Pour point depressant (PPD) is a crucial addition in the petroleum industry which can significantly enhance the flow properties of crude oil by preventing wax from precipitating out of it. The flow assurance effect of PPD on crude oil is impacted by its molecular structure. As a result, we concentrate on the PPD with various molecular structures, such as carboxyl and benzene rings, to investigate its impact on the flow behavior of crude oil. Then, FTIR and contact angle test were used to describe the characteristics of PPD (SAF-n and SAFS-m). The Karamay crude oil was tested using the following items: pour point, rheology, viscosity, viscoelasticity, and POM. When the crude oil was treated with 1000 ppm SAFS-1, the pour point decreased from 12 to −14 °C and the viscosity decreased from 40.1 to 6.3 pa·s at 0 °C. Meanwhile, the results show that the more variety polar groups PPD has, the more its dispersion increases and the stronger its interactions with crude oil are when its molar ratio of non-polar groups are suitable. These effects may be caused by the PPD changing the crystallization characteristics of wax and the aggregate state of resin and asphalt. Graphical Abstract

Ammonium carbonate solution was used instead of water to wash the impurities in the coprecipitation method, and oxides with increased oxygen vacancy content and catalytic effect were obtained.