Abstract
Polygranular nuclear graphite, manufactured at 2800–3000 °C from a carbonized filler and binder mix, has high graphitization degree, crystalline structure close to perfect graphite, and about 20% porosity. The pore surfaces expose large regions of rough, defective prismatic edges of graphite crystallites which are the locus of graphite materials surface sites active for oxidation, chemisorption, and electron transfer. However, we show that high-resolution N2 and Kr first monolayer adsorption on polygranular graphite (P/P0 < 0.015) occurs in many ways like adsorption on graphitized carbon blacks. This proves the presence of energetically homogeneous basal planes domains in graphite porosity, which was not fully acknowledged before. Using classical analysis methods (Langmuir, Hill-de Boer, adsorption potential distribution) we quantity the basal plane area (BPA) of several polygranular graphite types and correlate it with their microstructure. We propose that gas adsorption is uniquely positioned to reliably estimate the active surface area of graphite by subtracting BPA from the BET total surface area. Direct estimation based on adsorption is preferable to indirect calculations based on microstructural information.
| Original language | English |
|---|---|
| Pages (from-to) | 633-645 |
| Number of pages | 13 |
| Journal | Carbon |
| Volume | 179 |
| DOIs | |
| State | Published - Jul 2021 |
Funding
This work was supported by the U. S. Department of Energy, Office of Nuclear Energy , under the Advanced Reactor Technologies (ART) – Gas Cooled Reactor (GCR) Program. Oak Ridge National Laboratory is managed by UT-Battelle under contract DE-AC05-00R22725 . The authors thank Professor Duong D. Do (Queensland University, Australia) and Drs. Carlos Leon y Leon (Morgan Advanced Materials) and Michelle Kidder (ORNL) for critical reading and valuable suggestions on the manuscript. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE) . The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).This work was supported by the U. S. Department of Energy, Office of Nuclear Energy, under the Advanced Reactor Technologies (ART) ? Gas Cooled Reactor (GCR) Program. Oak Ridge National Laboratory is managed by UT-Battelle under contract DE-AC05-00R22725. The authors thank Professor Duong D. Do (Queensland University, Australia) and Drs. Carlos Leon y Leon (Morgan Advanced Materials) and Michelle Kidder (ORNL) for critical reading and valuable suggestions on the manuscript.
Keywords
- Active surface area
- Adsorption potential distribution
- Basal planes
- Krypton adsorption
- Nitrogen adsorption
- Nuclear graphite