Experimental Study On Preparation And Desulfurization And Denitration Performance Of Activated Coke

With the large consumption of traditional energy such as coal and petroleum,the raw materials for the preparation of activated coke are reduced,and serious environmental pollution will be caused.Since the 1980s,biomass as a carbon neutral raw material has been widely studied by scholars at home and abroad.At first,biomass was converted into biomass energy such as syngas and bio-oil.It was not until the beginning of the 21st century that the research on biomass activated carbon materials began to develop.Due to the poor mechanical strength of biomass based activated coke and the more developed pore structure of coal based activated coke,this paper proposed to use coal-biomass blends to prepare activated coke.This can not only make full use of the synergistic effect between coal and biomass co-pyrolysis to solve the problem of producing heavy components such as tar in the pyrolysis process of coal separately,but also reduce the dependence on traditional energy sources while ensuring the quality of activated coke,and effectively reduce the release of environmental pollutants.The activated coke can be used in the field of flue gas desulfurization and denitration.The activated coke desulfurization and denitration technology is a kind of dry removal technology with high reliability and stability,which solves the problems of the existing desulfurization and denitration technology,such as high operating cost,serious water waste and large occupation area.The activated coke modified by NH3 and K2CO3 solution has the characteristics of mutual promoting adsorption in flue gas desulfurization and denitration.Therefore,it is of great theoretical significance and practical value to study the activated coke with synergistic adsorption performance of SO2 and NO.On the basis of previous studies,this paper further improved the preparation process of activated coke.Using Zhundong coal and poplar bark as raw materials,the activated coke was prepared by physical one-step activation method and compared with the activated coke prepared by the previous two-step activation method to determine the optimal preparation conditions.Then the physicochemical properties were further regulated by NH3 and K2CO3 solutions.Activated coke prepared under different activation conditions was used to test its synergistic adsorption capacity of SO2 and NO.The adsorption and occurrence forms of SO2 and NO were determined by adsorption amount and FTIR and XRD patterns of activated coke after adsorption,so as to clarify the adsorption mechanism.The adsorption capacity of SO2 and NO of activated coke can be used to guide the preparation of activated coke,so as to determine the best conditions for the production of activated coke with specific adsorption properties.With the mixing ratio of coal and biomass of 2:1 and activation time of 60min as the basic conditions,the preparation experiment of one-step activated activated coke was carried out.The effects of different temperature and different concentration of activation medium components on the yield of activated coke,specific surface area and iodine adsorption value were explored.The experimental results show that when the activation temperature is 800℃ 10%steam and 20%CO2,the activated coke has the maximum specific surface area and iodine adsorption value,at around 663m2/g and 781 mg/g respectively.Compared with the two-step activation method,the physical properties of the activated coke,such as yield,specific surface area and iodine adsorption value,are similar,but the one-step activation method does not go through the carbonization process,shortening the preparation time and reducing the use of activation medium,which has a guiding significance in the actual production process.By using NH3 and K2CO3 solutions to regulate the physical and chemical properties of the activated coke,the effects of different NH3 mole fraction and different concentrations of K2CO3 solution impregnation on the specific surface area,pore size distribution,surface morphology and surface functional groups of the prepared activated coke were investigated.The experimental results show that NH3 has moderate effect on the formation of micropores,while K2CO3 can greatly increase the proportion of micropores in activated coke,up to 97%.In terms of mesopore formation,the activation behavior of K2CO3 solution has a competitive inhibition relationship with steam activation,resulting in the decrease of mesopore and total pore volume.After physical and chemical properties control,the micro surface of the activated coke becomes rough,showing a layered structure and a lot of cracks appear.From the FTIR map,it is found that many functional groups and bond structures are decomposed by heat,but new functional groups are also generated.Different preparation conditions of activated coke for SO2 and NO separate and simultaneous removal experiment,the experimental results show that the adsorption of SO2 and NO on untreated activated coke is competitive,while the activated coke treated with NH3 and K2CO3 solution mainly exists chemisorption when adsorbing SO2 and NO,and the presence of both can promote the adsorption of activated coke.Pyridine and pyrrole functional groups are formed on the surface of the activated coke modified by NH3,which is conducive to the adsorption of SO2 and NO by the activated coke,and the adsorption capacity is up to 14mg/g and 6 mg/g.A large number of active sites were formed in the microstructure of the activated coke modified by K2CO3 and loaded with K metal,which greatly improved its desulfurization ability.The adsorption capacity of SO2 and NO reached up to 68 mg/g and 18 mg/g respectively.Through XRD,it was found that CaSO4,NaSO4 and K2SO4 crystals appeared in the adsorbed activated coke.