Cracking catalyst with increased selectivity for coke

Abstract

are characterized by higher steaming stability and coke selectivity. In preparing the catalyst samples, we used ultrastable Y zeolite in the H form (USY) and Y zeolite in the RE form, as well as a kaolin clay and a binder [8]. The ultrastable zeolite was obtained by steaming NaY zeolite in the NH4 form with 30-50% steam for a period of 3.5 h at temperatures of 550-815~ The characteristics of these zeolites are listed in Table 1. In Fig. 1 we show the IR spectra of samples of domestic and foreign ultrastable zeolites. It will be seen that they are practically identical. The composition of the Prosyanoe kaolin BP-84 is as follows: A1203 46.6%, SiO 2 51.7%, Na20 0.19%, Fe203 0.465%. The binder was obtained by treating aluminum hydroxide with nitric acid. The catalysts were prepared by mixing slurries of the zeolite, clay, and binder, with subsequent molding of the particles, with dimensions 0.05-0.315 mm. The molded catalysts were dried and calcined at 500-750~ for 4 h and then stabilized at 750 ~ and 790~ over a 6-h period in a 100% steam atmosphere. The catalytic activity of the zeolites was determined in a unit that included a flow-type reactor with a fixed bed of catalyst, in the process of cracking a vacuum distillate at a temperature t = 500~ and a feedstock mass velocity w = 7 h -t. The reactor was charged with 1.5 g of the zeolite, diluted with quartz sand to 15 g [7].