Does BET theory apply to type H3 and H4 isotherm for calculating surface area? [closed]








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[![type H3 and H4 are classification of IUPAC for hysteresis loops](https://i.stack.imgur.com/0IliK.png)](https://i.stack.imgur.com/0IliK.png)


BET applies to type 2 and 4. That is basically unanimous. 




The sample that shows loop of H3 type have **(very likely) no** micropores (small uptake in low p/p0 range). In this case you can apply BET theory in common p/p0 range (0.05-0.3). The sample that shows H4 hysteresis **have** micropores (large uptake in low p/p0 range). The BET theory can be applied here, but in a much lower p/p0 range. For activated carbon, for example, one would look for a linear(!) range between p/p0 = 0.02-0.1. Generally, the BET theory is not suitable for microporous materials. 


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