I don't have experience with zeolites but have come across the issue for synthetic silicates. The way I tried to decide about degassing conditions was :

1. use TGA/DSC to determine which temperature was not to be exceeded and heat below it

2. try various degassing durations and see how BET value and C constant evolve : if you find a stable region, go for it.

I also sometimes optimize conditions using an experimental design (Doehlert matrix T° and duration), which will give you a response surface to choose your conditions from.

Degassing is usually performed at 110 Deere Cel. overnight. This helps to remove moisture from the sample.

Sometimes 110°C is not enough to remove all water in zeolites for example hydration complexes formed with cations need T>400°C. Anyway, I agree with Mr. Caulet's answer.

TGA is an effective way to determine the Degas conditions. But there is an optimization study behind determining the Degas conditions. Such as my material has its first mass loss at 140 °C. At first, I was doing Degas at 120 °C for 12 hours, but I recognized that my crystals started to change color. So I decided to limit the Degas time to 6 hours. When I compared the two BET surface areas obtained for two different Degas conditions, I recognized 120 °C for 6 hours give me the best result.

Thanks Aysu for your answer