Hydrocarbons and NH3 Professor Z.R.Ismagilov Laboratory of - PowerPoint PPT Presentation

36 th ISTC Japan Workshop on Advanced Catalysis in Russia/CIS Development of New Effective Catalytic Systems for Selective Reduction of NOx by Hydrocarbons and NH3 Professor Z.R.Ismagilov Laboratory of Environmental Catalysis, Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia, www.catalysis.ru/envicat/

Boreskov Institute of Catalysis: From Research on Molecular Level to Industrial Implementation St-Petersburg Moscow RUSSIA Volgograd Omsk Novosibirsk

Boreskov Institute of Catalysis Created by G.K.Boreskov at 1958 Directors: G.K.Boreskov (1958-1984); K.I.Zamaraev (1984-1995); V.N.Parmon (from 1995) staff: overall ca.1000, researchers ca. 450 web-page: http://catalysis.ru/

R&D Capabilities of BIC in Analysis Methods Analytical (composition of catalysts and catalytic reaction products) • Differential dissolution • Chromatography • Superrapid chromatography • Mass spectrometry Adsorptive (specific surface area, pore structure, adsorption heat) • Porosimetry • Calorimetry Kinetic • Gradientless and integral differential catalytic reactors • Fast relaxation technique • Stop flow technique

R&D Capabilities of BIC in Physical Methods • • X-Ray diffraction (including at small ESR • angles) NMR • • TEM and Scanning Electron ESCA (XPS and UPS), Microscopies Auger spectroscopy • • STM LEED • • EXAFS HREELS • • X-Ray spectroscopy Radiochemical and isotope • VUV electron spectroscopy methods • • UV-VIS electron spectroscopy Flash photolysis and radiolysis • • Vibrational spectroscopies X-Ray tomography • (IR and Raman) NMR microtomography

CAPOC 6 Sixth International Congress on Catalysis and Automotive Pollution Control Brussels, October 2003 • Lean DeNO x – SCR • NO x storages • Diesel Particulates • Soot- NO x • TWC - Mechanisms - Kinetics - Modelling • Ageing – Poisoning – Fuel Alternatives

California Emission Standards Category Durability NMOG CO NO x Basis nonmethane organics (miles) (g/mile) (g/mile) (g/mile) ______________________________________________________ TLEV 50.000 0.125 3.4 0.4 120.000 0.156 4.2 0.6 LEV 50.00 0.075 3.4 0.05 120.000 0.09 4.2 0.07 ULEV 50.00 0.04 1.7 0.05 120.000 0.055 2.1 0.07 SULEV 120.000 0.010 1.0 0.02 ZEV -0- -0- -0- -0-

Exhaust emission limits for passenger car engines (EU)

Diesel exhaust aftertreatment system: The challenge for NO x and Particulates

NO x -adsorber catalyst system

NOx Adsorber Catalyst Lean Conditions (  > 1) NOx-Adsorption Nitrogen oxide (NOx) Other Exhaust Components Clean Exhaust Gas Rich Conditions (  < 1) Regeneration

Schematic showing reactions within the adsorber catalyst during lean and rich conditions

Dual pore concept for hydrocarbon SCR involving oxidation in small pores and reduction in large pores

Goals and Objectives of Research at BIC Metal-substituted zeolites (Cu-ZSM-5) have high catalytic activity in direct decomposition of NO [1] and selective catalytic reduction of NO (SCR NO) with hydrocarbons [2], including propane, in presence of oxygen excess (2-3 vol.%) [1] Iwamoto M., et.al. Chem. Lett. 2 (1989) 213. [2] Iwamoto M., Hamada H. Catal. Today. 10 (1991) 57; Held W. et.al. SAE 900496 (1990) 13. The nature of active sites in Cu-ZSM-5 are still a matter of discussion. • Kucherov A.V., Slinkin A.A., et.al., Zeolite 5 (1985) 320. • Isolated ions Cu 2+ (Cu + ) • Dedecek J., Wichterlova B., J. Phys. Chem. B. 101 (1997) 10233. • Copper dimers with oxygen bridges, [CuOCu] 2+ or [Cu 2 (  -O) 2 ] 2+ • Groothaert M.H., Schoonheydt R.A. et.al., J. Am. Chem. Soc.125 (2003) 7629. • Copper-oxide clusters, Cu x O y • Shapiro E.S., Gruner W., et.al., Catal. Lett. 24 (1994) 159. Task: 1. The study of catalytic properties as function of Cu-ZSM-5 preparation conditions; 2. The study of the electron states of copper ions in the catalysts and their peculiarity as function of Cu-ZSM-5 preparation conditions;

Synthesis of Cu-ZSM-5. Ion-exchange condition. Copper precursor Zeolite H-ZSM-5 Si/Al=17, 30, 45 Cu(CH 3 COO) 2 Cu(NO 3 ) 2 рН solution 1%Cu-ZSM-5-30-71 рН ~ 4 рН ~ 6 • Copper loading (wt.%) рН ~ 10 (ammonia solution) • zeolite atomic ratio Si/Al Temperature • calculated copper exchange level (%) 25 о С 60 о С 80 о С Cu/Al EL = 2 х 100 х Cu/Al at Copper concentration in solution • M.Iwamoto, et. al., Chem. Lett. (1990) 1967 0.4  8 mg Cu / ml Ratio of solution volume to zeolite mass (S/Z) 10, 30, 50

Effect of ion-exchange condition on Cu-exchange level in Cu-ZSM-5 Aqueous copper acetate solution (рН  6) 8 mg Cu/ml 4 mg Cu/ml 100 1.6 mg Cu/ml Exchange level, % 125 50 100 Exchange level, % 75 S/Z = 10 0 0 10 20 30 40 50 50 Si/Al ratio S/Z = 10 25 Si/Al-17 Si/Al-30 Si/Al-45 0 0.0 1.6 3.2 4.8 6.4 8.0 9.6 Exchange level, % 100 Copper concentration in ion-exchange solution, mg/ml • The maximum achievable level of Cu 50 exchange with H-ZSM-5 is equal to 75 -100%. Si/Al-17 Si/Al-30 • Exchange level is determined mainly by Si/Al-45 8 mg Cu/ml 0 copper concentration in solution and by the 10 20 30 40 50 zeolite Si/Al ratio. S/Z

Effect of ion-exchange condition on Cu-exchange level in Cu-ZSM-5 Ammonia copper acetate solution (рН  10) 300 8 mg Cu/ml 4 mg Cu/ml 250 Exchange level, % 300 2 mg Cu/ml 200 250 Exchange level, % 150 200 100 150 50 S/Z = 10 100 0 10 20 30 40 50 Si/Al-17 Si/Al ratio 50 Si/Al-30 S/Z = 10 Si/Al-45 0 0 2 4 6 8 10 300 Copper concentration in ion-exchange solution, mg/ml Exchange level, % 250 200 • Ammonia copper acetate solution provides 150 the higher achievable level of Cu exchange with H-ZSM-5 (up to 300%). 8 mg Cu/ml 100 Si/Al-17 • Exchange level increase with rising of 50 Si/Al-30 Si/Al-45 copper concentration in solution and the 0 10 20 30 40 50 zeolite Si/Al ratio. Its increase is more S/Z apparent as compared with aqueous solution.

Correlation between Cu-ZSM-5 catalytic activity (NO conversion) and copper loading and exchange level DeNO x -C 3 H 8 test condition: 42000 h -1 ; (300 ppm NO, 1500 ppm C 3 H 8 , 3.5 vol.%O 2 , N 2 ) Cu loading, % 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 100 X(NO), % A X(NO), % C 80 80 40 at 400 o C 60 B X(NO), % 80 40 Cu-ZSM-5-30 1.83% Cu 20 40 1.45% Cu 1.12% Cu Si/Al=17: pH-6 ( ), pH-10 ( ) 0.52% Cu Si/Al=30: pH-4.6 ( ), pH-6 ( , ), pH-10 ( ) 0.36% Cu Si/Al=45: pH-6 ( ), pH-10 ( ) 0 50 100 150 200 250 300 350 300 350 400 450 500 o C Exchange level, % Temperature, .

Copper state in calcined catalysts: 1.1%Cu-ZSM-5-17-45 (1), 1.2%Cu-ZSM-5-30-71 (2), 1%Cu-ZSM-5-45-88 (3) ESR DPPH 3 2 1 A ฀ ฀ = 135 Oe g ฀ ฀ = 2.38 (A) g  =2.07 x2 3 H 0 100 Oe 2 1 A ฀ ฀ = 135 Oe g ฀ ฀ = 2.38 40-50% Cu are ESR silent after ESR: g  =2.38, g  = 2.08, A  = 135 Oe calcination in air at 500 o C UV-Vis:  (T 2g -E g ) = 12500-13400 cm -1 • reduction of Cu 2+ to Cu +  isolated Cu 2+ ions with d x • associate of Cu 2+ ions 2 - state 2 -y (similar to [Cu(H 2 O) 6 ] 2+ ) • CuO formation

Copper state in CuZSM-5 after vacuum treatment at 150 and 300 о С (UV-Vis) 1.5% Cu-ZSM-5-30-92 (N, 80 o C, pH=4) o C 20850 HVT 300 F(R) o C HVT 150 Initial 1.2 22900 0.8 19400 18200 Zeolite adsorbtion edge 0.4 CTB oxide clusters d-d transition 0.0 10000 15000 20000 25000 30000 35000 -1 cm O O O [Cu(H 2 O) 6 ] 2+ Cu Cu – O 2- — Cu 2+ -O 2- — Cu 2+ -O 2- - O O O  О - radical anions with weak exchange coupling through diamagnetic Cu+ ions in chains – O- — Cu+-O- — Cu+-O-- (p5d10)

Electron states of Cu n+ cation in Cu-ZSM-5 [Cu(H 2 O) 6 ] 2+ ,12500 cm -1 Ion exchange, [Cu n (OH) y (H 2 O) x ] (2n-y)+ , n= 1-3 washing [Cu(NH 3 ) 4 ] 2+ ,14500 cm -1 Calcination (air, 500 o C) Chains O O O Isolited ions Cu 2+ (Oh) Cu-O-Cu-O-Cu-O Cu Cu [Cu(H 2 O) 6 ] 2+ (ESR silent) O O O 12500-13400 cm -1 30000-32000 cm -1 1 = 2.38-2.39, A  1 = 130 Oe, g  Cu 2+ -O 2- -Cu 2+ -O 2- -Cu 2+ 18000-23000 cm -1 Dehydration g  = g e vacuum, 25-400 o C O O O Cu + -O - -Cu + -O - -Cu + Isolated ions Cu 2+ (distorted Oh) Cu Cu g  = 2.05, g  = 2.02 O O O without HFS 12000-14500 cm -1 1 = 2.30-2.33, A  1 =145-154 Oe, Cu 2+ -O 2- - Cu + -O - g  28000-32000 cm -1 2 = 2.28, A  2 = 165-170 Oe, g  15000-17000 cm -1 22500 cm -1 • Well-known for Cu- • Assumed based on ESR • Well-known for exchanged zeolites and UV-Vis experimental data Cu-oxide systems

Copper state in overexchanged Cu-ZSM-5 (Cu/Al>0.5) after heat vacuum treatment isolated Cu 2+ ions (12500-13400 cm -1 ) adjacent (nearby) isolated Cu 2+ ions binuclear Cu oxo/hydroxo complexes (???) linear Cu oxo/hydroxo oligomers (18000-23000 cm -1 ) clustered CuO-like nanoparticles (30000-32000 cm -1 ) • by analogy with proposed for Fe/ZSM-5 A.A.Battiston, J.H.Bitter, F.M.F.de Groot et.al. J.Catal. 213 (2003) 251