Sains Malaysiana 47(1)(2018): 207–214

http://dx.doi.org/10.17576/jsm-2018-4701-24

Catalytic Performance of Cu/ZnO/Al₂O₃/ZrO₂ for Slurry Methanol Synthesis from CO₂ Hydrogenation: Effect of Cu/Zn Molar Ratio

(Prestasi Pemangkinan Cu/ZnO/Al₂O₄/ ZrO₂ untuk Sintesis Metanol Sluri daripada Penghidrogenan CO₂: Kesan Nisbah Molar Cu/Zn)

SALINA SHAHARUN, MAIZATUL S. SHAHARUN*, MOHAMAD F.M. SHAH & NURUL A. AMER

Universiti Teknologi PETRONAS 32610 Seri Iskandar, Perak, Darul Ridzuan Malaysia

Received: 6 January 2016/Accepted: 22 June 2017

ABSTRACT

Catalytic hydrogenation of carbon dioxide (CO₂) to methanol is an attractive way to recycle and utilize CO₂. A series of Cu/ZnO/Al₂O₃/ZrO₂ catalysts (CZAZ) containing different molar ratios of Cu/Zn were prepared by the co-precipitation method. The catalysts were characterized by temperature-programmed reduction (TPR), field emission scanning electron microscopy-energy dispersive x-ray analysis (FESEM-EDX) and X-ray diffraction (XRD). Higher surface area, SABET values (42.6-59.9 m²/g) were recorded at low (1) and high (5) Cu/Zn ratios with the minimum value of 35.71 m²/g was found for a Cu/Zn of 3. The reducibility of the metal oxides formed after calcination of catalyst samples was also affected due to change in metal-support interaction. At a reaction temperature of 443 K, total gas pressure of 3.0 MPa and 0.1 g/mL of the CZAZ catalyst, the selectivity to methanol decreased as the Cu/Zn molar ratio increased, and the maximum selectivity of 93.9 was achieved at Cu/Zn molar ratio of 0.33. With a reaction time of 3h, the best performing catalyst was CZAZ75 with Cu/Zn molar ratio of 5 giving methanol yield of 6.4%.

Keywords: Carbon dioxide; copper; hydrogenation; methanol synthesis; zinc; zirconia

ABSTRAK

Penghidrogenan pemangkin karbon dioksida (CO₂) kepada metanol adalah satu cara yang menarik untuk mengitar semula penggunaan CO₂. Satu siri pemangkin Cu/ZnO/Al₂O₃/ZrO₂ (CZAZ) yang mengandungi nisbah molar Cu/Zn yang berbeza disediakan melalui kaedah pemendakan bersama. Kaedah pencirian yang dijalankan untuk pemangkin adalah melalui kaedah program penurunan suhu berkala (TPR), analisis pengimbas mikroskop pemancaran medan-serakan tenaga sinar-x (FESEM-EDX) dan pembelauan sinar-X (XRD). Luas permukaan tertinggi telah direkodkan iaitu (42.6-59.9 m²/g) pada nisbah Cu/Zn rendah (1) dan tinggi (5) dengan nilai minimum 35.71 m²/g pada nisbah Cu/Zn adalah 3. Kebolehpenurunan oksida logam yang terbentuk selepas sampel pemangkin dikalsinasi juga memberi kesan yang disebabkan oleh penukaran interaksi logam sokongan. Pada suhu tindak balas 443 K, jumlah tekanan gas 3.0M MPa dan 0.1 g/mL pemangkin CZAZ, pemilihan terhadap metanol berkurangan dengan peningkatan nisbah molar Cu/Zn, dan nilai pemilihan maksimum adalah 93.9 terhasil pada nisbah molar 0.33. Dengan masa tindak balas 3 jam, pemangkin dengan prestasi terbaik adalah CZAZ75 dengan nisbah molar 5 memberi hasil metanol 6.4%.

Kata kunci: Karbon dioksida; penghidrogenan; sintesis metanol; tembaga; zink; zirconia

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*Corresponding author; email: maizats@utp.edu.my