Ultrafine Au nanoparticles confined in three-dimensional mesopores of MCM-48 for efficient and regenerable Hg0 removal sorbent in H2S and H2O containing natural gas

Abstract The H2O and H2S in natural gas are frequently deemed to have inhibitory influences on Hg0 removal performance of most noble metal based Hg0 absorbents, it is extremely significant to develop an efficient and regenerable Hg0 removal absorbent with excellent H2S and H2O tolerance. In the work, the Au/MCM-48 absorbent was controllable synthesized using a facile yet robust method for Hg0 removal in H2S and H2O containing natural gas. The ultrafine Au nanoparticles with a diameter of 1.4 nm were embedded and uniformly dispersed in the three-dimensional channels of MCM-48. The absorbent of 1 wt% Au achieved a complete Hg0 capture performance at 60,000 h−1 and 30 °C by forming Au-Hg amalgam, and its Hg0 adsorption capacity achieved to 7.23 mg∙g−1 at 5% breakthrough. The spent sample could be easily regenerated by thermal treatment without distinct degradation over 5 cycles. The introduction of H2S and H2O in gas flow had an inappreciable impact on Hg0 removal performance over the Au/MCM-48 absorbent. The excellent Hg0 adsorption efficiency, outstanding capture capacity and good regeneration performance of the absorbent due to the nano-confinement of MCM-48 channels, which prevents Au nanoparticles from growing and agglomerating. Excellent H2O tolerance is attributed to the good hydrophobicity of MCM-48 modified by trimethylchlorosilane, and the high H2S tolerance is due to the fact that the Au nanoparticles lack reactivity toward H2S. This work provides a promising method for the preparation of effective and regenerable absorbents for demercuration in H2S and H2O containing natural gas.