稠油沥青质的基本化学组成结构与缔合性研究

摘要

从4种不同稠油中分离沉淀出正戊烷沥青质，用红外光谱表征了其官能团结构，用1 H-N MR 结合相对分子质量及元素分析测定了沥青质的基本结构参数，并得出了沥青质的平均分子式，同时测定了沥青质的偶极矩来表征其极性。研究结果表明：稠油沥青质分子中杂原子的存在使其含有较多的极性基团，沥青质具有较大极性。杂原子含量越高，其极性越大，缔合性越强，缔合数越高。此外，用两种方法计算了沥青质的分子直径，结果表明：相对分子质量越大时，沥青质分子尺寸越大，但特性黏度法测得的分子直径与其选用的溶剂有关，且关联出的分子直径偏大，而相对密度和相对分子质量法能较好地反映分子颗粒尺寸。%Four kinds of asphaltenes were obtained from four different heavy oils with n-pentane as solvent.Their functional structures were characterized by FTIR spectroscopy,and the basic structural parameters of the asphaltenes were determined by 1 H-NMR,then the average molecular formula of the asphaltene were given by molecular weight and element content.The dipole moments were also meas-ured to indicate the polarities of the asphaltene molecules.The results show that the presence of het-eroatom in asphaltene makes the asphalt form the polar groups with high polarity,and the higher the content of impurity atoms,the greater the polarity,the stronger the association,the higher the associa-tion numbers.In addition,molecular diameters were measured by two methods:intrinsic viscosity method,and relative density and relative molecular mass method.With the increase of relative molecu-lar mass,the molecular size of asphaltene becomes larger.However,the molecular diameter measured by viscosity method is related to the selected solvents and usually is larger than the size obtained by rela-tive density and relative molecular mass method,and the latter method can well reflect the molecular size.