Low temperature catalytic oxidation of H 2 S over V 2 O 5 /CeO 2 Catalysts

Transcription

1 DIIN- Department of Industrial Engineering University of alerno Low temperature catalytic oxidation of over V O 5 /CeO Catalysts Vincenzo Palma*, Daniela Barba, Paolo Ciambelli European Fuel Cell Technology & Applications *vpalma@unisa.it December 11-13, 013

2 Biogas INTRODUCTION Renewable Energy ource Agricultural Waste Biomass Utilization Industrial Waste ewage ludge Fuel Vehicles eat Electricity Fuel Cell

3 INTRODUCTION Molten Carbonate Fuel Cells (MCFC) CO + ½ O + e - CO 3 - Catode + CO 3 - O + CO + e - Anode Poisoning problem of the cells by (sulphur content allowed <1 ppm) q Can lead to the poisoning of the anode and electrolite q Can deactivate of sites for the oxidation

4 INTRODUCTION Clean- up Biogas : Purification Processes Dry Processes Biological Desulfurization Chemical Absorption in aqueous solutions Membrane eparation Physical olvent

5 INTRODUCTION Clean- up Biogas : Oxidation Processes Ø Catalytic Oxidation: Claus Process T= C T= C Ø elective Catalytic Oxidation at Low Temperature: T= C Innovative process for abatement 1 n n + O= O + 3 O= O + O + O= 3 n n+ O Temperature and catalyst influence the reaction mechanism and the process selectivity

6 Aim of the work Ø Previous works.. Among the others V/Ce seems to be most promising Ø IN TI WORK IMPROVE TE PROCE ELECTIVITY TO ULFUR Catalysts Formulation (.55%- 0% vo5) Temperature ( C) Contact Time (4-80 ms)

7 V O 5 /CeO Catalysts Preparation Method EXPERIMENTAL.55% Wet Impregnation of the support with N 4 VO 3 aqueous solution 5% 8% C overnight 10% 0% C for 3h, dt/dt =10 C/min Characterization Tecniques pecific urface Area X-RAY Diffraction Raman pectroscopy

8 Catalysts Characterization DECREAE OF TE PECIFIC AREA UPON V O 5 ADDITION (*) B.E.T. Method, Pretreatment in C for 1h ample Fresh Catalyst A, m /g CeO 80,55% VO5/CeO 75 5% VO5/CeO 57 8% VO5/CeO 39 10% VO5/CeO 3 0% VO5/CeO 17

9 Catalysts Characterization EXPERIMENTAL CeO CeO VO5 V=O Polyvanadate

10 Laboratory Apparatus Plant Feed ection Reaction ection FT- IR O Analysis ection Analysis ection Mass pectrometer

11 Laboratory Apparatus Plant OPERATING CONDITION: Atmospheric Pressure Temperature : C Concentration: 00 ppm O / (mol:mol) : 0.5 Total Flow Rate : 600 Ncm 3 /min GV : 180,000 h - 1 (τ : 0 ms)

12 Catalytic Activity Tests T=150 C, 60 min O O O signal, - O

13 Catalytic Activity Tests REULT igh Activity at any temperature conversion 00 C

14 Catalytic Activity Tests T, C CeO VO

15 Catalytic Activity Tests conversion (~100%) for the 0%Vo5/Ceo Minimization of o selectivity (~1%) for the 0%Vo5/Ceo

16 Catalytic Activity Tests Decrease of conversion With the temperature Increase of O selectivity With the temperature

17 Catalytic Activity Tests Increase of O concentration Oxidation of sulphur deposited on the catalyst surface --> --> O T=150 C Increase of the surface area A Fresh Catalyst = 17 m/g Contact Time, ms x, % T=150 C O, ppm Y O,% 0 0,5 1,7 3

18 Conclusion X- Ray Diffraction & Raman pectroscopy Ø Good dispersion of VO5 for all the catalysts Ø Low content of crystalline vanadium on the 0%VO5/CeO Influence of the vanadium loading Ø Improvement of the catalytic activity to the increase of VO5 Ø ighest conversion (~100%) and lowest O selectivity C for the 0%VO5/CeO catalyst Influence of the Contact Time Ø Effect on the specific area and the O selectivity FUTURE WORK Effect of Temperature (<150 C) with the Contact Time Influence of the vanadium loading (>0%) Identification of sulphur species

19 DIIN- Department of Industrial Engineering University of alerno Low temperature catalytic oxidation of over V O 5 /CeO Catalysts Vincenzo Palma*, Daniela Barba, Paolo Ciambelli *vpalma@unisa.it Piero Lunghi Conference, December 11-13, 013

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23 External and Internal Mass Transfer resistance Conversion, % Flow Rate: 00, 300, 400, 800 Ncm 3 /min External Diffusion T=50 C, =00 ppm, O / = Gas Velocity, cm/s t = ms conversion, % ize Particles, µm : ize Particles, micrometer Flow Rate, Ncm 3 /min V GA, cm/s X, % Internal Mass Transfer resistance was observed for size particles > 180 μm External Mass Transfer resistance was observed for linear gas velocity < 5 cm/s

24 Thermodynamic tudy + O ao + b + c 6 +d 8 + e O+ f Ø Pressure: 1 atm atm 3 atm Complex Equilibrium : Ø O / = 0.5 Conversion, % conversion igher At P=3 atm Ø Concentration = 00 ppm 370 C conversion igher at P=1 atm Temperature, C

25 Thermodynamic tudy + O ao + b + c 6 +d 8 + e O+ f Ø Pressure: 1 atm atm 3 atm Complex Equilibrium : Ø O / = 0.5 Ø Concentration = 00 ppm O seleckvity, % 00 C T<00 C Low O electivity Temperature,

26 Thermodynamic tudy + O ao + b + c 6 +d 8 + e O+ f Ø Pressure: 1 atm atm 3 atm 8 seleckvity, % Ø O / = 0.5 Ø Concentration = 00 ppm seleckvity, % T< 00 C T> 00 C Increase of Increase of electivity 8 electivity Temperatura, 800 C 1000 Temperatura, Temperature, C Temperature, C

27 Adsorption Test of T = 160 C, = 800 ppm adsorbs and reduces the catalyst producing O θ θ O ( g ) 1 f 1o + Concentration, ppm Reaction between adsorbed and O of the phase active O 7E-11 6E-11 5E-11 4E-11 3E-11 E-11 1E-11 O signal m/z=18, torr After the O activation via adsorption, the reoxidation of the previously reduced vanadium to the oxidized vanadium occurs Time, min 0 No O, O 3, O formation detected

28 Kinetics Mechanism tudy 1/1 T = 00 C, 600 ppm Langmuir-inshelwood Mechanism Design Equation for a Plug Flow Reactor (PFR) ( ) CAT dw r df = Kinetic Expression o o K r 1 ) ( θ θ = tot CAT O in O in O in O in in Q dw ) R X.( P K ) X ( P K ) R X ( P K ) X ( P K C K dx + + = = 1 O O P K P K P K + + θ 1o θ o 1 O O O O P K P K P K + + = RD

29 Kinetics Mechanism tudy /1 T = 00 C 600 ppm dx = C K in K 1 + K P P in in ( 1 X ( 1 X ) K O ) + K P O in O P in O X ( 1 ) R X.( 1 ) R dw Q CAT tot Experimental Data Calculation Model 100 ppm O Conversion, % ppm O 40 ppm O 0 ppm O Good fitting of the experimental data with the L- model 5 0 0, ,0000 0, ,00004 W/Q TOT, (g min/ncm 3 )

30 Effect of the C4 Concentration, ppm x = 96% C4 FEED = 30% C C 4 Concentration, vol% Time, min