Pure and Binary Adsorption Equilibria of Methane and Nitrogen on Activated Carbons, Desiccants, and Zeolites at Different Pressures
Bibliographic record
Abstract
Abstract Several commercially available adsorbents that show promise for the separation of CH4 from N2 including different activated carbons, desiccants, and zeolites were evaluated using single component adsorption isotherms of pure methane and nitrogen that were measured at 303 K for pressures of up to 10 atm using the gravimetric method. Following the screening, the adsorption of binary gas mixtures composed of methane and nitrogen were studied at 303 K and two different pressures on the adsorbents with the highest capacity for CH4 of each of the activated carbons, desiccants, and zeolites. These selected adsorbents included commercial zeolite 13X (Siliporite Nitroxy Pro from CECA Arkema Group), activated carbon (Xtrusorb A754 from Calgon Carbon Corp.), and silica gel (SG-B127 from Grace & Co). A concentration pulse chromatographic method was used to determine the pure component CH4 and N2 Henry’s Law constants, heats of adsorption, and the experimental binary adsorption isotherms for the three selected adsorbents. The effect of pressure on the binary CH4–N2 system was examined at 1 and 4 atm total pressures. The experimental equilibrium binary adsorption isotherm behavior was compared to the predictions based on the Extended Langmuir Model and the Ideal Adsorbed Solution Theory using the parameters from the pure component adsorption isotherms. The experimental equilibrium data for each adsorbent were compared through X–Y phase diagrams and selectivity curves. Both binary models show only a modest ability to describe adsorption equilibria of the binary system on activated carbon, silica gel, and 13X. The experimental binary CH4/N2 selectivity was shown to be different than the pure component data suggests for all of the adsorbents, indicating some competitive adsorption of CH4 and N2 in the binary system. Results of this study showed that for this system, 13X zeolite had a combination of the lowest binary selectivity and the highest heats of adsorption. Silica gel had low heats of adsorption for both N2 and CH4, but higher methane selectivity at high methane concentrations. Activated carbon provided high binary equilibrium selectivity and high capacity among the studied adsorbents, which has good implications for this gas separation application of natural gas treatment.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".