The Performance Research Of Graphene Oxide-carbon Nanotube Molecular Sieve Membrane Separation CO₂ And N₂ From The Blast Furnace Gas

The comprehensive utilization of blast furnace gas in secondary energy is the most important factor in energy saving and consumption reduction of steel plants.The direct discharge of blast furnace gas will produce a lot of toxic gases and pollute the environment.If used directly as fuel,not only a large amount of carbon dioxide will appear,but also bring The benefits are very low.An important reason for the downturn in blast furnace gas is that it contains a lot of inert gases N₂ and CO₂,which have poor combustion stability,low calorific value,and accompanying flame instability,occurrence of fire and fire extinguishing in the combustion process.The specific reason is that a large amount of CO₂ and N₂ are not involved in combustion to generate heat,nor can they support combustion.On the contrary,they will absorb a large amount of heat generated during the combustion process,resulting in a low theoretical combustion temperature of blast furnace gas（1300degrees）,and no combustion at normal temperature.stable.Separating CO₂ and N₂from blast furnace gas in advance is an effective method to solve the above problems,and the key to this method is to develop a molecular sieve membrane with low cost,high gas flux and high separation efficiency.In view of the above problems,this paper successfully prepared graphene oxide/carbon nanotube molecular sieve membranes（GO/SWCNTs）and amino groups and base groups by using graphene oxide and single-walled carbon nanotubes with high specific surface area and good adsorption capacity as raw materials.The modified graphene oxide/carbon nanotube molecular sieve membrane（NH₂-SH-GO/SWCNTs）is used to separate carbon dioxide and nitrogen in the blast furnace coal in advance to improve the recovery and utilization rate,and has high efficiency,low energy consumption,clean and environmental protection features.Preparation of graphene oxide（GO）by modified Hummer method;purification of single-walled carbon nanotubes（SWCNTs）by mixed acid method;preparation of GO/SWCNTs composite molecular sieve membrane by vacuum filtration;transmission electron microscopy（TEM）,scanning electron microscopy（SEM）X-ray diffractometry（XRD）,thermogravimetric analysis（TGA）,infrared spectroscopy（FTIR）,specific surface area（BET）were used to characterize the composition,structure,morphology and properties of the composite membrane materials.The results show that the prepared graphene oxide is repeatedly or ultrasonically stripped to obtain a single layer or a small number of graphene oxide sheets;single-walled carbon nanotubes（SWCNTs）are reduced by mixed acid to reduce the impurity content,and open carbon nanometers.The closed port of the tube reduces the phenomenon of agglomeration;after the graphene oxide and the purified carbon nanotube are ultrasonically combined,oscillated and stirred,the carbon nanotubes are successfully intercalated between the graphene oxide sheets and the graphene oxide sheets.Further increase;the added amino group and the sulfhydryl group are successfully loaded onto the surface of the material,further increasing its adsorption capacity and the agglomeration phenomenon is again improved.The separation performance of GO/SWCNTs and NH₂-SH-GO/SWCNT molecular sieve membrane for single gas CO₂ and N₂ and mixed gas CO₂,N₂ and CO under different experimental temperatures and inlet pressure conditions were studied.The results show that the permeability coefficients of single gas and mixed gas decrease with the increase of experimental temperature,the gas permeability coefficient increases with the increase of inlet pressure.during the separation process,as the temperature increases,the mean free path of the gas molecules increases to cause Knudesn diffusion,and the permeability coefficient is proportional to the pressure difference at a certain temperature.As the inlet pressure increases continuously,the increase of gas permeability coefficient decreases when P₀ approaches 0.2 MPa.At this time,surface diffusion occurs.At a certain temperature,the surface diffusion rate increases first with the increase of pressure difference.Post-saturated state.Regardless of whether it is a single gas or a mixed gas,the permeability coefficient of CO₂ is larger than N₂ in terms of permeability coefficient.When the mixed gas is separated,the CO₂ permeability coefficient reaches 1976 Barrer,the N₂ permeability coefficient reaches 1897Barrer,and the CO permeability coefficient is only 149 Barrer.The relationship betweenthegaspermeabilitycoefficientsofthecomponentsfollows P_CO2>P_N2>>P_CO.The magnitude relationship between the separation coefficients isα（CO₂/CO）>α（N₂/CO）>>α（CO₂/N₂）.According to the relationship between the above permeability coefficient and the separation coefficient,it can be proved that the molecular sieve can effectively separate CO₂ and N₂ from the blast furnace gas.After the addition of amino groups and sulfhydryl groups,the permeability coefficients of CO₂ and N₂ increase,and the separation coefficientsα（CO₂/CO）andα（N₂/CO）also increase.This is because the addition of groups increases the adsorption performance of molecular sieves.Increased the diffusion and adsorption capacity of CO₂ and N₂.