Deactivation and Regeneration Method for Ni Catalysts by H2S Poisoning in CO2 Methanation Reaction

Jeongyoon Ahn,Soonwoong Chang,Woojin Chung

doi:10.3390/catal11111292

Abstract

The carbon dioxide (CO2) methanation reaction is a process that produces methane (CH4) by reacting CO2 and H2. Many studies have been conducted on this process because it enables a reduction of greenhouse gases and the production of energy with carbon neutrality. Moreover, it also exhibits a higher efficiency at low temperatures due to its thermodynamic characteristics; thus, there have been many studies, particularly on the catalysts that are driven at low temperatures and have high durability. However, with regards to employing this process in actual industrial processes, studies on both toxic substances that can influence catalyst performance and regeneration are still insufficient. Therefore, in this paper, the activity of a Ni catalyst before and after hydrogen sulfide (H2S) exposure was compared and an in-depth analysis was conducted to reveal the activity performance through the regeneration treatment of the poisoned catalyst. This study observed the reaction activity changes when injecting H2S during the CO2 + H2 reaction to evaluate the toxic effect of H2S on the Ni-Ce-Zr catalyst, in which the results indicate that the reaction activity decreases rapidly at 220 °C. Next, this study also successfully conducted a regeneration of the Ni-Ce-Zr catalyst that was poisoned with H2S by applying H2 heat treatment. It is expected that the results of this study can be used as fundamental data in an alternative approach to performance recovery when a small amount of H2S is included in the reaction gas of industrial processes (landfill gas, fire extinguishing tank gas, etc.) that can be linked to CO2 methanation.

Highlights

Many abnormal climate phenomena, which have been recently occurring globally due to global warming, are causing various problems associated with the survival of mankind and preservation of the ecological environment
The CO2 methanation reaction was observed while injecting H2S by adjusting its concentration in the range of 0~100 ppm at temperatures of 180–350 ◦C (Figure 1)
Results of the experiment indicate that fresh catalysts with no H2S injection exhibited a high CO2 conversion of 90~85% at 350–240 ◦C, and a minor decrease in the CO2 conversion occurred from 220 ◦C and was measured to be 76%

Summary

Introduction

Many abnormal climate phenomena, which have been recently occurring globally due to global warming, are causing various problems associated with the survival of mankind and preservation of the ecological environment. According to the 6th Report of the International Panel on Climate Change (IPCC), the current climate conditions revealed that the global surface temperature has increased by 1.09 ◦C between 2011 and 2020 compared to pre-industrialization (1850–1900s) [1], thereby resulting in extreme weather changes. Countries around the globe exert to establish countermeasures to reduce global warming based on the expectation that the frequency and intensity of extreme weather changes will worsen when the average temperature rises further by 0.5 ◦C. Various policies are being introduced to implement carbon-neutral solutions that can alleviate the situation from deteriorating, and a carbon-neutral approach, in particular, is being developed in the field of energy production where large amounts of carbon are discharged [2,3]. CO2 methanation is one of the methods of CO2 applications for carbon-neutral solutions. It is a process that produces methane by reacting CO2 with H2. This process is mainly used as part of the Power-to-Gas (PtG) technology, which produces methane by reacting the CO2 emitted from industrial activities with H2, produced via electrolysis

Methods

Results

Conclusion