OXFORD AND CAMBRIDGE SCHOOLS EXAMINATION BOARD. General Certificate Examination - Advanced Level Chemistry (Salters') - Paper 3 mock.
ROBERT TAYLOR U6JW.
A Catalyst is a substance that alters the rate of a reaction. The catalyst remains unchanged at the end of the reaction. The process is called catalysis. In this report I aim going to explain the role of catalysts in chemical reactions and their importance in industry. I will also outline the problems associated with the use of some catalysts and discuss, using appropriate examples, new developments in this area which will help reduce damage to the environment.
The process of catalysis is essential to the modern day manufacturing industry. Ninety per cent, over a trillion dollars' worth, of manufactured items are produced with the help of catalysts every year. It is therefore logical that scientists are constantly searching for new improved catalysts which will improve efficiency or produce a greater yield.
An acidic catalyst works due its acid nature. Catalysts are strong acids and readily give up hydrogen ions, or protons: H+. Protons can be released from hydrated ions, for example H3O+, but more commonly they are released from ionisable hydroxyl groups (R-OH) where the O-H bond is broken to produce R-O- and H+. When the reactant receives protons from an acid it undergoes a conformational change, (change in shape and configuration), and becomes a reactive intermediate. The intermediate can then either become an isomer by returning a proton to the catalyst, or it may undergo a further reaction and form a completely new molecule.
Up until the mid - 1960's silica-alumina gels were used to catalyse the cracking of hydrocarbons. This form of cracking is where the large molecules in oil are converted into small, highly volatile molecules. However because the size of the pores of silica-alumina...