N. Mahata

Tuning of texture and surface chemistry of carbon xerogels

The influence of different activation processes on the textural and surface chemical properties of carbon xerogels was studied. Carbon xerogels were prepared by the conventional sol-gel approach using resorcinol and formaldehyde; two different pHs of sol-gel processing led to carbon materials with distinct pore size distributions. The materials were subjected to controlled activation by three different methods: activation by oxygen plasma, activation by HNO(3), and activation by diluted air. Treatments with HNO(3) and diluted air created oxygen groups on the external surface as well as inside the pore channels, whereas plasma is more suitable for introducing oxygen groups selectively on the external surface. Nevertheless, it was shown that samples with wider pores can be oxidized to some extent on the pore interiors by plasma. Significant changes in total surface area by air activation were observed.

Adsorption of phenol on supercritically activated carbon fibres: effect of texture and surface chemistry.

The influence of texture and surface chemistry on the phenol adsorption capacity of activated carbon fibres (ACFs) was studied. ACFs were prepared by carbonization of a phenolic textile fibre under nitrogen flow, followed by activation with H(2)O and CO(2) (under atmospheric pressure and supercritical state). The materials were characterised by N(2) and CO(2) adsorption, and by temperature programmed desorption studies. A strong correlation between the amount of adsorbed phenol and the micropore volume has been observed. The relationship between surface oxygen concentration and amount of physisorbed and chemisorbed phenol was assessed, and it was shown that higher amounts of surface oxygen groups decreased the phenol chemisorption capacity of ACFs.

Simultaneous Elimination of Pyrophoricity and Enhancement of Activity of Raney Nickel by Carbon Deposition: Synthesis of Highly Active NiC Catalysts

Nickel‐carbon composite materials (NiC catalysts) are synthesized by decomposing methane over Raney‐type skeletal nickel catalysts. The NiC catalysts are evaluated in the hydrogenation of cyclooctene, cyclooctadiene, nitrobenzene, and para‐chloronitrobenzene. Characterization by scanning electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy reveals that the catalysts consist of nickel in its metallic form with superficial oxide layers, carbon, and aluminum oxide/hydroxide. The catalysts exhibited excellent hydrogenation activity, superior to the parent Raney nickel.