Production technology of formic acid – sodium formate +/sulfuric acid or phosphorus pentoxide
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We know that there are two routes for synthesizing formic acid from sodium formate: 1. Sodium formate + sulfuric acid; 2. Sodium formate + phosphorus pentoxide. Many factories use the sulfuric acid method because it is relatively inexpensive. However, I read online that Chongqing Chuandong uses the phosphoric acid method. The phosphorus pentoxide method seems to result in higher costs, and it generates a by-product, sodium dihydrogen phosphate (NaH2PO4). From sodium dihydrogen phosphate, sodium tripolyphosphate can then be produced. Does anyone know the cost advantages of these two methods? Also, the sulfuric acid produced as a by-product in the sulfuric acid method likely does not need to be purified, and it is relatively easy to sell. But when using the phosphorus pentoxide method, does NaH2PO4 need to be purified? How to purify it? Is it still only necessary to purify the final product, sodium tripolyphosphate? Does purification require special equipment, or can simple crystallization suffice? Experts, share your opinions!!
No purification is required; after formic acid is distilled off, sodium dihydrogen phosphate remains
Does the guy upstairs work in a factory or in research? Could you give me his contact information?
Production is carried out using the sulfuric acid method; the by-product obtained in this case is sodium sulfate, not sulfuric anhydride. Sodium sulfate costs only a few hundred yuan per ton, so it has little value. When production is done using phosphoric acid, formic acid and sodium dihydrogen phosphate are produced. During distillation in a distillation tank, formic acid evaporates as a gas, and it is condensed to yield liquid formic acid, while sodium dihydrogen phosphate appears as a solid crystal. No purification is required; as long as all of the formic acid is evaporated, the concentration of sodium dihydrogen phosphate will be higher. Sodium dihydrogen phosphate can be used to produce not only sodium tripolyphosphate but also sodium hexametaphosphate – all that’s needed is to add alkali to adjust the pH level
Now many yellow phosphorus plants are using yellow phosphorus exhaust gas to produce formic acid.
I would like to ask what the advantages are of using phosphoric acid and phosphorus pentoxide respectively Furthermore, when using phosphoric acid, is hot-process phosphoric acid or wet-process phosphoric acid generally used? Thank you
Going back to what was said upstairs: if phosphoric acid or anhydrous phosphorus dioxide is used, the reaction principles and resulting products are essentially the same. Phosphoric acid is of the thermal process type, and its cost is higher than that of the sulfuric acid method; however, the by-products generated have better economic value
Production is carried out using the sulfuric acid method; the by-product obtained in this case is sodium sulfate, not sulfuric anhydride. Sodium sulfate costs only a few hundred yuan per ton, so it has little value. When production is done using phosphoric acid, formic acid and sodium dihydrogen phosphate are produced. During distillation in a distillation tank, formic acid evaporates as a gas, and it is condensed to yield liquid formic acid, while sodium dihydrogen phosphate appears as a solid crystal. No purification is required; as long as all of the formic acid is evaporated, the concentration of sodium dihydrogen phosphate will be higher. Sodium dihydrogen phosphate can be used to produce not only sodium tripolyphosphate but also sodium hexametaphosphate – all that’s needed is to add alkali to adjust the pH level
The methyl formate hydrolysis method is the most advanced production method
Firstly, this technology is suitable for enterprises with yellow phosphorus facilities to use in production, offering a range of resource advantages. The phosphoric acid method is based on a circular economy model that integrates carbon, phosphorus, and sodium. Starting from raw materials, yellow phosphorus is used to produce phosphoric acid; this process generates 8 kilograms of steam as a by-product, which can be utilized for the distillation of formic acid. There is thus no need to install new boilers for steam production, eliminating the associated costs and environmental management challenges related to such boilers. Phosphoric acid reacts with sodium formate to produce formic acid, and phosphodihydrogen salt is also produced as a by-product. This phosphodihydrogen salt can be used in the production of pentasodium and hexametaphosphate compounds. After purification, the exhaust gases from yellow phosphorus production can be used not only to make sodium formate but also as a heat source for drying pentasodium and hexametaphosphate compounds. This approach offers significant cost advantages over the sulfuric acid method, and once all these processes are integrated into a circular economy system, the costs become even lower.