Thermal and catalytic cracking of whole crude oils at high severity

The catalytic and thermal cracking of three types of whole crude oils, having API gravity at 34 degrees (AL), 39 degrees (AXL) and 51 degrees (ASL), were investigated via a fixed-bed micro-activity test (MAT) unit at high temperature between 600 and 650 degrees C. Equilibrium FCC catalyst (E-Cat)/ZSM-5 additive was used for catalytic cracking tests at 30 s and catalyst/oil (C/O) ratio of 2.0-6.0. For both thermal and catalytic cracking of all crude oils, the increase in reaction temperature resulted in higher conversion and enhanced yields of C-2-C-4 light olefins, LPG, coke, and dry gas at the expense of naphtha, heavy cycle oil (HCO), and light cycle oil (LCO). In thermal cracking, the yields of C-2-C-4 olefins at 650 degrees C were as follows: AL (22.8 wt.%) > AXL (19.0 wt.%) > ASL (18.8 wt.%) associated with naphtha yields of 34.4, 38.1 and 48.0 wt.%, respectively. Compared with thermal, catalytic cracking over E-Cat/ZSM-5 enhanced conversion, doubled the yields of light olefins and showed an increase in aromatics content of naphtha fraction. Contrary to thermal cracking, the yields of C-2-C-4 olefins in catalytic cracking were as follows: ASL (42.9 wt.%) > AXL (41 wt.%) > AL (39.1 wt.%) associated with naphtha yields of 31.7, 27.5, and 23.0 wt. %, respectively.