Related Experiment Video
Updated: May 24, 2025

Author Spotlight: Exploring Cellular Processes by Modeling Ligands in Cryo-EM Maps
Published on: July 19, 2024
Influence of Ligands on the Surface Characteristics of CoMo/γ-Al2O3 and Hydrodesulfurization Catalytic Activity on
Siphumelele Majodina1, Ryan Walmsley2, Alisa Govender3
1Department of Chemistry, Nelson Mandela University, Gqeberha, South Africa.
Abstract:
Refractory sulfur compounds in fuel oils combust, releasing sulfur oxides (SOx) into the atmosphere, which is a significant source of pollution. In this study, we focused on comparing the surface properties and hydrodesulfurization (HDS) activity of CoMo-(L)/γ-Al2O3 containing chelating ligands (L), specifically acetic acid (AA), with those of ethylenediaminetetraacetic acid (EDTA), citric acid (CA). CoMo/γ-Al2O3, CoMo-AA/γ-Al2O3, CoMo-EDTA/γ-Al2O3 and CoMo/γ-Al2O3 were prepared by hydrothermal treatment of the mixtures of Co(NO3)2.6H2O and (NH4)6Mo7O24.4H2O with stoichiometric Co/Mo ratios and enriched with chelating ligands (L=AA, CA and EDTA). Based on the product distributions of the hydrodesulfurization (HDS) of dibenzothiophene (DBT), a reaction pathway of dibenzothiophene (DBT) HDS was proposed to follow hydrogenation (HYD) and direct desulfurization (DDS) routes. In addition, the ligand modification of CoMo/γ-Al2O3 catalysts resulted in enhancement of surface properties and HDS activity which is in the order of CoMo-CA/γ-Al2O3 (98 %)> CoMo-AA/γ-Al2O3 (94 %) > CoMo-EDTA/γ-Al2O3 (90 %) > CoMo/γ-Al2O3 (43 %). CoMo-AA/γ-Al2O3 presented a higher HYD/DDS ratio compared to CoMo-CA/γ-Al2O3, CoMo-EDTA/γ-Al2O3, and CoMo/γ-Al2O3, respectively which makes it a promising HDS catalyst.
Related Concept Videos
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
Complexation Equilibria: The Chelate Effect
Cooperative Allosteric Transitions
Complexation Equilibria: Factors Influencing Stability of Complexes
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...

