Two stage pyrolysis–catalysis of used tyres was undertaken to upgrade the derived oil to a highly aromatic oil suitable to be used as a chemical feedstock rather than a liquid fuel. The tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a secondary fixed bed reactor containing zeolite catalyst. The pyrolysis reactor was maintained at 500 °C and the influence of catalyst temperature between 430 and 600 °C on the yield and composition of the derived oils was examined......
Sunday, August 24, 2008
There are numerous naturally occurring and synthetic zeolites, each with a unique structure. The pore sizes commercially available range from approximately 3 ? to approximately 8 ?. Some of the commercial materials are: A, beta, mordenite, Y, ZSM-5.
The combination of many properties, among them: the microporous character of the uniform pore dimensions, the ion exchange properties, the ability to develop internal acidity, the high thermal stability, the high internal surface area. These make zeolites unique among inorganic oxides.
Not all zeolites have been studied, but extensive studies have been done on zeolite A due to its use in consumer products. These studies have demonstrated that type A zeolite is essentially non-toxic via oral, dermal, ocular, and respiratory routes of exposure; type A zeolite was also found to be safe for the environment. Please consult the MSDS for product(s) of interest
Zeolites are three-dimensional, microporous, crystalline solids with well-defined structures that contain aluminum, silicon, and oxygen in their regular framework; cations and water are located in the pores. The silicon and aluminum atoms are tetrahedrally coordinated with each other through shared oxygen atoms. Zeolites are natural minerals that are mined in many parts of the world; most zeolites used commercially are produced synthetically. Zeolites have void space (cavities or channels) that can host cations, water, or other molecules. Because of their regular and reproducible structure, they behave in a predictable fashion.