Desorption of a Zeolite filled with Organic Matter - METTLER TOLEDO

Desorption of a Zeolite filled with Organic Matter

Introduction

The Swedish mineralogist Axel Fredrick von Cronstedt noted in 1756 that certain stones seemed to boil on heating and at the same time released considerable amounts of water vapor. He called these «boiling stones» zeolites (a word whose roots are derived from the Greek words «zeein» for boiling and «lithos» for stone) [1, 2]. The phenomenon of the boiling stones can be understood through the special structure of the zeolites. Zeolites are crystalline materials whose crystal lattices contain extensive pores and channels in which specific foreign molecules (e.g. water, ethanol, and ammonia) can be reversibly stored. As a result of the large internal surface of the pores and channels (up to 1000 m2/g), zeolites are able to adsorb up to 30% of their empty mass of foreign molecules depending on the density of the stored species. Adsorbed molecules can be removed from a zeolite by heating without affecting its structure. Zeolites can be used for any number of adsorption/desorption cycles. Naturally occurring zeolites consist mainly of SiO2- and AlO4- tetrahedrons that are connected to one another via oxygen atoms so that pores and channels are formed internally [3, 4].

The pores often contain free mobile cations (e.g. Na+) that can be exchanged for other ions (e.g. Ca +) or for free water. Most zeolites used nowadays are made synthetically. A wide range of zeolites is therefore available with very different chemical compositions and pore sizes optimized for specific applications. Zeolites have numerous fields of application. Natrolite is from the technical point of view of great importance and is used for hydraulic cement, as a filler material in the manufacture of paper, as an adsorption agent, for water softening and as an ion exchange material [3]. Synthetic zeolites, such as molecular sieves (Zeolite A, Na12[(AlO2)12(SiO2)12] 27H2O), which is available in different pore sizes, is used as drying agent in laboratories or as a catalyst [2]. Furthermore, zeolites are also employed in washing powder (as water softeners) or in cat litter in order to absorb both liquids and unpleasant odors. In the following example, decomposition products of a particular zeolite were investigated by means of TGA-MS.

Sample:     Zeolite containing 2,2’-(1,4-phenylene)bis(5-phenyl)oxazole.

Zeolite Filled with Organic Matter
Zeolite Filled with Organic Matter

Desorption of a Zeolite Filled with Organic Matter by TGA-MS | Thermal Analysis Handbook No.HB607 | Application published in METTLER TOLEDO TA Application Handbook Evolved Gas Analysis