Studies on the Catalytic Cracking Performance of Coker Gas Oil

Abstract

Catalytic cracking experiments in which various blend levels of coker gas oil (CGO) in fluidized catalytic cracking (FCC) feedstock were reacted over two kinds of commercial equilibrium catalysts (RGD-1 and LBO-16) demonstrate that the blending ratio affects the potential ability of a FCC unit treating CGO obviously. The limits of the blending ratio for Daqing CGO and Dagang CGO are 30 and 20 wt %, respectively, to obtain a desirable product distribution at a relatively high feed conversion. The operating condition of a high catalyst/ oil ratio in combination with a short residence time (or high weight hourly space velocity) and moderate reaction temperature is the optimal operating condition for catalytic cracking of CGO and its mixture. A FCC catalyst, such as RGD-1, which has proper acidities and high accessibility, is suitable for dealing with CGO effectively, which leads to an obvious improvement over conversion and product distribution. The analysis and contrast catalytic cracking experiments of narrow cuts of Daqing CGO show that the fraction of Daqing CGO is accumulated largely in the range of 300-450 °C and there exists high content of basic nitrogen and polycyclic aromatics. The lowest crackability of the cut from 400 to 450 °C constrains total CGO cracking performance, which is caused by a preferential chemisorption of the polycyclic aromatic molecules, and basic nitrogen compounds take place prior to the desirable adsorption of the other hydrocarbons, which is necessary for the cracking reaction to occur.

Catalytic Cracking of Diverse Vacuum Residue Hydrocracking Gas Oils

“…Due to the higher contents of nitrogen, Conradson carbon, and asphaltenes the secondary vacuum gas oils are not welcome in the fixed‐bed VGO hydrocrackers. The FCC is not so demanding as the fixed‐bed VGO hydrocracking, but the processing of secondary vacuum gas oils is always associated by a conversion decrease 1. It was found that FCC conversion linearly diminishes with enhancement of the secondary gas oils (coker gas oil and H‐oil VGO) content in the FCC feed blend consisting of straight run and secondary VGOs (Fig.…”

Characterization of nitrogen compounds in coker gas oil by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and Fourier transform infrared spectroscopy

“…Coker gas oil (CGO), a main product derived from the coking process, can be used as the feedstock of fluid catalytic cracking (FCC) unit. However, when the FCC unit is blended with a certain amount (generally less than 20 wt%) of CGO, the activity and selectivity of catalyst decrease, the feedstock conversion drops, recycle oil and slurry oil withdrawal increase, the yield of coke increases, product distribution deteriorates, and CGO bending ratio becomes strictly limited [ 1 – 3 ]. Earlier works [ 4 , 5 ] on this subject concluded that nitrogen compounds in CGO, especially basic nitrogen compounds, could heavily deactivate FCC catalysts.…”

Dependence of Fluid Catalytic Cracking Unit Performance on H‐Oil Severity, Catalyst Activity, and Coke Selectivity

“…To select the right catalyst for the FCC process in such a dynamical environment is a major challenge, because one catalyst can be the best option for a given feed, but not the optimum selection for a feed with a variable quality. FCC catalyst performance is feedstock‐dependent . Six catalysts were explored in this study, four of which were employed in the LNB FCCU during processing a feedstock with a variable quality.…”