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SUMMARY:Water gas shift catalysts for pure hydrogen production from biomas
 s steam gasification
DTSTART:20170118T110000
DTEND:20170118T120000
DTSTAMP:20260511T080115Z
UID:48f0387a258fb2604a29888441a79aa88f746c4b1f1bd1bbdb19d648
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Charlotte Lang\nGas production in the optic of biomass gas
 ification at atmospheric pressure is well known [1]. Hydrogen in the obtai
 ned gaseous mixture can be increase by the water gas shift reaction (WGS)\
 , before using it for energy source. The novel utilization of alumina cera
 mic foams (figure 1) in place of supports for the WGS catalyst leads to go
 od efficiency of the catalysts\, even at atmospheric pressure\, and allows
  decreasing the pressure drop in the system. It is necessary to proceed to
  a washcoat deposition\, chosen to be Cerium oxide\, before the catalyst
 ’s deposition. It leads to an increase in the specific surface area and 
 a better dispersion of the catalytic phase. Iron is typically used for Hig
 h temperature WGS (300-500 °C)\, and copper for low temperature WGS (150-
 300 °C). Another advantage of CeO2 is the oxygen storage\, which can limi
 t coke formation during the reaction [2].\nCerium deposition and iron depo
 sition are performed in two steps by dipping the foam in an aqueous cerium
  nitrate or iron nitrate solution. After drying\, the foam is calcined for
  4 h at 400 °C or 450 °C. Characterizations are performed by different m
 ethods (optical microscopy\, X-Ray diffraction\, BET analysis\, Temperatur
 e programmed reduction). Pressure drop measurements are performed at 25 °
 C under 450 ml/min of air before catalytic tests.\nThe active phase in hig
 h temperature WGS reaction is the magnetite (Fe3O4). It is not necessary t
 o reduce the catalyst before the reactivity test. The catalyst is reduced 
 in-situ\, in presence of the gas mixture corresponding to the gas mixture 
 observed at the gasifier outlet (H2\, CO\, CO2\, H2O\, N2\, CH4). Differen
 t parameters were studied: the H2O/CO ratio (0.65 to 3)\, the residence ti
 me (RT = 0.38 to 1.5 seconds)\, the temperature (300 to 600 °C)\, the com
 position of catalysts (different amounts of iron oxide and cerium oxide) a
 nd the porosity of the foam (30 ppi or 45 ppi). By adjusting the condition
 s to H2O/CO=2\, T=550°C\, RT=0.38s\, 5.8wt.%Fe/4.4wt.%CeO2/45ppi\, we obt
 ain a CO conversion of 40%.\nThe active phase in low temperature WGS react
 ion is metallic copper (Cu0). A pre-reduction (300 °C for 1h\, under 50 m
 l/min 40%H2 in N2) is necessary\; it leads to a better activation of the c
 atalyst\, and higher CO conversions. The low temperature catalysts were us
 ed with the same gas mixture that for high temperature catalysts. Differen
 t parameters were studied: the influence of the pre-reduction\, the temper
 ature (150 to 300 °C)\, the composition of the catalysts (different amoun
 ts of copper and cerium oxide)\, and the porosity of the foam (30 or 45 pp
 i). By adjusting the conditions to H2O/CO=2\, T=300°C\, pre-reduction\, R
 T=0.38s\, 5.4wt.%Cu/9.3wt.%CeO2/45ppi\, we obtain a CO conversion of 43%.\
 nAfter tests characterizations were performed by X-Ray diffraction. We can
  see the presence of the active phase for the high temperature catalyst an
 d for the low temperature catalyst. Particles size calculations shows only
  a little increase in iron oxide and cerium oxide particles size. In the c
 ase of the low temperature catalyst\, we do not see any increase in copper
  or cerium oxide particles size\, even after re-using the catalyst for sev
 eral reactivity tests.\nIron-based (HT) and copper-based (LT) catalysts we
 re finally used in combination\, in order to obtain an optimised CO conver
 sion.\nA kinetic study was performed for each catalyst. The adjustment of 
 different kinetic parameters leads to adapted kinetic models based on the 
 mechanism of the reaction on each catalyst [3-4].\n \nReferences:\n[1] K.
  Maniatis \; Progress in biomass gasification: an overview. General Direct
 orate of  Energy & Transport\, European Commission in Progress in A.Bridg
 water (ed.) Thermochemical Biomass Conversion\, pp. 1-31 Blackwell Science
 s Ltd Oxford (2001).\n[2] R. Di Monte\, J. Kašpar \; Catalysis Today\, 2
 005\, 100\, 27-35.\n[3] M. I. Temkin\, The Kinetics of Some Industrial Het
 erogeneous Catalytic Reactions\, Academic P. New York\,\n[4] N. E. Amadeo 
 and M. a Laborde\, “Hydrogen Production From the Low-Temperature Shift R
 eaction : Kinetics and Simulation of the Industrial Reactor Cp\,” Int.
  J. Hydrog. Energy\, 1995\, vol. 20\, 949.\n 
LOCATION:Zeuzier conference room\, EPFL Valais
STATUS:CONFIRMED
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