COMPUTATIONAL STUDY FORMATION OF BRANCHED HYDROCARBONS PRODUCTS FISCHER-TROPSCH SYNTHESIS WITH CATALYSTS NANOPARTICLES Fe4 (CLUSTER SYSTEM)

• Main Author: Londong Allo, Veliyana
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/32764
• Institution: Institut Teknologi Bandung

Theoretical Study mechanism of the Fischer-Tropsch synthesis to produce straight chain and branched chain hydrocarbons using a catalyst of iron nanoparticles cluster models. Geometry optimization and energy calculations were generated using density functional theory (DFT)/B3LYP with the basis set 3-21 for all atoms. The proposed mechanism consists of three phases: initiation, propagation and termination. At the initiation stage occurs the energy difference is quite large when the species ~C=O into the species MC with the activation energy (Ea) 332.41 kJ/mol. At the initiation stage of a process of hydrogenation produces the ~CH and ~CH2 species as an early stage in the propagation stage. From the calculation results obtained ~CH species is more stable than ~CH2 so the alkenyl mechanism is most acceptable. At the step of propagation and termination in linier alkenyl mechanism which produces straight alkene hydrocarbons and the branched alkenyl mechanism would produce an alkene hydrocarbon branches. Branching mechanism proposed by Maitlis in Fischer-Tropsch synthesis is originated from linier ?1-allyl intermediates (~CH2CH=CHR) that isomerise via a ?3-species to form branched ?1-allyl (~CH(R)CH=CH2) species. At the step of termination occurs elimination alkenyl by hydride species (MH) which form to the alkene hydrocarbons. The calculation of the energy of the termination phase to produce branched and linear products obtained activation energy of linear mechanisms of 78,32 kJ/mol and the activation energy of the branching mechanism of 161,79 kJ / mol so that it is consistent with the experimental results stating the linear product the main products formed over many branched products.