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

• 1. In/SiO2 is a good catalyst for the effective non oxidative

conversion of methane1.

• 2. In/SiO2 is cheap and effective hybrid catalyst.
• 3. Non oxidative CH4 activation reaction has a merit to produce CO2

and H2O (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. 2

Ref: Yuta Nishikawa et. al. Chemistry Select (2017) 4572 – 4576

Designed cell for high temperature operando measurements 3

EXAFS Equation

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

Analysed data using REX2000 1. In foil (30, 100, 200, 260 and 300 K) 2. In2O3 (30, 100, 200, 260 and 300 K) 3. In @SiO2, 0 h reaction time (30, 100, 200, 260 and 300 K) 4. In @SiO2, 3 h reaction time (30, 100, 200, 260 and 300 K) 5. In @SiO2, 12 h reaction time (30, 100, 200, 260 and 300 K) 5

In2O3

k ꭓ(k)

EXAFS oscillation

FT magnitude

Fourier Transform

Background subtracted In/SiO2

In foil

In2O3

XAFS analysis In foil, In2O3 and In/SiO2

Normalized absorption coefficient (a.u.)

In/SiO2

In foil

XANES

In2O3

k (A-1)

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7 XAFS analysis In foil, In2O3 and In/SiO2 From the above XAFS results:  XANES and EXAFS spectral patterns of In/SiO2 catalyst are similar to the In foil.  Therefore, the active metal Indium is in pure metallic state not In2O3.

0 h 3 h 12 h In K-edge XANES

XAFS : In/SiO2 catalysts for Methane Activation 0 hr, 3 hr and 12 h

Normalized absorption coefficient (a.u.) k (A-1)

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

In foil In/SiO2, 0 hr

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

In/SiO2, 12 hr In/SiO2, 3 hr 10

Debye-Waller Factor value Vs Temperature

In foil

3 hr 0 hr 12 hr

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 DW values are gradually increasing with the reaction temperature.

June-2018, Beam time data i. All the experimental raw data converted into .ex3 ii. Smoothing and Interpolation

• iii. Integrated the above data using REX2000 software

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I. Quick-EXAFS analysis under the CH4 flow

• II. Quick-EXAFS analysis under the He flow

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In-SiO2 catalyst for methane activation

(a) CH4 flow; (b) He gas flow

Edge height Vs Temperature

A3

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EXAFS oscillations (a) 300 K (b) 430 K (c) 873 K (d) 1173 K (e) 873 K (during 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)

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Fourier transforms spectra of In- SiO2 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)

Fourier transform spectra

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Evaluation of Structural Parameters Obtained by EXAFS Curve-Fitting of In-In and In-C Shells Catalyst@ Temp (K) Shell N R (Å) σ2 (× × × ×10-3) R-factor (%) In-SiO2 @ 33 In-In 2.85 3.26 0.062 8.14 In-In* 5.70 3.37 0.144 8.14 In-SiO2 @ 300 In-In 2.85 3.19 0.179 9.57 In-In* 5.70 3.39 0.320 9.57 In-SiO2 @ 430 In-In 2.85 3.02 0.210 4.34 In-In* 5.70 3.31 0.372 4.34 In-SiO2 @ 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-SiO2 @ 1173 In-In

• 2.96

0.392 8.19 In-In*

• 3.31

0.420 8.19

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Catalyst @ Temp (K) Shell N (nm) R (Å) σ (×10-2) R-factor (%) In-SiO2 @ 33 In-In 5.54 (1.04) 3.28 (0.01) 0.09 (0.01) 4.40 In-SiO2 @ 300 In-In 4.61 (0.66) 3.12 (0.01) 0.152 (0.01) 2.93 In-SiO2 @ 430 In-In 1.36 (0.30) 2.96 (0.01) 0.127 (0.2) 1.96 In-SiO2 @ 873 In-In 0.87 (0.13) 2.95 (0.01) 0.130 (0.01) 5.77 In-SiO2 @ 1173 In-In 1.08 (0.25) 2.84 (0.03) 0.159 (0.02) 0.84

Single shell curve-fitting results

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Conclusions

1) XANES and EXAFS spectral patterns of In/SiO2 catalyst are similar to the In foil. 2) In the present composite catalyst the active metal Indium is in pure metallic state not In2O3. 3) Almost the same XAFS patterns were observed for the different reaction time. 4) Operando quick-XAFS analysis technique was used to monitor In- SiO2 catalyst during the reaction conditions.

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Conclusions

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, CH4 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 oC, methane activation reaction is more favour due to thermal as well as catalytic dissociation of CH4. 8. Edge height analysis conforms that carbon formation may prevent the evaporation of In metal.

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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. 2) We need carry-out XANES spectra under operando CH4 reaction conditions. 3) We want to see the changes in XANES spectra by the addition

• f carbon into In metal under the operando conditions.

Continue…

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21 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.

Future plan

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1. Methane Activation by In/SiO2 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, 5th International Symposium of Institute for Catalysis (ICAT) and Pre-conference of TOCAT8, “Material Design for Efficient Catalysis and Sustainable Chemistry”. August 3-4th, 2018, Hokkaido University, Japan. 2. In situ quick X-ray absorption fine structure (QXAFS) study of In/SiO2 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 21st XAFS Discussion, Organizer: Japan XAFS Study Group, September 3-5th, 2018.

Recent conference presentations

Operando time-resolved QXAFS study of In K-edge on SiO2 supported catalyst: Non-oxidative CH4 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 Medical and Dental University, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan § § § §Tokyo Institute of Technology, Ookayama, Meguro-Ku, Tokyo, 152-8552, Japan

*Corresponding Author: Telephone; Fax: +81-11-706-9113; E-mail addresses: askr@cat.hokudai.ac.jp

Manuscript about XAFS under preparation

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Acknowledgements

 Japan Science and Technology (JST)-CREST project “Innovative Catalysts” JPMJCR15P4.  Prof. Jun-ya Hasegawa, Director of ICAT  Prof. Ichiro Yamanaka  All participants  All my colleagues

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Thank you for your kind attention ǃǃǃ

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