Dr. Upendar Kashaboina C/o Prof. Kiyotaka Asakura Institute for - PowerPoint PPT Presentation

Dr. Upendar Kashaboina C/o Prof. Kiyotaka Asakura Institute for Catalysis Hokkaido University

Introduction 2 1. In/SiO 2 is a good catalyst for the effective non oxidative conversion of methane 1 . 2. In/SiO 2 is cheap and effective hybrid catalyst. 3. Non oxidative CH 4 activation reaction has a merit to produce CO 2 and H 2 O (thermodynamically stable molecules) 4. Operando XAFS is good technique to know the reaction mechanisms as well as thorough understanding of real structural changes of the active metal during the reaction . 5. However, we have many difficulties to construct the new high- temperature cell and have finally made the one which could stable and homogenously heat up the sample at 1000 K. Ref: Yuta Nishikawa et. al. Chemistry Select (2017) 4572 – 4576

3 Designed cell for high temperature operando measurements

EXAFS Equation 4  For the analysis of XAFS experimental data we used the REX2000 software with FEFF program.

5 Analysed data using REX2000 1. In foil (30, 100, 200, 260 and 300 K) 2. In 2 O 3 (30, 100, 200, 260 and 300 K) 3. In @SiO 2 , 0 h reaction time (30, 100, 200, 260 and 300 K) 4. In @SiO 2 , 3 h reaction time (30, 100, 200, 260 and 300 K) 5. In @SiO 2 , 12 h reaction time (30, 100, 200, 260 and 300 K)

XAFS analysis 6 In foil, In 2 O 3 and In/SiO 2 Background subtracted Normalized absorption coefficient (a.u.) XANES In foil In 2 O 3 A1 In foil In 2 O 3 In/SiO 2 In/SiO 2 A2 EXAFS oscillation Fourier Transform FT magnitude k ꭓ (k) k (A -1 ) In 2 O 3

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XAFS analysis 7 In foil, In 2 O 3 and In/SiO 2 From the above XAFS results:  XANES and EXAFS spectral patterns of In/SiO 2 catalyst are similar to the In foil.  Therefore, the active metal Indium is in pure metallic state not In 2 O 3 .

XAFS : In/SiO 2 catalysts for Methane Activation 0 hr, 3 hr and 12 h 8 Normalized absorption coefficient (a.u.) In K-edge XANES 12 h 3 h 0 h k (A -1 )

9 In foil In/SiO 2 , 0 hr T (K) N R (Å) dE DW C3 R T (K) N R (Å) dE DW C3 R 30 5 3.35 8.61 0.096 4.47 30 5 3.35 8.61 0.104 3.58 2.5 3.24 8.61 0.076 2.5 3.24 8.61 0.079 100 5 3.35 8.61 0.125 10.45 100 5 3.35 8.61 0.128 3.58 2.5 3.24 8.61 0.091 2.5 3.24 8.61 0.09 200 5 3.35 8.61 0.194 5.59 3.35 0.187 3.694E-04/S 200 5 8.61 7.31 3.37 (1.462E-04) 2.5 3.24 8.61 0.112 3.24 2.5 8.61 0.114 3.22 6.659E-04/S 260 5 3.35 8.61 0.174 11.71 (2.319E-04) 3.34 7.725E-04/S 260 5 8.61 0.190 6.61 3.35 (2.000E-04) 2.5 3.24 8.61 0.124 3.21 2.5 8.61 0.126 3.24 1.141E-03/S 300 5 3.35 8.61 0.196 8.70 (2.444E-04) 1.204E-3/S 300 5 3.35 8.61 0.197 7.54 (2.136E-04) 2.5 3.24 8.61 0.128 2.5 3.24 8.61 0.125

10 In/SiO 2 , 3 hr In/SiO 2 , 12 hr N R (Å) dE DW C3 R- T factor (K) T (K) N R (Å) dE DW C3 R 3.35 8.61 0.100 6.43 30 5 2.254E-04/S 3.24 8.61 0.083 30 2.5 5 3.35 8.61 0.07 2.83 (7.211E-05) 3.35 8.61 0.139 7.606E-05/S 9.41 2.5 3.24 8.61 0.046 100 5 (9.653E-04) 100 5 3.35 8.61 0.128 5.96 3.24 8.61 0.094 16.78 2.5 2.5 3.24 8.61 0.079 3.39 8.61 0.163 29.43 4.683E-04/S 200 5 200 5 3.35 8.61 0.178 3.73 3.350 (1.380E-04) 3.25 8.61 0.114 2.5 3.24 8.61 0.105 2.5 3.24 9.360E-04/S 3.35 8.61 0.183 7.968E-04/S 9.22 260 5 3.35 8.61 0.200 3.15 (1.763E-04) 260 5 (2.548E-04) 2.5 3.24 8.61 0.112 3.24 8.61 0.128 2.5 3.35 8.61 0.182 1.387E-03/S 17.74 1.196E-03/S 300 5 3.35 8.61 0.185 11.4 300 5 (3.232E-04) (1.763E-04) 3.24 8.61 0.136 2.5 3.24 8.61 0.121 2.5

11 Debye-Waller Factor value Vs Temperature In foil 0 hr  DW values are gradually increasing with the reaction temperature. 3 hr 12 hr

June-2018, Beam time data 12 I. Quick-EXAFS analysis under the CH 4 flow II. Quick-EXAFS analysis under the He flow i. All the experimental raw data converted into .ex3 ii. Smoothing and Interpolation iii. Integrated the above data using REX2000 software

A3 13 Edge height Vs Temperature In-SiO 2 catalyst for methane activation (a) CH 4 flow; (b) He gas flow

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EXAFS oscillations (a) 300 K (b) 430 K (c) 873 K (d) 1173 K (e) 873 K (during 14 the cooling) (f) 300 K (during the cooling) (a) 300 K (b) 430 K (c) 873 K (d) 1173 K (e) 873 K (during the cooling) (f) 300 K (during the cooling)

15 Fourier transform spectra Fourier transforms spectra of In- SiO 2 catalysts for NOMC reaction (a) 300 K (b) 430 K (c) 873 K (d) 1173 K (e) 873 K (during the cooling) (f) 300 K (during the cooling)

Evaluation of Structural Parameters Obtained by EXAFS Curve-Fitting of 16 In-In and In-C Shells σ 2 ( × × 10 -3 ) × × Catalyst@ R-factor Shell N R (Å) Temp (K) (%) In-SiO 2 @ 33 In-In 2.85 3.26 0.062 8.14 In-In * 5.70 3.37 0.144 8.14 In-SiO 2 @ 300 In-In 2.85 3.19 0.179 9.57 In-In * 5.70 3.39 0.320 9.57 In-SiO 2 @ 430 In-In 2.85 3.02 0.210 4.34 In-In * 5.70 3.31 0.372 4.34 In-SiO 2 @ 873 In-C 1.91 2.13 0.225 5.59 In-In 2.85 2.96 0.256 7.76 In-In * 5.70 3.31 0.400 7.76 In-SiO 2 @ 1173 In-In -- 2.96 0.392 8.19 In-In * -- 3.31 0.420 8.19

17 Single shell curve-fitting results σ ( × 10 -2 ) R R-factor Catalyst @ Temp (K) Shell N (nm) (Å) (%) In-In 3.28 5.54 In-SiO 2 @ 33 0.09 (0.01) 4.40 (0.01) (1.04) 4.61 3.12 0.152 In-SiO 2 @ 300 In-In 2.93 (0.66) (0.01) (0.01) In-In 1.36 2.96 In-SiO 2 @ 430 0.127 (0.2) 1.96 (0.30) (0.01) In-In 0.87 2.95 0.130 In-SiO 2 @ 873 5.77 (0.13) (0.01) (0.01) 1.08 2.84 0.159 In-SiO 2 @ 1173 In-In 0.84 (0.25) (0.03) (0.02)

Conclusions 18 1) XANES and EXAFS spectral patterns of In/SiO 2 catalyst are similar to the In foil. 2) In the present composite catalyst the active metal Indium is in pure metallic state not In 2 O 3 . 3) Almost the same XAFS patterns were observed for the different reaction time. 4) Operando quick-XAFS analysis technique was used to monitor In- SiO 2 catalyst during the reaction conditions.

Conclusions 19 5. At 430 K, EXAFS oscillations are shifted to higher k values also in FT spectra the peak In-In peak shifted to lower R value due to In melts into liquid at this temp. 6. Interestingly, CH 4 conversion starts at 873K and at the same time a new peak found in EXAFS spectra owing to In-X (X=C/O). 7. At 900 o C, methane activation reaction is more favour due to thermal as well as catalytic dissociation of CH 4 . 8. Edge height analysis conforms that carbon formation may prevent the evaporation of In metal.

20 Future plan 1) Thorough analysis of all previous experimental data to find the static and thermal disorder to justify the decrease of bond length with respect to the time. A5 2) We need carry-out XANES spectra under operando CH 4 reaction conditions. A6 3) We want to see the changes in XANES spectra by the addition of carbon into In metal under the operando conditions. Continue…

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21 Future plan 4) We will construct a new cell for IR and XRD simultaneous measurements. 5) We need to do the FEFF theoretical calculations. 6) Finally, we also wants to do the Reverse Monte Carlo (RMC) simulations.

22 Recent conference presentations 1. Methane Activation by In/SiO 2 Catalyst: Structure Elucidation using Operando QXAFS technique. Kashaboina Upendar, Natee Sirisit, Hiroko Ariga-Miwa, Satoru Takakusagi, Kiyotaka Asakura, Takahiro Wada, Yuta Nishikawa, Fumiya Kuriyama, Arnoldus lambertus Dipu, Shoji Iguchii, Ichiro Yamanaka and Hitoshi Ogiwara, 5 th International Symposium of Institute for Catalysis (ICAT) and Pre-conference of TOCAT8, “Material Design for Efficient Catalysis and Sustainable Chemistry”. August 3-4 th , 2018, Hokkaido University, Japan. 2. In situ quick X-ray absorption fine structure (QXAFS) study of In/SiO 2 catalyst under thermal dehydrogenation of methane. Kashaboina Upendar, Nattee Sirisit, Hiroko Ariga-Miwa, Satoru Takakusagi, Kiyotaka Asakura, Takahiro Wada, Yuta Nishikawa, Fumiya Kuriyama, Arnoldus lambertus Dipu, Shoji Inokuchi, Ichiro Yamanaka and Hitoshi Ogiwara, The 21 st XAFS Discussion, Organizer: Japan XAFS Study Group, September 3-5 th , 2018. Manuscript about XAFS under preparation Operando time-resolved QXAFS study of In K-edge on SiO 2 supported catalyst: Non-oxidative CH 4 Conversion to Higher Hydrocarbons Upendar Kashaboina † , Natee Sirisit † , Hiroko Ariga-Miwa † , Satoru Takakusagi † , Takahiro Wada ‡ , Yuta Nishikawa § § § § , Fumiya Kuriyama § § § § , Arnoldus lambertus Dipu § § § , Shoji Inokuchi § § § § § , Ichiro Yamanaka § § § , Hitoshi Ogiwara § § § § § and Kiyotaka Asakura † * † Institute for Catalysis, Hokkaido University Sapporo 001-0021, Japan § § § § Tokyo Institute of Technology, Ookayama, Meguro-Ku, Tokyo, 152-8552, Japan ‡ Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan *Corresponding Author: Telephone; Fax: +81-11-706-9113; E-mail addresses: askr@cat.hokudai.ac.jp