Preparation of microporous sorbents from cedar nutshells and hydrolytic lignin

• Published in: Carbon (New York) Vol. 41; no. 9; pp. 1793 - 1800
• Main Authors: Baklanova, O.N, Plaksin, G.V, Drozdov, V.A, Duplyakin, V.K, Chesnokov, N.V, Kuznetsov, B.N
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2003
• Subjects: A. Porous carbon; B. Carbonization, activation; C. Adsorption; D. Microporosity; A. Porous carbon; D. Microporosity; B. Carbonization, activation; C. Adsorption
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/S0008-6223(03)00149-0

Carbon nutshells and hydrolytic lignin were used as starting materials for the preparation of microporous active carbons. Optimum parameters for cedar nutshell carbonization have been selected (temperature of carbonization 700–800 °C, rate of heating less than 3 °C/min) for the preparation of microporous carbons (average pore width 0.56 nm). The textural characteristics of microporous carbons made from nutshell are similar to those of a ‘Coconut’ carbon molecular sieve, but the latter has both a higher CO 2 adsorption capacity and a higher coefficient of N 2/O 2 separation. The influence of carbonization and steam-activation parameters on the microtexture and molecular-sieve properties of granular carbons made from hydrolytic lignin was also investigated. A low rate of heating (less 3 °C/min) promotes the formation of micropores with average sizes around 0.56–0.58 nm at carbonization temperature 700 °C. At the same carbonization temperature the average sizes of micropores were 0.7–0.78 nm at rates of heating more than 3 °C/min. The activation of lignin-char with steam at 800 °C resulted in the formation of active carbons with more developed micropore volume (0.3–0.35 cm 3 g −1) and with micropores of widths around 0.6–0.66 nm which are able to separate He from a He–CH 4 mixture. The size of the micropores was varied as a function of burn off value.