Preparation of porous carbons from cypress using super-heated steam. II. Pore structure of carbonized products

Abstract

Cypress charcoals were prepared under super-heated steam at different conditions; different temperatures of super-heated steam of 700-950°C, supplying rates of cypress chips of 15 and 30 kg/h, and transferring rates with the rotation of the paddles of 4.7-18.8 rpm. Pore structure of cypress charcoals was studied by α_s plot analysis of adsorption isotherm of N₂ gas at 77 K. Pores were developed in the charcoals at temperatures above 800°C; abrupt increase in external surface area S_ext. at about 800°C and then increase in microporous surface area S _micro. above 850°C. Total surface area S_total reached up to 1000 m²/g and external surface area S_ext. obtained was more than 300 m²/g. Particularly, very high external surface area S_ext. of 400-500 m²/g was obtained under a mild condition, i.e., cypress chips are supplied by a rate of 15 kg/h and transferred by a rotation rate of the paddles of 4.7 rpm in carbonization furnace.