Named after Stephen Brunauer, P.H. Emmet and. Edward Teller. Developed in They were working on ammonia catalysts. First method to measure the. Brunauer–Emmett–Teller (BET) theory aims to explain the physical adsorption of gas . The BET method is widely used in surface science for the calculation of Concept · Derivation · Applications · Activated Carbon. A method developed by Bruner, Emmett, and Teller for measuring surface area by using nitrogen adsorption condensation in pores at liquid nitrogen temperatu. This information is used to predict the dissolution rate, as this rate is proportional to the specific surface area. The specific surface area of a powder is determined by physical adsorption of a gas on the surface of the solid and by calculating the amount of adsorbate gas corresponding to a monomolecular layer on the surface. The determination is usually carried out at the temperature of liquid nitrogen. Als ersten gelang es Brunauer, Emmett und Teller, eine für die praktische Anwendung geeignete Adsorptionsisotherme für die Mehrschichtenadsorption abzuleiten. These have included argon, carbon dioxide, and water. Let us consider a given amount of solid sample in a controlled atmosphere. The ISO standard for calculating the specific surface area of solids is based on the BET method. Navigation menu Personal tools Not logged in Talk Contributions Create account Log in. For this reason, standard BET analysis is most often conducted at the boiling temperature of N 2 77 K. Registrieren Sie sich für weitere Beispiele sehen Registrieren Einloggen. These circumstances may be verified by comparing values of specific surface area determined by the single-point method with that determined by the multiple-point method for the series of powder samples. Not logged in Not affiliated For the calculation of certain quantities see Table 1 a desorption step is also required where a vacuum is applied in the reverse of Step 5. The samples are dried with nitrogen purging or in a vacuum applying elevated temperatures. Sample Considerations and Preparations A general guideline is that you will need 0. Skip to content Andy Connelly. The test for linearity, the treatment of the data, and the calculation of the specific surface area of the sample are described above. It is this correlation calculation, volume absorbed to surface area, that BET theory gives you. Admit a small amount of dry nitrogen into the sample tube to prevent contamination of the clean surface, remove the sample tube, insert the stopper, and weigh it. Scientific techniques Physical chemistry Gas technologies. If the quantity of adsorbed water vapor is measured at different levels of relative humidity a BET plot is obtained. Proudly powered by WordPress Education Hub by WEN Themes. Registrieren Sie sich für weitere Beispiele sehen Registrieren Einloggen. Measuring surface area and porosity of powders is difficult.