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

The H2O and H2S in natural gas are frequently deemed to have inhibitory influences on Hg-0 removal performance of most noble metal based Hg-0 absorbents, it is extremely significant to develop an efficient and regenerable Hg-0 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 Hg-0 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 Hg-0 capture performance at 60,000 h(-1) and 30 degrees C by forming Au-Hg amalgam, and its Hg-0 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 Hg-0 removal performance over the Au/MCM-48 absorbent. The excellent Hg-0 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.