Synthesis of Cu-Zn on graphene-based support for direct methanol synthesis from CO2 hydrogenation

Name: Varisara Deerattrakul

LCSH: Kasetsart University -- Dissertations. Ph.D. (Chemical Engineering) 2019

Classification :.LCCS: TA455.G65

LCSH: Kasetsart University. -- Department of Chemical Engineering -- Dissertations

LCSH: Graphene -- Synthesis

LCSH: Methanol -- Synthesis

LCSH: Carbon dioxide

LCSH: Global warming

LCSH: Greenhouse gases

LCSH: Heterogeneous catalysis

LCSH: X-ray diffractometer

Abstract: There has been enormous interest in using two dimensional (2D) materials (especially, graphene) as catalyst support in recent year. A monolayer graphene displays an extremely high surface area up to 2630 m2 g -1 , which seems to be a good candidate for catalyst support. However, a single layer graphene is prefer to restack forming multilayer graphene or indeed graphite due to the Van der Waals interactions between the adjacent sheets, which is not ideal to be used as a catalyst support. In order to address this issue, a graphene structure by introduced nitrogen atom into graphene sheets so-called “nitrogen-doped reduced graphene oxide (N-rGO)” nanosheets was synthesized and used as copper (Cu)-zinc (Zn)/N-rGO catalyst for carbon dioxide (CO2) hydrogenation reaction. Interestingly, it is found that the CuZn/N-rGO displays the highest methanol productivity ever reported in carbonaceous catalyst support (up to 591 mgMeOH gcat -1 h -1 ). The performance of catalyst directly related to the catalyst reduction time, and it was further studied via in situ XANES. In addition to two dimensional graphene sheets, the three dimensional (3D) graphene aerogel was synthesised via the hydrothermal reduction of graphene oxide (GO). It was found that the reduction temperature at 140 °C provided the graphene aerogel with the highest surface area about 457.8 m2 g –1 . Generally, the surface area of reduced graphene oxide (rGO) was reported to be ~100 m2 g -1 . The supported CuZn on graphene aerogel catalysts were also tested for CO2 hydrogenation to methanol for the first time. Even if the surface area of the graphene aerogel is high, the methanol productivity is still lower than that of N-rGO nanosheets. This confirms that the doped nitrogen atom plays a significant role to enhance the catalytic performance. Moreover, there has been considerable activity of nitrogen species (i.e., pyridinic, graphitic, and pyrrolic nitrogen). Thus, the role of each of the nitrogen species has been investigated by controlling the nitrogen doping level using different nitrogen sources (i.e., ammonia, hydrazine hydrate, and urea). It is evident that the pyridinic nitrogen plays an important role to increase catalytic activity because it can donate an electron, which impacts on the binding between catalyst and support. This impact attributed to prevent the metal aggregation, facilitate the hydrogen (H2) dissociation and enhance CO2 adsorption. Conclusively, the obtained results from this work have improve the understanding of graphene and carbonaceous catalyst support in different aspects, leading to their continuing development for use in CO2 conversion technology.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Paisan Kongkachuichay

Role: Thesis Advisor

Name: Paweena Prapainainar

Role: Thesis Co-Advisor

Created: 2019

Modified: 2025-06-29

Issued: 2025-06-29

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2562/varisara-dee-all.pdf

CallNumber: TA455.G65 .V37

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Chemical Engineering

Grantor: Kasetsart University

©copyrights Kasetsart University

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