Study On Preparation,Adsorption And Separation Performance Of Mesoporous Titanium-based Adsorbents

Adsorption separation method has the advantages of high selectivity,low energy consumption,easy regeneration,simple operation,good adsorption effect and high purity of products,which makes the adsorption method more and more widely used and concerned Among them,adsorbent is the key to adsorb and separate mixed gases.Based on the unique structure of titanium-based materials,a novel functional composite adsorbent was obtained by introducing organic amines or metal oxides,which can be used to adsorb and separate CO2/CH4 from coal-bed gas(CBM).Purification and utilization of this part of CBM is of great significance to reduce environmental pollution and develop new energy sources in China.In this thesis,we synthesized a series of titanium-based materials and their CO2/CH4 adsorption properties were investigated.The summaries of the results are as follows1?Compared with traditional hydrothermal synthesis method,microwave hydrothermal synthesis of titanate nanotubes(TiNTs)shows that the morphology and particle size of TiNTs synthesized by microwave hydrothermal synthesis are more uniform,the maximum surface area is 197.6 m2/g and pore volume is 0.426 cm3/g respectively,and the heating time of solution is shortened.Diethylenetriamine(DETA),triethylenetetramine(TETA)tetraethylenetramine(TEPA)were used to modify TiNTs.The sorbents were characterized by scanning electron microscopy(SEM),low-temperature nitrogen adsorption(BET),Fourier transform infrared spectroscopy(FTIR),and the adsorption properties of CO2 and CH4 were studied by using static and dynamic adsorption experiments.The separation coefficients of CO2 and methane are simulated and calculated.The results showed that the 60-TEPA/T1 wa more suitable for the adsorptive separation of the mixtures of CO2/CH4 than other samples The amine-modified TiNTs not only has higher CO2 adsorption capacity,but also has good separation ability,indicating that it has great potential for removal of CO2 from coalbed methane.2.The objective of this paper is to synthesize the protonated titanate nanotubes with high specific surface area and large pore size.Firstly,the mesoporous titanate was prepared by sol-gel method,and then the titanate nanotube(PTNT)was synthesized by microwave hydrothermal method.The specific surface area and pore volume increased,reached 420 m2/g and 1.205 cm3/g separately,and the adsorption capacity of CO2 increased too.The separation factor of 60-TETA/P reached 96.382 at 40 ?,which was higher than other adsorbents reported recently.The triethylenetetramine(TETA),tetraethylenepentylamine(TEPA),2-amino-2-methyl-l-propanol(AMP)were loaded to prepare amino modified PTNT by impregnation method.The adsorption properties of CO2 and CH4 were studied by Beishide adsorption instrument,and the penetration curves were measured by fixed bed.The experimental results show that the adsorption capacity of 60-TETA/P pure CO2 atmospheres reached 5.38 mmol/g,which is higher than that of TETA-modified titanate nanotubes,60-TETA/IG-CTNs composite adsorbents and TETA-impregnated materials reported previously.The separation factor of 60-TETA/P reached 96.382 at 40 ?,which was higher than other adsorbents reported recently.3?The PTNT modified by inorganic materials were compared with those modified by organic amines.The properties of alkaline metal oxides with smaller radius and lower valence state were selected to increase the number of alkaline active sites in order to adsorb acidic CO2 more quickly.A series of alkali metal oxide/PTNT composite adsorbents were prepared by loading calcium chloride and magnesium chloride on titanate nanotubes in different proportions.The adsorption properties of CO2 and CH4 were measured by thermogravimetry.The experimental results show that the adsorption capacity of PTNT/CaO for CO2 is as high as 8.086 mmol/g at 800 ?,after two adsorption cycles,the adsorption capacity decreased by only 1.4%,which indicated that the composite adsorbent had good recycling performance;and the adsorption capacity of PTNT/MgO for CO2 is 2.327 mmol/g at 30 ?,with separation factor of 5.52,indicating that the composite adsorbent has a good adsorption and separation effect of CO2/CH4.