Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

Iwona Pełech,Piotr Staciwa,Daniel Sibera,Urszula Narkiewicz,Robert Cormia

doi:10.3390/molecules25225328

Iwona Pełech, Piotr Staciwa + Show 3 more

Open Access

https://doi.org/10.3390/molecules25225328

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Abstract

In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the effect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly different from those obtained at higher pressures. In addition, CO2 uptake was not affected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more effect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 °C, but had no effect on it at 0 °C.

Highlights

Carbon dioxide concentrations in the atmosphere continue to rise and are currently approaching420 ppm, coincident with rising global temperatures and climate change (CDIAC)
Microporous carbon spheres with high CO2 adsorption efficiency were synthesized in an autoclave and at pressureless conditions, and show that pressure treatment is not necessary to produce high-quality carbon spheres
The morphology and porosity of the spheres produced without activation step under pressureless conditions were not significantly different from those obtained at higher pressures

Summary

Introduction

Carbon dioxide concentrations in the atmosphere continue to rise and are currently approaching. There are several methods used to produce carbon spheres, including arc discharge [12], laser ablation [13], chemical vapor deposition (CVD) (decomposition of chemical substances containing carbon), and pyrolysis and catalytic decomposition of organic compounds by heat treatment of polymers or other materials, often in an autoclave [14,15,16] In the latter approach, reactants are placed in various types of metal autoclaves and usually heated to a (rather low) desired temperature. I.e., how low-pressure or pressureless (atmospheric) conditions during the synthesis of carbon spheres influences morphology, microporous structure, and CO2 adsorption efficiency. The effect of reaction time, temperature, and addition of activating agent during formation of carbon spheres from resorcinol and formaldehyde through synthesis in an autoclave was investigated and discussed

Results and Discussions

2.46 Figure 4a

Results oxalate

Materials Preparation

Materials Characterization

Conclusions