Selective oxidation of methane over copper oxide (CuO) catalyst

Methane is the main fraction of natural gas, which is found in abundance in nature. For this reason, there is a motivation for the production of useful organic liquids from methane. Those products would be available for use in the chemical industry and in transportation.

The goal of this research is to prove the probability of controlled oxidation of methane over copper oxide catalysts, to form methanol or formaldehyde.

The experiments involved 3 types of catalysts with different geometry and size that were based on copper. All the catalysts were regenerated after each experiment.

The research was carried using two systems, both systems included a fixed bed quartz reactor (loaded with the catalyst) inside a cylindrical heater. The outbound products were directed to liquid traps or towards a mass spectrometer that measured them online. The traps for the methane experiments were loaded with water.

Each catalyst was weighted before and after each experiment. Total Carbon (TC and TOC) analytical method was used in order to quantify the amount of CO₂ and organic compounds that were produced. Samples of each catalyst were taken to SEM surface scan, EDS and XRD analysis, in order to determine the composition of the surface area.

A colorimetric analysis and an online mass spectrum scan of the products showed the presence of formaldehyde and Carbon dioxide, without methanol.

The surface area of the used catalysts detected the presence of Cu or Cu₂O in the samples, in contrast to the native and regenerated catalysts, that detected a dominant presence of CuO on the surface.

The "Needle catalyst" proved to be the most efficient among the catalysts.

The results of the experiments demonstrated that the selectivity to form formaldehyde raises with temperature. The maximal conversion is achieved at high temperatures and it is near 50%.