Mechanical Activation Of The Electrochemical Behavior And Interfacial Behavior Of Pyrite In Organic Media

During the coal direct liquefaction, the interface character and dispersibility of pyrite catalyst can affect the contiguity of pyrite with coal and the catalytic effect to the liquefaction reaction. As the electrochemical performance of pyrite powder under mechanical activation can reflect its interface character and dispersibility, the electrochemical performance and interface behavior of pyrite powder in organic medium can provide definite theory proof for developing catalysts with excellent performance in the coal direct liquefaction reaction.Pyrite powder was prepared by mechanical activation. By adopting pyrite powder microelectrode as work electrode, the absolute ethyl alcohol as electrolyte, proper amount of cationic surfactants, such as cetylpyridinium chloride, as ion conductor, the electrochemical behavior and its interface behavior of pyrite powder with or without mechanical activation in absolute ethyl alcohol were compared and studied through cyclic voltammetry scanning. The main conclusions are summarized as follows.(1) The granularity of pyrite powder under mechanical activation becomes smaller, the specific surface area increases, aberrance of the crystal lattice occurs, the surface energy ascends and the activity becomes larger.(2) Compared with the cyclic voltammetry curve of pyrite powder , the distinction of the peak potential is not obvious, but the peak current increases obviously for pyrite powder with mechanical activation. That is, the activity of pyrite powder with mechanical activation becomes larger. With the progress of cyclic voltammetry scanning, the activity of pyrite powder becomes smaller. The electrode process is non-reversible and is not under diffusion control.(3) Grinding additives can be absorbed on the surface of pyrite powder under mechanical activation by chemical or physical process. As a result, the adsorption of oxygen on the surface of pyrite is weakened. The physical adsorption of Stearic acid on the surface of pyrite under mechanical activation is beneficial for the ball grinding of pyrite. But Octadecanol and Span80 are not beneficial for the ball grinding of pyrite in alcohol.(4) Grinding additives were added in the experiments of cyclic voltammetry scanning to detect their absorption behavior on the surface of pyrite powder. It was found the anodic peak of cyclic voltammetry curve for pyrite powder disappeared with the addition of Stearic acid when the scanning rate was slowed down. That is, Stearic acid can be absorbed on the surface of pyrite electrode by physical process and restrain the ability of pyrite under mechanical activation. Similar phenomenon is not observed in the experiments when Octadecanol or Span80 were added in the experiments.