Ethanol steam reforming Ni(II) Al(III) using layered double hidroxide as catalyst precursor. Kinetic study.”

VERÓNICA MAS; PABLO ARENA; GRACIELA BARONETTI; NORMA AMADEO; MIGUEL LABORDE

Bilbao- España

Simposio; Chemical Reactor Engineering XI. Green Chemical Reactor Engineering; 2007

The kinetic of ethanol steam reforming reaction using Ni(II)-Al(III) layered double hydroxide (LDH) as catalyst precursor is studied. The carbonate form of Ni(II)-Al(III) LDH (Takovite) was prepared using a homogeneous alkalinization procedure. The experiments were performed in a laboratory fixed bed reactor; since ethanol conversion rate is very fast, previous experiments were carried out in order to determine the experimental conditions free from external and internal diffusional resistances. The kinetics parameters were obtained using the integral reactor model. The ethanol reforming reaction can be represented as: C2H5OH + 3 H2O = 2 CO2 + 6 H2. Nevertheless, several reactions can occur and different products such as methane, acetaldehyde and ethylene can be produced depending on catalyst and operating conditions. Previous studies based on experimental evidence demonstrated that methane steam reforming reactions determine the products distribution, and then the following reaction scheme was used: C2H5OH = CH4 + CO + H2  C2H5OH +H2O= CH4 + CO2 + 2H2       CH4 + H2O = CO + 3 H2 CH4 + 2 H2O = CO2 + 4 H2 The H2 yield for ethanol steam reforming using the reduced LDH sample reaches values of 5 mol of H2 per mol of ethanol fed. The others products obtained during steady state conditions operating between 823 and 923 K, are CO, CO2 and CH4. It is found that the reaction order respect to ethanol is lower than 1. It is verified that, for each reaction temperature, there is a water/ethanol molar ratio at which ethanol conversion has a maximum. This means that a competition between both reactants adsorbed on the same active site is verified.