Preparation And Characterization Of Coke-based Columnar Activated Carbon

Coke powder is the larger amount of powders resulting that come from the production,transportation and storage of coke.Coke powder doesn't use as carbonaceous reducing agent or gasification feedstock of fixed bed in metallurgy and calcium carbide industry due to its small particle size.Coke powder is useless and usually discard as a waste in the early time.It is gradually applied in the preparation of carbon materials in recent years.The selection of the binder plays a very important role in the preparation of activated carbon with a certain strength produced by coke powder.Therefore,an intensive study of the binder is very urgent.Asphalt has condensed polycyclic aromatic hydrocarbon structure,with high carbon residue value.It has homology with carbon materials and a deep affinity with powder.Hence,it is fit for serving as the components of composite adhesives.Carboxymethyl cellulose(CMC)and high temperature coal tar have good soak and could ensure the molding quality of activated carbon products.In this paper,the coke powder as raw material,the asphalt,CMC and high temperature coal tar as adhesives were used to prepare columnar activated carbon via molding,carbonization and activation technologies.The influences of process parameters of molding,carbonization and activation on the structural property of activated carbon were studied.The effects of different kinds and contents of binders on the performances of activated carbon were also investigated.The main results of this paper were summaried as following:(1)Columnar activated carbon was prepared from coke powder used asphalt and CMC adhesives via water vapor physical activation.The effects of molding,carbonization and activation technology on the performances of activated carbon were investigated.It was found that the particle size,water content and kneading time mainly influenced the mixing uniformity and compactness of raw materials.A better uniform and dense mixing was beneficial for the molding.The activation temperature,time and heating rate mainly affected the formation of the carbon skeleton and initial pore.The optimal activation temperature,time and water vapor flux for the preparation of coke-based and columnar activated carbon were determined.(2)IR spectra,1H-NMR and TGA analyses of asphalt,CMC and high temperature coal tar were compared.The results indicated that the condensed structure,the aromatics,beta component content and residue value of the coal asphalt binder were higher than that of petroleum asphalt.The effects of contents of CMC,the contents and asphalt kinds of asphalt on the activated carbon structure and properties were investigated.It was found that the iodine adsorption value of activated carbon was increased,firstly and then decreased with the contents of CMC and asphalt increasing,the strength of coke-based carbonized material increased,while the yield declined with the increase of the contents of CMC and asphalt.Ultimately,the optimun contents of CMC and asphalt were 8%and 30%,respectively.It was also found that the strength,iodine adsorption value and yield of activated carbonincreased with the value of carbon residue and content of beta component increasing.The specific surface area,strength,iodine adsorption value and yield of columnar activated carbon prepared were 619 m2·g-1,0.077 MPa,583 mg/g and 37.4%,respectively.(3)The structural properties of activated carbon were analyzed by physical adsorption,SEM and XRD.The results indicated that activated carbon prepared by coal asphlt with higher carbon residue value and beta components had abundant structure,larger specific surface area,small and less air hole less.