High-Temperature Selective Oxidation of H₂S to Elemental Sulfur on a β-SiC-Supported Cerium Catalyst

Abstract

H2S-selective catalytic oxidation at high temperatures is a cost-effective way to directly treat lean acid gas. Herein, cerium supported on a β-SiC catalyst was synthesized by a simple impregnation method, and the catalytic behavior for the H2S-selective oxidation reaction was evaluated at a relatively high-temperature range (300–550 °C). The 10%CeO2/β-SiC catalyst exhibited excellent H2S conversion (93%) and outstanding sulfur selectivity (94%) at 300 °C and could maintain it at 82 and 87%, respectively, even at temperatures up to 550 °C. Remarkably, the catalyst revealed prominent reaction stability, which could proceed consecutively at 550 °C for 30 h and could also run circularly from 300 to 550 °C three times without notable deactivation. This demonstrated that the β-SiC support allowed good dispersion of CeO2 particles, which further improved the reducibility of the 10%CeO2/β-SiC catalyst. Furthermore, the abundant oxygen vacancies on the catalyst surface facilitated O2 activation by providing a large amount of surface adsorbed oxygen and by improving the lattice oxygen mobility. Particularly, the high thermal stability of the β-SiC support displayed a significant role in high-temperature reactions, and the strong Ce–O–Si interaction between the β-SiC support and the CeO2 phase allowed the catalyst a good resistance to SO2 poisoning. This work provides a prospective way for the treatment of lean acid gas.

Ce–Mn Oxide Nanocomposites for Catalytic Removal of H2S

“…With the development of processes, the sulfur recovery efficiencies could be enhanced to 98.8–99.5% through the mobile direct oxidation process or the Super-Claus-99 process, but the released H 2 S still needs further treatment . Selective catalytic oxidation of H 2 S (H 2 S-SCO) is one of the most promising technologies for eliminating the low concentration of H 2 S, since it can directly convert H 2 S to elemental sulfur (H 2 S + 1/2O 2 → 1/ x S x + H 2 O) at lower temperatures without thermodynamic limits . One of the key issues of H 2 S-SCO is the suppression of undesired side reaction (1/ x S x + O 2 → SO 2 ) that is prone to occur at temperatures higher than 300 °C .…”

“…6 Selective catalytic oxidation of H 2 S (H 2 S-SCO) is one of the most promising technologies for eliminating the low concentration of H 2 S, since it can directly convert H 2 S to elemental sulfur (H 2 S + 1/2O 2 → 1/xS x + H 2 O) at lower temperatures without thermodynamic limits. 7 One of the key issues of H 2 S-SCO is the suppression of undesired side reaction (1/xS x + O 2 → SO 2 ) that is prone to occur at temperatures higher than 300 °C. 8 The conversion of H 2 S and the yield of sulfur are highly dependent on the catalyst, so it needs to be rationally constructed.…”

Carbon-doped boron nitride nanosheets as an efficient metal-free catalyst for the selective oxidation of H2S

“…Among other approaches, the selective oxidation of H 2 S is attractive due to its low capital cost and environmental friendliness. 5,6…”

“…Among other approaches, the selective oxidation of H 2 S is attractive due to its low capital cost and environmental friendliness. 5,6 The metal oxide-based catalysts (V 2 O 5 , Fe 2 O 3 , TiO 2 , ZrO 2 and many others) are the most widely adopted catalysts in the continuous process of selective oxidation of H 2 S. [7][8][9] However, this series of catalysts cannot meet the demand of high sulfur selectivity and durable stability. Moreover, the formation of metal-S bonds, due to the large overlap between sulfur p and metal d orbitals, could be induced, leading to the deactivation of the catalysts.…”