The contact method is the main industrial method for manufacturing sulfuric acid. This process mainly includes four steps: high-temperature roasting of sulfur or sulfide ore to produce sulfur dioxide; sulfur dioxide and oxygen catalyze at high temperature to generate sulfur trioxide; use concentrated sulfuric acid to absorb sulfur trioxide to produce sulfur dioxide. oleum; finally dilute the oleum with water to obtain the finished sulfuric acid.
Step One: Preparing Sulfur Dioxide Burning sulfur in the air produces sulfur dioxide gas. The sulfur dioxide and air are first purified to remove impurities that could affect the catalyst used in the next process.
Step 2: Catalytic oxidation. Under normal pressure and 450 degrees Celsius, sulfur dioxide and air are passed through a vanadium pentoxide (V2O5) catalyst to perform a catalytic oxidation reaction to produce sulfur trioxide. This reaction is reversible, so precise control of temperature and pressure is required to optimize yield.
Step 3: Absorb sulfur trioxide. In the absorption tower, sulfur trioxide will dissolve in 98% sulfuric acid to form fuming sulfuric acid. The reaction between sulfur trioxide and water is very violent. If it is directly dissolved in water, it will release a large amount of heat energy and form sulfuric acid mist, which hinders the dissolution process and is difficult to collect. Therefore, 98.3% sulfuric acid is usually used to absorb SO3 and then diluted with water.
Step 4: Dilute the oleum. After the oleum is diluted with an appropriate amount of water, 98% sulfuric acid is formed. The sulfuric acid produced will be cooled and stored. Since the solubility of sulfur trioxide in sulfuric acid is higher than that of water, sulfur trioxide manufacturers do not directly dissolve sulfur trioxide in water.
During the entire process of the contact method, the selection of catalysts and the control of reaction conditions are crucial to the yield and quality of sulfuric acid. Vanadium pentoxide is the most commonly used catalyst because it effectively promotes the conversion of sulfur dioxide to sulfur trioxide. In addition, the safety protection of equipment and operators throughout the production process is also very important because sulfuric acid is highly corrosive.
The advantages of the contact method include its high efficiency, ability to produce continuously, and low energy consumption. However, this process also requires a high degree of technical control, including precise management of temperature, pressure, and catalysts to ensure the smooth progress of the reaction and product quality. With the advancement of science and technology, the contact method process is also constantly improving to increase productivity, reduce costs, and reduce the impact on the environment.
