Amphiphilic cerium(III) β-diketonate as a catalyst for reducing diesel/biodiesel soot emissions

This work reports on the synthesis, characterization and applications of the new cerium(III) β-diketonate Ce(hdacac)3(Hhdacac)3·2H2O (where hdacac and Hhdacac denote, respectively, the hexadecylpentane-2,4-dionate and hexadecylpentane-2,4-dione ligands) as catalyst for the reduction of automotive emissions. Due to its amphiphilic character, this complex can be solubilized in non-polar fuels, thus generating cerium(IV) oxide particles, which efficiently catalyze the oxidation of diesel/biodiesel soot.The synthesized complex was characterized by microanalysis (C, H), thermal analysis, and infrared spectroscopy. Scanning electron microscopy, X-ray diffractometry, and specific surface area measurements attested that the complex can act as a soluble precursor of homogeneous CeO2 spherical nanoparticles. The efficiency of this compound as catalyst for the reduction of soot emission was evaluated through static studies (comprising carbon black oxidation), which confirmed that increasing concentrations of the complex result in lower carbon black oxidation temperatures and lower activation Gibbs free energies. Dynamic studies, which embraced the combustion of diesel/biodiesel blends containing different amounts of the solubilized complex in a stationary motor, allowed a comparative evaluation of the soot emission through diffuse reflectance spectroscopy. These analyses provided very emphatic evidences of the efficiency of this new cerium complex for the control of soot emission in diesel/biodiesel motors.

The amphiphilic β-diketonate Ce(hdacac)3(Hhdacac)3·2H2O was synthesized and characterized as a potential metal fuel additive. Due to its expressive solubility in non-polar fuels, this complex can act as a homogeneous precursor for CeO2 nanoparticles, which efficiently catalyze the oxidation of soot derived from diesel/biodiesel combustion. These properties were confirmed in studies comprising carbon black oxidation and combustions of additived diesel/biodiesel blends.Figure optionsDownload as PowerPoint slide