Development of Mercury Adsorbent from Naphtha

Abstract

Crude oil and natural gas condensate contain various metals including low levels of mercury. This mercury can cause various problems, such as catalyst degradation, piping corrosion and so on. For example, corrosion of piping in natural gas production plants, blockage of LPG vaporizers, and damage to aluminum components in heat exchangers have been reported. Silicates, alumina, activated carbon, and other materials are all effective adsorbents combined with metal sulfides for removing mercury from natural gas. However, these conventional adsorbents result in a further problem that the metal sulfide dissolves in the petroleum products, such as naphtha. The bonding energy was calculated by computer chemistry to identify new effective materials for mercury removal. Based on the bonding energy calculation, adsorbents with good predicted performance based on alkaline metal sulfide and metal chlorides were prepared using activated carbon with very large surface area as a support. Experiments identified a mercury removing adsorbent which has no effect on the properties of naphtha. Mercury removal equipment with the newly developed adsorbent has been operated in the Shikoku refinery of Taiyo Oil Co. since November 1995. This equipment is operated at normal temperature and pressure, and has processed over 5 million kl during 8 years. This is the one of the longest running mercury removal plants in the world.