Application of Methods of Autoclave Dissolution for Studying Oil Refining Catalysts

Abstract

Specific features and potentialities of autoclave technologies for decomposition of oil refining catalysts were studied to develop a method for in-process monitoring of changes in the chemical and phase composition of the catalysts. Under autoclave conditions, the time of complete dissolution of oxide phases (hydrotreatment catalysts) was established to shorten from 2 hours to 5–10 min, and the time of platinum opening (reforming catalysts) to be no more than 10 min. In addition, the opening in a closed system prevents from the component loss and from environmental air contamination. It was shown that individual components of the catalysts can be selectively dissolved, isolated and concentrated; the concentrated phases can be used for XPS studies. For example, XPS studies of the dissolved aluminium-containing phase of the spent reforming catalyst revealed the presence of the corundum phase (1,5 %) that indicated the catalyst operation at too high temperatures. A method for estimation of platinum particle size in the catalysts using the quantity of the metal dissolved under the action of chemisorbed oxygen in non-oxidizing acidic media under autoclave conditions was suggested. In the reforming catalysts, the platinum particles were shown to change in size from 4 to 25 nm during operation.