A Monte Carlo Simulation Study on Adsorption of Nitrogen Oxides (NOx) in zeolites

Master thesis (2020)

Authors

G.V. Colaco Mechanical Engineering

Contributors

O. Moultos Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering (mentor)
T.J.H. Vlugt Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering (mentor)
M. Erdös Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering (mentor)
Earl Goetheer Process and Energy (graduation committee member)
Faculty
Mechanical Engineering, Mechanical Engineering
Copyright: © 2020 Grevil Colaco
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Published Date

12-06-2020

Language

English

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Faculty

Mechanical Engineering

Abstract

Nitrogen
oxides (NOx) are significant sources of air pollution. Nitrogen oxides like
Nitric oxide (NO) and Nitrogen dioxide (NO2) are mainly responsible for the
acid rain and smog. Nitrous oxide (N2O), also known as the laughing gas, is the
major greenhouse gas that is responsible for the ozone layer's damage in the
troposphere. According to the Environmental Protection Agency (EPA) report, one
pound of N2O is 300 times more potent greenhouse gas than one pound of CO2. The
significant emitters of Nitrogen oxides (NOx) are automobiles, agricultural
sources, thermal power plants, and chemical processes like Nitric acid
production plants, paint manufacturing, etc.   This study mainly focuses on the tail gas
emitted from the Nitric acid production facility. The tail gas emitted during
the HNO3 production consists of almost 2% of O2, 200-400 ppm of NO2, and NO,
whereas 800 ppm of N2O.  As N2O is the
most emitted gas from the Nitric acid production facility, it is followed by
NO2 and NO, so it is essential to reduce these pollutants from the tail gas.
Selective catalytic reduction (SCR) is a well-known technique currently
involved in reducing NOx via the adsorption process from the Nitric acid
production facility. But the costs involved in these methods are quite high.
Nanoporous materials like zeolite exhibit uniform pore size and high thermal
stability are said to be the promising adsorbents of NOx. The availability of a
large number of zeolites makes it impossible to identify the proper zeolite for
NOx adsorption experimentally. In such situations, molecular simulations are a
powerful tool that can help identify the perfect zeolite. The time and cost
involved in the process of molecular simulations are very low.  In this work, Monte Carlo simulations
involving reaction ensemble are implemented to obtain the equilibrium
composition of NOx components at desired operating conditions in the Brick
molecular simulation package. This is followed by Grand Canonical Monte Carlo
simulations (GCMC) and Reactive Grand Canonical Monte Carlo simulations
(RXMC-GCMC) for pure and quaternary NOx gas mixture adsorption in five
different zeolites (FAU, FER, MOR, MFI, and TON) using simulation package
RASPA. The composition results from the reaction ensemble are validated with
the composition results obtained using the Gibbs minimization technique in the
MATLAB model, and the results are in good agreement. The quaternary gas mixture
adsorption results in five different frameworks from RXMC-GCMC simulations are
then validated in Ideal adsorbed solution theory in the Python model, and the
results are in good agreement at the given operating conditions.