Preparation Of Porous Carbon Materials With Controllable Environment For The Adsorption And Separation Of Mixture Gases

With the rapid development of the global economy,the environmental problems caused by the rapid combustion of fossil energy have become more serious,and human demand for clean energy has become stronger.Carbon dioxide is an important emission of fossil fuels and the main gas that causes greenhouse gases.Low-carbon hydrocarbons are a new type of clean energy.Their adsorption,separation and purification are the top priorities of environmental protection and the use of clean energy in the modern world.Adsorption separation technology has been widely researched and’ developed due to its low energy consumption,small equipment investment,and simple operation.The core of its research is the development of efficient adsorbents.The porous carbon material can specifically adjust the interaction between the adsorbent and the gas molecules and the adsorption capacity of the adsorbent to the gas based on its adjustable pore structure and the pore environment,thereby achieving a gas separation effect.At the same time,porous carbon materials have the characteristics of high chemical stability,thermal stability,water stability,and cheap and easy industrial production,and are very promising for industrial adsorption and separation processes.In this dissertation,the preparation of porous carbon and the regulation of its pore channel and pore environment are closely studied.The solvent-free synthesis of porous carbon polymer precursors on a large scale,the preparation of ultra-microporous carbon with uniform and narrow pore size distribution by in-situ ion thermal activation,one pot method to synthesize porous carbon with high nitrogen and high specific surface area,and the separation performance of all there materials on mixed gases were researched,as follows:(1).A facile one-pot melting-assisted and solvent-free method was successfully developed for the first time for preparing nitrogen-containing polymers.Followed by activation at temperatures ranging from 600 to 800℃ led to the formation of N-rich microporous carbons possessing narrow pore size distribution(ca.0.5～3nm),high specific surface area(ca.1021.4-3657.0 m2 g-1),large pore volume(ca.0.43-2.00 cm3 g-1)and high nitrogen content(ca up to 5.11 wt%).Particularly,the porous carbons exhibited outstanding CO2 adsorption capacity of 2.65 and 7.38 mmol g-1 at 273 K and 0.15 and 1 bar,respectively;meanwhile,it also exhibited extremely large CO2 storage capacity of 22.06 mmol g-1 at 298 K and 20 bar.Moreover,the outstanding CO2/N2,CO2/CH4 and CH4/N2 selectivity up to 36.5,6.9 and 5.1 at 298 K and 1 bar were achieved.The determinant factors on CO2 capture at 0.15,1 and 20 bar were carefully investigated.Furthermore,this method could be 10-fold scaled up to produce almost identical high-performance carbons.For real-world applications,pressure/vacum swing adsorption(P/VSA)working capacity,gas-mixture transit breakthrough experiment,and recycle feasibility are evaluated.Thus,these novel materials are promising candidates for CO2 capture from dilute gas mixtures.(2).Developing highly selective,cycle reliable,and moisture resistant adsorbents is of great importance for gas separation.It is very challenging to control and optimize pore sizes within the ultramicroporous ranges(<0.7 nm),especially for biomass-derived carbons.Moreover,porous carbons featured with random micropore sizes usually exhibited inferior gas separation performances.Herein,we developed an in-situ ionic activation method,in which the chemically bonded K+ions that are uniformly distributed in the carbon precursor are able to create ultramicroporous carbons with uniform and narrow pore size distributions.Thus,the obtained carbons exhibited high CO2 uptakes(4.17 mmol g-1)and selectivities(333.2 and 34.9)for CO2/N2(15v/85v)and CO2/CH4(40v/60v)separation at ambient conditions.The dynamic breakthrough experiments clearly demonstrate their superior and applicable gas-mixture separation performances.Upon the detailed evaluation of vacuum swing adsorption(VSA)working parameters,a record-high adsorbent selective parameter(S)of 1906.4 is obtained.Hence,the in-situ ionic activation approach is an effective method for preparing ultramicroporous carbons with narrow and uniform pore size distributions.(3).Light hydrocarbons are important alternative energy sources and raw materials,thus developing efficient adsorbents is of great importance for separating each C1/C2/C3 component in a pressure swing adsorption(PSA)process.Herein,we selected low-cost and ultrafast-growing algae as the precursor and applied the facile one-pot method to prepare N-doped porous carbons.The obtained algae-derived N-doped porous carbons(ANPCs)showed ultrahigh specific surfaces areas of 1437～3177 m2 g-1,large pore volumes of 0.637～2.18 cm3 g-1,and rich N-heteroatom content of 1.74～10.37 wt%.Moreover,the ANPC samples exhibited outstanding C3H8(11.5 mmol g-1),C3H6(11.3 mmol g-1),C2H6(6.84 mmol g-1),and C2H4(5.71mmol g-1)adsorption capacities with excellent I AST separation selectivities of C3/C1(189),C2/C1(15.3),and C3/C2(9.81)at 298 K and 1.0 bar.Impressively,ANPC-1-800 showed the C2H6-selective adsorption feature that is much more favorable in C2H4/C2H6 separation.Furthermore,the detailed evaluation of VS A working parameters,dynamic breakthrough experiment,and adsorption cycle experiment confirmed that the ANPCs are potent and promising adsorbents for practical light hydrocarbon separation.