Catalyst Supports and Carriers Information
Catalyst supports and carriers serve as media for the delivery of catalytic substances to aid chemical process. This is achieved by coating the components with the substance, which in turn increases the number of catalytic sites available. They facilitate the reaction mechanism by providing a controlled surface area with a particular surface chemistry. Chemical properties of the structures depend on the shape, dimension or overall composition. Some materials remain inert while others react by forming a bond with the surface atoms. Suitable media include alumina and silica as well as different types of carbon.
Conditions that rely on the catalyst’s mechanical strength or precise quantity require the use of carriers or supports for delivering the substance. They are often used in heterogeneous catalysis systems and are employed in a variety of tasks such as:
- Ammonia synthesis (Haber-Bosch process)
- Hydrogen production via steam reforming
- Synthesis of Ethylene oxide
- Ziegler-Natta ethylene polymerization
- Petroleum desulfurization
An extensive range of catalyst supports and carriers exists offering unique features for specialized uses. The main types include:
Fumed silica and metal oxides: This category of products is featured in various types of catalyst manufacturing. Their key functions include:
- Controlling the surface reactivity and profile in the catalytic system.
- Providing a silica source for aiding zeolite synthesis.
- Acting as binders or rheology control agents to aid the formation process.
The materials offer the following advantages:
- The ability to adjust the surface area
- Regulated surface chemistry in continuous production
- High levels of purity and heat stability
- Tailored production
- Increased tamped density
- Defined porosity
Pressed ceramic ring supports and carriers: Rings made of ceramic are pressed in multi-cavity molds. This results in precise dimensions and geometrical construction facilitating optimum volume capabilities. They are found in applications serving such industries as chemical manufacturing and petrochemicals. Material selections comprise steatites, alumina and silicon carbides providing the following characteristics:
- Reduction in the particulate contamination effect
- High purity
- Corrosion resistance in aggressive chemical environments
- Reduction in grit and fine powder clogs
Ceramic honeycomb catalyst supports and carriers: These elements cover petrochemical, waste incineration, and similar applications. They are based on the honeycomb structure with a greater surface area, limited airway resistance, and superior structural strength. After reduction firing, they are covered with a layer of active rare earth, transition or precious metals.
In case of a ceramic composition, dense carriers accompany shell type catalysts, while porous forms are paired with impregnated catalysts. Ceramic elements possess the following attributes:
- Chemical inertness
- Mechanical strength and stability
- Low surface profile
- Bulk material uniformity
Colloidal silica supports and carriers: The products act as binders and supports/carriers for catalytic materials exhibiting the following properties:
- Exceptional inorganic binding
- Inertness in the majority of chemical systems
- High stability at normal reaction temperatures
- Large specific surface area to enhance catalytic activity
Hydrocarbon cracking and disproportionation are some examples of processes that rely on colloidal silica components to prepare catalytic substances. In cases where a catalyst has a high concentration of alumina, its preparation involves taking steps to precipitate alumina and gel colloidal silica simultaneously. As a result, an output of the desired alumina-to-silica ratio is formed.
Polyolefin manufacturers utilize silica in particle form as a carrier for compounds essential to producing polyethylene. The silica functions as an active participant in the process of polymerization in addition to delivering catalytic agents. The size and shape of the selected silica compound have a significant effect on the ultimate performance of the mechanism and polymer characteristics.
Zeolites: These aluminosilicate molecular sieves function as both supports and simple catalysts. Recent research was focused on zeolites with exchanged alkali metal cations and alkali metal oxides produced by occlusion. Basic zeolites serve as ideal supports in conditions where clusters of Ru metal nanoparticles drive the catalysis in the ammonia synthesis reaction.
How Catalyst Supports and Carriers Work
Preparing supported catalysts is achieved using two methods. The first method, impregnation, involves treatment of a solid support with a pre-catalyst solution. When the consequent output is activated, the pre-catalyst assumes a more active state. Standard supports are in pellet form made of metal salt. In the second method, the co- precipitation method is used to obtain the catalytic substances from a homogenous solution.
The carrier elements are chosen for their thermal stability and ability to endure pre-catalyst activation environment. Some reactions engage high-temperature hydrogen streams to stimulate pre-catalysts. Others rely on oxidation-reduction occurring at high temperatures to treat contaminated catalysts.
A process called “spillover” may happen during catalysis where the adsorbates, including hydrogen and oxygen, interact with and travel across a support or carrier without re-entry into a gaseous phase. Heterogeneous elements exhibit strong metal-support interactions, as with spillover, demonstrating the interactivity of catalytic substances with their supports and carriers.
Catalyst supports and carriers are present in a diverse set of applications, including:
- Fixed bed reactors
- Slurry bed reactors
- Grinding and polishing tools
- Thick film circuit substrates
- Decoration materials
- Vacuum fluorescent displays
- Washcoat components
- Metal forming
- Chemicals manufacturing
- Waste incineration
- Waste gas treatment
- Waste water treatment
- Polyethylene manufacturing
An assortment of materials serves as supports and carriers, including:
- Silicon carbides
- Platinum and other precious metals
- Fumed silica
- Fumed metal oxide
Selecting Catalyst Supports and Carriers
Catalyst supports and carriers come in a vast range of materials and attributes. Many of these structures are designed for specific tasks and environments. When selecting a product, check manufacturer’s specifications to determine whether it fits the intended purpose.