Fabrication of an Organocobalt derived Nanocatalyst for Methane Decomposition

Abstract

Elevated Methane levels in the atmosphere present an opportunity for the production of a cleaner hydrogen fuel. This requires either reasonably higher temperatures or highly efficient catalysts. To come up with a convenient solution, nanocatalyst crystal faceting has been discovered to not only provide structural heterogeneity for modulating surface adsorption but also subdue the relevance of size and shape for catalysis. This research provides an alternative approach employing thermal treatment of an organometallic precursor (synthesized from microalgal extract) to fabricate higher miller indexed FCC (face centered cubic) Co3O4 nanocatalyst structures. The microalgae was identified to be Dictyosphaerium sp. by ITS Sequencing and was subjected to chemical profiling. The Co3O4 nanocatalyst derived from the organocobalt precursor was compared to conventionally co-precipitated (using sodium borohydride) Co3O4 nanocatalyst. The as synthesized precursor along with the two nanocatalysts was subjected to extensive physicochemical characterization. Crystallography, performance efficiency and cytotoxicity of the organocobalt derived Co3O4 nanocatalysts was markedly better when compared with the conventionally co-precipitated Co3O4 nanocatalyst on Al2O3 coated p type Silicon substrate in an LPCVD (Low Pressure Chemical Vapor Deposition) reactor. Subsequently, the research also proves that while these high miller indexed catalysts are devoid of magnetic properties, they are smaller in size, greater in catalytic efficiency and less cytotoxic (evaluated by calculating IC50 for WBCs and U-87 cell line, along with hemolysis assay) than the nanocatalyst formed by conventional co-precipitation. The carbon structures formed as a result of methane decomposition significantly varied on the two catalysts under similar reaction conditions. Carbon nanofilaments were observed in the case of highly faceted organocobalt derived Co3O4 nanocatalyst while particle sintering and graphitic cauliflowers dominated the conventional Co3O4 nanocatalyst. Simultaneously, in order to evaluate reaction kinetics and thermodynamics at different conditions of temperature, pressure and feed rates, a pseudo first order reaction model for volumetric reactions was developed using ANSYS FLUENT. The study finds future prospects in mounting the prepared nanocatalysts on an alternative support of microalgal derived activated hydrochar instead of aluminum coated silicon, computational evaluation of particle surface reactions and purification of resultant carbon nanostructures to be used in drug delivery.