Catalytic microchannel configurations for hydrocracking of Fischer-Tropsch hydrocarbons

Abstract

Petroleum crude oil is an important commodity as the primary source of energy and petrochemical industry but su ers from decreasing reserves and quality. Hydrocarbon commodities can also be produced synthetically by Fischer-Tropsch (FT) synthesis. Products of FT synthesis consist of a mixture of n-para ns with wide ranges of molecular weights, boiling point fractions and poor cold ow properties due to their linear nature. These properties require improvement by catalytic hydrocracking for meeting the quality speci cations. Hydrocracking of FT products decrease the heavy cut fractions by cracking and improves cold ow properties by isomerization. Hydrocracking reactions of FT hydrocarbons are exothermic and require precise temperature control; high temperatures lead to overcracking, whereas low temperatures inhibit the process. Integration of hydrocracking with microchannel reactor technology is a promising process, since sub millimeter dimensions of this technology minimizes transport resistances and allows temperature control and e cient use of catalyst. This work investigates the applicability of a heat-exchange integrated microchannel reactor for hydrocracking of FT hydrocarbons by parametric analysis in operational aspects. The reactor has parallel reaction, coated with a Pt based catalyst, and cooling channels separated by metallic walls. Integrated operation of simultaneous catalytic reactions and heat transfer are modeled and simulated using FEM based techniques. Kinetic model describes conversion of hydrocarbons species with in C1-C70 range. The results show the possibility of isothermal operation at high temperatures and space velocities. Jet and diesel yields are found to be sensitive to reactant and coolant feed temperatures, feed ow rate and pressure of the reactant and wall material and almost una ected by to H2-to-wax ratio.