Acetylene hydrochlorination is currently an important industrial process used to manufacture vinyl chloride, which is the monomer used to synthesize polyvinyl chloride (PVC). Although the catalysts in acetylene hydrochlorination have been studied extensively, the development of suitable catalysts is still a significant challenge from the standpoint of catalyst activity and deactivation.
It is known from our experiment that the catalyst support have important effect on the catalytic performance in acetylene hydrochlorination. Such a finding has prompted us to consider whether the texture and graphitic properties of activated carbon support could influence the activity of catalyst in acetylene hydrochlorination.
In this study, supported Ru catalysts for acetylene hydrochlorination were prepared by incipient wetness impregnation of four different carbon materials: activated carbon (AC), multiwalled carbon nanotubes (CNT), carbon balck (CB) and graphene oxide (GO). The four carbon materials have various shapes, sizes and graphitic properties. The influences of the texture and graphitic structures of carbon supports on the activities of the catalysts were examined. Their catalytic performances for acetylene hydrochlorination were tested in a fixed-bed reactor under the fixed reaction conditions of temperature 140 ºC, C2H2 hourly space velocity 180 h-1, feed volume ratio V(HCl)/V(C2H2) = 1.05. And the catalytic activity over supported Ru catalysts is ranked as Ru/GO(graphene oxide carbon) < Ru/CNTs (carbon nanotube) < Ru/CB < Ru/AC. All these samples were characterized by X-ray diffraction (XRD), N2 adsorption, Raman spectra, H2 chemisorption and Transmission electron microscopy (TEM). Characterization by transmission electron microscopy (TEM), X-ray diffraction pattern (XRD) showed that Ru particles are highly dispersed on carbon supports and the optimum range of Ru particle sizes is around 3-6 nm. The catalytic performance combined with characterization results demonstrates that the graphitic structure of the carbons is critical for the supported Ru catalyst, while the surface area of carbons is less important. The degree of disordering is a significant factor determining the catalytic activity of the carbon-supported catalyst compared to the pore structures of the carbon supports.
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