Süperkiritk depozisyon ve gözenek hacminde çözelti emdirme yöntemleriyle hazırlanmış katalizörlerin hidrakraking aktivitelerinin ve seçiciliklerinin karşılaştırılması

Hydrocracking is the most profitable operation in the petroleum refinery due to its role of converting heavy petroleum cuts, such as gas oil and asphaltenes, to the more valuable products like diesel and heavy naphtha. The process involves the cracking of long chained hydrocarbons followed by hydrogenation of the cracked chains. Thus, the catalyst used in hydrocracking has both cracking and hydrogenation function which are generally supplied from an acidic support and loaded noble or earth metal. The balance between these two functions makes the hydrocracking process very flexible for the production of wide range of products from variety of feed stocks. In this study, the aim was to compare hydrocracking activities and selectivities of catalysts prepared by two different methods as incipient wetness and supercritical deposition. For this purpose, three commercial were selected as reference materials. N-decane was chosen as a model feed in order to have better understanding of catalysts by tracking the product distributions using GC-MS for preliminary studies. Supports were prepared with different amounts silica-alumina, USY zeolite and Ludox binder. The characterization of synthesized materials was performed by XRF, N2 physisorption and TPD. Then, three different types of catalysts, commercial, prepared by impregnation and by supercritical deposition (SCD) methods, were tested for n-decane reactions in a laboratory scale plug flow trickle bed reactor which was developed during this study. Furthermore, heavy vacuum gas oil was replaced with n-decane and catalyst performance tests were repeated for this feed. The product analyses were done with ASTM standard distillation and GC Simdist analaysis, which was in agreement with the former. Finally, kinetic modelling of gas oil cracking was done using discrete lumping method in order to compare kinetic parameters of the catalysts. Results showed catalysts prepared with impregnation and supercritical deposition methods had comparable activities relative to the commercial catalysts for both n-decane and gas oil hydrocracking. Moreover, the catalysts prepared by SCD method had a superior activity and slightly higher middle distillate selectivity than the other catalysts. This finding was also supported by the results of the modeling studies.