30 C. Then, a 12 ml NH 3 BH 3 (40 mg) aqueous solution was rapidly added into the ethanol solution. The products were detected by gas chromatography (GC-9720, Zhejiang Fuli chromatogram analysis Co., Ltd, China) equipped with a FID detector and a 30 m HP-5 capillary column.
Figure S1. TEM images of Pt/TiO 2 catalysts coated with an outer TiO 2 or Al 2 O 3 layer of different ALD cycle numbers. A) Pt/TiO 2, B) 10TiO 2 /Pt/TiO 2, C) 30TiO 2 /Pt/TiO 2, D) 50TiO 2 /Pt/TiO 2, E) 100TiO 2 /Pt/TiO 2, and F) 100Al 2 O 3 /Pt/TiO 2. The average particle size of Pt nanoparticles is 3 nm. The pores on TiO 2 layer were circled in red.
Outer TiO 2 layer thickness (nm) 16 12 8 4 0 0 20 40 60 80 100 ALD TiO 2 cycle number (x) Figure S2. Thickness of the outer TiO 2 layer versus ALD cycle number (x).
Intensity (a.u.) Pt/TiO 2 10TiO 2 /Pt/TiO 2 30TiO 2 /Pt/TiO 2 50TiO 2 /Pt/TiO 2 100TiO 2 /Pt/TiO 2 10 20 30 40 50 60 70 80 2 theta (degree) Figure S3. XRD patterns of different catalysts.
Figure S4. XPS O-1s (A) and Ti-2p (B) analyses of different samples: pure ALD TiO 2, Pt/TiO 2, 10TiO 2 /Pt/TiO 2, and 30TiO 2 /Pt/TiO 2.
Figure S5. Catalytic performance of the catalysts for semihydrogenation of phenylacetylene to styrene.
Figure S6. Catalytic performance of the catalysts for semihydrogenation of phenylacetylene to styrene over 50TiO 2 /npt/tio 2 with different Pt ALD cycles (n).
Figure S7. H 2 generation rate catalyzed by (A) Pt/TiO 2 and (B) 30TiO 2 /Pt/TiO 2. Reaction condition: 1) pure AB (ammonia borane): 10 mg catalysts, 40 mg ammonia borane, 12 ml H 2 O, 8 ml ethanol, 30 C; 2) AB+C 8 H 6 : 10 mg catalysts, 40 mg ammonia borane, 0.18 mmol phenylacetylene, 12 ml H 2 O, 8 ml ethanol, 30 C; 3) Total value: calculated by adding the real yield of H 2 and H 2 consuming in hydrogenation of phenylacetylene. The decomposition of ammonia borane is near quasi-zero-order reaction. The addition of phenylacetylene slows down the decomposition rate over both Pt/TiO 2 and 30TiO 2 /Pt/TiO 2, indicating that the ammonia borane decomposition and hydrogenation share same active sites.
Figure S8. Decomposition of ammonia borane to hydrogen over 50TiO 2 /Pt/TiO 2. (A)The influence of stirring rate (Reaction conditions: 10 mg 50TiO 2 /Pt/TiO 2, 40 mg AB, 12 ml H 2 O, 8 ml ethanol, 30 C, 300, 400 or 500 r/min). (B)The influence of ammonia borane addition for hydrogen generation (Reaction conditions: 10 mg 50TiO 2 /Pt/TiO 2, 12 ml H 2 O, 8 ml ethanol, 30 C, 400 r/min).
Table S1. Physicochemical characteristics of Pt/TiO 2 catalysts. Catalyst Pt loading a / wt.% BET surface area / m 2.g -1 BJH pore diameter / nm BJH pore volume / cm 3.g -1 HK micro pore volume / cm 3.g -1 H 2 chemisorption /µmol. g -1 Pt/TiO 2 4.6 49.7 2.37 0.14 0.017 77.1 30TiO 2/Pt/TiO 2 3.1 50.1 2.24 0.13 0.017 27.6 50TiO 2/Pt/TiO 2 2.8 34.0 2.55 0.08 0.013-100TiO 2/Pt/TiO 2 1.4 25.7 2.97 0.07 0.009 27.4 100Al 2O 3/Pt/TiO 2 4.0 73.2 2.18 0.17 0.024 - a Measured by ICP-OES.
Table S2. Activity and selectivity for phenylacetlyene conversion of different catalysts. Catalyst T P Reaction rate Selectivity Ref. / C /MPa /mol alkyne.mol -1 metal.h -1 /% Lindlar catalyst 25 0.1 30 81 [5] Pd-Pb octahedra 25 0.1 24 91 [5] Pd0-AmP-HSN r.t. 0.1 285 95 [6] Au@CeO 2 r.t. 3 1 >99 [7] Au 25 (SR) 18 /TiO 2 100 0.2 1 99 [8] Ni 5 Mg 4 Ga 3-500 40 0.3 3 92 [9] Pd@MPSO/SiO 2-2 30 0.1 82 97 [10] Pd@Ag-0.2 r.t. 0.1 10 >99 [11] 50TiO 2 /Pt/TiO 2 30-34 95 This work
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