Efficient scrubbing of mercury vapour from natural gas streams has been demonstrated both in the laboratory and on an industrial scale, using chlorocuprate(II) ionic liquids impregnated on high surface area porous solid supports, resulting in the effective removal of mercury vapour from natural gas streams. This material has been commercialised for use within the petroleum gas production industry, and has currently been running continuously for three years on a natural gas plant in Malaysia. Here we report on the chemistry underlying this process, and demonstrate the transfer of this technology from gram to ton scale.

Solid-supported ionic liquids (ILs) have recently received attention as a potential effective technology for mercury removal from a gas stream. However, the leaching of ILs from the solid support has not been investigated in detail. In the present study, the stability of 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) impregnated on silica and activated carbon was evaluated during elemental mercury removal (Hg 0 ) from a gas stream. Silica-and carbon-supported [Bmim]Cl-based adsorbents were characterized before and after Hg 0 adsorption by using Fourier transform infrared spectroscopy, Brunauer−Emmett−Teller surface area analysis, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermal gravimetric analysis. The carbon-supported adsorbent showed better stability (no leaching of ILs) compared to the silica-supported adsorbent because of the availability of substantial micropores. The lower stability of silica-supported ILs is attributed to the presence of mesopores on silica support, which holds [Bmim]Cl ineffectively in a gas flow of a high concentration of Hg 0 (15 ppm). The activated carbon-supported ILs, especially in a powdered form, showed higher adsorption efficiency of Hg 0 from a gas stream. The adsorption capacity of powdered carbon-supported [Bmim]Cl was 21 mg/g in 68 h of continuous adsorption.

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An increasing trend of contaminants in the oil and gas streams has been observed worldwide in the past recent years, and one of the eminent naturally occurring contaminant is mercury. Mercury has been found to be hazardous to health, safety, and environment as well as detrimental to process equipment at the oil and gas plants. The complexity in removing mercury is due to its existence in different species, mainly elemental, organo-and inorgano-mercury.Most available technologies for mercury removal are located downstream of the acid gas removal and dehydration units and thus, leading to contamination of these units as well as mercury release to the environment. Besides its potential to be located upstream of these units to better protect the plant operations, the new technology is capable of treating the full range of mercury species by a single adsorbent or treatment step to meet the current targeted mercury level at outlet of mercury removal unit of less than 0.01 ug m-3. In addition, it can be applied to the existing mercury removal units without requiring any plant modifications or retrofitting.A joint collaboration between PETRONAS and Queen's University Belfast has led to a development of a new technology that effectively removes mercury from oil and gas streams utilising ionic liquids. Efficient scrubbing of mercury vapour from natural gas streams has been demonstrated both in the laboratory and on an industrial scale, using chlorocuprate(II) ionic liquids impregnated on high surface area porous solid supports. This material has been tested for use within the petroleum gas production industry, and has currently been running continuously at a number of gas processing plants in Malaysia for more than three years. Since it was originally revealed, further innovative developments have been undertaken to improve its efficiency and performance for applications in liquid hydrocarbon streams. Recognitions and awards have also been received from various organisations including iChemE for the technology.Since it was originally revealed, further innovative developments have been undertaken to improve its efficiency and performance for applications in liquid hydrocarbon streams.

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