Tri-reforming of surrogate biogas over Ni/Mg/ceria–zirconia/alumina pellet catalysts

ABSTRACT

The performance of catalytic tri-reforming under industrially relevant situations (e.g., pellet catalysts, pressurized reactor) was investigated using surrogate biogas as the feedstock. Tri-reforming using Ni/Mg/Ce_0.6Zr_0.4O₂/Al₂O₃ pellet catalysts was studied in a bench scale fixed-bed reactor. The feed molar ratio for CH₄:CO₂:air was fixed as 1.0:0.70:0.95. The effects of temperature (800–860°C), pressure (1–6 bar), and H₂O/CH₄ molar feed ratio (0.23–0.65) were examined. Pressure has substantial impact on the reaction and transport rates and equilibrium conversions, making it a key variable. At 860°C, CO₂ conversion increased from 4 to 61% and H₂/CO molar ratio decreased from 2.0 to 1.1 as the pressure changed from 1 to 6 bar. CO₂ conversion and H₂/CO molar ratio were also influenced by the temperature and H₂O/CH₄ molar ratio. At 3 bar, CO₂ conversion varied between 4 and 43% and the H₂/CO molar ratio varied between 1.2 and 1.9 as the temperature changed from 800 to 860°C. At 3 bar and 860°C, CO₂ conversion decreased from 35 to 8% and H₂/CO molar ratio increased from 1.7 to 2.4 when the H₂O/CH₄ molar ratio was increased from 0.23 to 0.65. This work demonstrates that the tri-reforming technology is feasible for converting biogas under scaled-up conditions in a fixed-bed reactor.

KEYWORDS:

• Biofuels
• biogas
• catalyst pellet
• packed beds
• synthetic fuel
• tri-reforming

Acknowledgments

The authors would like to thank Nada Elsayed, Anthony Elwell, Yolanda Daza, Bryan Hare, and Andrew Orbeck for their help during this project. The authors would like to thank Dr. Shengqian Ma for the use of Micrometrics ASAP 2020 Instrument.

Disclaimer

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Additional information

Funding

This material is based upon work supported by the U.S. Department of Energy, Office of Science, under Award Number (DE-SC0015221). This study was also funded by T2C-Energy, LLC and the Florida High Tech Corridor.