THESIS
2022
1 online resource (vii, 119 pages) : illustrations (chiefly color)
Abstract
Nylon 66 can be synthesised through the polycondensation of adipic acid and
hexamethylenediamine (HMDA). In which, HMDA can be produced by the hydrogenation of
adiponitrile (ADN) industrially with the use of Raney nickel (Raney Ni) or Raney cobalt
(Raney Co) catalysts. However, the HMDA production by the hydrogenation reaction of
ADN over Raney Ni or Raney Co catalysts requires a large amount of alkali metal hydroxide
solution or ammonia to prevent side reactions. Therefore, electrocatalytic hydrogenation
(ECH) is a promising alternative. Since 1961, the ECH of ADN to HMDA has been studied
by different research groups. Many of these studies rely on the use of Raney Ni. However,
there are some limitations and disadvantages regarding the use of Raney Ni in the ECH of
AND to HMDA. Firstly,...[
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Nylon 66 can be synthesised through the polycondensation of adipic acid and
hexamethylenediamine (HMDA). In which, HMDA can be produced by the hydrogenation of
adiponitrile (ADN) industrially with the use of Raney nickel (Raney Ni) or Raney cobalt
(Raney Co) catalysts. However, the HMDA production by the hydrogenation reaction of
ADN over Raney Ni or Raney Co catalysts requires a large amount of alkali metal hydroxide
solution or ammonia to prevent side reactions. Therefore, electrocatalytic hydrogenation
(ECH) is a promising alternative. Since 1961, the ECH of ADN to HMDA has been studied
by different research groups. Many of these studies rely on the use of Raney Ni. However,
there are some limitations and disadvantages regarding the use of Raney Ni in the ECH of
AND to HMDA. Firstly, Raney Ni is pyrophoric in nature. Secondly, Reney Ni is a fine-grained
solid and it cannot be utilised in flow cells.
In this research, it is mainly divided into 2 parts. The first part is about the electrode
fabrication. Since Raney Ni cannot be utilised in flow cell, nickel foam (Ni foam) is applied
to replace Raney Ni. Nanoporous nickel on nickel foam (NP Ni on Ni foam) with a larger
active surface area is fabricated. In addition, nickel-aliminium on Ni foam (NiAl on Ni foam)
is fabricated to mimic Raney Ni. The second part is the study of ECH of ADN to HMDA at 4 different electrodes (Raney Ni, Ni foam, NP Ni on Ni foam and NiAl on Ni foam). In
addition, the effects of electrochemical operation condition (temperature and current density)
and the electrolyte composition (supporting electrolyte and organic cosolvent) are
investigated to understand their impacts on the faradaice efficiency towards HMDA.
The ultimate aims of this research is to identify the electrode, formuation of the electrolyte
and electrochemical operation conditions that can help enhance the reaction performance and
the product yield in the ECH of ADN to HMDA.
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