Mesoporous alumina infiltrated with a very thin and complete carbon layer

Abstract

The mesoporous composite material “carbon-infiltrated alumina” was synthesized via chemical vapor infiltration of pyrocarbon in a porous alumina (γ-Al2O3) matrix. The process was carried out under continuous flow conditions at 650–800 °C and 1 bar of the reaction gas mixture containing ethylene (5 or 15 vol. %) and Ar (balance). A number of the synthesis parameters were examined to determine the conditions that are necessary for the formation of a thin but complete carbon layer over the alumina surface. A special acquisition mode of X-ray photoelectron spectroscopy was suggested and validated for the fast and reliable testing of completeness and uniformity of the carbon deposits on the outer alumina surface. Low-temperature N2 adsorption and electron microscopy were used to study the porous structure of γ-Al2O3 after high-temperature pretreatments and the carbon-infiltrated materials as well as the same samples after treatment with an aqueous hydrochloric acid solution. As a result of these studies, the mesoporous carbon-infiltrated aluminas with an extremely thin (1–1.5 carbon layers) and complete carbon coating, high electrical conductivity and excellent endurance in acidic medium have been prepared.