A Review on Mercury in Natural Gas and Its Condensate: Accurate Characterization and Efficient Control Technologies for Total and Speciated Mercury

The requirement to characterize and remove mercury from natural gas and its condensate span a wide range of subject fields, from environmental science and analytical chemistry to material design and chemical engineering. The first part of this review discusses the mercury species and exposure limits in natural gas and gas condensate. In the second and third parts, the analytical techniques and pretreatment steps for analyzing mercury in natural gas and gas condensate are described separately. In the fourth part, the conventional gas processing operations are introduced together with the limit values of mercury distribution in natural gas processing operations. By analyzing the distribution and transformation of mercury in natural gas processing, the location of the mercury removal unit (MRU) for natural gas plants is optimized. In the fifth part, the different types of adsorbents for mercury removal from natural gas and liquid media are enumerated based on different mechanisms. The wet and acidic resistance of the different adsorbents in removing Hg0 from natural gas and flue gas is introduced. In the sixth part, as the species of mercury in a condensate are more complex than those in natural gas, the adsorption selectivity of each adsorbent for mercury removal from natural gas condensate is listed for comparison. Finally, the remaining challenges for mercury species determination and removal together with the expected future developments for mercury adsorbents are concluded.