Zeolites Ziegler-Natta

Zeolites, 321, 322 Ziegler-Natta catalysts, 174 Zirconium chlorides, 194 Zirconium compounds as catalysts, 188... 

Ziegler-Natta catalysts. The second one involves hydrocarbon coupling in the solid acid zeolite chabazite. 

Zeise s salt, 240 zeolite, UA, 266, 270 Ziegler-Natta catalyst, 269 zinc blende structure, 104 Zintl compound, 112, 160, 202... 

The dimerization of propylene in liquid phase over nickel-ion exchanged zeolites with various structures modified by treatment with AlEtiCl is studied. The mechanism of propylene dimerization on these catalysts is similar to the mechanism of olefin dimerization on Ziegler-Natta catalytic systems. The different catalytic behaviours of the studied zeolites are connected with their crystalline structure. The X-ray investigation of the crystalline structure of zeolites after the repeated treatment with AlEt2Cl demonstrates its preservation. 

A small selection of major reaction types has been studied, but the list is by no means complete. Enzymes, solid acids such as zeolites and Envirocats (see Table 16.3), and new oxidation catalysts are obvious cases where the new technology can bring genuine improvements to chemistry on an industrial scale. Metallocenes are now causing a revolution in polymer production, replacing conventional Ziegler-Natta catalysts for as many as sixty monomers [28]. Further catalyst improvements are still desirable, particularly in the areas of oxidation and aromatic substitution. 

As the number of important catalyst families increased in the post World War II decades, researchers began to specialize in areas such as ammonia catalysts, reforming and cracking of petroleum fractions, Ziegler-Natta catalysts, zeolites, homogeneous catalysis, and use of enzymes as industrial catalysts. Creating a unified discipline of catalysis from all these fields continues to be challenge today as it was in the past. 

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