Development Of Cd Residue Based Activated Carbon

Propane deasphalted residue is the by-product of the process that the high value-added oil and high value-added chemical products made from vacuum residuum via solvent deasphalst technology.It is composed of glial,aspaltenc and a small amount of oil.Propane deasphalted residue has high softing point,larger viscosity and poor bonding performance.Nevertheless,it can be used as a raw material of carbon material producing high value-added products due to its unique physical and chemical properties.Activated carbon is a porous structure absorption material.Activated carbon with less impurity,strong adsorption capacity,high mechanical strength and low production cost can be applied in many different application areas.Therefore,the preparation of activated carbon from propane deasphalted residue provides a new way to expand the traditional oil processing and realizes the comprehensive utilization of resources.In this work,the propane deasphalted residue as an raw material was used to prepare high performance activated carbon via pretreatment,pre-oxidation and charring processes.The effects of process parameters of each steps on the structure property of activated carbon were investigated.The main results and conclusions are summarized as following:(1)In the process of pretreatment,the influences of oxidation temperature,oxidation time and air flow rate on the structure property of modified asphalt were studied.It was found that the softening point and carbon residue increased with the increase of oxidation temperature,oxidation time and air flow rate.This was ascribed to the fact that the oxidative crosslinking reaction of oxyradical in air and asphalt-based molecules at high temperature increased the average molecular weight of modified asphalt.As a result,the softening point and coking value of modified asphalt increased.The modified asphalt with high softening point was finally prepared at 335 ℃ with an air flow rate of 0.9 L/min for 60 min.(2)In the process of non-melting,the effects of non-melting temperature,heating rate and air flow rate on the structure property of non-melting carbon were investigated.The results indicated that strength of non-melting carbon firstly increased and then decreased with the non-melting temperature,heating rate and air flow rate increasing.These were due to a better cross-linking and solidity between the functional groups of the cylindrical carbon surface and oxygen atoms,which in turn led to a stronger ring compounds after dehydrogenation and decarbonization.However,the combination between cylindrical carbon and oxygen would be unstable and deform easily with over oxidation,resulting in a decrease of pore volume and strength of non-melting carbon.The non-melting carbon was prepared at 310 ℃,with an heating rate of 4 ℃/min and air flow rate of 0.9 L/min.(3)In the process of activation,the impacts of activation temperature and flow of water vapor on the structure property of propane deasphalted residue were studied.It was found that the specific surface area and iodine adsorption first increased and then decreased with the increase of activation temperature.Due to the reaction between water vapor and carbon,the internal surface area of the carbon material and the pores could produce a large number of micropores and mesopores.This led to the increase of activated carbon’s adsorption.When the activated carbon was over activated,the water vapor continues reacted with the carbon material,which in turn led to a decrease of the specific surface area of activated carbon and adsorption capacity.The activated carbon was prepared at 800 ℃ with 20%binder and the water vapor flow of 0.4 mL/min.The iodine adsorption value,specific surface area and porosity of the activated residue was 1198 mg/g,1251 m2/g,and 65%,respectively.(4)In order to modulate the pore structure of activated carbon,biochar porogen was added to prepare mesoporous activated carbon.The iodine,specific surface area and porosity was 915 mg/g and 980 m2/g.respectively.The porosity of the oil-based activated carbon increased by 25.7%.