Catalysts are used in the production of chemicals and fuels to control or regulate the speed, operating conditions (e.g., temperature) and byproducts of chemical reactions. Although it might seem obvious to add the catalyst directly to the reacting material, there are practical limitations, such as differences in specific gravity, mixing variations, chemical reaction and speed, that require a more deliberate approach.
Catalyst carriers are solid structures, usually with high surface areas, onto which catalysts are deposited (Figure 1). These are mixed together with the reacting material in order to improve the distribution and chemical efficiency of the manufacturing process. These carriers must be engineered for each specific application and developed hand-in-hand with the catalysts themselves.
This article provides a brief technical overview of catalyst carriers, introduces Saint-Gobain NorPro’s new micro-sized Accu® sphere catalyst carriers and describes how Saint-Gobain NorPro can assist chemical engineers in developing catalyst carriers that can optimize their manufacturing processes.
As a result of the numerous technical considerations that must go into the design of the catalyst carrier and the catalyst, there is not a single “one-size-fits-all” catalyst carrier structure that is ideal for the various applications. Ideally, the catalyst carrier must be developed together with the catalyst to fully optimize the manufacturing process while considering numerous trade-offs. For example, the design of the catalyst carrier can affect the thermal stability of the process by increasing or decreasing the reaction rate between the catalyst and reacting material. Furthermore, the shape and packing density of the catalyst carrier can affect fluid flow rates and pressures. Finally, the catalyst carrier itself may be subjected to thermal, pressure or chemical loads, or the carrier materials may react chemically, causing a reduction in lifetime or reliability.
Figure 1 (right). Saint-Gobain NorPro catalyst carriers come in a variety of shapes and sizes.
These factors can have a large effect on the cost, availability and security of the supply chain for catalyst carriers. Several technical considerations must go into the design of catalysts and catalyst carriers that will ultimately govern the rate of specific chemical reactions. Among the most fundamental factors that govern the chemical reaction are the catalyst carrier surface area and porosity. It is typically desirable to maximize surface area to gain the maximum exposure of a catalyst to reacting materials.
The porosity (including pore size and volume) is a measure of the distribution of surface irregularities on the catalyst carrier, which may further increase surface area and provide pathways for the catalyst to distribute within the reacting material. The overall size and shape of the catalyst carrier can affect manufacturing process parameters in that a balance must be made between the pressure drop through the catalyst bed versus catalyst activity. Generally, smaller catalyst carriers and geometries enhance packing efficiency and increase the amount of catalyst per volume and the pressure drop in the catalyst bed. Finally, the catalyst carrier material and surface chemistry affect impurity levels and the reaction tolerance to these impurities.
As the technical and market leader in advanced ceramic technologies, Saint-Gobain NorPro has profound knowledge of the technical considerations that must go into the design, development and manufacturing of catalyst carriers. Saint-Gobain NorPro’s catalyst carriers enable the delivery of catalysts with improved selectivity, activity and extended life. As an example, Saint-Gobain NorPro's new "micro" sized Accu® sphere catalyst carriers are engineered for small-diameter catalytic systems, requiring carriers in the 0.3mm to 4.0mm size range (Figure 2). This smaller size range enables high surface area, uniform packing and even flow distribution in applications such as slurry or moving bed reactors, often where catalyst generation is required. Accu® spheres are available in multiple formulations, compositions and properties, including an expanded variety of chemistries and mixed oxides (alumina, silica, titania, zirconia) that are tailored for specific customer applications.
Figure 2 (above). Accu® sphere catalyst carriers
Saint-Gobain NorPro has been servicing the petrochemical, chemical, refining, environmental and gas processing industries for well over 100 years. It is one of the largest industrial corporations in the world and an undisputed leader in providing an impressive collection of engineered ceramic media and shapes. Saint-Gobain NorPro’s state-of-the-art research and development facilities enable them to work together with customers to develop custom solutions that incorporate the latest technology to improve their overall manufacturing processes and profitability.