Mn-Co/MCM-41吸附剂表征及脱除烟气中单质汞研究

针对燃煤烟气中单质汞(Hg0)不溶于水而颇难去除的问题,采用浸渍法制备了不同Mn和Co物质的量比的Mn-Co/MCM-41介孔分子筛吸附剂,在固定床实验台架上考察了各吸附剂的脱汞效率.采用N2吸附/脱附、X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、H2程序升温还原(H2-TPR)和X射线光电子能谱(XPS)等技术对吸附剂进行了物理化学性质表征.结果表明:Mn和Co复合后,吸附剂的脱汞效率显著提高.Mn/Co物质的量比为3/1时,吸附剂的脱汞效率最高,反应温度为150℃时,其脱汞效率高达90%.与单一组分Mn或Co负载MCM-41吸附剂相比,Co的掺杂不但使Mn和Co在MCM-41上的分散更均匀,还会促进Mn3+和Mn2+向Mn4+的转化和提高吸附剂的还原特性,增强吸附剂的脱汞性能.

Characterization and performance of Mn-Co/MCM-41 for elemental mercury removal from simulated flue gas

Aiming at the difficulty of Hg0 removal from flue gas due to its indissolubility in water, a series of studies on the performance of elemental mercury (Hg0) removal from simulated flue gas were carried out with a laboratory-scale fixed-bed reactor using the Mn-Co/MCM-41 mesopore molecular sieve prepared by the wet impregnation method. The adsorbents were characterized by a variety of techniques such as N2 adsorption/desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), hydrogen gas temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectra (XPS). The results showed that the additions of Mn and Co significantly enhanced the efficiency of Hg0 removal. With a Mn/Co molar ratio of 3/1, the Hg0 removal efficiency reached as high as 90% at 150℃. Compared with the single Mn or Co supported MCM-41 adsorbent, the presence of Co could not only lead to better dispersions of Mn and Co over MCM-41, but also promote the conversion of Mn3+ and Mn2+ to Mn4+ and the reduction abilities of Mn-Co/MCM-41 adsorbents, which would play important roles in promoting Hg0 removal.