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ABSTRACT
Spent catalysts generated from petroleum refining contain some valuable metals and their surface is covered by elemental sulfur. During the recovery of valuable metals in the spent catalysts, the sulfur present in the surface of spent catalyst should be treated. In order to develop an environment-friendly process to treat these spent catalysts, the dissolution behavior of elemental sulfur between nonaqueous solvents (octanol/decanol) and NaOH solution was compared, which has never been reported. Sulfur was dissolved in decanol and octanol and the dissolved sulfur was recrystallized as the solution cooled to room temperature. The optimum treatment conditions of sulfur in nonaqueous solvents were obtained. The interaction of sulfur with these nonaqueous solvents was analyzed through a radical mechanism and its mechanism was first proposed in the current work. Unlike the treatment of sulfur with decanol and octanol, the dissolution of sulfur in NaOH solution is assumed to occur through oxidation/reduction reaction and the optimum conditions were obtained. The application of these methods is expected to have a meaningful impact on the recovery of sulfur from spent catalyst materials.
초록
석유화학 정제공정에서 발생하는 폐촉매는 유가금속을 함유하고 있으며 황 원소가 표면에 존재한다. 폐촉매로부터 유가금속을 회수하기 위해서는 폐촉매 표면에 있는 황의 처리가 필요하다. 이러한 폐촉매를 환경친화적으로 처리할 수 있는 공정을 개발하기 위해 수산화나트륨용액과 비수용액(octanol/decanol)에서 원소 황의 침출거동을 비교하였다. Octanol과 decanol에 황이 용해되며 용액을 상온까지 냉각시킴에 따라 황이 결정화되었다. 비수용액에 의한 황의 처리에 관한 최적조건을 조사했으며, 비수용액에서 황의 용해반응은 radical기구로 설명했다. 한편 수산화나트륨용액에서 황의 침출반응은 산화/환원 반응기구에 의해 일어나며 최적조건을 도출하였다. 본 논문에서 개발된 기술은 폐촉매에 함유된 황의 회수 공정에 이용될 수 있다.
Disclosure statement
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.