University:
Colorado State University
Course:
CHEM 107 | Fundamentals of Chemistry (GT-SC2)
Academic year:

2023
Views:

309

Pages:

1
Author:

P. Tron

Types of Catalyst The term catalyst originates from Berzelius' (1836) research on the process of accelerating reaction rates and explaining it as a result of the catalytic force. The term "force" of catalysis is apparently not proven, but the term catalyst is still used to describe the influence of certain substances that participate in the process without undergoing change. Negative catalyst or inhibiotr is compounds that reduce the reaction. Acid-Base Catalyst In chemical kinetics the acid-base catalyst play an important role. The beginning of research into the kinetics of reactions catalyzed by an acid or base coincided with the development of the theory of electrolyte dissociation, where Ostwald and Arrhenius proved that the ability of an acid to catalyze these reactions did not depend on the nature of the anion but was closer to the nature of its electrical conductivity. Other research that used acid-base catalysts included Kirrchoff who examined the hydrolysis of starch under the influence of dilute acids, Thenard who examined the decomposition of hydrogen peroxide under the influence of bases and Wilhelmy who studied the inversion of sugar cane catalyzed by acid. Ziegler-Natta catalyst The Ziegler-Natta catalyst was discovered by Ziegler in 1953 and was used for the polymerization of ethane, then in 1955 Natta used this catalyst for the polymerization of propene and other saturated monomers. Ziegler-Natta catalysts can be made by mixing alkyl or aryl from group 11-13 elements in a periodic arrangement, with halides as transition elements. Currently ZieglerNatta catalysts are used for mass production of polyethylene and polypropylene. Friedle-Crafts Catalyst In 1877 Charles Friedel and James M.Crafts conducted research on the manufacture of amyl iodide compounds by reacting amyl chloride with aluminum and iodine which turned out to produce hydrocarbons. Furthermore, they discovered that using aluminum chloride could replace aluminum to produce hydrocarbons. Thus Friedel and Crafts were the first to show that the presence of metal chloride was very important as a reactant or catalyst. Until now, the application of Friedel-Crafts chemistry is very broad, especially in the chemical industry. Catalysts in Metathesis Reactions In 1970 Yves Chauvin of the Institut Francais du Petrole and Jean-Louis Herrison discovered the catalyst carbene metal (a metal that can double bond with carbon atoms to form compounds), or also known as metal alkylidene. Through this carbene metal compound, Chauvin succeeded in explaining how the composition of the metal functions as a catalyst in a reaction and what the metathesis reaction mechanism is. Metathesis can be interpreted as the exchange of atomic positions of two different substances. For example, in the reaction AB + CD -> AC + BD, B exchanges position with C.