Methane gas has higher desorption affinity than the carbon dioxide gas and it desorbs at a faster rate. However, if the experiments are carried out in different ranks of coals, how will be comparative studies for the desorption among different ranks (let's say, bituminous vs sub-bituminous vs lignite etc..) will look like. Assume the experiments for all types of coals are done in similar temperature conditions at the varying pressure.
Have a look on recently published article available at https://www.pnnl.gov/news-media/methane-emissions-coal-mines-are-higher-previously-thought.
the higher the pressure, the greater the desorption power on methane
Syamsul Bakhri that's a good point. I think you are absolutely correct but still how the rank can change the desorption trends. We know that higher the declining pressure higher will be desorption rate for methane gas. However, I am still concerned how the desorption trends will change as the rank of the coal changes. Thank you again for your response.
Alok Dhaundiyal
thank you for the response. Langmuir pattern meaning, a simple Langmuir model or when you say pattern it refers to something else. I have fitted my data using Langmuir model and have looked over other models like Freundlich models. There are six different models that describes on how to fit the adsorption data as a function of increasing/decreasing pressure and volume. As you mentioned these models slightly talk about moisture and ash content. To my knowledge, what I have heard is that Bituminous coals will have slightly less moisture content than that of sub-bituminous which can change the rates of desorption of methane as a function of declining pressure. However, I want to more sure about it. Can you please recommend me some article that talks in details about on how Langmuir patterns can predict the different ranks of coals and how it further will predict the desorption phenomena of Methane gas. Thank you again.