Catalyst – solid sorbent – or support therefor: product or process – Regenerating or rehabilitating catalyst or sorbent – Treating with a liquid or treating in a liquid phase,...
Patent
1999-03-26
2000-08-08
Dunn, Tom
Catalyst, solid sorbent, or support therefor: product or process
Regenerating or rehabilitating catalyst or sorbent
Treating with a liquid or treating in a liquid phase,...
502 25, B01J 2034, B01J 3864, B01J 3866
Patent
active
061002100
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for treating spent catalysts contaminated by mercury so as to regenerate them and reuse them.
At the present time, the treatment of contaminated, spent products is becoming an activity of increasing importance. Environmental constraints are requiring all types of liquids, solids or gases to be purified for the purpose of lowering their content of pollutants and of avoiding the latter being discharged into the environment.
Many catalysts have been developed for the purpose of eliminating these impurities by absorption, adsorption or chemical reactions. However, once the contaminated products have been purified, the impurities have high concentrations in these catalysts, which must be stored or destroyed.
Currently, the trend is to try to treat these spent catalysts so as to remove the impurities therefrom. The aim of this treatment is, on the one hand, to recover impurities for the purpose of their reutilization or conversion into an easily storable form and, on the other hand, to regenerate the spent catalysts so as to be able to reuse them. This second aspect furthermore allows savings to be made since a new charge of fresh catalyst does not have to be purchased.
Among impurities particularly harmful to the environment, mercury, in any of its forms, is of great importance. In particular, it is present in natural gas or petroleum cuts. One way of removing the mercury from these gases is to bring them into contact with a catalyst based on a sulphur compound, for example a supported catalyst having a mineral support and an active phase based on a sulphur compound, for example copper sulphide.
Mercury present in the gases reacts on contact with these catalysts to form a mercury compound, especially mercury sulphide, which remains adsorbed or absorbed on the catalyst.
Currently, spent catalysts comprising these mercury compounds are destroyed or stored; and a new charge of fresh catalyst must be used in order to continue treating the gases.
One object of the present invention is to provide a process for treating spent catalysts of this type which make it possible not only to remove the mercury therefrom but also to regenerate the initial active phase of the said catalyst so as to be able to use it again in the same application without having to redeposit a new active phase.
To this end, the invention relates to a process for regenerating a supported catalyst having an active phase based on a sulphur compound and a mineral support, contaminated by a mercury compound, in which the following steps are carried out: at least one sulphide chosen from alkali metal sulphides, alkaline-earth metal sulphides or ammonium sulphide,
Further advantages of the invention will appear more clearly on reading the description and the examples.
The invention therefore relates to a process for regenerating a supported catalyst having an active phase based on a sulphur compound and a mineral support, contaminated by a mercury compound in which the following steps are carried out: at least one sulphide chosen from alkali metal sulphides, alkaline-earth metal sulphides or ammonium sulphide,
According to the process of the invention, the spent catalyst from which it is necessary to remove the mercury compounds is brought into contact with a basic aqueous solution of one or more sulphides, as defined above.
Preferably, the basic aqueous solution is a solution of sodium sulphide or potassium sulphide.
According to a preferred way of carrying out the process of the invention, this basic aqueous solution is obtained by mixing an aqueous solution of one of these sulphides and sodium hydroxide.
In this case, the concentration of the sodium hydroxide is preferably at least 0.1M in the mixture, especially of at least 0.5M.
In general, it is recommended to use a basic aqueous solution whose pH is at least 10, preferably at least 12.
In order to optimize the quantities of products to be employed, the catalyst is preferably brought into contact with the basic aqueous solution in quantities such that the
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Bournonville Jean-Paul
Le Cloirec Pierre
Nocher Bernard
Ollivier James
Dunn Tom
Procatalyse
Rhee Michael J.
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