Synthesis of multi-alkylpolyamines and their performance as flow improver in crude oil

Abstract In this work, three multi-alkyl polyamines, i.e., pentahexadecyl diethylenetriamine (PHDETA), hexahexadecyl triethylenetetramine (HHTETA) and heptahexadecyl tetraethylenepentylamine (HHTEPA), were synthesized and evaluated as pure flow improvers for crude oil. Under certain conditions, PHDETA, HHTETA and HHTEPA were able to improve the flow properties of L401 crude oil samples by reducing the viscosity of the crude oil by 97.5%, 94.3% and 97.1%, respectively. The three synthesized alkyl polyamines PHDETA, HHTETA and HHTEPA were able to reduce the viscosity of L1316 crude oil to a maximum of 94.3%, 93.7% and 94.9%, respectively. The pour point of L401 crude oil could be greatly reduced by 3.1 °C, 3.3 °C and 3.4 °C with PHDETA, HHTETA and HHTEPA, respectively. The pour point of L1316 crude oil with PHDETA, HHTETA and HHTEPA was strongly decreased by 2.8 °C, 2.9 °C and 3.2 °C, respectively. Photomicrographs showed the co-crystallization of L401 and L1316 crude oil in the presence of PHDETA, resulting in the formation of a non-close-packed network of wax crystals. The multi-alkyl polyamines have multiple alkyl side chains that extend in different directions into the oil phase and can co-crystallize with the wax molecules, allowing the wax crystals to disperse.