Catalytic Cracking of Light Crude Oil: Effect of Feed Mixing with Liquid Hydrocarbon Fractions

The direct catalytic cracking of Arab Extra Light (AXL) crude oil was conducted in a microactivity test (MAT) unit at 550 °C, where product recycling was simulated by mixing feed and liquid products in varying proportions. The effect of AXL mixing with total liquid product (LP) or a mixture of light cycle oil (LCO) and heavy cycle oil (HCO) was investigated at various ratios to determine the dependence of light olefins yield on feed composition. It was observed that mixing the least amount of LP with AXL yielded ∼20.3 wt % light olefins and 39.6 wt % naphtha. The cracking of AXL and LCO+HCO yielded similar results as the case of cracking LP. A configuration of 100% recycle of liquid product without blending with AXL feed showed an increase in the yield of light olefins from 20 wt % to 29 wt % associated with a decrease in naphtha yield from 40 wt % to 27 wt %. A second configuration of 100% recycle of LCO+HCO without blending with AXL feed showed that the yield of light olefins increased from 20 wt % to 26 wt % associated with an increase in naphtha yield from 40 wt % to 50 wt %. The study has shown that the recycling of low-value heavy fraction (LCO+HCO) is a cost-effective means to supplement the AXL feed without loss in the yield of desired light olefins and naphtha.