Increasing the Selectivity of DeNNOx Photocatalysts and

Increasing the Selectivity of DeNIncreasing the Selectivity of DeNIncreasing the Selectivity of DeNS i h E l i f TSuppressing the Evolution of ToxSuppressing the Evolution of Toxpp gJ. Patzsch, J. Z. Bloh| e‐mail: patzsch@dechema.de| BMWi via AiF| PeriodJ. Patzsch,  J. Z. Bloh| e mail: patzsch@dechema.de| BMWi via AiF| Period

h lPhotocatalysisPhotocatalysis• Reduction of O2 to superoxide 2  p

• Oxidation of water to ∙OH by V• Oxidation of water to  OH by V

O H O d OH idi• O2∙‐, H2O2 and ∙OH can oxidize 2 2 2 

• Removal of NO3‐ from the surfRemoval of NO3 from the surf

• Adsorbed NO ‐ can be re‐reduc• Adsorbed NO3 can be re‐reduc‐

electronselectrons

R d i i i i• Re‐reduction in competition w

• Co‐Catalysts support the full oy pp

and suppress the back reactionand suppress the back reaction

Influence of iron graftingInfluence of iron grafting

• Up to 120 % hig• Up to 120 % higOptimum concentration for P25: 

Th l f N

p

• The release of N0 003 to 0 1 mol% iron

h l

0.003 to 0.1 mol% iron

• Higher toleranc10 to 400 Fe3+/particle g10 to 400 Fe3 /particle

• Higher possibleHigher possible

Environmentally relevant mixture of NO NO and OEnvironmentally relevant mixture of NO, NO2 and O3NO NO NO O NO NO

200

NO NO2 NO

x O

3

200

NO NO

200 200

150 150150

ppb

150

pb]

n / p

n [p

p

100atio

n

100atio

n

100

entr

a 100

entr

a

once

once

Co

Co

50 50

0 7 1 7 2 70

0 0 0 2 0 4 0 60

0,7 1,7 2,7

time [h]

0,0 0,2 0,4 0,6

titime [h] ti

U difi d P25Unmodified P25:  P25 grafted with jug j

• Low activity for NOx degradation (8%) • Degradation of Ny x g ( ) Degradation of N

• NO is mainly converted to NO2 • High NO degradNO is mainly converted to NO2 • High NOx degrad

• NO is increased by 40% • 40% decrease in• NO2 is increased by 40%. • 40% decrease in

Hi hli hHighlighHighligh201720172017

Chemical TechnologyChemical Technology

NOx Photocatalysts andNOx Photocatalysts andNOx Photocatalysts and i B P dxic By‐Productsxic By‐Productsy

d: 01.06.2015‐31.08.2017d: 01.06.2015 31.08.2017 

1 2Measurements

1 2Measurements

or H2O2 by CB electrons2 2 y• Based on the ISO

VB holesBased on the ISO

VB holesstandard 22197 1

O h istandard 22197‐1

NOx to the nitrate  G fl f 3 L/ ix • Gas flow of 3 L/minface by rain

/ ²face by rain 

• UV light of 1 mW/cm²ced to NO by CB

g /ced to NO2 by CB  • 50 % relative humidity50 % relative humidity

• 1 ppm NO or 1 ppm Oi h O d i

• 1 ppm NO or 1 ppm O3

with O2 reduction • Aeroxide P25 (Evonik)2 • Aeroxide P25 (Evonik)xidation to nitrate 

n from nitraten from nitrate 

33

gher selectivity and 110 % activity by modification with Fe3+gher selectivity and 110 % activity by modification with Fe3

NO i d ti ll d l d d l h ft l tiNO2 is drastically delayed and only happens after long exposure times

d h h h l d f h lce towards nitrate poisoning, the high selectivity is retained for a much longer timep g g y g

e nitrate accumulation on the surfacee nitrate accumulation on the surface

4 5Summary & Literature

4 5Summary & Literature

hl l d h l bO NO O

• Highly selective and active photocatalyst by O

2 NO

x O

3 g y p y y

grafting of low amounts of iron on the surfacegrafting of low amounts of iron on the surface

• Long term stable materials against catalyst• Long term stable materials against catalyst 

poisoning of nitratepoisoning of nitrate

Si ifi d d i f NO NO d• Significant degradation of NO, NO2 and ozone 2

in environmentally relevant mixtures y

0 8 1 0 1 2 1 4 1 6

• J Patzsch J Z Bloh Catal Today accepted0,8 1,0 1,2 1,4 1,6

ime [h] • J. Patzsch, J. Z. Bloh, Catal. Today, accepted ime [h]

(201 )(2017)ust 0.04 mol% Fe:

• J. Patzsch, A. Folli, D. MacPhee, J. Z. Bloh,NO, NO2 and O3 J. Patzsch,  A. Folli, D. MacPhee,  J. Z. Bloh, NO, NO2 and O3

PCCP accepted (2017)dation activity (50%) PCCP,  accepted (2017)dation activity (50%)

n NOn NO2

t P j tt Projectt Project