Action mechanism of diesel pour point depressant
1. Nucleation theory
At a temperature higher than the oil cloud point, the depressant molecules precipitate and act as nuclei, active centers or crystallization centers to form wax crystal growth centers, which increase the number of small wax crystals in oil products and achieve the effect of reducing the freezing point or cold filter point.
2. Eutectic Theory
Wax crystals in diesel fuel grow in two dimensions. The polar part of pour point depressant molecule can hinder the growth of wax crystals on X and Y axes, and accelerate the growth speed of wax crystals on Z axes. Therefore, the crystal form changes from irregular block to quadripyramid and quadriprism. This crystalline form of wax reduces the specific surface area relative to the surface energy, which makes it difficult to form three-dimensional network junctions.
3. Adsorption theory
Under the cloud point temperature of oil, the crystallization of pour point depressant precipitates. The polar groups in pour point depressant change the surface characteristics of wax crystals, hinder the growth of wax crystals or change the growth habit of wax crystals, increase the dispersion of wax crystals, make it difficult to coalesce into a network, and thus play a pour point depressant effect.
4. Theory of Improving Wax Solubility
The pour point depressant increases the solubility and dispersion of wax in oil, which makes it difficult to coalesce into a three-dimensional network structure due to surface charge repulsion, thus reducing the condensation point.
At a temperature higher than the oil cloud point, the depressant molecules precipitate and act as nuclei, active centers or crystallization centers to form wax crystal growth centers, which increase the number of small wax crystals in oil products and achieve the effect of reducing the freezing point or cold filter point.
2. Eutectic Theory
Wax crystals in diesel fuel grow in two dimensions. The polar part of pour point depressant molecule can hinder the growth of wax crystals on X and Y axes, and accelerate the growth speed of wax crystals on Z axes. Therefore, the crystal form changes from irregular block to quadripyramid and quadriprism. This crystalline form of wax reduces the specific surface area relative to the surface energy, which makes it difficult to form three-dimensional network junctions.
3. Adsorption theory
Under the cloud point temperature of oil, the crystallization of pour point depressant precipitates. The polar groups in pour point depressant change the surface characteristics of wax crystals, hinder the growth of wax crystals or change the growth habit of wax crystals, increase the dispersion of wax crystals, make it difficult to coalesce into a network, and thus play a pour point depressant effect.
4. Theory of Improving Wax Solubility
The pour point depressant increases the solubility and dispersion of wax in oil, which makes it difficult to coalesce into a three-dimensional network structure due to surface charge repulsion, thus reducing the condensation point.
