| Natural gas is a kind of fossil fuel that is friendlyto environment, and its proportion inenergy consumption structure of our countryhas grown substantially. Absorbed NaturalGas(ANG) is a new technology to storage natural gas with high efficiency. The preparation ofporous material with large natural gas storage capacity is key to ANG.Taking into accountfactors such as adsorption capacity, production cost and repeated times, high specific surfacearea activated carbon is considered to be natural gas adsorbent with promotion prospect andpotential value. KOH activation method is a traditional method to prepare high specific surfacearea activated carbon. The existed problems were as follow: first, it was often used protectivegas to prevent excessive oxidation on the surface of the carbon layer in laboratory study, theguiding significance of which to industrialized production was not obvious.Second, few studiesof the influence of the ingredient of raw materialto KOH activation methodwere reported,therefore, itwas difficult to judge which raw material pretreatment methodswere right forpreparation.Third, it was urgent to reduce the amount of alkali, becausepotassium hydroxidemight corrodeequipment and destroy the environment. In this article, coconut shell carbide wasused as raw material to prepare activated carbon with specific surface areareached as high as3000m2/g. The methane adsorption amount was studied in high pressure volume analyzer.Detail information were as follow:1) The production method to prepare in an airtight reactor after boiling was studied. Thebest preparation situation was to let KOH and raw material with the ratio of4:1reacting at1073K for60min.The basic microcosmicinformationof activated carbon prepared at suchcondition were as follow: the specific surface areawas3421m2/g, the total pole volume was2.01cm~3/g.2) Volatile of raw materials mainly came from oxygen-containing functional groups onthe surface and subtances containing oxygen inside the material. It was found that the amountof volatile in raw material had a positive correlation with the amountof hydroxyl and phenolic hydroxyl groups on the surface of raw material.Activated carbon with specific surface areareached more than3000m2/g could be prepared, when the volatile of the carbide was controlledin the range of13~22%. The specific surface areaand iodine number of activated carbon wasimproved as much as190%and81%after volatile content of the raw material was decreased tocertain degree.3) The mechanism of KOH activation method was studied from the results of Gibbs freeenergy of related chemical equations. It was proved feasible in thermodynamic that KCl couldbe used as assistant agent activated with KOH. From experiments, it was proved that theadding of KCl was helpful to the KOH activation, as a result, the amount of K of which couldbe replaced5~15%of the amount of K of KOH.4) Polyacrylamide was used as binder to prepare granule activated carbon. By controllingthe dosage of binder, the iodine number, specific surface area, packing density, abrasionresistance of activated carbon after forming could reach as high as1958mg/g,2212m2/g,0.33g/cm~3,82%, respectively. The methane adsorbed quantity, uptake volume,desorbedquantity and desorbed volume can reach138mg/g,62.4cm~3/cm~3,130.1mg/g,and41.2cm~3/cm~3,which is31%,31%,120%and52%morethan commercial natural gas absorbent. |
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