Granular palm shell activated carbon (AC) was impregnated separately with monoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP) to improve its natural capacity and selectivity for carbon dioxide (CO2) adsorption. The total surface area, micropore volume, as well as the heterogeneity of the impregnated AC particles was considerably reduced due to impregnation. CO2 intake of impregnated 500 μm AC particles improved significantly and adsorptive capacity of 500 μm MEA-impregnated AC particles improved by 172 % and 44 % comparing to non-impregnated and AMP-impregnated AC particles respectively. Solid state amine stoichiometric results indicated that adsorption capacity of unhindered amine (MEA) is higher than that of hindered amine (AMP) by 50 % contrary to liquid amines standard stoichiometry. Exhausted AMPimpregnated beds were regenerated by sweeping at room temperature with stream of pure nitrogen (N2) flowing at 60 ml/min for 4 hours. Heating up to 75 °C was required to regenerate exhausted MEA-impregnated beds. Increasing feed gas flow rate has adverse effect on breakthrough time more than increasing bed operating temperature. Breakthrough time was utilized to evaluate the performance of the different adsorption beds.
Table of Contents
1. Introduction
2. Materials and Methodology
2.1. Materials
2.2. Methodology
2.2.1. AC samples characterization
3. Results and Discussion
3.1. Breakthrough time results
3.2. Dynamic adsorption beds capacity improvement
3.3. Unhindered MEA and hindered AMP stoichiometry
3.4. Adsorption isotherm of impregnated and non-impregnated 500 μm AC beds
3.5. Linear regression of Dubinin-Astakhov (D-A) equation
3.6. Thermal characterization of the AC beds
3.7. Effect of regeneration with high temperature on the performance of MEA- impregnated AC beds
Research Objectives and Focus
The study investigates the enhancement of CO2 adsorption capacity in granular palm-shell activated carbon (AC) through impregnation with monoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP). The primary objective is to evaluate how these amine modifications influence surface chemistry, breakthrough time, and adsorption capacity, while also determining optimal regeneration strategies for the exhausted beds.
- Impregnation of AC with primary (MEA) and sterically hindered (AMP) amines.
- Characterization of AC surface properties, micropore volume, and heterogeneity via gas adsorption isotherms.
- Assessment of dynamic CO2 adsorption performance and breakthrough time metrics.
- Stoichiometric analysis of CO2 reactions with solid-state amine-impregnated adsorbents.
- Evaluation of thermal regeneration methods for exhausted amine-impregnated beds.
Excerpt from the Book
3.1. Breakthrough time results
Results in Figure 2 are showing the differences in breakthrough time for three adsorption beds at room temperature. Adsorption of CO2 molecules is considered concluded when the display of the CO2 monitor, which is connected to the outlet of the adsorption column, is showing that CO2 molecules start to exit the bed. These results were obtained using 5 g of each adsorbent, at room temperature and 10 ml/min feed gas flow rate.
Breakthrough time values in Figure 2, increased from 34 min for non-impregnated AC bed to 62 min and to 90 min for AMP-impregnated for MEA-impregnated AC bed respectively. The increase in breakthrough time for MEA and AMP-impregnated beds compared with non-impregnated AC bed was due to that amine molecules have formed many active sites for CO2 adsorption, where chemisorption was dominant over physisorption leading to adsorb selectively more CO2 molecules from the feed gas stream. Steric hindrance influence is responsible for breakthrough time reduction of AMP-impregnated AC beds in comparison with MEA-impregnated AC beds.
Summary of Chapters
1. Introduction: Discusses the context of climate change and the greenhouse effect, highlighting the need for effective CO2 capture technologies and the role of porous activated carbon as an adsorbent.
2. Materials and Methodology: Details the properties of the used palm-shell activated carbon, the amine impregnation process with MEA and AMP, and the experimental setup for dynamic CO2 adsorption tests.
3. Results and Discussion: Analyzes the breakthrough time, adsorption capacity, reaction stoichiometry, surface characteristics via BET/D-A equations, and the thermal regeneration performance of the impregnated adsorbents.
Keywords
Activated carbon, CO2, Adsorption, Impregnation, MEA, AMP, Breakthrough time, Chemisorption, Steric hindrance, Micropore volume, Regeneration, Greenhouse gases, Palm-shell AC, Stoichiometry, Dubinin-Astakhov equation.
Frequently Asked Questions
What is the core focus of this research?
The research examines the effectiveness of modifying granular palm-shell activated carbon with amines (MEA and AMP) to improve its performance in capturing CO2 from gas mixtures.
What are the primary themes addressed?
The study centers on surface chemistry modification, adsorption capacity, breakthrough time dynamics, and the regeneration efficiency of exhausted carbon beds.
What is the main research objective?
The main objective is to determine if amine impregnation enhances CO2 uptake compared to non-impregnated carbon and to identify the impact of steric hindrance and temperature on these adsorption processes.
What scientific methods are utilized?
The work employs physical activation for carbon preparation, slurry impregnation methods, dynamic breakthrough time testing using a real-time CO2 monitor, and the Dubinin-Astakhov (D-A) model for surface characterization.
What is covered in the main body?
The main body covers the experimental setup, comparative analysis of breakthrough times, stoichiometric investigations of amine reactions with CO2, and the thermal characterization of the adsorption process.
Which keywords best describe this study?
The study is characterized by keywords such as activated carbon, CO2 adsorption, amine impregnation (MEA/AMP), and breakthrough time analysis.
Why is MEA more effective than AMP in this specific study?
The study indicates that unhindered MEA provides more active sites for CO2 adsorption compared to sterically hindered AMP, which experiences steric hindrance that reduces its effective binding capacity under these experimental conditions.
How does temperature affect the regeneration of these beds?
The results show that heating is necessary for efficient regeneration, especially for MEA-impregnated beds, where higher temperatures help sever the stronger chemical bonds formed between the amine and CO2.
- Citation du texte
- Saad Khalil (Auteur), Mohamad K. Aroua (Auteur), 2018, Effects on Surface Area. Intake Capacity and Regeneration of Monoethanolamine, Munich, GRIN Verlag, https://www.grin.com/document/437683
