Sol–gel La2O3–ZrO2 mixed oxide catalysts for biodiesel production

Different La2O3 contents（0, 1, 2, 3, and 5 wt%） were used to prepared La2O3-ZrO2 mixed oxides calcined at 600 ℃ by the sol-gel method. The catalytic activity was measured as biodiesel production from canola oil through a transesterification reaction. The characterization results indicate that the La2O3 monolayer formation and extent of basicity of m-ZrO2 have a large influence on biodiesel production.Greater biodiesel conversion（56% at 4 h） was obtained with the 3% La2O3-ZrO2 catalyst in the presence of basic sites and the formation of a monolayer of La2O3. The decrease in the catalytic activity for 5% La2O3-ZrO2 resulted from the loss of active sites on the catalyst because of agglomeration, which was suggested by XPS and the isoelectric point. The kinetic data fit to a pseudo-first order constant, and the largest kinetic constant corresponds to 3% La2O3-ZrO2, currently the largest heterogeneous non-alkaline metal catalyst reported for a transesterification reaction.

Engineering operando methodology： Understanding catalysis in time and space

The term operando was coined at the begin- ning of this century to gather the growing efforts devoted to establish structure-activity relationships by simulta- neously characterizing a catalyst performance and the relevant surface chemistry during genuine catalytic opera- tion. This approach is now widespread and consolidated; it has become an increasingly complex but efficient junction where spectroscopy, materials science, catalysis and engineering meet. While for some characterization techni- ques kinetically relevant reactor cells with good resolution are recently developing, the knowledge gained with magnetic resonance and X-ray and vibrational spectro- scopy studies is already huge and the scope of operando methodology with these techniques is recently expanding from studies with small amounts of powdered solids to more industrially relevant catalytic systems. Engineering catalysis implies larger physical domains, and thus all sort of gradients. Space- and time- resolved multi-technique characterization of both the solid and fluid phases involved in heterogeneous catalytic reactions （including temperature data） is key to map processes from different perspectives, which allows taking into account existing heterogeneities at different scales and facing up- and down-scaling for applications ranging from microstructured reactors to industrial-like macroreactors （operating with shaped catalytic bodies and/or in integral regime）. This work reviews how operando methodology is evolving toward engineered reaction systems.

Highly efficient multi-metal catalysts for carbon dioxide reduction prepared from atomically sequenced metal organic frameworks

The precise control on the combination of multiple metal atoms in the structure of metal-organic frameworks(MOFs)endowed by reticular chemistry,allows the obtaining of materials with compositions that are programmed for achieving enhanced reactivity.The present work illustrates how through the transformation of MOFs with desired arrangements of metal cations,multi-metal spinel oxides with precise compositions can be obtained,and used as catalyst precursor for the reverse water-gas shift reaction.The differences in the spinel initial composition and structure,determined by neutron powder diffraction,influence the overall catalytic activity with changes in the process of in s itu formation of active,metal-oxide supported metal nanoparticles,which have been monitored and characterized with in situ X-ray diffraction and photoelectron spectroscopy studies.

Isolation and Screening of Filamentous Fungi Producing Extracellular Lipase with Potential in Biodiesel Production

Nineteen fungal strains were isolated from a chicken slaughterhouse effluent and within those, only one showed high values of lipolytic activity in submerged cultures. This fungus was identified as Trametes hirsuta. The crude extract was immobilized in chitosan/clay beads, with an immobilization yield of 80.9%. The analyses of the crude extract and the immobilized derivative at different temperatures, pH (s), solvents, metallic ions and storage showed that the immobilization process increased the enzyme life span. Ethyl esters were obtained in solvent free systems using chicken viscera oil and the enzyme crude extract. For effective comparison, a reaction using viscera oil and commercial lipase Novozym 435 was carried out. The result revealed 35% and 28% esters conversion in the reactions containing chicken viscera oil, using Novozym 435 and the crude extract respectively. The extract was also used in a reaction with soybean oil, traditionally used as starting substrate for biodiesel production.