TY - JOUR
T1 - Design of nanostructured multifunctional Pd-based catalysts from layered double hydroxides precursors
AU - Tichit, Didier
AU - Ortiz, María de Jesús Martínez
AU - Francová, Denisa
AU - Gérardin, Corine
AU - Coq, Bernard
AU - Durand, Robert
AU - Prinetto, Federica
AU - Ghiotti, Giovanna
PY - 2007/2/20
Y1 - 2007/2/20
N2 - Three types of multifunctional supported Pd catalysts (0.2 wt.% Pd) have been obtained from layered double hydroxides (LDH) precursors by: (i) impregnation with Pd(acac)2 of a Mg(Al)O support, (ii) coprecipitation of a multicationic Pd/Mg/Al LDH, and (iii) synthesis of a Pd colloid Mg/Al LDH nanocomposite. The precursors have then been calcined at 773 K and reduced at 523 K to obtain the catalysts, which exhibit very different basic properties and Pd particle size distributions. Their potential was evaluated in the one-pot synthesis of 2-methyl-3-phenyl-propanal (MPPAL) from benzaldehyde and propanal. The full one-pot synthesis of MPPAL was performed sequentially operating in two stages, i.e. for 20 h in N2, then for 7 h in H2 atmospheres. The activities of the catalysts in the first stage of the reaction (condensation and dehydration steps) are related to their reconstruction ability in the propanol/water solvent to give Brønsted basic sites. The hydrogenation ability of the catalysts decreases when the average Pd0 particle size decreases. The specific behavior of the nanosized particles accounts for a decrease of the adsorption strength of C{double bond, long}C bond due to the enhancement of the metal-support interaction. The catalyst prepared from a Pd nanocomposite precursor ensures the best balance between the different functions. It leads to a MPPAL selectivity of 77% at 64% benzaldehyde conversion. Benzyl alcohol formed by hydrogenation of benzaldehyde on Pd and hydrogen transfer from propanol is the main secondary product. However, the process is negatively affected by the high consumption of propanal from self-condensation.
AB - Three types of multifunctional supported Pd catalysts (0.2 wt.% Pd) have been obtained from layered double hydroxides (LDH) precursors by: (i) impregnation with Pd(acac)2 of a Mg(Al)O support, (ii) coprecipitation of a multicationic Pd/Mg/Al LDH, and (iii) synthesis of a Pd colloid Mg/Al LDH nanocomposite. The precursors have then been calcined at 773 K and reduced at 523 K to obtain the catalysts, which exhibit very different basic properties and Pd particle size distributions. Their potential was evaluated in the one-pot synthesis of 2-methyl-3-phenyl-propanal (MPPAL) from benzaldehyde and propanal. The full one-pot synthesis of MPPAL was performed sequentially operating in two stages, i.e. for 20 h in N2, then for 7 h in H2 atmospheres. The activities of the catalysts in the first stage of the reaction (condensation and dehydration steps) are related to their reconstruction ability in the propanol/water solvent to give Brønsted basic sites. The hydrogenation ability of the catalysts decreases when the average Pd0 particle size decreases. The specific behavior of the nanosized particles accounts for a decrease of the adsorption strength of C{double bond, long}C bond due to the enhancement of the metal-support interaction. The catalyst prepared from a Pd nanocomposite precursor ensures the best balance between the different functions. It leads to a MPPAL selectivity of 77% at 64% benzaldehyde conversion. Benzyl alcohol formed by hydrogenation of benzaldehyde on Pd and hydrogen transfer from propanol is the main secondary product. However, the process is negatively affected by the high consumption of propanal from self-condensation.
KW - Benzaldehyde
KW - Layered double hydroxides
KW - Nanocomposites
KW - One-pot reactions
KW - Palladium
KW - Propanal
UR - http://www.scopus.com/inward/record.url?scp=33846037737&partnerID=8YFLogxK
U2 - 10.1016/j.apcata.2006.10.052
DO - 10.1016/j.apcata.2006.10.052
M3 - Artículo
SN - 0926-860X
VL - 318
SP - 170
EP - 177
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
ER -