Preparation of Adsorbent(s) using Nano-Casting Technique for Carbon Dioxide Capture from Flue Gases

Abstract

Increasing awareness of the influence of greenhouse gases on global climate change has led to recent efforts to develop strategies for the reduction of CO2 emissions. CO2 capture and storage (CCS) technology is therefore being developed for application to power plants and in CO2-intensive industries to reduce the carbon footprint of these activities and mitigate the potentially harmful effects of climate change. CO2 capture from large point sources, such as power plants, can be achieved through continued research, development and demonstration. The main challenge in CO2 capture technology is to reduce the overall cost by lowering both the energy and the capital cost requirements. While costs and energy requirements for today’s capture processes are high, the opportunities for significant reductions exist, since researchers have only recently started to address these needs. Adsorption has received much attention for its low energy consumption, low equipment cost, and ease of application. Efficient adsorbents and well designed reactor will further improve the process economics. Adsorption of CO2 using basic adsorbents requires high pressure operation, hence modified adsorption routes need to be developed with higher adsorption capacity, less energy and cost intensive. This can be achieved by two ways, namely (i) modification of adsorbents and (ii) development/modification of nanostructured adsorbents. The focus of the present work is to develop the nano-structured adsorbents and evaluate the CO2 adsorption capacity. For the development of nano-structured adsorbents, melamine-formaldehyde resin was used as the precursor and mesoporous silica was used as the template. Development of adsorbent included two steps namely synthesis of resin (precursor) and carbonization of the templated resin samples. The process conditions for the resin synthesis were optimized. After this, carbonization was done at 500 °C for 1 hour, resulting in the thermal degradation of the precursor. Five porous carbon adsorbents were obtained having different template to precursor ratio. X-ray diffraction analysis was done from 2• = 10–80° which showed that the synthesized material is nano-structured carbon. Surface morphological changes were observed by scanning electron microscopy. Irregular and heterogeneous types of pores were observed. FTIR spectra were taken to identify the v functional groups present in the synthesized adsorbents. No peak for nitrogen was observed. Absence of nitrogen in the synthesized adsorbents was confirmed by Kjeldahl test. Both texture and surface chemistry influence the CO2 capture performance of the prepared adsorbents. If an adequate and well developed porosity is joined to a favorable chemistry, the CO2 adsorption capacity is considerably enhanced. Porous and nanostructured adsorbents are obtained but due to the loss of nitrogen, CO2 did not adsorb on the synthesized materials when a mixture of CO2 and N2 is passed over them at room temperature. To confirm the integrity of the new adsorption study set up, CO2 adsorption study was carried out for zeolite 13X at room temperature.