Tackling elemental mercury removal from the wet-gas phase by enhancing the performance of redox-active copper-based adsorbents utilising an operando pre-heating system,Reaction Chemistry & Engineering

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Tackling elemental mercury removal from the wet-gas phase by enhancing the performance of redox-active copper-based adsorbents utilising an operando pre-heating system
Reaction Chemistry & Engineering ( IF 3.4 ) Pub Date : 2020-08-05 , DOI: 10.1039/d0re00240b
Syamzari Rafeen _{1,

2,

3} , Rafin Ramli _{1,

2,

3} , Geetha Srinivasan _{1,

2,

3,

4,

5}

Affiliation

A simple and facile technology to capture the elemental mercury selectively from moisture-containing natural gas (wet-gas) streams of petrochemical industries is presented. We aimed at exploiting the established redox chemistry of copper(II) towards mercury(0), by utilising simple copper(II) chloride impregnated adsorbents. Tuning the copper coordination sphere with temperature as a control by taking advantage of moisture in the feed, has been successful in enhancing the mercury adsorption through a viable process design. Mercury removal was achieved through chemisorption when the CuCl₂ (Cu(II) : Hg(II) mol ratio = 1.35 : 1) impregnated on solid supports, such as silica, γ-alumina and activated carbon via the wet incipient method and have been used as adsorbents. Supported CuCl₂-based adsorbents were characterised using UV-visible, scanning electron microscopy, energy dispersive X-ray spectroscopy and powder X-ray diffraction, wherein copper complexation was not observed on freshly prepared adsorbents. An in-house experimental setup (wet-gas rig) was designed to perform mercury breakthrough experiments through mercury online monitoring, wherein an add-on moisture saturator was included to allow water vapour in the feed and mimic a wet-gas scenario. In the wet-gas testing rig, two modes of testing were implemented, i.e., with and without pre-heating the incoming gas feed in front of the adsorbent column. The gas pre-heating method introduced for the test under wet-gas conditions resulted in an enhancement of mercury adsorption performance as compared to the dry conditions for selected CuCl₂-containing adsorbents. This enhancement of mercury removal was particularly predominant for CuCl₂ supported on silica, in which the performance increased by four-fold, accounting for a slight pre-heating by 10 °C for the wet-gas in comparison to the test under dry-gas conditions. The redox centre on copper at the hydration sphere, was influenced particularly on the silica support, which consequently resulted in superior reactivity with elemental mercury in the vapour state. Moreover, the gas pre-heating avoided capillary condensation, thereby contributing to the enhancement on mercury adsorbent's life-time. The mercury capture on the adsorbent has been expected to be due to complexation on the silica support that led to a better fixation.

中文翻译：

通过使用操作性预热系统提高氧化还原活性铜基吸附剂的性能来解决从湿气相去除元素汞的问题

提出了一种简单易行的技术，可从石油化工行业的含湿天然气（湿气）流中选择性地捕获元素汞。我们的目标是通过利用氯化铜（II）浸渍的简单吸附剂，利用已建立的铜（II）对汞（0）的氧化还原化学。通过利用进料中的水分调节铜配位球的温度作为控制，已经通过可行的工艺设计成功地增强了汞的吸附。当CuCl ₂（Cu（II）：Hg（II）摩尔比= 1.35：1）浸渍在固体载体（例如二氧化硅，γ-氧化铝和活性炭）上时，通过化学吸附去除汞通过湿起始方法并已用作吸附剂。使用紫外可见光，扫描电子显微镜，能量色散X射线光谱和粉末X射线衍射对负载的CuCl ₂基吸附剂进行了表征，其中在新鲜制备的吸附剂上未观察到铜络合。设计了一个内部实验装置（湿式气钻机），以通过在线监测汞来进行汞突破实验，其中包括一个附加的水分饱和器，以使进料中的水蒸气和模拟湿气情况。在湿气测试台上，实施了两种测试模式，即，在有或没有预热的情况下，进入吸附塔前的进料气体。在潮湿气体条件下为测试引入的气体预热方法与选定的含CuCl ₂吸附剂的干燥条件相比，提高了汞吸附性能。除汞的这种增强作用对于CuCl ₂尤其重要支撑在硅胶上，其性能提高了四倍，与在干燥气体条件下进行的测试相比，湿气的预热略有提高，为10°C。水合球上铜上的氧化还原中心特别受到二氧化硅载体的影响，因此导致与蒸气态元素汞的优异反应性。此外，气体预热避免了毛细管凝结，从而有助于延长汞吸附剂的使用寿命。预期吸附剂上的汞捕获是由于二氧化硅载体上的络合导致更好的固定。

更新日期：2020-08-25

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