Adsorption Performance Indicator to Screen Carbon Adsorbents for Post-combustion CO2 Capture

N Álvarez-Gutiérrez,F Rubiera,C Pevida,Y Jin,J Bae,S Su

doi:10.1016/j.egypro.2017.03.1382

Abstract

This work is the result of the collaboration between INCAR-CSIC (Spain) and CSIRO Energy (Australia) in the framework of the European Commission FP7 project HiPerCap (High Performance Capture) that started in January 2014. The HiPerCap project aims to develop novel post-combustion CO2 capture technologies and processes which are environmentally benign and have high potential to lead to breakthroughs in energy consumption and overall cost, involving all main separation technologies for post-combustion CO2 capture. The present contribution focuses on adsorption with low temperature solid sorbents as a promising technology to capture CO2 from the flue gas. More precisely, CSIRO and CSIC have developed CO2 adsorbents from different carbon precursors including petroleum pitch, phenolic resin and agricultural by-products.The performance of new materials can be evaluated either experimentally or by means of numerical simulations, but each methodology has drawbacks. Thus, it is of utmost importance to seek a simple method for evaluating and comparing materials on the basis of readily available adsorption data. It is well known that the ideal adsorbent has a high selectivity, a high working capacity, and a low adsorption enthalpy; however, in practice, it is very rare to find a material which combines all of these attributes. Therefore, the selection of the adsorbent will often involve a trade-off among these factors, making comparisons of varied adsorbents even more difficult. In this work, the potential of the activated carbons developed by INCAR-CSIC and CSIRO for a post-combustion CO2 capture process has been evaluated and compared by means of an adsorption performance indicator.

Highlights

Nowadays, efforts to mitigate the rising levels of CO2 in the short-term via the development of effective methods for CO2 capture are of high priority and they could provide a mid-term solution allowing humanity to continue using fossil energy until renewable energy technologies mature [1, 2].One potential scenario under which CO2 capture could be rapidly deployed is in the context of post-combustion capture since it can be used for retrofitting existing facilities without requiring substantial changes to the combustion process [3,4,5]
Solid lines correspond to the fitting of the Toth model and points represent the experimental data for carbon fiber composite (CFC), CNT, macadamia nut shell-derived carbon composite (MNS), and almond shells (AS)
Four different carbon adsorbents (CFC, CNT, MNS and AS) were produced by means of activation with CO2 that constitutes a more environmentally benign procedure when compared to chemical activation

Summary

Introduction

Efforts to mitigate the rising levels of CO2 in the short-term via the development of effective methods for CO2 capture are of high priority and they could provide a mid-term solution allowing humanity to continue using fossil energy until renewable energy technologies mature [1, 2]. The composition of a typical post-combustion flue gas from a coal fired power plant has a relatively low CO2 concentration (13-16% v/v), while the bulk of the effluent is composed of N2 (73–78% v/v) and other minor components, such as H2O (5–7% v/v), O2 (3–4% v/v), CO, NOx, and SOx (ppm) and it is released at a total pressure of approximately 100 kPa [6]. The performance of new materials can be evaluated either experimentally in the lab or by means of numerical simulations. All of the equilibrium data were integrated in a performance indicator defined so as to evaluate and compare these adsorbents in terms of selectivity, working capacity and adsorption enthalpy under conditions relevant to post-combustion CO2 capture [21, 22]

Materials

Fitted equations

Calculation of adsorbent performance indicator

Results and discussion

Conclusions