Mechanistic Understanding of Methane
Hydroxylation by Cu-Exchanged Zeolites
Muhammad Haris Mahyuddin, Hermawan Kresno Dipojono,
and Kazunari Yoshizawa
Abstract Methane direct conversion to methanol or methane hydroxylation by Cuexchanged zeolite catalysts through a stepwise approach is a promising process
for fulfilling the increasing energy demand in the midst of declining fossil energy
and unreadiness of renewable energy technologies. However, there are still many
challenges hampering this process from yielding methanol with amount that meets
industrial expectations. Therefore, understanding the mechanism of how the strong
C–H bond of methane is cleaved and how methanol is formed only in the presence of
a particular solvent could help optimizing the process or finding novel approaches.
In this chapter, we overview the mechanistic understanding on the methane’s C–H
cleavage through the homolytic hydrogen atom abstraction and evaluate the formation of methanol through a mechanism where a surface methoxy is formed as an
intermediate species and a water molecule acts as a reactant or an assistant to form
methanol through a hydrolysis or an indirect HO–CH 3 rebound.
Keywords Copper · Zeolites · Methane activation · Methanol formation
1 Introduction
Nature, through a certain kind of enzymes that contain iron or copper centers in
its active site (soluble or particulate methane monooxygenase, sMMO or pMMO,
respectively), has shown its ability to hydroxylate methane with O 2 under ambient
conditions [1–4]. Since the reaction between the triplet (O 2 ) and singlet (CH 4 )
M. H. Mahyuddin (B) · H. K. Dipojono
Research Group of Advanced Functional Materials, Faculty of Industrial Technology,
Institut Teknologi Bandung, Bandung 40132, Indonesia
e-mail: haris@tf.itb.ac.id
H. K. Dipojono
e-mail: dipojono@tf.itb.ac.id
K. Yoshizawa
Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku,
Fukuoka 819-0395, Japan
e-mail: kazunari@ms.ifoc.kyushu-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
K. Yoshizawa (ed.), Direct Hydroxylation of Methane,
https://doi.org/10.1007/978-981-15-6986-9_4
75
Hydroxylation by Cu-Exchanged Zeolites
Muhammad Haris Mahyuddin, Hermawan Kresno Dipojono,
and Kazunari Yoshizawa
Abstract Methane direct conversion to methanol or methane hydroxylation by Cuexchanged zeolite catalysts through a stepwise approach is a promising process
for fulfilling the increasing energy demand in the midst of declining fossil energy
and unreadiness of renewable energy technologies. However, there are still many
challenges hampering this process from yielding methanol with amount that meets
industrial expectations. Therefore, understanding the mechanism of how the strong
C–H bond of methane is cleaved and how methanol is formed only in the presence of
a particular solvent could help optimizing the process or finding novel approaches.
In this chapter, we overview the mechanistic understanding on the methane’s C–H
cleavage through the homolytic hydrogen atom abstraction and evaluate the formation of methanol through a mechanism where a surface methoxy is formed as an
intermediate species and a water molecule acts as a reactant or an assistant to form
methanol through a hydrolysis or an indirect HO–CH 3 rebound.
Keywords Copper · Zeolites · Methane activation · Methanol formation
1 Introduction
Nature, through a certain kind of enzymes that contain iron or copper centers in
its active site (soluble or particulate methane monooxygenase, sMMO or pMMO,
respectively), has shown its ability to hydroxylate methane with O 2 under ambient
conditions [1–4]. Since the reaction between the triplet (O 2 ) and singlet (CH 4 )
M. H. Mahyuddin (B) · H. K. Dipojono
Research Group of Advanced Functional Materials, Faculty of Industrial Technology,
Institut Teknologi Bandung, Bandung 40132, Indonesia
e-mail: haris@tf.itb.ac.id
H. K. Dipojono
e-mail: dipojono@tf.itb.ac.id
K. Yoshizawa
Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku,
Fukuoka 819-0395, Japan
e-mail: kazunari@ms.ifoc.kyushu-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
K. Yoshizawa (ed.), Direct Hydroxylation of Methane,
https://doi.org/10.1007/978-981-15-6986-9_4
75