What are the main sulfuric acid catalysts?

At present, China mainly uses the contact process to produce sulfuric acid, and the catalyst for the oxidation of sulfur dioxide in this process is key to its production. Its development has involved gas-liquid reactions catalyzed by nitrogen oxides (the lead chamber method and the tower chamber method), as well as gas-solid reactions using platinum as a catalyst with asbestos, magnesium sulfate, or silica gel as carriers. However, platinum is expensive, sensitive to toxic substances such as arsenic and fluorine, and tends to become deactivated due to poisoning, which limits its use. Therefore, it was replaced by vanadium catalysts that are highly active, have strong toxicity resistance, and are inexpensive and readily available. The vanadium-based catalysts currently used in industry are based on V0. O is the active component, in the form of a sulfate of an alkali metal (K. SO or Na. SO) as a catalyst aid, and a multi-component catalyst using diatomite as a carrier; these are commonly referred to as vanadium-potassium(sodium)-silicon system catalysts.

There are medium-temperature S101 models and those in other shapes, low-temperature S107, as well as arsenic- and cesium-resistant models such as TS112 and 121.

In China, there are mainly two types of catalysts for sulfuric acid production: S101 and S108. These two are generally used together, and there is no such thing as a yield for either one alone. The main difference lies in the ignition temperature, that is, the temperature required to achieve a catalytic effect. S101 starts to function at around 440 degrees, while S108 begins to function at about 390 degrees. Their optimal conversion temperatures are both around 520 degrees, but at this temperature the conversion efficiency of S101 is significantly better than that of S108. Others such as cesium-containing catalysts also fall under the S108 category; the main difference lies in the minimum ignition temperature. It is said that abroad there are three sections with dedicated catalysts, while the other sections all use one type

Regarding the types of catalysts, in the past there were iron catalysts and platinum catalysts, but now barium catalysts are used – they are cost-effective and highly active. In terms of temperature, there are high temperature, medium temperature, and low temperature.

In the early days, sulfuric acid was produced using iron as a catalyst; although the cost was low, the conversion rate was relatively low. Later, platinum catalysts were developed, which offered a high conversion rate but at a cost that was too high for ordinary companies to afford. In the 1940s, vanadium catalysts were invented, enabling a conversion rate of almost 100% while maintaining an appropriate loading level. In China, the S101 catalyst was developed by Nanhua Company back in 1955, and it has been in use for over 40 years to date. For medium-temperature processes, the S101 type is still used, while for low-temperature processes, the S107 type is employed (some manufacturers use the name S108, but it’s the same catalyst). There have been several improvements in terms of design – such as the development of the S101-2H (ring-shaped) and S101-2H(Y) (chrysanthemum-shaped) variants – as well as a clover-shaped variant that has not been put into industrial use. These improvements only increase the specific surface area; at the same time, the effective content of the catalyst decreases. Companies can choose the appropriate catalyst based on their specific needs. Currently, there are more than 10 companies in China that produce sulfuric acid catalysts, and the quality of these catalysts is more or less similar. The only regrettable aspect is that Nanhua Company, the first company to produce sulfuric acid catalysts, no longer manufactures them for export. Companies that produce sulfuric acid simply need to send their catalysts to Nanhua Research Institute to check whether their activity level meets the required standards; there’s no need to purchase more expensive catalysts (this is just my personal opinion). There is still a certain difference between domestic catalysts and imported catalysts, mainly in terms of strength and bulk density (Basf’s catalysts seem to have the best strength, while Topso’s catalysts have the best bulk density). If a 3+1 process is being used, it might be advisable to consider imported catalysts; however, for 3+2 processes, domestic catalysts are sufficient. (The above are merely my personal opinions.)

Additional note to the above reply: I forgot to mention that in China, there are now S11* series catalysts containing cesium; these catalysts simply lower the temperature required to activate them. If you decide to use them, I recommend purchasing only a small amount to be placed in the upper sections of the low-temperature zone (for example, a small amount in the upper part of section 1, or in sections 4 and 5). In my opinion, this product merely has a higher loading capacity compared to imported versions, but otherwise it’s quite good

Everyone’s answers are too one-sided. Why not provide a systematic overview of the various types and characteristics of catalysts available both domestically and internationally? For example, those from Topsoe in Denmark, BASF in Germany, Monsanto in the United States, as well as those from Nanhua – this would make things much clearer

We use types 101 and 107.

Please see the following link: Introduction to sulfuric acid catalysts (excerpted from \"Sulfuric Acid\", edited by Tang Guihua) http://bbs.hcbbs.com/viewthread.php?tid=582865&extra=

BASF: 10# Flash