Ethylene production desiccation

Effects on Ethylene. Direct desiccation of detached leaves causes a rapid increase in ethylene production. Since the response is larger in leaves with an abscission zone, this stress-induced ethylene production may be related to stress-induced abscission (Aharoni 1977). 

Thioureas mainly find use for the vulcanisation of CR, epichlorohydrin (ECO) and some ethylene propylene diene terpolymer (EPDM) compounds. They show high crosslinking activity, with usually adequate compound flow time before onset of the crosslinking. In EPDMs, the thioureas are used as activators for low activity third monomer types and, in the presence of calcium oxide desiccants, in free state vulcanisation of extrudates, etc. The use of thioureas can overcome the retardation caused by the desiccant. In this case some care must be taken otherwise overcompensation may occur. Thioureas are not used in food product applications and are a known health hazard, particularly for pregnant women. 

Cracked Gas Drying. Ethylene and propylene are two of the most important petrochemical raw materials today. They are manufactured by a thermal cracking of ethane, propane, or naphtha. One of the important separation-purification steps in the production of ethylene and propylene is removal of water before low temperature separation. Although alumina has been the most commonly used desiccant in drying cracked gas in the past, 3A molecular sieve adsorbents have an overall economic advantage 32), and many cracked gas plants are using the 3A molecular sieves today. 

At the end of the reaction period, the unreacted ethylene is released, and the polymer is immediately collected on a coarse glass frit where it is quickly washed with three 200 ml portions of ice water and then with 50 ml of ice-cold acetone. The product is dried in darkness overnight in a vacuum desiccator at room temperature connected to a cold trap at -80 C. The dried product weights 13.5 grams. 

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