High-Temperature Cleaning for Chlorine-Containing Coal Gas by Supported Manganese Oxide Sorbent

Ting Ke Tseng,Hsin Chu,Ling Wang

doi:10.4209/aaqr.2012.02.0036

Ting Ke Tseng, Hsin Chu + Show 1 more

Open Access

https://doi.org/10.4209/aaqr.2012.02.0036

Copy DOI

Abstract

This research aimed to achieve HCl removal for chlorine-containing hot coal gas by using supported oxide sorbents in a fixedbed reactor at 673-873 K. Mn2O3/SiO2 was chosen as the optimal sorbent to eliminate chlorine species, after thermodynamic screening of the dechlorination potential of sorbents based upon various metals. The dechlorination experiments and results of the ICP, BET, XRD, XPS, and FTIR analyses provided in-depth views of the reaction chemistry behind the complex system of HCl removal in a simulated syngas containing 3,000 ppm HCl, 25 vol% CO, 15 vol% H2, and N2. When the sorbent composed of 23 wt% Mn2O3/SiO2 came into contact with HCl, CO, and H2, the reaction mechanism contained two paths. At lower temperatures Mn2O3 tended to react with HCl, while at higher temperatures it might first be reduced into Mn3O4 and then react with HCl. The probable products from the reaction (Mn2O3 and HCl or Mn3O4 and HCl) are MnCl2, Cl2, and H2O. That is, as the reaction temperature increased, the second path started to become more important. The final product of this reaction might also include metallic manganese in addition to MnCl2. Furthermore, when the temperature increased, the equilibrium constants of all the reactions reduced, and subsequently resulted in the decreasing sorbent performance.

Highlights

With the increasing population and the burgeoning industrial development, the growing demand for energy resources has been a matter of world concern
The rising temperature intensified the formation of Mn3O4 from Mn2O3 contained in the sorbents (Fig. 3), assumed to be associated with the chemical reaction rate accelerated by the increasing temperature
Though the rising temperature seemed at first glance to be favorable for HCl elimination since it motivated the production of Mn3O4 that had the highest equilibrium constant (Fig. 5), in comparison with the whole thermodynamic trend this alone according to Fig. 5 contributes only a smaller proportion to the reaction system

Summary

Introduction

With the increasing population and the burgeoning industrial development, the growing demand for energy resources has been a matter of world concern. As currently the most abundant fossil fuel with relatively low and constant price, is a popular option to fulfill the future energy demand. Technology of clean energy production from coal becomes one of society’s greatest needs. Integrated gasification combined cycle (IGCC), one of the most advanced and efficient clean coal technologies, has recently gripped the world’s attention. IGCC generates electricity by integrating coal gasification and combinedcycle power generation technology. Sulfur and chlorine contained in coal will be emitted mostly in the form of H2S (0.2–3.0 vol%) and HCl (50–2,000 ppm) (Davidson, 1996; Bakker, 2004; Yang et al, 2006; Wang et al, 2009; Lin et al, 2010), during the process of gasification (Tu et al, 2011). Distinguished for low pollution to the environment, IGCC requires the removal of these deleterious contaminants prior to the combustion of syngas for electricity production

Objectives

Results

Conclusion