CRYSTALLIZATION OF N-PARAFFIN FROM MELT UNDER DIFFERENT TEMPERATURE CONDITIONS
E.A. Volkova, A.N. Guseva and N.I. Leonyuk
Moscow State University, Geological Faculty Dept. of Crystallography and Crystallo-chemistry, Moscow 119899, Russia leon@goel.msu.ru
Keywords: n-paraffin, melt, crystallization
It is known[1], studies of paraffinium crystallization and crystal morphology play an essential role. The practical reason to study the paraffin crystal growth and morphology are that crude oil, diesel and etc. contain significant propotion of higher n-alcanes paraffins and during cold conditions they can crystallize into thin, flat plates which can gel the fuel. Sizes and morphology of crystals also play an important role in processes of oil dewaxing [2].
To date, there are publications on the n-paraffin crystallization from solutions. However, among them, there has practically never been a systematic investigations concerned with n-paraffin crystal growth from the melt. For this reason, in the present work attempts have been made in this direction.
The crystal growth experiments were carried out from paraffinium melt in temperature range of 55-45oC. The grown crystals were studied by electron and optical microscopies, and also by X-ray diffraction method.
It was identified both hexagonal and orthorhombic crystals. Hexagonal and orthorhombic forms of n-paraffin crystallize at the cooling rates of 25.5, 10 and 4 C/h in the above temperature range, and dimentions of the plate-like crystals increase in about 1.5-2 times with decreasing cooling rates. Final crystalline solids contain about 85% of their mass of orthorhombic paraffin crystals. Hexagonal crystal were partly presented by dendrites.