Since the capacity of an adsorbent is expressed in terms of the surface area or the amount adsorbed per weight unit, high-density adsorbents are required. The dried leftover lignocellulose of furfural production due to its good self-binding properties can be granulated or palletized and used as a potential raw material for production of high- density activated carbon sorbents with double density, in comparison with activated carbon from charcoal.
The activated carbon prepared by short-term steam activation of carbonized pressed lignocellulose materials has properties of microporous sorbents of high density, appropriate for purifying gaseous media. During our experiments, three different samples of LC charcoal (granularity 3-5 mm) were investigated. The difference was in the concentration of the catalyst used in prehydrolysis experiments (1%, 2% and 3% of sulphuric acid on the o.d. wood basis). The composition of these charcoal samples was almost identical: the fixed carbon content – 84.2-86.1%, the volatiles – 10.1-11.7%. A minor increase in the ash content parallel to the catalyst concentration increase was observed (2.9%, 3.8% and 4.7%, respectively). To study the impact of the catalyst concentration, the superheated steam and charcoal ratio 3:1 was taken. Our aim was to achieve the maximum adsorption capacity, high enough crushing strength and activated carbon yield. Therefore, the activation temperature 850-900oC was chosen. This temperature is the lowest temperature level possible, if superheated steam is the oxidizing medium. If microporous sorbents with a narrow distribution of pores’ dimensions are necessary, prehydrolysis with 2% of the sulphuric acid catalyst is preferable.
The deciduous wood hydrolytic and thermal processing cluster, autonomous in terms of heat energy, which is designed for production of furfural, acetic acid and sorbents, is an environmentally friendly and economically attractive possibility of biomass complex processing.
Keywords: High-density activated carbon, Steam activation, Lignocellulose utilization
Authors
J.Rizhikovs
Agency Latvian State Institute of Wood Chemistry, Riga, Latvia
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