Effect of the substrate and catalyst chirality on the diastereoselective epoxidation of limonene using Jacobsen-type catalysts.

Chiral and achiral Jacobsen's catalysts in their homogeneous form or immobilized on Al-MCM-41 exhibit similar catalytic activity during diastereoselective epoxidation of limonene when in situ generated dimethyldioxirane is used as oxidizing agent. Experimental observations suggest that not only the catalyst chiral center but also the substrate chiral center participates in the preferential formation of most diastereomers. Remarkable turnover numbers (TON), up to 288, was achieved over the heterogeneous catalysts in comparison to their homogeneous counterparts (TON up to 46).

Characterization of fly ash from a hazardous waste incinerator in Medellin, Colombia.

Bag filter (BF) fly ash from a hazardous waste incinerator located in Medellín, Colombia was characterized. Particle size distribution, chemical composition, metal loading, surface area, morphology, and chemical environment were assessed before and after fly ash extraction with toluene. Fly ash consists of low surface area platelets of SiO(2) smaller than 0.

The effect of NaOH on the liquid-phase hydrodechlorination of dioxins over Pd/gamma-Al2O3.

The effect of sodium hydroxide on the-liquid phase hydrodechlorination (LPHDC) of polychlorinated dibenzo- p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) over 2% Pd/gamma-Al 2O 3 was evaluated. Reactions were carried out using 2-propanol both as a hydrogen donor and as a solvent. Fresh and used catalyst samples were characterized by BET, hydrogen chemisorption, TEM/EDS, XPS, and TPR.

Synthesis of nopol over MCM-41 catalysts.

MCM-41 was found to be an active heterogeneous catalyst for the synthesis of nopol by the Prins condensation of beta-pinene and paraformaldehyde, but Sn-MCM-41 in which Sn has been grafted on MCM-41 by chemical vapor deposition is far more active and combines high efficiency and recyclability.