【Abstract】With the development of modern industry, automobiles have become a common means of transportation in our lives. Car exhaust has become one of the main sources of air pollution, causing damage and impact on all aspects of our lives. Direct or indirect adverse effects on plants. Among many materials, solid adsorbents are one of the important means of environmental treatment. In this paper, the control variable method was used to study the absorption of automobile exhaust by the common adsorbent of activated alumina. Through experimental comparison and analysis of automobile exhaust gas composition, the results show that the carbon molecular sieve adsorbent has a good adsorption effect on hydrocarbons and automobile exhaust gas with higher carbon oxide content.
Key words: activated alumina; adsorbent; experimental analysis; application;
Alumina is the reason why metal aluminum is not easily corroded in the air. Pure metal aluminum readily reacts with oxygen in the air to form a thin film of aluminum oxide that covers the surface of the aluminum exposed to air. This aluminum oxide film prevents aluminum from being oxidized. The thickness and properties of the oxide film can be treated by a process called anodizing (anode anti-corrosion). This process has been strengthened. (Al2O3·H2O and Al2O3·3H2O) are the main minerals of aluminum. After pulverization, it was impregnated with a high-temperature sodium hydroxide solution to obtain a sodium metaaluminate solution; the residue was removed by filtration, the filtrate was cooled, and aluminum hydroxide crystals were added. After a long period of stirring, the sodium aluminate solution is separated into aluminum hydroxide precipitate; the precipitate is separated and washed, and then calcined at a temperature of 950 to 1200 ° C to obtain an α-type alumina powder, and the mother liquor can be recycled. This method was invented by the Austrian scientist K.J. Bayer remained the main method of alumina production in 1888. It is called the Bayer method.
Alpha alumina
In the crystal lattice of the α-type alumina, oxygen ions are tightly packed by the hexagonal, and Al 3+ is symmetrically distributed at the octahedral coordination center surrounded by the oxygen ions. The lattice energy is large, so the melting point and boiling point are very high. The α-type alumina is insoluble in water and acid. It is also known in the industry as alumina. It is the basic raw material for the manufacture of metal aluminum. It is also used in the manufacture of various refractory bricks, refractory enamels, refractory tubes, high temperature laboratory equipment and abrasives. , flame retardant, filler, etc.; high-purity α-alumina is also a raw material for producing artificial corundum, artificial ruby and sapphire; also used for the production of large-scale integrated circuit substrates
Gamma alumina
The γ-type alumina is obtained by dehydrating aluminum hydroxide at a low temperature of 140 to 150 ° C, and is also referred to as activated alumina or aluminum rubber in the industry. In this structure, oxygen ions are closely packed in the vertical direction, and Al 3+ is irregularly distributed in octahedral and tetrahedral voids surrounded by oxygen ions. The cerium type alumina is insoluble in water, soluble in a strong acid or strong alkali solution, and is converted to α-alumina by heating to 1200 °C. Bismuth-type alumina is a porous material with an internal surface area of several hundred square meters per gram, which has high activity and high adsorption capacity. Industrial products are usually colorless or micro-striped cylindrical particles with good pressure resistance. It is a commonly used adsorbent, catalyst and catalyst carrier in the petroleum refining and petrochemical industries; it is an industrial deacidification agent for turbine oils and turbine oils, and is also used for chromatographic analysis; it is a laboratory neutral strong desiccant. The drying capacity is not lower than that of phosphorus pentoxide. After use, regeneration and reuse can be carried out by heating at 175 ° C for 6-8 hours.
The world's alumina produced by Bayer Process accounts for more than 90% of total production. Most aluminas are used to make metal aluminum, and other uses are less than 10%.
