Method for producing bio or fossil fuels through light olefins oligomerization over zeolite catalysts and a system for producing the same

A process for producing bio or fossil fuels, the process comprising:

• feeding mixed hydrocarbon to a fixed-bed reactor system containing a zeolite catalyst, wherein the mixed hydrocarbon comprises one or more components of propene, 1-butene, 2-butene, isobutene, pentene, hexene, and octene;
• operating the fixed-bed reactor system for oligomerization of one or more C3-C8 hydrocarbons to form an oligomerized effluent comprising one or more oligomers of propene, 1-butene, 2-butene, isobutene, pentene, hexene and octene;
• separating the oligomerized effluent into a C3-fraction, a gas stream, and a liquid stream in a gas/liquid separation unit;
• feeding at least a first portion of the liquid stream to a distillation unit;
• recycling at least a second portion of the liquid stream to the fixed-bed reactor system;
• separating the first portion of the liquid stream in the distillation unit into a light fraction and a heavy fraction;
• and
• recycling the light fraction to the fixed-bed reactor system,
• wherein, when jet fuel is a targeted fuel product, the light fraction comprises a C4-C8 fraction and the heavy fraction comprises a C9+ fraction, and
• wherein, when diesel fuel is the targeted fuel product, the light fraction comprises a C4-C11 fraction and the heavy fraction comprises a C12+ fraction.