The Role Catalysts In Chemical Reactions, Their Importance In Industry, Problems 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 ....