Oligomerization of Fischer—Tropsch Olefins to Distillates over Amorphous Silica—Alumina

摘要

The oligomerization of Fischer—Tropsch-derived olefins over amorphous silica—alumina (ASA) has been investigated at pilot-plant scale in the region of 140—265℃ and 3.5—6.8 MPa. The distillate yield is thermodynamically limited, and yields of 65?70% were observed during once-through operation at 180℃, 6 MPa, and a liquid hourly space velocity (LHSV) of 0.5 h~(-1). The ASA-derived distillate typically has a density of 810 kg/m~3, a kinematic viscosity of 2.8—3.6 cSt, and good cold flow properties, but a low cetane number (28—30). Despite the high hydrogen transfer propensity of ASA, cycle lengths of more than 100 days were achieved and catalyst activity could be fully restored by controlled burnoff of the carbon. Deactivation occurred at a rate of 0.03—0.04 mg/h carbon per gram of catalyst.