(264j) Combustion Synthesized Nickel-Cobalt Catalyst Deactivation By Coking during Ethanol Decomposition Reaction

Combustion
synthesized nickel-cobalt catalyst deactivation by coking during ethanol
decomposition reaction

Anchu Ashok^a, Anand
Kumar^b, Faris Tarlochan^a

a.     
Department
of Mechanical and Industrial Engineering

b.     
Department
of Chemical Engineering

College
of Engineering, Qatar University, P O Box – 2713, Doha, Qatar

                                                                                                                                                             *
Email: akumar@qu.edu.qa

In this work, we
report the catalytic dehydrogenation of ethanol over porous cobalt oxide and nickel-cobalt
bimetal oxide (NiCoO₂). Catalyst deactivation and the nature of carbon
formation on these two catalysts are studied in detail to correlate the active phase
with carbon formation. In-situ FTIR analysis was conducted between 50°C to
400°C on Co₃O₄ and NiCoO₂ catalysts to
understand the reaction mechanism and product selectivity. Addition of Ni
improves the activity for ethanol decomposition by achieving complete ethanol conversion
at 350°C as compared to 420°C for cobalt alone. The crystallinity, morphology
and particle analysis of the spent catalyst after reaction was identified using
XRD, SEM and TEM respectively. The XRD shows a phase change of porous NiCoO₂
to NiCo alloy, whereas SEM indicates the presence of fibrous structure on the
surface with 91.7 % of carbon while keeping 1:1 ratio of Ni and Co after the
reaction. The detailed analysis of carbon structure using HRTEM-STEM (Fig. 1)
shows simultaneous growth of carbon nanofibers (CNFs) and multiwalled carbon
nanotubes (MWCNTs) that were favored by larger and smaller crystallites
respectively. Detailed mechanism of the filament formation is also proposed to
be discussed in the conference.

Figure 1: TEM image of carbonaceous deposit
over the catalyst after ethanol decomposition reaction