Catalytic combustion is a purification method that uses catalysts to oxidize and decompose combustible substances in exhaust gas at lower temperatures. So, catalytic combustion is also known as catalytic chemical conversion. Due to the acceleration of the oxidation decomposition process by the catalyst, most hydrocarbons can be oxidized through the catalyst at temperatures of 300-450 ℃.
Compared with the thermal combustion method, catalytic combustion requires less auxiliary fuel, consumes less energy, and has smaller equipment and facilities. However, the promotion and application of this method in industrial production processes have been affected by issues such as catalyst poisoning, replacement of catalytic beds, and high cleaning costs.
A catalyst is a substance that can change the rate of a chemical reaction without altering its chemical properties before and after the reaction. Catalysts are usually composed of catalytically active materials and catalytic carriers. Catalytic active materials are generally metals or metal oxides. Among them, precious metal catalysts mainly include platinum, palladium, ruthenium, etc., while ordinary metal catalysts mainly include copper, chromium, nickel, vanadium, manganese, iron, cobalt and other metals and oxides. The catalytic carrier is a porous material, mainly used to give the active material a large surface area. Catalytic carriers are divided into metal carriers, ceramic carriers, and carbon fiber carriers. Metal carriers are generally made of nickel or nickel chromium alloy as carriers in the form of strips, sheets, pellets, wires, etc. Platinum and palladium are plated on these carriers through "electroplating" or "chemical plating" (i.e. solution immersion), and molded into molds that are easy to assemble and disassemble. Catalysts based on ceramics are generally supported on silicon aluminum oxide, and their structures come in two types: granular and honeycomb like. Generally, a thin layer of 0.13mm thick alpha alumina is coated on the ceramic structure, and active platinum, palladium and other metal catalysts are deposited or dispersed in a microcrystalline state in the porous alumina thin layer, and made into a mold drawer that is easy to assemble and disassemble. Carbon fiber carriers can be made into shapes such as linear, felt, and mesh, and catalytic active materials can be coated on the carrier to create molds that are easy to assemble and disassemble.