Date of Award

2016

Document Type

Open Access Dissertation

Department

Chemical Engineering

Sub-Department

College Of Engineering and Computing

First Advisor

Bihter Padak

Abstract

Due to increasing concerns associated with the emissions created from the combustion of coal, technologies are being modified or developed to limit many of these harmful emissions. The content of this thesis will focus on two technologies and the specific pollutants they seek to limit. The first investigated is selective catalytic reduction, which is utilized to decrease NO emissions. Due to the recent promulgation of the MATS regulations, focus has been on reducing the Hg emissions through the optimization of the SCR catalysts, making them bi-functional for NO reduction and Hg oxidation. The work presented here focuses on a novel SCR catalyst, Cu-SSZ-13, that has already been investigated for diesel applications. Cu-SSZ-13 is compared to a commercial SCR catalyst under a variety of gas compositions to determine the effect of the various flue gas components would have on Hg oxidation. Further tests attempt to optimize the reaction conditions for Hg oxidation over the Cu-SSZ-13 catalysts. Finally, As, which is also present in coal flue gas, is a known poison for SCR catalysts limiting their NO reduction activity and lifetime. The mechanism and extent of As poisoning is examined on the commercial and novel catalysts.

The second technology of interest is oxy-combustion which operates by separating N2 to produce a concentrated CO2 stream for capture or storage. Due to the proposed design of oxy-combustion facilities, sulfur concentrations are likely to increase several fold with SO3 being of particular concern. During traditional air-combustion, sulfur emissions are mitigated through their interaction with the coal fly ash, a major component of which is CaO. To better understand the impact of the changing gas composition on the SOx reactions with CaO, a combination of experimental and computational experiments were conducted. Experimentally, exposed CaO samples are characterized using a combination of techniques to examine the effect from air to oxycombustion environments at high temperatures. Additionally, DFT calculations are conducted in tandem with the experiments to study the reactions on a more atomistic scale. The effect of lateral interactions between the various flue gas components on sulfur adsorption is investigated.

Rights

© 2016, Benjamin D. Galloway

Download

Share

COinS