Phthalic acid (Phthalic Acid) is an important organic chemical raw material, widely used in plastics, dyes, pharmaceuticals, pesticides and other fields. In this article, we will introduce the manufacturing method of Phthalic Acid, including raw materials, process flow, operation points and other aspects.
I. Raw materials
The raw materials for the manufacture of phthalic acid are mainly phthalic anhydride (Phthalic Anhydride) and alkali. Among them, Phthalic Anhydride can be obtained by benzene oxidation method, while the base can use strong alkali such as sodium hydroxide or potassium hydroxide.
II. Processes
There are two main manufacturing processes for phthalic acid: acid digestion and alkali digestion. Among them, the acid digestion method is more widely used, and the following is an example of the acid digestion method to introduce the manufacturing process of phthalic acid.
1. Batching
Add phthalic anhydride and concentrated sulfuric acid into the batching tank according to a certain proportion, and mix well.
2. Acidolysis
Pump the mixture in the dosing tank into the acidolator, and carry out the acidolysis reaction under certain temperature and pressure to produce phthalic acid and sulfuric acid.
3. Crystallization
The reaction solution from the acid solubilizer is pumped into the crystallizer and cooled for crystallization to obtain phthalic acid crystals.
4. Centrifugal Separation
The crystals from the crystallizer are pumped into a centrifuge for centrifugal separation to obtain phthalic acid solids and mother liquor.
5. Washing
Wash the phthalic acid solid with pure water to remove surface impurities.
6. Drying
The washed phthalic acid solids are fed into the dryer for drying process to get the final phthalic acid product.
3. Operation points
1. Control the reaction temperature and pressure to ensure the smooth progress of acidolysis reaction.
2. Control the crystallization temperature and cooling speed to get the phthalic acid crystals with uniform particle size and high purity.
3. Centrifugal separation needs to control the centrifugal speed and time to avoid crystal fragmentation and mother liquor residue.
4. Parameters such as water temperature, washing time and drying temperature need to be controlled during washing and drying to ensure product quality.
4. Safety production and environmental protection requirements
1. In the production process, it is necessary to strictly comply with the safety production regulations to ensure the safety of employees and equipment.
2. Pollutants such as waste gas, waste water and solid waste generated need to be treated and disposed of to meet the environmental requirements.
V. Summary and Prospect
Phthalic acid, as an important organic chemical raw material, has a wide range of applications in the fields of plastics, dyestuffs, pharmaceuticals and so on. This paper describes the process flow and operation points of manufacturing phthalic acid by acid digestion method with phthalic anhydride and concentrated sulfuric acid as raw materials. In the actual production process need to strictly control the parameters to ensure product quality and production safety. At the same time, it is also necessary to pay attention to environmental protection requirements to take effective measures to reduce the impact of production on the environment. Looking to the future, with the progress of science and technology and the expansion of application areas, the production process and product quality of phthalic acid are expected to be further improved.
