The Influence of Particle Size and Shape in Cobalt 2‐Methylimidazolate Polymers on Catalytic Properties

Abstract

The reaction products between in situ generated Co(OH)2 and 2‐methylimidazole were studied and characterized. Using 9 fold excess of ligand, the well studied polyhedral (dodecahedral) particles (1–3 μm diameter) of the zeolitic imidazolate framework were obtained, i. e. ZIF‐67. When a stoichiometric amount of 2‐methylimidazole was employed, amorphous spheres of ca 500 nm diameter were obtained with low dispersion in size. Both samples were pyrolyzed at 700 and 900 °C under inert atmosphere. The external morphology was kept, however TEM images of the spherical particles showed that they were mainly composed of carbon nanotubes. Co nanoparticles embedded in the carbonaceous matrix could be observed in both samples. The activity of the pyrolyzed (700 and 900 °C) acid leached samples towards the Oxygen Reduction Reaction was studied. Upon the same thermal treatment both types of samples showed similar electrokinetic parameters.

Biocatalysts Synthesized with Lipase from Pseudomonas cepacia on Glycol-Modified ZIF-8: Characterization and Utilization in the Synthesis of Green Biodiesel

“…The presence of Zn atoms in the structure of Gly@ZIF-8 allows lipase anchoring because Zn induces lipase aggregation [ 63 ]; however, the distribution of Zn atoms on the surface of this porous material is not homogeneous, and many Zn atoms are immersed in the carbonaceous network, as reported by Díaz Durán and Roncaroli for cobalt [ 51 ], hence the lower mass percentage of the FAMES components of the biodiesel (BIOGly@ZIF-8-PCL) synthesized from Gly@ZIF-8-PCL. These structural and textural changes can be evidenced in the N 2 adsorption–desorption isotherms at 77 K of Gly@ZIF-8 and the pore size distribution curves ( Figure 1 ).…”

“…MOFs have also been used as self-templates for the generation of metal oxides [ 49 ], and Pd-loaded ZnO nanotubes have been synthesized from ZIF-8 derivatives [ 50 ]. In this context, pyrolysis at 700 and 900 °C of ZIF-67 in the presence of Co(OH) led to the formation of a carbonaceous matrix with a ZIF-67-type structure [ 51 ]. In this order of ideas, this work synthesized and characterized biocatalysts with applicability to the conversion, in condensed phase, of triacylglycerides, diacylglycerides, monoacylglycerides present in commercial palm oils, and glycerol as a by-product, in biodiesel components, from two synthesis routes.…”