A Chemical Engineering Approach to Catalyst Development
Chemical Product Design and Engineering (CPD&E)
Chemical Product Design & Engineering - II (CPD&E - 2)
Keywords: Product design, Catalyst, sulphuric acid
The desire to reduce production costs and energy consumption in industry has been a major driving force for the development of new catalysts and catalytic processes, and in the past decades an increased focus on environmental protection has called for new catalysts for removal of SO2, NOx and organic compounds from off-gases in the chemical industry, from power plants, refineries and from auto-exhaust. The development of catalytic products includes both practical and theoretical knowledge and experience with a palette of disciplines known to the chemical engineer, e.g. inorganic chemistry, physical and chemical characterisation techniques, nano-scale materials, unit operations, chemical reaction engineering, catalyst kinetics, and transport phenomena.
The starting point for development of a new commercial catalyst is typically new market opportunities or requirements to performance identified in a competitive market. However, ideas fostered from observations in the laboratory or elsewhere in an organisation may also be recognised as a source of new product opportunities. In the first stages of the catalyst development, formulations with different carriers, shapes, compositions and calcinations are tested with respect to catalytic activity, mechanical strength and pressure drop. In the later stages of the development, full-scale production is demonstrated, the catalyst stability and durability are validated and detailed performance data are acquired. An innovative attitude is important especially in the first stages of development, where different catalyst formulations are proposed and selected, but in all steps of the testing much can be learned from the experimental observations. The decisions to move forward through the stages of the development process are based on evaluations of the profitability of the catalyst product based on the measured performance, estimated production cost and market analyses. However, the profitability should be taken into account throughout the development process in order to avoid e.g. exotic production routes or expensive raw materials that will fail to pass the evaluations anyway.
As a case study of chemical product design in the catalyst industry, the strategy and the methods used for catalyst development and design at Haldor Topsøe to develop and design a new commercial low-temperature sulphuric acid catalyst called VK69 are presented. The individual tasks and methods used for the development are described and a selection of results are presented and discussed. The main driver for this development was the desire to reduce SO2 emissions from sulphuric acid plants without costly tail gas cleaning or an additional interbed absorption step, which would require high investment cost and reduce the energy efficiency of the process. Because of the unfavourable position of the equilibrium at high temperature, this task addressed a serious limitation of the vanadium-potassium-based sulphuric acid catalyst, being a drastic decrease of activity below 400-430°C. The development was based on Cs as an excellent low-temperature promoter, carrier optimization and clever pellet design.
Presented Wednesday 19, 16:40 to 17:00, in session Chemical Product Design & Engineering - II (CPD&E - 2).
