Preparation And Modification Of Porous Carbon For CO₂ Adsorption

Since the large-scale use of fossil fuels such as coal, oil and natural gas, a large number of CO2 and other greenhouse gases were emitted to the atmosphere directly. Among these greenhouse gases, CO2 contributes over 60%to global warming due to its huge emission amount. Accordingly, developing technologies for efficient carbon capture and sequestration (CCS) on large scale is highly desired.In this thesis, in order to improve the adsorption capacity of sorbents, we through the methods of nitrogen doped and TEPA modified.and the characteristics of pore structure can be changed by adjusting the roasting temperature. N2 adsorption, Powdered X-ray diffraction patterns (XRD), fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron (XPS) measurements, transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) on MC carriers and adsorbents were characterized. There were two methods to evaluated the CO2 capture performances of the adsorbents, one was using a fixed-bed reactor equipped with an online mass spectrometer (MS), the other was measured on the Beshide 3H-2000PS2 adsorption analyzer. The results include the following three aspects:l.The objective of this research is to develop a new type of CO2 sorbents. The sorbents were synthesized with mesoporous carbon (MC) and tetraethylenepentamine (TEPA). It was found that the synthesized mesoporous carbons (MC) can be used as the supports of high-capacity solid CO2 sorbents. MC800 is better as amine support than MC600 due to its larger pore volume and larger pore size. The optimal loadings for MC600 and MC800 are 60%and 70%, respectively. And the highest CO2 adsorption capacity (4.68 mmol/g) was achieved on MC800-70. It was also found that moisture has a positive effect on the CO2 capture performance of sorbents., TEPA loading (MC800-70) without and with uses of water vapor are 4.68 mmol/g and 5.19 mmol/g, respectively. Besides the excellent CO2 adsorption capacity and amine efficiency, the MC800-70 possessed good stability and regenerability after 5 adsorption-desorption cycles.2. Mesoporous carbon materials were synthesized using a using citric acid and magnesium nitrate as raw materials and urea as the nitrogen source. The synthesized carbon materials were characterized using XRD, N2 sorption, FTIR, and XPS. The results indicate that the synthesized carbon materials possess high surface area in the range of 1221-1571 m2 g-1 with abundant of mesopores and micropores. Nitrogen element was successfully doped into the carbon and with increasing urea content during the synthesis process, the structure of the carbon materials have changed obviously and the amount of the effective nitrogen functionalities are also changed. It has been demonstrated that the synthesized nitrogen-containing mesoporous carbon materials are good adsorbents for CO2 capture. This method offers a simple but effective pathway to produce nitrogen-containing mesoporous carbon materials, and it may hold great promise for a variety of applications, especially for electrochemistry.