Most Combi-lipases (CL) are based on mixtures of different lipases immobilized on different supports. The increased CL efficiency has been attributed solely to the complementary selectivity of lipases. However, the role of the immobilization support in CL or in co-immobilized systems (coCL) and the application of kinetic models to account CL composition effects, have not been assessed. In this work, commercial lipases from Thermomyces lunuginosus (TLL), Candida antarctica (CALB) and Rhizomocur miehei (RML) and supports as Lewatit®VPOC1600 (LW) and Purolite®ECR1604 (PU), were combined to produce new CL systems for the production of fatty acid ethyl esters (EE) which are the main component of ethylic biodiesel: Co-immobilization slightly altered palm olein EE yields with regard to that of equivalent CL systems, e.g., the best coCL of TLL and CALB in LW (89.5%) and the respective CL (81.8%). The support did affect CL behavior: (i) The best coCL of TLL and RML on LW produced 80.0% EE while on PU 76.4%; (ii) CL based on mixtures of the same enzyme, but immobilized on different supports (semiCL) show complementarity: The best TLL semiCL produced 86.1% EE while its constituents (LW) and (PU) produced individually 78.2 and 70.3%, respectively. The proposed model accounts adequately the EE production properties for CL systems based on TLL, CALB and LW. This work expands the tools to obtain new CL systems for EE production.
BACKGROUND: Pd nanoparticles over different supports were evaluated during the alkyne selective hydrogenation of medium chain (C 7 and C 5 ) and the 1-pentene purification at mild operational conditions (150 kPa and 303 K). The role of support and chloride was investigated; γ-Al 2 O 3 , γ-Al 2 O 3 modified with Mg, CaCO 3 and activated carbon were used as supports, and PdCl 2 as precursor salt. The classical Lindlar catalyst was used as reference.RESULTS: Surface acidity of supports, active sites dispersion and surface species (MgO, Pd x Cl y O z and/or functional groups) can favor or disfavor the desorption of 1-alkene during the purification of 1-pentene stream. The smallest particle sizes (3.8-10.0 nm) favor the dissociative adsorption of hydrogen over Pd°active sites, promoting good catalytic behavior. The best synthesized catalysts are Pd/Al-Mg and Pd/Ca, and their high selectivity (≥90%) is favored by the presence of superficial acidic Lewis sites. On the contrary, lower selectivity (74-80%) is assessed on catalysts with Brönsted acidic sites (Pd/Al and Pd/RX3) that favored the undesired overhydrogenation or isomerization reactions.
CONCLUSION:The geometric and electronic properties of the support have a major influence on the activity and selectivity of the catalysts. Low loaded Pd catalysts supported on Al 2 O 3 -Mg and CaCO 3 (Pd/Al-Mg, Pd/Ca) can be used for the purification of medium or large terminal alkenes at mild reaction conditions as an alternative to the toxic Lindlar commercial catalyst.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.