Effect of the acid-base properties of additives for a cracking catalyst on the sulfur content in liquid products

Abstract

The effect of the nature and methods for the production of additives for a cracking catalyst on the sulfur content in liquid cracking products was studied. The influence of the acidbase properties of the addi� tives for a cracking catalyst on the redistribution of sulfur raw material between gaseous and liquid products, including that in a gasoline fraction with T EP = 200°C, is analyzed. It is shown that, in contrast to the earlier concept of the approach to choosing such additives, we must consider not only the effect of the acidbase properties of additives but also the aromatization reactions facilitating the formation of hydrogenated thiophene derivatives, which are unstable under catalytic cracking conditions. It is shown that an increase in the additive acidity promotes the reduction of the residual sulfur content in liquid cracking products. The enhancement of both the strength and the concentration of basic sites does not reduce the sulfur content. The simultaneous presence of acidic and basic sites in the structure of a mixed Mg-Al oxide with a spinel structure affords deeper sulfurrefinement of gasoline than the presen ce of only acidic sites. Oxides of a series of metals (Zn, Zr, Cr, Ce, Cu, Ca, Mg, Al) with variable acidbas e properties were used as an additive for a LYUKS cracking catalyst (OAO Gazpromneft'-ONPZ). The data obtained allows us to develop new cracking cata� lysts (or additives for already existing catalysts) that facilitate the production of motor fuels (gasoline) answer� ing the more stringent requirements for sulfur content.