Studies on the Catalytic Cracking of Different Gas Oils for Maximizing Propylene

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.