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Fischer Tropsch synthesis of syngas to liquid hydrocarbons 235

discharge. During the straight conversion process, it has been considered
that the catalyst surface is oxidized by water to produce H 2 and then sub-
sequently reduced by CO, forming CO 2 [32,61]. Several experimental
outcomes with different supported iron catalysts showed limited change in
Fe cations; Rethwisch and Dumesic [128] discharged the direct oxidation
process that was a favorable formiate with WGS reaction [35,107].

7.5 Process simulation for Fischer Tropsch synthesis
The FT synthesis process is extremely reliant on several parameters as
temperature, partial pressure, feed flow rate, molar ratio of CO and H 2 O,
and property of catalyst. To obtain a better product yield, researchers
often conduct the experiments studying the effect of many parameters,
especially for the development of new catalysts and could not afford the
time and cost to carry out all the parameter combinations. Therefore
computer modeling is necessary to explore the several parameters to
understand the effects of new processing conditions, catalyst kinetics, and
different kinetic mechanisms. There are four types of FT reactors available
in commercial applications: (1) circulating fluidized bed reactor, (2) stan-
dard fluidized bed reactor, (3) fixed packed bed reactor (FPBR), and (4)
SPR [79]. Furthermore, FBR is recognized as nonfavorable for the pro-
duction of liquid transportation fuels, because liquid phase products may
cause catalyst agglomeration and a loss of fluidization [23,28,42,48,59].
Moreover, FT synthesis reactors are also described as low temperature
(LTFT) or high temperature (HTFT) reactors. The main difference is that
a liquid phase forms when operating in LTFT reactors, while HTFT reac-
tors operate entirely in the gas phase. LTFT fixed bed and slurry-phase
are suitable for producing liquid hydrocarbons products. However,
FPBRs could deactivate the catalyst, which may lead to temperature
increase. On the other hand, these reactors show several benefits, such as
ease operation, extra product separation device not required, and
easy scale-up process. Several research studies for design and modeling of
SPR exist in literature, while limited investigations on deigning and
modeling are available on the FPBR. Furthermore, heterogeneous and
single-dimensional PFR was developed to optimize the operational para-
meters on large-scale reactors [12,42,43,113,126,129 131]. First two-
dimensional plug flow, pseudo homogeneous model without intraparticle
diffusion limitations was developed by Bub et al. [102]. Jess et al. [132]
also described the use of a two-dimensional, pseudo homogeneous model