Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Sulfur or sulfur containing component
Patent
1987-01-02
1988-09-27
Heller, Gregory A.
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Sulfur or sulfur containing component
423230, 423245, B01J 800, C10B 1700, C10B 1716, C10B 3120
Patent
active
047740671
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a regenerative process for removing mercaptans contained in a gas by means of an absorbing agent based on at least one active metal oxide, that is, susceptible of retaining the mercaptans by chemical action. The invention more particularly refers to an improvment on the regeneration of the absorbing agent that has fixed the mercaptans.
It is known that gases of different origins, specially natural gases, synthesis gases or also residual gases contain by way of impurities small concentrations of mercaptans and that it is necessary to eliminate said mercaptans due to their extremely unpleasant odor and mainly to their toxicity prior to sending said gases either toward the circuits of use of these gases, specially in the case of natural gases or synthesis gases, or also toward the atmosphere in case of residual gases.
Among the processes proposed for removing the mercaptans contained in a gas, there is known a regenerative process that makes use of a solid absorbing agent based on an active metal oxide such as cupric oxide for retaining the mercaptans by formation of mercaptides, said process being particularly adpated for the treatment of natural gases containing mercaptans, since it is not disturbed by the presence of hydrocarbons.
This regenerative process includes an absorption step in the course of which the gas to be treated is brought into contact with the solid absorbing agent at temperatures below 100.degree. C. for retaining the mercaptans on the absorbing agent, a regeneration step in the course of which the absorbing agent that has retained the mercaptans is swept by means of a gas containing free oxygen while operating at temperatures of from 200.degree. C. to 280.degree. C., thereafter the absorbing agent is treated by steam under pressure and by ammonia after which said absorbing agent is washed with hot water and dried and the dried absorbing agent is subjected to an oxidation by a gas containing free oxygen at a temperature of about 200.degree. C., and a cooling step in the course of which the regenerated absorbing agent is brought to an appropriate temperature below 100.degree. C. for being re-used in the absorption step.
A first inconvenience in such a process is the complexity of the operation of regeneration of the absorbing agent, which makes difficult an industrial use of the process. A second inconvenience of said process results from the fact that the first phase of the regeneration operation, namely, the sweeping of the absorbing agent that has retained the mercaptans by a gas containing free oxygen at temperatures of from 200.degree. C. to 280.degree. C., leads to the formation of metallic sulfate, specially copper sulfate, which accumulates inside the absorbing agent and causes a quick reduction of the activity of the latter, which reduces the performances of the process.
There have now been found particular conditions for carrying out the regeneration of the absorbing agent that has retained the mercaptans, which prevent the formation of metallic sulfate and which greatly simplifies the regeneration.
The regeneration according to the invention of the absorbing agent that has retained the mercaptans is easy to carry out and in addition results in maintaining in the time of activity of the regenerated absorbing agent a high value and as result of that an elevated level of performance of the process.
Therefore, the invention proposes a regenerative process for the removal of the mercaptans contained in a gas by making use of a solid absorbing agent based on at least one active metallic oxide, that is, susceptible of retaining the mercaptans by chemical action, said process being of the type including an absorption step in the course of which the gas to be treated is brought into contact with said absorbing agent, while operating at temperatures below 100.degree. C. for retaining the mercaptans on the absorbing agent, and a step of regeneration and of cooling in the course of which the absorbing agent subjected to the regeneration is swept with a gas containing
REFERENCES:
patent: 2259409 (1941-10-01), Wenzel et al.
patent: 2551905 (1951-05-01), Robinson
patent: 2747968 (1956-05-01), Piqache
Chemical Abstracts, vol. 73, 100679d, p. 115, Nov. 1970.
Elgue Jean
Voirin Robert
Heller Gregory A.
Societe Nationale Elf Aquitaine (Production)
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