3. Institute for Catalysis, Hokkaido University 3
Heterogeneous catalysis: we need to consider wide range of length and time scale
Length, time
God made the bulk;
the surface was invented by the Devil.
ACS Catalysis 2020 (Review)
触媒分野などの物質のダイナミクスが重要となる分野では実験と計算の乖離が大きい
4. Institute for Catalysis, Hokkaido University 4
Operando modeling
Lukas Grajciar, et al., Chem. Soc. Rev., 2018, 47, 8307-8348
既存の第一原理計算で固体触媒プロセスの全てを計算するのは不可能
5. Institute for Catalysis, Hokkaido University 5
Matlantis for heterogeneous catalysis research
https://matlantis.com/ja/
6. Institute for Catalysis, Hokkaido University 6
https://www.catalysis-hub.org/
https://opencatalystproject.org/
Public databases
既存のデータベースではバルク物性がほとんど、
一部の表面(反応)を扱ったデータベースでも、比較的構造が単純なモノ(金属等)がほとんど+そもそも数足りない
といった状況で、NNPベースの計算(Matlantis)がどこまで精度がでるかは、ユーザー(鳥屋尾)としては興味深い
7. Institute for Catalysis, Hokkaido University 7
本日の話題
✓ NH3脱硝用WO3/CeO2触媒の計算
✓ 固体表面のアニオン欠陥生成エネルギーの計算
✓ Global Reaction Route Mapping (GRRM)とMatlantisを用いた、Cu-zeolite上でのNH3酸化反応機構解析
✓ 機械学習用の「元素/担体記述子」取得
Matlantisを用いた固体触媒研究(我々の取り組み)
※まだ始めたばかりで、まとまった話になっていなくて申し訳ございません。。。
実験系の触媒研究者の視点から、Matlantisの使用例、使用感を共有できればと思っています。
8. Institute for Catalysis, Hokkaido University 8
The need for low-temperature de-NOx (NH3-SCR) systems
Supported
vanadium oxide
Support
Cu
High
200 °C 300 °C
NH3-SCR catalysts
Low temperature NH3-SCR catalysts are required (<150 oC)
Cu-zeolite
Selective catalytic reduction of nitrogen oxides (NOx) using NH3 as the reducing agent (NH3–SCR)
- A commercially utilized de-NOx system to reduce emissions from exhausts in the presence of O2
V2O5/TiO2: Stationary systems such as in power plants
Cu-zeolite: Diesel vehicles
9. Institute for Catalysis, Hokkaido University 9
100 200 300 400 500
0
20
40
60
80
100
T (
o
C)
NO
x
conv.
(%)
WO3(10)/CeO2
V(1)-W(5)/TiO2
CeO2
(a)
0 1 2 3 4 5
0
0.5
1
W density (nm
-2
)
NO
reduction
rate
(mol
g
-1
h
-1
)
(b)
WO3/CeO2 for low-temperature NH3-SCR
ACS Catal. 2023, 13, 9274
11. Institute for Catalysis, Hokkaido University 11
Possible structures of WO3/CeO2
事前検討では、40以上の構造を検討
12. Institute for Catalysis, Hokkaido University 12
NH3脱硝用WO3/CeO2触媒の計算
VASP Matlantis
3D and 2D Phase diagrams showing the species with the lowest relative Gibbs free energy (ΔG) in terms of temperature and H2O partial pressure (log scale) and
the two possible structures: trimeric species W3O12H6/CeO2(111) and tetrameric species W4O13H2/CeO2(111); yellow: Ce; red: O; blue: W; white: H.
ACS Catal. 2023, 13, 9274
13. Institute for Catalysis, Hokkaido University 13
NH3脱硝用WO3/CeO2触媒の計算
EOvac versus minimum distance to a W atom from the O site obtained using VASP (left) and Matlantis (right); yellow: Ce; red: O; blue: W; white: H.
ACS Catal. 2023, 13, 9274
O欠陥生成エネルギー
※WO3の担持によりO欠陥生成が容易に
14. Institute for Catalysis, Hokkaido University 14
DOS計算はVASPで行いました
Partial DOS of the CeO2(111) surface, W3O12H6/CeO2(111), and local DOS of W3O12H6 of W3O12H6/CeO2(111)
without O vacancy (a) and with O vacancy (b). The energies are aligned at the vacuum level.
ACS Catal. 2023, 13, 9274
16. Institute for Catalysis, Hokkaido University 16
固体表面のアニオン欠陥生成エネルギーの計算
(i) 表面エネルギー (ii) 表面のアニオン欠陥生成エネルギー
arXiv:2304.10820
(現所属)産総研
峯真也
17. Institute for Catalysis, Hokkaido University 17
本日の話題
✓ NH3脱硝用WO3/CeO2触媒の計算
✓ 固体表面のアニオン欠陥生成エネルギーの計算
✓ Global Reaction Route Mapping (GRRM)とMatlantisを用いた、Cu-zeolite上でのNH3酸化反応機構解析
✓ 機械学習用の「元素/担体記述子」取得
Matlantisを用いた固体触媒研究(我々の取り組み)
18. Institute for Catalysis, Hokkaido University 18
Global Reaction Route Mapping (GRRM)
前田 理 教授
(ICReDD拠点長)
(プログラム開発者)
武次 徹也 教授
(ICReDD PI)
(共同研究者)
斉田 謙一郎
特任助教
(共同研究者)
プログラムが自動的に反応パスを網羅計算
GRRMプログラムを利用した反応経路探索
S. Maeda et al., Journal of Computational Chemistry, 2018, 39, 233
系内の任意の2原子に人工力
をかけて反応を誘発させる
大量の量子化学計算が必要 固体触媒開発への適用が限られる
19. Institute for Catalysis, Hokkaido University 19
より大規模な反応経路探索が可能に
(現所属)東京大学
安村駿作
GRRMプログラムとMatlantisを組み合わせた反応経路探索
20. Institute for Catalysis, Hokkaido University 20
Cu交換ゼオライトを用いた脱硝反応において、
望まれない反応であるNH3分解反応の反応経路を解明
※主要経路についてはVASPとの比較を行い、結果が概ね一致している
ことを確認
出発構造
GRRMプログラムとMatlantisを組み合わせた反応経路探索
21. Institute for Catalysis, Hokkaido University 21
本日の話題
✓ NH3脱硝用WO3/CeO2触媒の計算
✓ 固体表面のアニオン欠陥生成エネルギーの計算
✓ Global Reaction Route Mapping (GRRM)とMatlantisを用いた、Cu-zeolite上でのNH3酸化反応機構解析
✓ 機械学習用の「元素/担体記述子」取得
Matlantisを用いた固体触媒研究(我々の取り組み)
22. Institute for Catalysis, Hokkaido University 22
Reverse Water-Gas Shift (RWGS) reaction at low temperature (T ≤ 250 ˚C)
H2
CO2 +
Catalyst
CO ( + CH4 )
Catalyst H2/CO2 T (˚C) P (bar)
CO2 conv.
(%)
CO selec.
(%)
CO formation rate
(mmol gcat
-1 min-1)
Reference
Cu(10)-C/ZnO(5)/SiO2 3 250 30 6.0 99.0 <0.05 Sustain. Energy Fuels 2020, 4, 2937–2949
Li(10)-Rh(5)/Zeolite 3 250 30 13.0 87.0 0.12 Catalysts. 1998, 175, 67–81.3
Rh(0.4)/SiO2 3 250 10 2.5 84.6 <0.05 J. Am. Chem. Soc. 2019, 141, 8482−8488
K80-Pt(0.05)/zeolite L 1 250 1 1.0 100 0.19 Appl. Catal. B Environ. 2017, 216, 95–105
Au(1)/TiO2 4 250 1 11.5 100 0.13 ACS Catal. 2018, 8, 7455−7467
Pt(5)/TiO2 1 250 1 4.0 97.5 0.07 Catal. Today 2017, 281, 312–318
NH2MPA/Pt(5)/TiO2 14 250 1 8.4 95.1 0.06 J. Am. Chem. Soc. 2020, 142, 5184–5193
Pt(1)/CeO2 1 250 1 0.6 100 0.06 J. Energy Chem. 2016, 25, 1051–1057
In2O3-CeO2 1 250 1 <0.1 - <0.05 Catal. Today 2016, 259, 402–408
Pd(3)In/SiO2 1 250 1 <0.1 - <0.05 Chem. Eng. Sci. 2015, 135, 193–201
Pt(3)/MoOx(10)/TiO2 4 250 1 9.4 100 0.66 Our previous work (identified without use of ML)
T ≤ 250 ˚C
Through studies using in situ/operando spectroscopies and DFT calculations,
we have identified that MoOx species play important roles for progression of the reaction
23. Institute for Catalysis, Hokkaido University 23
Dataset (originally 45 datapoints) and ML models
Original dataset
Elemental properties as descriptors
Pt(3)/M1(X1)-M2(X2)-M3(X3)-M4(X4)-M5(X5)/TiO2
H2
CO2
250 ˚C, 1 atm
+ CO
X = 0, 1, 2, ..., 10 wt%
Electronegativity
Density
Enthalpy of fusion
Melting point
Group
Band gap in the most stable oxide form
Oxidation number in the most stable oxide form
Ead of CO2 on metallic surface (obtained using VASP)
ML models
ExtraTrees Regression (ETR)
Containing the catalysts consisting of 2 types of M elements
We explored up to 5 by using ML
The number of catalyst composition candidates considered is
more than 25 trillion
50C5 x 105
(50 elements except PGM, toxic, unstable elements)
* Even for four elements, 50C4 x 104 = approximately 60 billion
24. Institute for Catalysis, Hokkaido University 24
ML-assisted catalysts discovery
Original
Current
Dataset
ML
prediction
Catalysts
synthesis
Catalytic
reactions
Pt(3)/Rb(1)-Ba(1)-Mo(0.6)-Nb(0.2)/TiO2
(45) (79) (115) (162)
Number of
datapoints (catalysts tested)
(256) (300)
Pt/Mo-Cs-Ba-Tb-Lu/TiO2
Pt/Al-Mo-Re/TiO2
Pt/V-Sr-Nb-Mo-Re/TiO2
Datapoint
The best CO form. rate at each iteration
Prediction accuracy (R2) at each iteration
25. Institute for Catalysis, Hokkaido University 25
75%
lower
Development of effective DeNOx catalysts meet industrial requirements becomes increasingly necessary
R. Farrauto et al., Nat. Catal. 2 (2019) 603–613.
Hu, Z.; Yang, R. T. Industrial and Engineering Chemistry Research 2019, 58 (24), 10140–10153.
Several technologies applied for NOx abatement:
• NOx Storage and Reduction
• Selective Catalytic Reduction (SCR)
◆ NH3-SCR: ammonia slipping and
low activity at low temperature
◆ HC-SCR: low activity at low temperature
◆ H2-SCR: requires only low reaction temperature
(typically below 200 ˚C)
Nitrogen oxides (NOx)
emitted from combustion of fossil fuels Air pollution (photochemical smog, acid rain, etc)
Harm to human health
Selective catalytic reduction of NOx with H2 (H2-SCR)
26. Institute for Catalysis, Hokkaido University 26
NOx
O2
H2
N2
H2O
Selective catalytic reduction of NOx with H2 (H2-SCR)
Shortage of current H2-SCR technology:
Still relatively low efficiency at low temperature
It is highly desired to develop further efficient H2-SCR catalysts especially at low temperature region
Schott, F. J. P.; Balle, P.; Adler, J.; Kureti, S. Applied Catalysis B: Environmental 2009, 87, 18.
Pt/W/ZrO2
*X: Conversion
*S: Selectivity
27. Institute for Catalysis, Hokkaido University 27
Support
Additive precursor
H2O
M1(Y1)-M2(Y2)-M3(Y3)/Support
M1(Y1)-M2(Y2)-M3(Y3)/Support
PGMs precursor
H2O
Stirring at r.t. for 30 min.
Evaporation under vacuum at 50 ˚C
Calcination in air at 700 ˚C for 3 h
PGM1(X1)-PGM2(X2)-PGM3(X3)/M1(Y1)-M2(Y2)-M3(Y3)/Support
Stirring at r.t. for 30 min.
Evaporation under vacuum at 50 ˚C
Calcination in air at 700 ˚C for 3 h
ML target: average N2 yield (50-150 ˚C)
PGM1(X1)-PGM2(X2)-PGM3(X3)/M1(Y1)-M2(Y2)-M3(Y3)/Support
Light-off profile of Pt(2)/W(10)/Al2O3
Reaction conditions:
1000ppm NO, 6000ppm H2, 6%O2, 5%CO2, 1%H2O and He balance.
Total reaction flow rate = 100ml/min.
Pre-aging for 0.5 h under reaction gas flow at 300 ˚C
ML-assisted discovery of H2-SCR catalysts
28. Institute for Catalysis, Hokkaido University 28
Pt(2)/W(10)/Al2O3_gamma
Pt(1.3)-Ir(0.2)/Ba(1.5)-Co(1)/H-ZSM-5_11
※最後の数字はSi/Al比
ML-assisted discovery of H2-SCR catalysts
Dataset
ML
prediction
Catalysts
synthesis
Catalytic
reactions
29. Institute for Catalysis, Hokkaido University 29
Choice of descriptors_elements
Matlantisを利用して各元素(metal)表面上での吸着エネルギーを計算 → 記述子として利用
30. Institute for Catalysis, Hokkaido University 30
Choice of descriptors_supports
Matlantisを利用して各担体上での吸着エネルギーを計算 → 記述子として利用
31. Institute for Catalysis, Hokkaido University 31
XAFS measurements
Summary
✓ NH3脱硝用WO3/CeO2触媒の計算
✓ 固体表面のアニオン欠陥生成エネルギーの計算
✓ Global Reaction Route Mapping (GRRM)とMatlantisを用いた、Cu-zeolite上でのNH3酸化反応機構解析
✓ 機械学習用の「元素/担体記述子」取得
Matlantisを用いた固体触媒研究(我々の取り組み)
※まだ始めたばかりで、まとまった話になっていなくて申し訳ございません。。。
32. Institute for Catalysis, Hokkaido University 32
Acknowledgements
北海道大学
清水研究室メンバー
(現所属)産総研
峯真也
(現所属)東京大学
安村駿作