Mercury (Hg) is a natural, trace component of natural gas. Corrosion of aluminum heat exchangers by liquid metallic Hg can lead to dramatic issues. The quantification of the gaseous Hg concentration in natural gas streams is therefore crucial prior to the implementation of Hg removal units for preventing the formation of liquid Hg. Different methodologies exist for the determination of the Hg concentration in natural gas, one of which relies on the sampling of natural gas at high pressure using stainless-steel cylinders prior to off-site Hg measurement. An inert internal coating is supposed to hamper Hg adsorption, presumably making the Hg analysis reliable. Here, we challenge this statement by showing that even silicon-coated cylinders are inefficient for preventing Hg adsorption on internal walls. Different cylinders were tested for gaseous Hg concentration stability over time in a clean argon matrix. We find that the gaseous Hg concentration sharply declines in almost all tested cylinders (uncoated, polytetrafluoroethylene-coated, and silicon-coated) to reach undetectable levels within a day or two as a result of adsorption, with the notable exception of a brand new silicon-coated cylinder. Heating cylinders up to 190 °C allowed for the recovery of most adsorbed Hg and revealed the occurrence of two distinct Hg species with distinct release temperatures. Our results suggest that Hg 0 is first physically adsorbed and further oxidized, presumably in relation to sulfur compounds covering the internal walls of the cylinders. The newly purchased silicon-coated cylinder kept a constant gaseous Hg concentration over 6 months because it never interacted with any real natural gas sample containing substantial sulfur concentrations relative to Hg.

The presence of arsenic in natural gas and liquid hydrocarbons is of great concern for oil companies. In addition to health risks due to its toxicity as well as environmental issues, arsenic is responsible for irreversible poisoning of catalysts and clogging of pipes via the accumulation of As-containing precipitates. To address these problems and to better design treatment units, robust methods for the analysis of arsenic and its compounds in oil streams are required. In addition, the use of feedstocks as a novel source of energy is becoming increasingly important. Most biomasses used as feedstocks are contaminated with arsenic. To avoid problems related to the presence of this element, it is therefore also necessary to have reliable methods for the analysis of arsenic and its compounds in these new fluids. This review outlines the sampling techniques, sample preparation methods, and arsenic analysis techniques developed during recent decades and commonly used in the oil industry and in the new feedstock energy domain.

Mercury is one of most dangerous contaminants of natural gas and petroleum and petroleum fractions present in the crude oil industry due to its corrosive properties. The determination of Hg levels in petroleum products is a prerequisite for risk evaluation and ensuring an efficient Hg removal. This Review focuses on total and speciation analyses of Hg in the petroleum industry. We describe the constraints related to sampling and analysis for both natural gas and liquid petroleum products and the different methodologies developed over the past decades. Despite the low detection limits reached with various methodologies, the reliability of measurements might strongly depend on sampling and storage practices. The preservation of all Hg species from sampling to analysis might require some further evaluation. We evaluated the speciation methodologies based on reported performances. We however conclude that the lack of reference material for Hg speciation analysis in petroleum hampers a robust evaluation of the methods. Future developments might allow a better characterization of the different Hg species, helpful to understand the partitioning of Hg between the different petroleum phases.