Removal of PAH compounds from liquid fuels by Pd catalysts.
Palladium catalysts supported on gamma-alumina (AN, AS), amorphous silica-alumina (ASA), and beta-zeolite (betaZ) were prepared with the aim to reduce the content of polycyclic aromatic hydrocarbons (PAHs) in diesel fuels. The removal of PAH compounds was evaluated with a model feed (toluene, naphthalene, and dibenzothiophene)that approached the composition of diesel fuel. The catalysts were characterized by N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, transmission electron microscopy, temperature-programmed reduction/temperature-programmed oxidation, Fourier transform (FT) IR of absorbed CO, and diffuse reflectance FT spectroscopy of adsorbed NH3. When palladium was supported on ASA instead of AN or betaZ, the intrinsic activity improved considerably. Such behavior is discussed in terms of larger Brønsted acidity and the degree of reduction of the Pd species on Pd/ASA. For the 2.2 Pd/betaZ catalyst, interaction of the Pd clusters with zeolite protons led to formation of Pddelta+ species, which are not active in the hydrogenation of aromatics. All catalysts were resistant to poisoning by S compounds.
Pawelec
B
B
Instituto de Catálisis y Petroleoquímica, CSIC, c/ Marie Curie, 2, Cantoblanco, 28049 Madrid, Spain.
Campos-Martin
J M
JM
Cano-Serrano
E
E
Navarro
R M
RM
Thomas
S
S
Fierro
J L G
JL
D002384:Catalysis; D004785:Environmental Pollutants / Q000302:isolation & purification*; D007854:Lead / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry; D011084:Polycyclic Aromatic Hydrocarbons / Q000302:isolation & purification*; D013696:Temperature
D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D007854:Lead; D010165:Palladium