Poisoning effect of chlorine

Chlorine compounds. The permanent poisoning effect of chlorine compounds is two orders of magnitude worse than that of oxygen compounds. Concentrations of about 0.1 ppm are viewed as the uppermost allowable limit in order not to affect adversely the life of ammonia catalysts [384]. The deactivation effect is based at least in part on the formation of alkali chlorides that are volatile at the upper synthesis temperatures. 

RuCls 3H2O is the most common ruthenium compound containing chlorine with stable properties. It easily dissolves in water and is cheaper than other ruthenium compounds. In the past, the ruthenium catalysts were prepared by impregnation with RuCIs as the precursor and water as solvent. However, the chlorine of remnant after reduction can poison the ruthenium catalysts when a metal oxide is adopted as a support. The poison effect of chlorine is not so obvious for ruthenimn catalysts with activated carbon as support. ... 

Chlorine is a serious poison for common metal catalysts including ruthenium-based and iron-based ammonia synthesis catalyst. Therefore, chlorine must be eliminated and its content is limited in the lowest by all means. The exploration of the poisoning effect of chlorine will be beneficial to further increase the activity of the catalyst. 

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