CO2 Methanation of Biogas over 20 wt% Ni-Mg-Al Catalyst: on the Effect of N2, CH4, and O2 on CO2 Conversion Rate

Danbee Han,Wonjun Cho,Hyunseung Byun,Youngsoon Baek,Yunji Kim

doi:10.3390/catal10101201

Abstract

Biogas contains more than 40% CO2 that can be removed to produce high quality CH4. Recently, CH4 production from CO2 methanation has been reported in several studies. In this study, CO2 methanation of biogas was performed over a 20 wt% Ni-Mg-Al catalyst, and the effects of CO2 conversion rate and CH4 selectivity were investigated as a function of CH4, O2, H2O, and N2 compositions of the biogas. At a gas hourly space velocity (GHSV) of 30,000 h−1, the CO2 conversion rate was ~79.3% with a CH4 selectivity of 95%. In addition, the effects of the reaction temperature (200–450 °C), GHSV (21,000–50,000 h−1), and H2/CO2 molar ratio (3–5) on the CO2 conversion rate and CH4 selectivity over the 20 wt% Ni-Mg-Al catalyst were evaluated. The characteristics of the catalyst were analyzed using Brunauer–Emmett–Teller surface area analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The catalyst was stable for approximately 200 h at a GHSV of 30,000 h−1 and a reaction temperature of 350 °C. CO2 conversion and CH4 selectivity were maintained at 75% and 93%, respectively, and the catalyst was therefore concluded to exhibit stable activity.

Highlights

The recent years have witnessed a growing interest in the regulation of greenhouse gases and the quest for sustainable renewable energy to combat global warming
Much attention has been drawn to the utilization of biogas, as it can be obtained from livestock waste and urban solid waste
Al2 O3 -supported Ni catalysts with different metal loadings, and the results revealed that the specific surface area and CO2 conversion increased with an increase in the Ni loading from 15, 20, and 25 wt%, whereas the specific surface area and CO2 conversion decreased at 33 wt%

Summary

Introduction

The recent years have witnessed a growing interest in the regulation of greenhouse gases and the quest for sustainable renewable energy to combat global warming. This has culminated in the demand for an efficient energy storage system (ESS) that can stabilize electric power systems with high output fluctuations. The lithium-ion battery is an ESS widely employed in various energy generation systems owing to its high energy density and efficiency; its short shelf life and low storage capacity limit its long-term power storage [1]. Much attention has been drawn to the utilization of biogas, as it can be obtained from livestock (organic) waste and urban solid waste. The power-to-gas technology generates H2 from water by employing renewable energy and produces CH4 via the methanation of

Methods

Results

Conclusion