Cellulose-based Composites for Carbon Capture

Abstract

Several CO2 reduction technologies are currently being investigated to offset the negative impact caused due to CO2 emissions. Among them, the most prominent technology is Carbon Capture, Utilization, and Storage (CCUS). At present, absorption using liquid amines are being utilized extensively in industries to capture CO2 from flue gas but it has several drawbacks as a result, alternative methods are currently being studied.

This research aims at exploring the use of functionalized cellulose-based solid adsorbents in capturing CO2 by reusing and recycling waste paper. Office paper comprises 85% cellulose which can be extracted using a simple alkali and bleaching treatment. Cellulose has various favorable properties such as being inexpensive, non-toxic, and biodegradable. Furthermore, it can be easily functionalized with CO2-philic functionalities due to the presence of abundant hydroxyl groups. To further enhance the CO2 uptake of cellulose-based materials, aerogels are synthesized and combined with graphene oxide (GO) which is a 2D material comprising several oxygen functional groups. The synthesized cellulose-GO aerogels were evaluated for CO2 adsorption as a function of temperature (25oC, 40oC, and 60oC) and absolute pressure. Additionally, the effect of different GO concentrations in cellulose-GO aerogels was analyzed. The optimized sample had been functionalized with an aminosilane called (3-Aminopropyl) triethoxysilane (APTES) at different concentrations to study the effect of introducing APTES in adsorbing CO2 at different temperatures and absolute pressure. By functionalizing the aerogel with APTES, it is observed that the aerogel can uptake a good amount of CO2 at low pressures which makes the material promising for low-concentration CO2 capture such as Direct Air Capture (DAC) and industrial capture applications. Moreover, several other key parameters have also been analyzed in this study such as i) selectivity with respect to Nitrogen (N2), ii) water adsorption and CO2 adsorption at humid conditions, iii) isosteric heat of adsorption, iv) kinetics, regeneration & cyclability, v) model fitting using Langmuir, Freundlich, Toth and Sips models vi) thermal and mechanical stability. The optimized aerogel CGO-0.25APTES has shown promising results in all these parameters with a CO2 uptake of 2.52 mmol/g at 25oC and 1 bar with an increasing uptake as temperature increased due to the chemisorption mechanism taking place which was further observed with the increase in the isosteric heat of adsorption in comparison to the non-functionalized cellulose-GO aerogel. This sample also presented high selectivity, suppressed water adsorption capacity due to increasing hydrophobicity, good cyclability up to 10 cycles using Temperature-Pressure Swing Adsorption (TPSA), and presented fast kinetics.

Date of Award	Aug 2023
Original language	American English