Material Discovery and High Throughput Exploration of Ru based Catalysts for Low

Temperature Ammonia Decomposition

October 31st 2018 Ammonia Fuel and Energy Storage: Cracking & Fuel Cells

AIChE Annual Conference

Katie McCullough, Travis Williams, Calvin Thomas and Jochen Lauterbach

Department of Chemical Engineering, University of South Carolina, Columbia, SC 29205 USA

Pittsburgh, Transylvania

Thermocatalytic Ammonia Decomposition

2

𝑁𝐻↓3 → 𝑁𝐻↓2 →𝑁𝐻→𝑁−𝐻 −𝐻 −𝐻

𝑁+𝑁→𝑁↓2 

𝐻+𝐻→𝐻↓2 

Dehydrogenation

Recombination

Zheng et al., Catal Lett 119 (2007) 311-318.Torrente-Murciano et al., Catal. Today 286 (2017) 131-140.Mukherjee et al., App. Catal B: Environmental 226 (2018) 162-181.

Thermodynamic Equilibrium of NH3

RuNiCo

0 100 200 300 400 500 600 7000.0

0.2

0.4

0.6

0.8

1.0

1 bar

NH

3 Con

vers

ion

Temperature (oC)

Materials for Ammonia Decomposition

3

Ru Ni Fe Co Ir Cu Mo VC Rh Pt Pd Zr Ca CrRh-NiNi-Ru Ni-

Ir

Cu-ZnNi-Cu

Co-MoFe-Mo

0

50

100

150

200

Num

ber o

f Stu

dies

(200

1-20

18)

Active Metal Studied

MonometallicsBimetallics

Ammonia Decomposition

Many theoretical models exist that correlate different energies to NH3 decomposition activity

No correlation found between 7 models and 13 metals

4Ganley et al., Catalysis Letters (2004) 96:117

Design Space

Incipient Wetness ImpregnationBaseline 4wt% Ru on Al2O3

Total 4wt% metal 3wt% Ru + 1wt% M 2wt% Ru + 2wt% M 1wt% Ru + 3wt% M+12 wt% K

5

105 unique formulations + repeats

Pyrz et al.,Top Catal (2008) 50:180-191.

High-Throughput Reactor System

•  16 parallel plug flow reactors•  Capillary flow distribution system•  Individual catalyst bed thermocouples•  Four furnaces with PID control

(Tmax=950°C)•  Powder catalysts: 0.05-1 g•  Atmospheric pressure•  Moving top plate and winch system

for efficient loading/unloading

6Sasmaz et al., Engineering 1(2), 2015Hendershot et al., Appl. Catal. A 254, 107 – 120 (2003)

Effluent Gas Analysis

•  IR gas-phase spectroscopy Works for any gas with IR signature

7

FPA

•  16-element gas-phase arrayAnalyze all 16 product streams in parallel in < 2 sec

Snively, C.M. and J. Lauterbach Applied Spectroscopy 59(2005)Snively, C.M., S. Katzenberger, G. Oskarsdottir, and J. Lauterbach Optics Letters 24 (1999)

128 pixels

128 pixels

Spatially resolved IR spectra 128 x 128 = 16,384 detectors

Groupings of RuMK

8

4 Ru

4,12 R

uK

3,1,12

RuC

uK

2,2,12

RuC

uK

1,3,12

RuC

uK3,1

,12 R

uYK

2,2,12

RuY

K

1,3,12

RuY

K3,1

,12 R

uMgK

2,2,12

RuM

gK

1,3,12

RuM

gK3,1

,12 R

uMnK

2,2,12

RuM

nK

1,3,12

RuM

nK3,1

,12 R

uNiK

2,2,12

RuN

iK

1,3,12

RuN

iK3,1

,12 R

uCrK

2,2,12

RuC

rK

1,3,12

RuC

rK3,1

,12 R

uWK

2,2,12

RuW

K

1,3,12

RuW

K3,1

,12 R

uCaK

2,2,12

RuC

aK

1,3,12

RuC

aK3,1

,12 R

uHfK

2,2,12

RuH

fK

1,3,12

RuH

fK3,1

,12 R

uScK

2,2,12

RuS

cK

1,3,12

RuS

cK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsio

n

311222121312

Reaction ConditionsTemperature = 300oC1% NH3 in balance Ar Pressure = 1.01 bar200 mg catalyst

30,000 mL/g↓cat ∙hr 

3,1,12

RuR

hK

2,2,12

RuR

hK

1,3,12

RuR

hK3,1

,12 R

uZnK

2,2,12

RuZ

nK

1,3,12

RuZ

nK3,1

,12 R

uSrK

2,2,12

RuS

rK

1,3,12

RuS

rK3,1

,12 R

uBiK

2,2,12

RuB

iK

1,3,12

RuB

iK3,1

,12 R

uPdK

2,2,12

RuP

dK

1,3,12

RuP

dK3,1

,12 R

uInK

2,2,12

RuIn

K

1,3,12

RuIn

K3,1

,12 R

uMoK

2,2,12

RuM

oK

1,3,12

RuM

oK2,2

,12 R

uIrK

1,3,12

RuIr

K3,1

,12 R

uReK

2,2,12

RuR

eK

1,3,12

RuR

eK3,1

,12 R

uFeK

2,212

RuF

eK

1,3,12

RuF

eK3,1

,12 R

uCoK

2,2,12

RuC

oK

1,3,12

RuC

oK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsio

n

Reaction Results

93,1,12

RuR

hK

2,2,12

RuR

hK

1,3,12

RuR

hK3,1

,12 R

uZnK

2,2,12

RuZ

nK

1,3,12

RuZ

nK3,1

,12 R

uSrK

2,2,12

RuS

rK

1,3,12

RuS

rK3,1

,12 R

uBiK

2,2,12

RuB

iK

1,3,12

RuB

iK3,1

,12 R

uPdK

2,2,12

RuP

dK

1,3,12

RuP

dK3,1

,12 R

uInK

2,2,12

RuIn

K

1,3,12

RuIn

K3,1

,12 R

uMoK

2,2,12

RuM

oK

1,3,12

RuM

oK2,2

,12 R

uIrK

1,3,12

RuIr

K3,1

,12 R

uReK

2,2,12

RuR

eK

1,3,12

RuR

eK3,1

,12 R

uFeK

2,212

RuF

eK

1,3,12

RuF

eK3,1

,12 R

uCoK

2,2,12

RuC

oK

1,3,12

RuC

oK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsio

n

4 Ru

4,12 R

uK

3,1,12

RuC

uK

2,2,12

RuC

uK

1,3,12

RuC

uK3,1

,12 R

uYK

2,2,12

RuY

K

1,3,12

RuY

K3,1

,12 R

uMgK

2,2,12

RuM

gK

1,3,12

RuM

gK3,1

,12 R

uMnK

2,2,12

RuM

nK

1,3,12

RuM

nK3,1

,12 R

uNiK

2,2,12

RuN

iK

1,3,12

RuN

iK3,1

,12 R

uCrK

2,2,12

RuC

rK

1,3,12

RuC

rK3,1

,12 R

uWK

2,2,12

RuW

K

1,3,12

RuW

K3,1

,12 R

uCaK

2,2,12

RuC

aK

1,3,12

RuC

aK3,1

,12 R

uHfK

2,2,12

RuH

fK

1,3,12

RuH

fK3,1

,12 R

uScK

2,2,12

RuS

cK

1,3,12

RuS

cK

0.00.10.20.30.40.50.60.70.80.91.0

Baseline Conversion

NH3 C

onve

rsio

n

Reaction ConditionsTemperature = 300oC1% NH3 in balance Ar Pressure = 1.01 bar200 mg catalyst

30,000 mL/g↓cat ∙hr 

Reaction Results

10

4 Ru

4,12 R

uK

3,1,12

RuC

uK

2,2,12

RuC

uK

1,3,12

RuC

uK3,1

,12 R

uYK

2,2,12

RuY

K

1,3,12

RuY

K3,1

,12 R

uMgK

2,2,12

RuM

gK

1,3,12

RuM

gK3,1

,12 R

uMnK

2,2,12

RuM

nK

1,3,12

RuM

nK3,1

,12 R

uNiK

2,2,12

RuN

iK

1,3,12

RuN

iK3,1

,12 R

uCrK

2,2,12

RuC

rK

1,3,12

RuC

rK3,1

,12 R

uWK

2,2,12

RuW

K

1,3,12

RuW

K3,1

,12 R

uCaK

2,2,12

RuC

aK

1,3,12

RuC

aK3,1

,12 R

uHfK

2,2,12

RuH

fK

1,3,12

RuH

fK3,1

,12 R

uScK

2,2,12

RuS

cK

1,3,12

RuS

cK

0.00.10.20.30.40.50.60.70.80.91.0

Baseline Converison 4,12 RuK Conversion

NH3 C

onve

rsio

n

Reaction ConditionsTemperature = 300oC1% NH3 in balance Ar Pressure = 1.01 bar200 mg catalyst

30,000 mL/g↓cat ∙hr 

3,1,12

RuR

hK

2,2,12

RuR

hK

1,3,12

RuR

hK3,1

,12 R

uZnK

2,2,12

RuZ

nK

1,3,12

RuZ

nK3,1

,12 R

uSrK

2,2,12

RuS

rK

1,3,12

RuS

rK3,1

,12 R

uBiK

2,2,12

RuB

iK

1,3,12

RuB

iK3,1

,12 R

uPdK

2,2,12

RuP

dK

1,3,12

RuP

dK3,1

,12 R

uInK

2,2,12

RuIn

K

1,3,12

RuIn

K3,1

,12 R

uMoK

2,2,12

RuM

oK

1,3,12

RuM

oK2,2

,12 R

uIrK

1,3,12

RuIr

K3,1

,12 R

uReK

2,2,12

RuR

eK

1,3,12

RuR

eK3,1

,12 R

uFeK

2,212

RuF

eK

1,3,12

RuF

eK3,1

,12 R

uCoK

2,2,12

RuC

oK

1,3,12

RuC

oK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsio

n

Reaction Results

4 Ru

4,12

RuK

3,

1,12

RuC

uK2,

2,12

RuC

uK1,

3,12

RuC

uK3,

1,12

RuY

K2,

2,12

RuY

K1,

3,12

RuY

K4,

0.5,

12 R

uYK

3,1,

12 R

uMgK

2,2,

12 R

uMgK

1,3,

12 R

uMgK

3,1,

12 R

uMnK

2,2,

12 R

uMnK

1,3,

12 R

uMnK

3,1,

12 R

uNiK

2,2,

12 R

uNiK

1,3,

12 R

uNiK

3,1,

12 R

uCrK

2,2,

12 R

uCrK

1,3,

12 R

uCrK

3,1,

12 R

uWK

2,2,

12 R

uWK

1,3,

12 R

uWK

3,1,

12 R

uCaK

2,2,

12 R

uCaK

1,3,

12 R

uCaK

3,1,

12 R

uHfK

2,2,

12 R

uHfK

1,3,

12 R

uHfK

3,1,

12 R

uScK

2,2,

12 R

uScK

1,3,

12 R

uScK

0.00.10.20.30.40.50.60.70.80.91.0

Baseline Conversion 4,12 RuK Conversion

NH

3 Con

vers

ion

113,1,

12 R

uRhK

2,2,

12 R

uRhK

1,3,

12 R

uRhK

3,1,

12 R

uZnK

2,2,

12 R

uZnK

1,3,

12 R

uZnK

3,1,

12 R

uSrK

2,2,

12 R

uSrK

1,3,

12 R

uSrK

3,1,

12 R

uBiK

2,2,

12 R

uBiK

1,3,

12 R

uBiK

3,1,

12 R

uPdK

2,2,

12 R

uPdK

1,3,

12 R

uPdK

3,1,

12 R

uInK

2,2,

12 R

uInK

1,3,

12 R

uInK

3,1,

12 R

uMoK

2,2,

12 R

uMoK

1,3,

12 R

uMoK

2,2,

12 R

uIrK

1,3,

12 R

uIrK

3,1,

12 R

uReK

2,2,

12 R

uReK

1,3,

12 R

uReK --

3,1,

12 R

uFeK

2,21

2 Ru

FeK

1,3,

12 R

uFeK --

3,1,

12 R

uCoK

2,2,

12 R

uCoK

1,3,

12 R

uCoK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsio

n

Mg Ca Hf

RhSr

YSc

Reaction Conditions: Temperature= 300oC, 1% NH3 in balance Ar, Pressure = 1.01 bar, 200 mg catalyst, 30,000 mL/g↓cat ∙hr 

3,1,12 RuYK

12

Catalytic Activity in 100% NH3, atmospheric pressure and 52,000 mL NH3·(min·gcat)-1

[1] Hill, Applied Catalysis B: Environmental 172–173, (2015), 129-135.Mukherjee et al., Applied Catalysis B: Environmental 226 (2018) 162-181.Provisional Patent Pending: “Ammonia Decomposition Catalysts and Systems”, US patent application 62/720,356, August 2018.

Catalyst Conversion @ 673K Activation Energy (kJ/mol)

3,1,12 RuYK – Al2O3 95 54.17,4 RuCs – CNT1 64 78.6

2.4 2.8 3.2 3.6 4.0-7.0

-6.5

-6.0

-5.5

-5.0

-4.5

-4.0

-3.5

ln(T

OF)

Inverse Temperature (1/1000 K-1)

500 550 600 650 7000.0

0.2

0.4

0.6

0.8

1.0 3112 RuYK 7,4 RuCs - CNT1

Frac

tion

NH

3 C

onve

rsio

n

Temperature (K)

Single Reactor Results

13

Reaction Conditions: 10% NH3 in balance Ar, Pressure = 1.01 bar, 200 mg catalyst, 30,000 mL/g↓cat ∙hr 

Provisional Patent Pending: “Ammonia Decomposition Catalysts and Systems”, US patent application 62/720,356, August 2018.

300 350 400 4500.0

0.1

0.2

0.3

0.4

0.5

NH

3 Con

vers

ion

(%)

Temperature (oC)

4,12 YK 4 Y

300 350 400 450 500 5500.0

0.1

0.2

0.3

0.4

0.5

NH

3 Con

vers

ion

(%)

Temperature (oC)

4,12 HfK 4 Hf

Application of Machine Learning in Experimental Catalysis

14

Data Features

Machine Learning

Feature Impacts

Predictions

Determine which features cause

better performance

Find optimally performing material faster and with

less experiments

4 Ru

4,12 R

uK3,1

,12 R

uCuK

2,2,12

RuC

uK1,3

,12 R

uCuK

3,1,12

RuY

K2,2

,12 R

uYK

1,3,12

RuY

K3,1

,12 R

uMgK

2,2,12

RuM

gK1,3

,12 R

uMgK

3,1,12

RuM

nK2,2

,12 R

uMnK

1,3,12

RuM

nK3,1

,12 R

uNiK

2,2,12

RuN

iK1,3

,12 R

uNiK

3,1,12

RuC

rK2,2

,12 R

uCrK

1,3,12

RuC

rK3,1

,12 R

uWK

2,2,12

RuW

K1,3

,12 R

uWK

3,1,12

RuC

aK2,2

,12 R

uCaK

1,3,12

RuC

aK3,1

,12 R

uHfK

2,2,12

RuH

fK1,3

,12 R

uHfK

3,1,12

RuS

cK2,2

,12 R

uScK

1,3,12

RuS

cK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsion

2,2,12

RuR

hK1,3

,12 R

uRhK

3,1,12

RuZ

nK2,2

,12 R

uZnK

1,3,12

RuZ

nK3,1

,12 R

uSrK

2,2,12

RuS

rK1,3

,12 R

uSrK

3,1,12

RuB

iK2,2

,12 R

uBiK

1,3,12

RuB

iK3,1

,12 R

uPdK

2,2,12

RuP

dK1,3

,12 R

uPdK

3,1,12

RuIn

K2,2

,12 R

uInK

1,3,12

RuIn

K3,1

,12 R

uMoK

2,2,12

RuM

oK1,3

,12 R

uMoK

2,2,12

RuIr

K1,3

,12 R

uIrK

3,1,12

RuR

eK2,2

,12 R

uReK

1,3,12

RuR

eK --3,1

,12 R

uFeK

2,212

RuF

eK1,3

,12 R

uFeK --

3,1,12

RuC

oK2,2

,12 R

uCoK

1,3,12

RuC

oK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsion

Catalyst Predictions

15

RuScK

RuYK

RuSrK

Predicted

RuScK

RuYK

RuSrK

Experimental

Predicted NH3 conversion using RuCaK, RuMnK, and RuInK catalysts tested at 250, 300, and 350°C as a training set

ML – Knowledge Extraction

16

Work Function

Mean Absolute Deviation (MAD) ∑↑▒1/𝑛 ( 𝑥↓𝑖 −𝜇) 

𝒙↓𝒊  = value of property𝝁 = average𝒏 = number of samples

Li et al., J. Mater. Chem. A, 2017 5, 24131-24138.Liu et al., J. Materiomics, 2017 3 (3) 159-177.

Number d-shell Valence ElectronsT = 300oC

17

2212 RuYK3112 RuMgK3112 RuHfK

Mea

sure

d C

onve

rsio

n

MAD of Number d-shell Valence Electrons

Feature InteractionsT = 300oC

18

MADofWorkFunction

MADofN

umbe

rd-shellV

alen

ceElectron

1.761.681.601.521.441.361.281.20

5.0

4.5

4.0

3.5

3.0

2.5

> –––––< 0.3

0.3 0.40.4 0.50.5 0.60.6 0.70.7 0.8

0.8

ConversionMeasured

Vayenas et al., Nature 1990. 343, 625-627.Haller, J. Catal. 216 (2003) 12-22.Binninger et al., Phys. Rev. B. 96, 165405 (2017).

2212 RuYK

3112 RuMgK

3112 RuHfK

2212 RuInK

1312 RuZnK

3112 RuMoK

Conclusions

• HTE allows us to screen large amounts of catalysts for low temperature NH3 decomposition

•  New catalysts formulations discovered substituting Ru with Y and Hf•  At 300oC, we achieved 30% higher conversion than the “state of the

art” catalyst, which has more than 2x Ru• ML allows to unravel important factors and interactions from

HTE data•  Extraction of features•  Systematic trends from feature interactions

• Guide future iterations of catalyst design

19

Acknowledgements

• Strategic Approach to the Generation of Electricity Center (SAGE)

• NSF IGERT DGE-1250052• ARPA-E DE-AR0000931• Travis Williams

•  Data Science in Catalysis•  Nov 1 @ 12:30pm Rm 402

20

Supplemental Slides

Ammonia Decomposition• Efficient method for hydrogen

storage and transportation• Liquid at 8 bar and 298K• Less volume and weight than

alternative hydrogen storage methods

22

𝑁𝐻↓3 → 𝑁𝐻↓2 →𝑁𝐻→𝑁−𝐻 −𝐻 −𝐻

𝑁+𝑁→𝑁↓2 

𝐻+𝐻→𝐻↓2 

Dehydrogenation

Recombination

Sakintuna et al., Internation Journal of Hydrogen Energy. (2007). 32:1121-1140.Mukherjee et al., Applied Catalysis B: Environmental 226 (2018) 162-181.

Comparison of equivalent mass and volume of 10 kg of hydrogen stored in different materials

Ammonia DecompositionRu supported catalysts

23

•  100% conversion at 823K (550oC)

•  >95% conversion at low temperatures to avoid degradation of fuel cell

Zheng et al., Catal Lett (2007) 119:311-318.Itoh, Catal. Today (2014)236:70-76.

Ammonia Decomposition Promoters

24

•  Tested K, Cs, Ba, Sr, Rb, Ca, Na and Li•  K, Cs and Ba loadings optimized through a surface response study•  Developed response surface model as a function of promoters•  Promotional effects completely dominated by K

Response surface model for Ba/Cs/K promoters on 4wt%Ru on Al2O3

Pyrz. Top Catal (2008) 50:180-191.

Promotion of Ru/γ-Al2O3 Catalysts

25

0 10 20 30 40 50 60 70 80 90 1000

10

20

30

40

50

60

70

80

90

100

Mod

elP

redicted

%N

H3Con

version

E xperimenta l% NH3C onvers ion

■Model Development Points

Term Coefficients Constant 35.7

Ba -1.8 K 22.3 Cs -2.6

Ba*Ba -0.5 K*K 5.6

Cs*Cs -3.0 Ba*K -0.9 Ba*Cs -1.0 K*Cs -4.7

).....*()*(......)()()......()()( 212

22

1321 CsBaKBaKBaCsKBaCR λλββααα +++++++=

Carbon Free Hydrogen Storage and Generation materialsMetal Hydrides •  NaAlH4 - 5.6% H2 but needs 10-40MPa to

dehydrogenate •  LaN5H6 - 1.37% H2

•  MgNiH4 - 3.59% H2

26

Ammonia•  17.4 wt% H2 •  Liquefied at RT and 8 bar•  Established transportation infrastructure and

safety precautions

Comparison of equivalent mass and volume of 10 kg of hydrogen stored in different materials

Sakintuna B., Internation Journal of Hydrogen Energy. (2007). 32:1121-1140.Christensen et al., Journal of Materials Chemistry. (2005) 15:4106-4107.Mukherjee et al., Applied Catalysis B: Environmental 226 (2018) 162-181.

Metal Amines•  Metal chlorides easily complex with amines•  Mg(NH3)6Cl2•  Complete decomposition at 620K

27Li et al., J. Mater. Chem. A, 2017 5, 24131-24138.

Ammonia Decomposition Particle Size and Morphology

28Zheng et al., Catal Lett (2007) 119:311-318.

100 mg cat, 30,000 𝑚𝐿/hr∙g↓cat  , 100% NH3

Ru wt% 0.7 1.9 2.9 4.7 5.7Mean particle size (TEM) 1.9 2.2 2.9 3.5 4.2

Spatial,x

Spatial,y

HyperspectralDataCube

FTIRImaging

FTIRSpectrometer

Sample

128x128MCTFPA

Wavenumber(cm-1)

Absorban

ce

29

Snively,C.M.andJ.LauterbachAppliedSpectroscopy59(2005)

Parallel FTIR Imaging

30

Reaction ResultsT = 400oC

31Reaction Conditions: 1% NH3 in balance Ar, Pressure = 1.01 bar, 200 mg catalyst, 30,000 mL/g↓cat ∙hr 

3,1,

12 R

uScK

2,2,

12 R

uScK

1,3,

12 R

uScK

3,1,

12 R

uScK

2,2,

12 R

uRhK

1,3,

12 R

uRhK

3,1,

12 R

uZnK

2,2,

12 R

uZnK

1,3,

12 R

uZnK

3,1,

12 R

uSrK

2,2,

12 R

uSrK

1,3,

12 R

uSrK

3,1,

12 R

uBiK

2,2,

12 R

uBiK

1,3,

12 R

uBiK

3,1,

12 R

uPdK

2,2,

12 R

uPdK

1,3,

12 R

uPdK

3,1,

12 R

uInK

2,2,

12 R

uInK

1,3,

12 R

uInK

3,1,

12 R

uMoK

2,2,

12 R

uMoK

1,3,

12 R

uMoK

2,2,

12 R

uIrK

1,3,

12 R

uIrK

3,1,

12 R

uReK

2,2,

12 R

uReK

1,3,

12 R

uReK

0.00.10.20.30.40.50.60.70.80.91.0

NH

3 Con

vers

ion

4 Ru

4,12

RuK

3,

1,12

RuC

uK2,

2,12

RuC

uK1,

3,12

RuC

uK3,

1,12

RuY

K2,

2,12

RuY

K1,

3,12

RuY

K4,

0.5,

12 R

uYK

3,1,

12 R

uMgK

2,2,

12 R

uMgK

1,3,

12 R

uMgK

3,1,

12 R

uMnK

2,2,

12 R

uMnK

1,3,

12 R

uMnK

3,1,

12 R

uNiK

2,2,

12 R

uNiK

1,3,

12 R

uNiK

3,1,

12 R

uCrK

2,2,

12 R

uCrK

1,3,

12 R

uCrK

3,1,

12 R

uWK

2,2,

12 R

uWK

1,3,

12 R

uWK

3,1,

12 R

uCaK

2,2,

12 R

uCaK

1,3,

12 R

uCaK

3,1,

12 R

uHfK

2,2,

12 R

uHfK

1,3,

12 R

uHfK

0.00.10.20.30.40.50.60.70.80.91.0

Baseline Conversion

NH

3 Con

vers

ion

Reaction Conditions: 1% NH3 in balance Ar, Pressure = 1.01 bar, 200 mg catalyst, 30,000 mL/g↓cat ∙hr 

Reaction ResultsT = 350oC

32

4 Ru

4,12

RuK

3,1,

12 R

uCuK

2,2,

12 R

uCuK

1,3,

12 R

uCuK

3,1,

12 R

uYK

2,2,

12 R

uYK

1,3,

12 R

uYK

3,1,

12 R

uMgK

2,2,

12 R

uMgK

1,3,

12 R

uMgK

3,1,

12 R

uMnK

2,2,

12 R

uMnK

1,3,

12 R

uMnK

3,1,

12 R

uNiK

2,2,

12 R

uNiK

1,3,

12 R

uNiK

3,1,

12 R

uCrK

2,2,

12 R

uCrK

1,3,

12 R

uCrK

3,1,

12 R

uWK

2,2,

12 R

uWK

1,3,

12 R

uWK

3,1,

12 R

uCaK

2,2,

12 R

uCaK

1,3,

12 R

uCaK

3,1,

12 R

uHfK

2,2,

12 R

uHfK

1,3,

12 R

uHfK

3,1,

12 R

uScK

2,2,

12 R

uScK

1,3,

12 R

uScK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsio

n2,

2,12

RuR

hK1,

3,12

RuR

hK3,

1,12

RuZ

nK2,

2,12

RuZ

nK1,

3,12

RuZ

nK3,

1,12

RuS

rK2,

2,12

RuS

rK1,

3,12

RuS

rK3,

1,12

RuB

iK2,

2,12

RuB

iK1,

3,12

RuB

iK3,

1,12

RuP

dK2,

2,12

RuP

dK1,

3,12

RuP

dK3,

1,12

RuI

nK2,

2,12

RuI

nK1,

3,12

RuI

nK3,

1,12

RuM

oK2,

2,12

RuM

oK1,

3,12

RuM

oK2,

2,12

RuI

rK1,

3,12

RuI

rK3,

1,12

RuR

eK2,

2,12

RuR

eK1,

3,12

RuR

eK --3,

1,12

RuF

eK2,

212

RuFe

K1,

3,12

RuF

eK --3,

1,12

RuC

oK2,

2,12

RuC

oK1,

3,12

RuC

oK

0.00.10.20.30.40.50.60.70.80.91.0

NH3 C

onve

rsio

n

Ammonia Decomposition

33

Global Production of Elements in 2010

Bell, T. E. Top. Catalysis. (2016) 15:1438-1457.

Substitutional Metals for Low T Ammonia Decomposition

34

Promising Ru Substitutes

Au USD/g  Ru Hf Mg Ca Sc Sr Rh Y Mn

5.54 14.0 1.20 .003 .20 14.0 1.0 130.0 4.30 .065

Metal prices https://www.chemicool.com/

•  Hf•  Mg•  Ca•  Mn

•  Sc•  Rh•  Sr•  Y

kg/yr Ru Hf Mg Ca Sc Sr Rh Y Mn

104 107 1010 1011 103 109 104 107 1010

Global Production 2010

Price of Metal 2018

Unknown Structures

35

(a) 2,2,12 RuFeK (b) 2,2,12 RuIrK (c) 2,2,12 RuCoK

•  Defect density is increased from decomposition of needle like precursor state, increasing catalytic activity over the nanoparticle counterparts

XPS 4,12 RuK Hollandites

36

490 480 470 460 450

Cou

nts

Binding Energy (eV)

Ru0 3p3/2

Ru0BindingEnergy(eV) 3p3/2 3p1/2Reference 462.0 484.0

Actual 462.1 484.1

Briggs, D., 1981. Handbook of X‐ray Photoelectron Spectroscopy

4,12 RuK Hollandite XPS after reduction in H2 for 1hr at 450oC

Machine Learning Features

37

•  AtomicNumber•  AtomicVolume•  AtomicWeight•  BoilingTemperature•  Column-PeriodicTable•  Conductivity•  CovalentRadius•  Density•  DipolePolarizability•  ElectronAffinity•  Electronegativity

•  FusionEnthalpy•  GroundStateBandgap•  GroundStateEnergy•  HeatCapacity•  HeatofFusion•  1st–8thIonizationEnergy•  MeltingTemperature•  MendeleevNumber•  Polarizability•  Row–PeriodicTable•  WorkFunction

ElementalProperties•  Numbers-shellvalanceelectrons•  Numberp-shellvalanceelectrons•  Numberd-shellvalanceelectrons•  Numberf-shellvalanceelectrons•  Numberunfilleds-shellvalanceelectrons•  Numberunfilledp-shellvalance

electrons•  Numberunfilledd-shellvalance

electrons•  Numberunfilledf-shellvalanceelectrons•  Totalnumbervalenceelectrons•  Totalnumberunfilledelectrons

ElectronProperties

•  IsAlkalimetal?•  Ismetal?•  Ismetalloid?•  Isnonmetal?•  Isdblock?•  Isfblock?

BinaryProperties•  WeightLoadings•  ReactionTemperature•  SpaceVelocity•  #ofprecursorClligands

OtherProperties

Algorithm Selection

38

39

400CDecisionTree

Ward,L.,Agrawal,A.,Choudhary,A.&Wolverton,C.Ageneral-purposemachinelearningframeworkforpredictingpropertiesofinorganicmaterials.npjComputationalMaterials,2016

Feature Importance T slices

40

Feature TrendsT = 300oC

41

Mean Absolute Deviation (MAD) ∑↑▒1/𝑛 ( 𝑥↓𝑖 −𝜇) 

𝒙↓𝒊  = value of property𝝁 = average𝒏 = number of samples

Li et al., J. Mater. Chem. A, 2017 5, 24131-24138.Liu et al., J. Materiomics, 2017 3 (3) 159-177.

Mea

sure

d C

onve

rsio

n

MAD of Number d-shell Valence Electrons

Feature Interaction T = 300oC

42

MADofWorkFunction

MADofN

umbe

rd-shellV

alen

ceElectron

1.761.681.601.521.441.361.281.20

5.0

4.5

4.0

3.5

3.0

2.5

> –––––< 0.3

0.3 0.40.4 0.50.5 0.60.6 0.70.7 0.8

0.8

ConversionMeasured

Vayenas et al., Nature 1990. 343, 625-627.Haller, J. Catal. 216 (2003) 12-22.Binninger et al., Phys. Rev. B. 96, 165405 (2017).

2212 RuYK

3112 RuMgK

3112 RuHfK

2212 RuInK

1312 RuZnK

3112 RuMoK

250 300 350_mad # dshell unfilled

43

250 300 350_mad # valence

44

250 300 350 _mad Covalent radius

45

250 300 350_mad Work Function

46

250 300 350_mad 2nd ionization E

47

300 mad

48

250 top_mad

49

3112RuScK

3112RuMgK

1312RuMgK

3112RuYK

1312RuCuK

350 top_mad

50