Supporting Information

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S1

Supporting Information

Theory-aided Discovery of Metallic Catalysts for Selective Propane Dehydrogenation to Propylene

Tao Wang,a,f_{Xinjiang Cui,}b,*_{Kirsten T. Winther,}a_{Frank Abild-Pedersen,}c,*_{Thomas Bligaard,}d,*_{Jens K Nørskov}e

a_{SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, Stanford, California,} 94305, USA.

b_{State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of} Sciences, No.18, Tianshui Middle Road, 730000 Lanzhou, China.

c_{SUNCAT Center for Interface Science and Catalysis, Stanford Linear Accelerator Center, Menlo Park, California, 94025, USA.} d_{Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.}

e_{Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.}

f_{Center of Artificial Photosynthesis for Solar Fuels, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024,} Zhejiang Province, China.

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Computational details. All computations were performed using periodic plane-wave based DFT method as implemented in Quantum Espresso code [1]_{with pseudo-potentials GBRV version 1.5.} [2]_{The energy cutoffs for plane wave and electron density were set to be 500 eV and 5000 eV.} BEEF-vdW functional was used to describe the exchange correlation contribution to the electronic energy.[3]_{The close-packed surfaces were simulated using four-layer 4 × 2 supercells with} topmost two layers relaxed and bottom two layers constrained. The (2 × 4 × 1) Monkhorst-Pack k-point grids[4]_{was applied for sampling. Structure optimizations were done when forces became} smaller than 0.05 eV/Å and the energy difference was lower than 10-5_{eV. A vacuum layer of 12} Å was set between periodically repeated slabs. Spin-polarization was included for Co and Ni systems to correctly describe magnetic properties. Transition state geometries were located with the climbing-image nudged elastic band (NEB) method.[5]_{The formation energies (∆E) all the} species are calculated with references to gaseous CH4 and H2 as: ∆ECxHy = E(CxHy) – E(slab) – x(ECH4 – 2EH2) – y EH2 / 2, where E(CxHy), E(slab), ECH4, and EH2 denote the electronic energies of the surface slab with adsorbates, clean surface slab, gas phase CH4 and H2 molecules, respectively. Note that using other gaseous molecules such as C3H8 and C3H6 will not change the conclusion of this work because the reaction free energies and energy barriers that the micro-kinetics model relies on are relative energies, the differences in formation energies between two states, i.e., initial state and final state. The free energies are calculated applying an ideal gas approximation for gas phase species and the harmonic approximation for adsorbates with the specific modules in Atomic Simulation Environment (ASE),[6]_{where the C}

p and H(T) are included in the method.

Catalyst Preparation: The Ni-Mo/Al2O3 catalyst was prepared by incipient wetness co-impregnation method. Typically, (NH4)6Mo7O24·4H2O (30 mg) and Ni(NO3)2·6H2O (148.75 mg) were used as precursors and dissolved in water and γ-Al2O3 (1000 mg, provided by Taizhou Tianping Co., Ltd) was used as support. After impregnation, the catalysts were placed in the atmosphere statically overnight and then dried in static air at 353K for 12 h. Afterwards, the catalyst precursor was calcined at 873 K at a rate of 10 K min−1_{and retained at 873 K for 4 h. The} Pt/Al2O3 was prepared use the similar method replacing Mo and Ni aqueous by H2PtCl6·6H2O (26.2 mg) solution.

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S3

emission spectroscopy (ICP-AES) was used to determine the content of Ni, Mo and Pt in all samples.

Catalytic performance measurements. Catalytic tests were performed in a ﬁx-bed reactor with 8 mm inner diameter and 45 cm length under atmospheric pressure. Typically, 500 mg of calcined sample with the particle size of 20-40 mesh was packed between quartz wool plugs. The inlet gas flow rates were tested by mass flow controllers. The sample was first heated to 843K at a rate of 10 K min-1_{and retained at 843K for 2 h in flowing 10}

vol% H2/Ar. Next, a mixture gas of C3H8, H2, and Ar with a volume rate of 4:4:40 was fed at a rate of 50 mL min-1_{. The feed and product gas} streams were monitored online by a mass spectrometer (MS). Meanwhile, the conversion and selectivity were calculated from the changes of the molar flow rates in the inlet and outlet gas which are measured by the online mass spectrometer using Ar as an internal standard.

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Table S1: The predicted 30 promising Pt based and 11 nonprecious catalysts for PDH process screened from 125 bimetallic alloys with accurately calculated CH3CHCH2 (ECH3CHCH2) and CH3CH2CH (ECH3CH2CH) formation energies.

Pt_based_Alloy ECH3CHCH2 ECH3CH2CH

Pt2Au2 2.06 2.30 Pt2Tl2 1.68 2.53 Pt3Ga 2.10 2.65 Pt3Mo 1.95 2.30 Pt3Nb 2.20 2.43 Pt3Sc 2.21 2.40 Pt3Ta 2.06 2.26 Pt3W 1.66 1.72 PtGa3 2.20 2.41 PtHg3 1.01 2.09 PtIn3 1.57 1.87 PtMo3 1.48 1.90 PtPb3 1.26 2.77 PtPd3 2.13 2.33 PtRe3 1.52 1.80 PtSn3 0.69 2.19 PtW3 1.30 1.76 Pt3Ni 2.05 2.53 Pt2Cu2 2.10 2.20 Pt2Sn2 2.14 2.83 Pt3Mn 2.16 2.27 Pt3Zn 2.12 2.45 Ni2Pt2 2.20 2.33 Pt2Ag2 2.20 2.42 Pt3Co 2.16 2.60 Pt3Tc 2.05 2.26 Pt3Rh 2.00 2.27 Pt3Cu 2.10 2.46 Pt3Ag 2.07 2.39 Pt3Au 2.02 2.28

Nonprecious Alloys ECH3CHCH2 ECH3CH2CH

Ga2Mo2 1.59 2.51

Ga3Mo 1.62 1.92

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S5 Mo3Ni 1.27 1.83 MoNi3 1.99 2.34 Co3Ga 2.52 2.79 InMo3 2.03 2.07 Mo2Zn2 1.81 2.14 In2Mo2 2.04 2.23 Mo2Ni2 1.56 1.76 Ni2W2 1.52 1.73

Table S2: The comparison of catalytic performance between Ni3Mo and Pt.

Catalyst

T(

o

_C)

_Conversion

_Selectivity

_Ref

Pt/Al

2

O

3

550

o

C

60.7

14.7 a

Pt/Al

2

O

3

600

o

C

~17

~52

b

Pt/Al

2

O

3

570

o

C

28.5

16.6 This work

NiMO/Al

2

O

3

570

o

C

11.9

63.1 This work

a: S. B. Kogan, H. Schramm, M. Herskowitz, Dehydrogenation of propane on modified Pt/θ-alumina Performance in hydrogen and steam environment, Appl. Catal. A: Gen. 2001, 208, 185–191.

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Figure S4. The coverage map of each adsorbate in the reaction networks as a function of CH3CHCH2

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ECH3CHCH2(eV)  EC H 3 C H 2 C H (e V ) lo g( T O F /s -1) (a) E_CH3CHCH2(eV)  EC H 3 C H 2 C H (e V ) S el ec tiv ity (b) ECH3CHCH2(eV)  EC H 3C H 2C H (e V ) 1.0 1.5 2.0 2.5 3.0 3.5 1.5 2.0 3.0 2.5 3.5 4.5 4.0 1.0 ECH3CHCH2(eV) E C H 3 C H 2 C H (e V ) (c)

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Figure S6. The XRD analysis of the fresh NiMo/Al2O3 after 2h reduction, the used NiMo/Al2O3 catalyst and NiMo/Al2O3 after 4h reduction.

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Figure S8. Line-scan analysis and EDX spectra and the elements ratio of Ni to Mo in the Figure 5h and 5i.

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S13 References

Supporting Information