In a pioneering research study, experimental data for the absorption rates of CO2, H2S and a mixture of both in hindered amine, 2-amino-2-methyl-1-propanol (AMP) aqueous solutions (0.03M, 0.1M, 0.2M and 0.3M) are presented for the first time. Results are compared with the absorption rate in monoethanolamine (MEA) solutions of similar concentrations. The obtained results describe the conditions under which AMP can be a better solvent than MEA and mention the opposing factors of the absorption of CO2 by the steric hindrance effect of AMP and the concentration of the unstable carbamate.
Table of Contents
1. INTRODUCTION
2. THEORY OF ABSORPTION
3. CHEMICAL REACTIONS AND KINETICS
4. DESCRIPTION OF THE APPARATUS AND OPERATING PROCEDURE
5. REPRODUCIBILITY OF THE EXPERIMENTAL RESULTS
6. ABSORPTION OF CARBON DIOXIDE INTO AMINE SOLUTIONS
7. ABSORPTION OF HYDROGEN SULPHIDE INTO AMINE SOLUTIONS
8. SIMULTANEOUS ABSORPTION OF CO2 AND H2S INTO AMINE SOLUTIONS
9. CONCLUSION
Research Objectives & Topics
This master thesis investigates the experimental absorption rates of carbon dioxide (CO2), hydrogen sulfide (H2S), and their mixtures in aqueous solutions of the sterically hindered amine 2-amino-2-methyl-1-propanol (AMP). The primary research goal is to evaluate the "hindered effect" on absorption efficiency and compare these results with those obtained from the conventional amine monoethanolamine (MEA) in a batch reactor setup.
- Comparative analysis of absorption rates between hindered amine (AMP) and linear amine (MEA).
- Study of the impact of amine concentration on absorption kinetics.
- Investigation of partial pressure effects on the absorption of acid gases.
- Experimental assessment of competitive absorption in gas mixtures.
Excerpt from the Book
6 ABSORPTION OF CARBON DIOXIDE INTO AMINE SOLUTIONS
According to the mathematical model developed in Danckwert’s book [1], the absorption of a gas accompanied by a first order reaction into a liquid solution is proportional to the partial pressure of the gas prevailing over the surface and proportional to the exposure time when k1t >> 1. The slope of the curve representing the amount of a gas absorbed as function of exposure time is A*(D.k1) and for a pseudo-first order reaction, the slope becomes A*(D.k2.B°) where the total amount of gas absorbed is proportional to the square root of the liquid reactant concentration B°. The interest of this chapter is to study the rate of absorption of carbon dioxide with amines. The objective is to calculate the rate of CO2 absorption in AMP amine solution and to compare it with the linear MEA amine solution.
6-1 Experimental investigation for the hindered amine AMP
The hindered amine 2-amino-2-methyl-1-propanol (AMP) was first used during our experimental investigation. The aim of this investigation was to study the effects of changing the partial pressure of carbon dioxide on the amount of gas absorbed for the two concentrations of amine 0.1M and 0.05M respectively. The results are represented in Tables 2-7 and Figures 6 and 7.
Summary of Chapters
INTRODUCTION: Provides an overview of gas purification processes and introduces the rationale for researching sterically hindered amines like AMP as alternatives to traditional industrial solvents.
THEORY OF ABSORPTION: Establishes the mathematical foundation for gas-liquid absorption processes, including diffusion models and enhancement factors for chemical reactions.
CHEMICAL REACTIONS AND KINETICS: Details the chemical pathways for CO2 absorption in water and amines, highlighting the carbamate formation mechanism and reversible reaction kinetics.
DESCRIPTION OF THE APPARATUS AND OPERATING PROCEDURE: Describes the design of the laboratory batch reactor, calibration methods for instrumentation, and the specific step-by-step experimental protocol.
REPRODUCIBILITY OF THE EXPERIMENTAL RESULTS: Validates the experimental rig using CO2-water absorption tests to ensure consistency and precision of the recorded data.
ABSORPTION OF CARBON DIOXIDE INTO AMINE SOLUTIONS: Presents experimental findings on CO2 absorption rates using AMP and MEA, analyzing the influence of amine concentration and gas pressure.
ABSORPTION OF HYDROGEN SULPHIDE INTO AMINE SOLUTIONS: Investigates the absorption characteristics of H2S in amine solutions, demonstrating that the kinetics are instantaneous compared to CO2 absorption.
SIMULTANEOUS ABSORPTION OF CO2 AND H2S INTO AMINE SOLUTIONS: Examines the competitive absorption of mixed acid gases to determine the industrial viability of these amines for natural gas purification.
CONCLUSION: Synthesizes the experimental findings, confirming the higher absorption efficiency of hindered amines under specific conditions and summarizing the impact of the "hindered effect."
Keywords
Carbon Dioxide, Hydrogen Sulfide, Gas Absorption, Hindered Amine, AMP, Monoethanolamine, MEA, Chemical Kinetics, Carbamate Stability, Mass Transfer, Natural Gas Purification, Batch Reactor, Absorption Rate, Steric Hindrance, Diffusion.
Frequently Asked Questions
What is the primary focus of this research?
This work explores the absorption rates of CO2 and H2S in hindered amine (AMP) solutions compared to traditional monoethanolamine (MEA) to improve gas purification techniques.
What are the main thematic fields?
The study spans chemical engineering, specifically focusing on gas-liquid mass transfer, chemical reaction kinetics, and solvent efficiency in industrial purification processes.
What is the key objective of the thesis?
The objective is to investigate the "hindered effect" in AMP solutions and determine the specific conditions where AMP outperforms conventional amines in capturing acid gases.
Which methodology is employed in this study?
The author uses a semi-infinite quiescent liquid model in a laboratory batch reactor to measure gas pressure changes, calculating absorption rates indirectly.
What topics are discussed in the main chapters?
The chapters cover the underlying absorption theory, kinetic reaction models, experimental setup, and detailed data analysis for pure gases and mixed gas systems.
Which keywords best describe this work?
Key terms include Carbon Dioxide, Hydrogen Sulfide, Hindered Amine (AMP), Absorption Rates, Chemical Kinetics, and Mass Transfer.
Why are hindered amines specifically studied?
Hindered amines are studied because they form less stable carbamates, which can potentially improve the absorption rate and capacity for carbon dioxide compared to traditional linear amines.
What conclusion does the author reach regarding the gas mixture?
The author concludes that in competitive absorption scenarios, the hindered amine AMP often shows different selective absorption properties depending on the partial pressure of the gas mixture.
- Quote paper
- Zin Eddine Dadach (Author), 1984, Absorption of Carbon Dioxide and Hydrogen Sulfide by Sterically Hindered Amine Amp, Munich, GRIN Verlag, https://www.grin.com/document/309149
