How to Make Sulfuric Acid? | Detailed Explanation

Sulfuric acid plays an essential role in the industry. So how to make sulfuric acid? Let’s know more about this question.

What is sulfuric acid?

Sulfuric acid is a strong acid with strong corrosiveness and requires careful use. It has a strong affinity for water. However, water is ubiquitous in various forms in nature, and pure anhydrous sulfuric acid is completely absent in nature. It can dissolve with water in any ratio and release a large amount of heat to make water boil.

Pure sulfuric acid appears colorless and is an oily liquid. According to different concentrations, it can be mainly divided into concentrated sulfuric acid and dilute sulfuric acid. The two exhibit different characteristics. The former has strong oxidation and dehydration properties, while the latter involves more chemical reactions, such as reacting with alkali to form corresponding sulfates and hydrogen gas. The dehydration ability of concentrated sulfuric acid is fully utilized in industrial production, such as serving as a dehydrating agent.

The most easily associated natural form of sulfuric acid liquid in our lives is acid rain. The sulfuric acid aerosols generated during volcanic eruptions can be converted into sulfur dioxide, which is also present in acid rain. Although this is not the main cause of acid rain.

In the current context of global warming, acid rain has long become a noteworthy issue. The sulfur dioxide in acid rain reacts with water in the atmosphere to produce sulfite, which then oxidizes and follows the rainwater into the soil, further leading to acidic soil. Improving acidic soil usually utilizes the feature that it can react with alkali to produce sulfate and hydrogen to neutralize to achieve the effect of soil improvement.

Sulfuric acid is widely used in industries such as metallurgy and petroleum, especially in the production of non-ferrous metals. Sulfuric acid can be used to dissolve other impurities to extract precious metals, dissolve iron oxide on the surface of steel, or purify crude oil with concentrated sulfuric acid, and so on.

How to make sulfuric acid?

Sulfuric acid has a long history. During the reign of Emperor Gaozong of Tang, Chinese alchemists used bile alum to produce sulfuric acid. Chemists and pharmacists in Germany and England made it possible for it to be produced on a wide scale up to the 17th and 18th century. Peregrine Phillips, a British vinegar merchant, developed the contact process for the industrial manufacturing of sulfuric acid.

Nowadays, the industrial production of sulfuric acid adopts the contact process. Manufacturing materials include water, air or oxygen, and sulfur. The following are three mainly steps.

Firstly, to produce sulfur dioxide. Generally speaking, sulfur burns in the air to produce sulfur dioxide. In addition, metal sulfides such as zinc sulfide and lead sulfide can also be burned to provide sulfur dioxide. Then purify the sulfur dioxide and proceed to the second step.

Secondly, to convert sulfur dioxide into sulfur trioxide. The pure mixture of sulfur dioxide and pure oxygen obtained in the first step is passed through the converter, and sulfur trioxide is generated using catalysts like metallic element chemical compound at a hot temperature of 450℃.

Thirdly, use sulfur trioxide in the absorber to produce oleum, then dilute the oleum with water, and eventually turn out 98% concentrated sulfuric acid within the dilator.

In principle, in the third step, sulfur trioxide can react with water to form sulfuric acid, but this approach is not adopted in the industry because the process generates a large amount of heat and may pose an explosion risk, as well as acid smoke that is difficult to condense, which may pollute the air.

The above is about how to make sulfuric acid.

Conclusion

To sum up, this article discusses what sulfuric acid is, its usefulness, its historical development, and how to make sulfuric acid. The production of it mainly adopts the contact method, which entails three main phases. Sulfur dioxide is produced in the first step, the second is the transformation of sulfur dioxide into sulfur trioxide, and the third step is to provide sulfuric acid with sulfur trioxide.