Coker gas oil (CGO) is difficult to be cracked in the conventional FCC process, due to their high nitrogen content, especially the basic nitrogen compounds. To enhance the conversion of CGO, the high reaction temperature and catalyst to oil ratio processing scheme was performed in a pilot-scale riser FCC apparatus. To study the impact of (basic) nitrogen content, two kinds of CGO were tested. The results show that increasing the reaction temperature and CTO is an effective method for enhancing the conversion of CGO. The (basic) nitrogen content significantly influences the cracking behavior of CGO and the choose of optimal reaction conditions.
The effects of feedstock’s properties on the propylene yield of catalytic cracking were investigated in a fluid catalytic cracking (FCC) pilot scale riser test unit operating with a circulating catalyst. Under simulated conditions, the results of catalytic cracking with four different gas oils (including two kinds of vacuum gas oil (VGO) and two kinds of coker gas oil (CGO)) show that the yield of propylene is increasing with the ascending hydrogen content of feed. When the hydrogen content is almost the same, propylene yield fed with paraffinic-base VGO is higher than that fed with intermediate-base or naphthenic-base VGO. The lowest yield is fed with CGO because of the more nitrogen compounds, which can poison the acid sites of the zeolitic catalyst.
Retardation effect of nitrogen compounds and condensed aromatics on shale oil catalytic cracking processing and their characterization