CeO₂–TiO₂ Sorbents for the Removal of Elemental Mercury from Syngas

Abstract

A series of CeO2-TiO2 (CeTi) sorbents with different CeO2/TiO2 mass ratios were prepared by an impregnation method and employed to remove elemental mercury (Hg(0)) in simulated syngas. The CeTi sorbents with a CeO2/TiO2 mass ratio of 0.2 exhibited superior Hg(0) removal efficiency from 80 to 150 °C, which could be ascribed to the greater amount of surface chemisorbed oxygen resulted from Ce(3+) on the sample surface. H2S was the most effective syngas component responsible for Hg(0) removal. The use of 400 ppm H2S resulted in 98% Hg(0) removal efficiency under the experimental conditions. H2 and CO had a negligible effect on the efficiency of Hg removal. In the presence of H2S, a prohibitive effect of HCl and NH3 on Hg(0) removal was observed because of the consumption of the surface oxygen. Water vapor also inhibited Hg(0) removal due to competitive adsorption with H2S. Hg(0) removal over CeTi sorbents was proposed to follow the Eley-Rideal mechanism, in which active surface sulfur reacts with gas-phase Hg(0). This large oxygen storage capacity of CeTi sorbents is quite favorable to H2S catalytic oxidation and Hg(0) emission control in an extremely reducing environment, such as when there is a deficiency of O2.

Different crystal-forms of one-dimensional MnO2 nanomaterials for the catalytic oxidation and adsorption of elemental mercury

“…The cost of traditional activated carbon and modified activated carbon materials inhibits their wide application for capturing Hg 0 [7,10]. Many reports showed that the transition metal oxides (such as FeO x , MnO x and CuO x ) are potentially suitable materials for the removal of Hg 0 [11][12][13][14][15][16][17]. Among the transition metal oxides, manganese oxides are considered suitable alternative materials that are abundant, nontoxic and cheap.…”

An efficient Ce-doped MoO3 catalyst and its photo-thermal catalytic synergetic degradation performance for dye pollutant

“…Cerium and molybdenum oxides are widely applied in various fields due to their unique physicochemical properties. Ceria is often employed as an oxygen storage and release (OSR) reservoir, due to the facile mutual transformation of Ce 4+ /Ce 3+ [12][13][14]. For example, N. Aman et al [15] have reported cerium-doped titania at the cerium concentration from 0 to 10 wt.%.…”

Regeneration mechanism of CeO2-TiO2 sorbents for elemental mercury capture from syngas

“…The fixed-bed test system used in the present experiments has been described in our previous publication [5]. The Hg 0 concentration in the gas flow was recorded by a mercury continuous emissions monitor (MS-1A/DM-6B, Nippon Instrument Corporation, Japan).…”

“…In our previous research, the CeTi sorbent was developed to remove Hg 0 and exhibited high activity for mercury removal from syngas [5,6]. However, the high cost of CeTi sorbents is a current limitation for developing this technology.…”