ZnO/Carbon Spheres with Excellent Regenerability for Post-Combustion CO2 Capture.

Iwona Pełech,Agnieszka Wanag,Piotr Staciwa,Joanna Kapica-Kozar,Urszula Narkiewicz,Ewelina Kusiak-Nejman,Daniel Sibera,Antoni W Morawski

doi:10.3390/ma14216478

Abstract

This paper examines the synthesis of the ZnO/carbon spheres composites using resorcinol—formaldehyde resin as a carbon source and zinc nitrate as a zinc oxide source in a solvothermal reactor heated with microwaves. The influence of activation with potassium oxalate and modification with zinc nitrate on the physicochemical properties of the obtained materials and CO2 adsorption capacity was investigated. It was found that in the case of nonactivated material as well as activated materials, the presence of zinc oxide in the carbon matrix had no effect or slightly increased the values of CO2 adsorption capacity. Only for the material where the weight ratio of carbon:zinc was 2:1, the decrease of CO2 adsorption capacity was reported. Additionally, CO2 adsorption experiments on nonactivated carbon spheres and those activated with potassium oxalate with different amounts of zinc nitrate were carried out at 40 °C using thermobalance. The highest CO2 adsorption capacity at temperature 40 °C (2.08 mmol/g adsorbent) was achieved for the material after activation with potassium oxalate with the highest zinc nitrate content as ZnO precursor. Moreover, repeated adsorption/desorption cycle experiments revealed that the as-prepared carbon spheres were very good CO2 adsorbents, exhibiting excellent cyclic stability with a performance decay of less than 10% over up to 25 adsorption-desorption cycles.

Highlights

The intensification of the greenhouse effect in the last 200 years has contributed to the phenomenon of global warming
This paper presents the results of the synthesis of microporous carbon spheres doped with zinc oxide in a microwave reactor
The CO2 uptake of carbon spheres modified with zinc nitrate was presented

Summary

Introduction

The intensification of the greenhouse effect in the last 200 years has contributed to the phenomenon of global warming. The increased CO2 concentration in the atmosphere is related to development of the energy industry, progressive urbanization and combustion of fossil fuels For this reason, various materials have been tested as solid sorbents for CO2 capture: microporous zeolites [1], silica [2], activated carbons [3], ordered porous carbons [4], activated carbon fibers [3], graphene [5] and microporous carbon materials including carbon spheres. In order to develop the surface area and improve the adsorption capacity of carbon materials, physical and chemical activation is one of the most frequently used methods. Ludwinowicz and Jaroniec obtained carbon spheres using potassium oxalate as an activator with a high surface area (2130 m2 /g) and a high CO2 adsorption capacity equal 6.6 mmol/g at 0 ◦ C [18]. The highest achieved CO2 adsorption equalled 8.9 mmol/g at 0 ◦ C [20]

Methods

Results

Conclusion