Zeolites Word Scramble
|
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Term | Definition |
What is a zeolite? | Inorganic crystalline solid with high surface area, attributed to small pores (1-100A in diameter) present throughout structure. A mineral with a honeycomb-type structure and a unique "open" microporous molecular structure. |
General structure of a zeolite | They are an aluminosilicate framework structure with corner sharing SiO4 and AlO4 tetrahedra alternating throughout, in a lattice-like configuration. |
Pore characteristics of a zeolite | Sharply defined and shape selective. Act like molecular sieves. |
Rules that dictate the build of zeolites | Two aluminium ions cannot be adjacent to one another. Si/Al ratio of 1 to infinity. |
Some properties of low Si/Al ratios | Alkaline when in water, hydrothermally unstable, hydrophilic. |
Some applications for natural zeolites | Pollution control. Mining. Crops/Pastures. Horticulture. Stockfeeds. Aquaculture. Turf. Vermaculture. |
Building of zeolites | Structure of fused 4 and 6 membered rings. |
How to control zeolite structure? | Pore size and shape can be controlled by growing zeolites around a template. |
Steps of zeolite synthesis | To autoclave: sodium silicate, sodium aluminate, template, H2SO4 at 100-150C. Gels. Crystals: Filtering, washing, drying, calcination. Ion-exchange, drying, calcination. Zeolite. |
Techniques for zeolite characterisation | XRD, FTIR, Raman, surface area, XPS. |
Shape-selective catalysis by zeolites | Certain zeolites can be used to catalyse reactions and be specific to what product(s) is formed. |
Reactant-selective | Only one type of reactant molecule can be allowed to pass through the catalyst pores, due to size and shape. |
Product-selective | Only one type of product molecule can be allowed to pass through the catalyst pores, due to size and shape. Therefore, only a certain product is formed. "Observed" product |
Applications of shape-selective catalysts | Undesirable impurities can be continuously converted to easily removable compounds or harmless substances, the selectivity of a desired product can be increased and coke formation can be reduced. |
What is Zeolite Y? | ZY is a synthetic zeolite with structural type FAU, with a high Si/Al ratio. Ultra-stable Y. |
Applications of Zeolite Y? | FCC - Fluid CAtalytic Cracking is the process to "crack" heavy gas oils from larger molecules into small molecules, by breaking carbon bonds. Alkylation - Introduction of an alkyl group onto a molecule. |
Green chemistry and zeolites | Solid acid properties have been utilised extensively. Catalysts for: Friedels-craft acylation, salt-free esterfication of amino acids, green caprolactam process. Used in methanol to gasoline production. |
Zeolite A | Largest volume zeolite produced. Water softener in laundry detergents. Replaced harmful tri-phosphates. |
Created by:
PrincessBulldozer
Popular Chemistry sets