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Contrast experiments of fluid catalytic cracking (FCC) were conducted in a technical pilot scale riser FCC apparatus. The results showed that the use of a low-temperature regenerated catalyst and high ratio of catalyst to oil (CTO) improved the initial contact between the catalyst and feedstock. Thermal cracking was inhibited and catalytic cracking was promoted in the FCC riser, which were favorable for increasing the conversion and generation of desirable products. A modified FCC process was proposed and numerical simulation were used in the selection of the equipment structure for mixing cold and hot regenerated-catalyst streams to achieve optimal contact between the catalyst and the feedstock. A commercial unit was revamped based on the experimental results to test the modified FCC process. Results from industrial practice showed that product distributions under optimal conditions of low-temperature contact and high ratio of catalyst to oil in the modified FCC process were superior to those from routin...

The influences of the boiling point and fractional composition of coker gas oil (CGO) on the fluid catalytic cracking performance were investigated. Nitrogen compounds and condensed aromatics in CGO were identified by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) and gas chromatography-mass spectrometry (GC-MS), respectively, and their effects were studied systematically. The result shows that the catalytic cracking performance of CGO does not correspond to the boiling point of narrow fractions but rather to the basic nitrogen compounds and condensed aromatics that have high molecular weight and/or high condensation tendencies adversely. On the basis of these results, a divisional fluid catalytic cracking (DFCC) process was proposed where a separate reaction zone was added to reduce the contents and effects of the adverse compounds in CGO during catalytic cracking. The simulation experiments of the DFCC process show that improved conversion and enhance...

The coking phenomenon of coker gas oil (CGO) feedstock during fluid catalytic cracking (FCC) using a commercial equilibrium catalyst was investigated. Different types of coke formed via coker gas oil (CGO) catalytic cracking were also analyzed. The coke formed was composed of adsorption coke (Cad), dehydrogenation condensation coke (Cdh), and hydrogen transfer coke (Cht). Cad, derived from nitrogen compounds, adsorbed on the acid sites of the catalyst and accounted for 37 wt % of the total coking content under conventional reaction conditions. Cdh was formed by the dehydrogenation condensation of polycyclic aromatic hydrocarbons and accounted for about 43 wt % of the total coking content. The coking content of Cht was greatly determined by the degree of the secondary reaction. Coke selectivity can be decreased and Cht yield can be controlled by simultaneously increasing the reaction temperature and shortening the reaction time.

Contrastive fluid catalytic cracking (FCC) performances of coker gas oil (CGO) narrow-boiling fractions before and after HCl aqueous solution and furfural further treatment were investigated. Nonbasic nitrogen compounds and condensed aromatics in test oil samples were identified by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) and gas chromatography and mass spectrometry (GC–MS), respectively. The results show that basic nitrogen compounds mainly retard the feed conversion and liquid products due to their interaction with Bronsted acid sites or Lewis acid sites during catalytic cracking reactions, while the nonbasic nitrogen compounds and condensed aromatics are hard to convert into smaller molecules, just resulting in obvious effects on yields of gasoline and diesel. Moreover, nonbasic nitrogen compounds with single N species are dominant in CGO, identified as carbazoles, cycloalkyl-carbazoles, benzocarbazoles, and cycloalkyl-benzocarbazo...

The basic nitrogen compounds in coker gas oil (CGO) narrow fractions were enriched, and their influences on hydrocarbons during fluid catalytic cracking (FCC) were investigated. The results show that the content of basic nitrogen compounds has influence on hydrocarbons cracking during CGO FCC reaction, but it is not as obvious as reported before. Furthermore, the compositional and structural identification of basic extracts by positive-ion electrospray Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) shows that basic nitrogen compounds in CGO include N, N2, NO, N2O1, and NS class species. The N1 class species centered at 9 < DBE < 13 with a carbon number ranging from 20 to 24 is the most abundant, and it is a key for CGO’s retarding performance. The effect of structure and composition of basic nitrogen compounds is much more obvious than that of content, and it is stronger with the increase of their rings plus double bond equivalence (DBE).

Coker gas oil (CGO), heavy cycle oil (HCO), and a CGO-HCO blend were treated by solvent refinement and then cracked in a FCC pilot plant over a commercial Y zeolite-based catalyst at selected react...