Catalytic cracking of crude oil to light olefins and naphtha: Experimental and kinetic modeling

Abstract

The direct catalytic cracking of three light crude oils have been evaluated over an equilibrated FCC catalyst (E-Cat) blended with MFI zeolite in a microactivity test unit at 550°C and catalyst/oil ratio between 1 to 4. At 60% conversion, the Super Light (ASL) crude oil yielded about 10wt.% C2–C4 olefins and 60wt.% naphtha over E-Cat, Extra Light (AXL) crude oil yielded 13wt.% light olefins and 52wt.% naphtha, while for Arab Light (AL) crude oil, light olefins and naphtha produced were 12 and 51wt.%, respectively. The addition of MFI with varying Si/Al molar ratio (Z30, Z280 and Z1500) to E-Cat increased the yield of light olefins with a maximum at 21.3wt.% for AXL over E-Cat/Z280. PIONA analysis of co-produced naphtha showed an increase in aromatics content over all additives with a maximum obtained from the cracking of AL over Z30 (91wt.%). Steam treatment of Z280 led to a slight change in the yield of light olefins and reduction of naphtha aromatics for the three types of crude oils. A four-lump kinetic model accurately predicted experimental yields of AL cracking over E-Cat and E-Cat/Z280 between 500°C and 550°C. From the kinetic model, the apparent activation energy for the conversion of naphtha to gases decreased from 21.2kcal/mol over E-Cat to 16.2kcal/mol over E-Cat/Z280 which indicates that Z280 facilitated the increased cracking of naphtha-range species to light olefins