Optimization of Cu/MnO₂ catalyst for enhanced methane bi-reforming: a response surface methodology approach for sustainable syngas production

Abstract

Hydrogen or syngas, valued for its clean and high-energy properties, stands as a promising solution to future energy shortages by converting CO₂ and CH₄ waste into renewable syngas through a reaction known as methane bi-reforming. Hence, the purpose of this current research is to examine the effectiveness of Cu/MnO₂ catalyst in methane bi-reforming (MBR) using response surface methodology (RSM). The synthesis of the 15%Cu/MnO₂ catalyst was accomplished using the ultrasonic impregnation method, followed by a comprehensive analysis and characterization of the catalyst using CO₂-TPD, BET, H₂-TPR, TPO, and XRD evaluation. The effect of reaction parameters was investigated using RSM analysis, including temperature, CO₂/CH₄ ratio, and gas hourly space velocity (GHSV) (700–900 °C, 0.2–1.0, and 16–36 L g cat⁻¹ h⁻¹, respectively). According to the analysis of variance and three-dimensional response surface plots, it was determined that CH₄ conversion and H₂ yield were largely influenced by temperature, whereas CO₂ conversion and CO yield could be manipulated through CO₂/CH₄ feed ratio. Meanwhile, the GHSV appeared to have a significant influence on the H₂/CO ratio and CH₄ conversion. From the experimental data, it was found that the 15%Cu/MnO₂ catalyst performed best under specified optimal conditions of 800 °C, a CO₂/CH₄ ratio of 0.6, and a GHSV of 26 L g cat⁻¹ h⁻¹. These optimal conditions resulted in the maximum conversion of CH₄ (54.67%), CO₂ conversion (47.52%), H₂ yield (43.81%), CO yield (36.29%), and H₂/CO ratio (1.384). Despite the inevitability of carbon formation resulting from the breakdown of CH₄ and CO at high temperatures, the examination of the spent catalysts under optimal conditions yielded a smaller quantity of carbon of approximately 28.27% in comparison to the suboptimal conditions with 55.37%.

Keywords:

• Cu-based catalyst
• hydrogen
• methane bi-reforming
• reforming
• response surface methodology optimization
• syngas

The authors gratefully acknowledge Universiti Malaysia Pahang Al-Sultan Abdullah (UMPSA) for the financial support provided through the UMPSA Distinguished Research Grant (RDU 233007). Ms. Irna Haslina extends her heartfelt appreciation to UMPSA for the Master Research Scheme (MRS) Scholarship.

Authors’ contributions

Irna Haslina Ibrahim: Writing – original draft, review & editing. Nuremirah Syafiqah Suhaimi: Writing - original draft. Mohd-Nasir Nor Shafiqah: Writing – review & editing. Maoshuai Li: Writing – review & editing. Van Cuong Nguyen: Writing – review & editing. Sumaiya Zainal Abidin: Writing – review & editing.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The research was financially supported by Universiti Malaysia Pahang Al-Sultan Abdullah (UMPSA) through the UMPSA Distinguished Research Grant (RDU 233007).