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

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. Mn 2 O 3 /SiO 2 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% H 2 , and N 2 . When the sorbent composed of 23 wt% Mn 2 O 3 /SiO 2 came into contact with HCl, CO, and H 2 , the reaction mechanism contained two paths. At lower temperatures Mn 2 O 3 tended to react with HCl, while at higher temperatures it might first be reduced into Mn 3 O 4 and then react with HCl. The probable products from the reaction (Mn 2 O 3 and HCl or Mn 3 O 4 and HCl) are MnCl 2 , Cl 2 , and H 2 O. 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 MnCl 2 . Furthermore, when the temperature increased, the equilibrium constants of all the reactions reduced, and subsequently resulted in the decreasing sorbent performance.

Single-Step Synthesis of Magnesium-Doped Lithium Manganese Oxide Nanosorbent and Their Polymer Composite Beads for Selective Heavy Metal Removal

“…The diffraction peak marked with “*” is assigned to Mn 2 O 3 (JCPDS card no. 00-031-0825), which disappears in protonated samples due to dissolution of Mn 2 O 3 in protonation process . The Scherrer equation was employed to calculate the crystallite size, which was found to be 18 nm for LMMO-400, 33 nm for LMMO-500, 18 nm for HMMO-400, and 30 nm for HMMO-500 corresponding to diffraction peak of the (111) plane.…”

“…00-031-0825), which disappears in protonated samples due to dissolution of Mn 2 O 3 in protonation process. 52 The Scherrer equation was employed to calculate the crystallite size, which was found to be 18 nm for LMMO-400, 33 nm for LMMO-500, 18 nm for HMMO-400, and 30 nm for HMMO-500 corresponding to diffraction peak of the (111) plane. The increase of crystallite size with the increase of temperature is possibly due to enhancement of nucleation rate with temperature.…”

Thermodynamic Possibilities and Limits for Producer Gas Desulfurization and HCL Related Interferences for Zn, Mn, Ce and La Based Sorbents of Sulfur Compounds

“…Recently, also sorbents based on rare earth oxides have been studied (both theoretically and experimentally) for deep syngas desulfurization [5][6][7][8][9]. Possibilities of removal of HCl from syngas by transition metals [1,9,10] and alkali based sorbents [1,11,12] at temperatures 200 -800 o C have shown possible applicability of soda and K 2 CO 3 -based sorbents. Interferences of HCl and HF in H 2 S sorption by solid sorbents at higher temperatures have been studied only rarely [1,13].…”