High-temperature H2S removal performance over ordered mesoporous La-Mn-supported Al2O3-CaO sorbents

•Novel Mn-La/OMA-2Ca exhibited excellent desulfurization performance.•Mesostructure and basic modifier promoted dispersion of particles and adsorption of acidic H2S.•Ordered mesoporous γ-Al2O3 possessed high thermal stability.•Abundant elemental sulfur was produced due to synergistic catalysis of γ-Al2O3 and La2O2S.

A series of La-Mn supported on ordered mesoporous Al2O3-CaO (OMA-2Ca) sorbents with various Mn/La molar ratio were first designed and synthesized for removal of H2S at 650-850 °C. 40% 98Mn2La/OMA-2Ca exhibited satisfactory desulfurization performance at 800 °C with a breakthrough sulfur capacity (BSC) of 16.15 g S/100 g sorbent. Elemental sulfur was formed during desulfurization as a result of synergistic catalysis of γ-Al2O3 and lanthanum oxysulfide at high temperature. The existence of high content steam in hot coal gas obviously reduced the sulfur capacity because of the formation of MnAl2O4. After five successive sulfidation-regeneration cycles, high BSC (about 90% of the initial BSC) was maintained. In addition, the characterization results indicated that the mesostructure of OMA-2Ca remained intact during sulfidation and regeneration except that the amorphous wall was converted to γ-Al2O3 phase, and active species were still well dispersed on support, which indicated the stability of Mn-La/OMA-2Ca sorbent.

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