Mason T G, Lin M Y
Corporate Strategic Research, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, New Jersey 08801, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2003 May;67(5 Pt 1):050401. doi: 10.1103/PhysRevE.67.050401. Epub 2003 May 21.
We study the structure and phase behavior of asphaltenes comprised of large polyaromatic molecules in blends of naturally occurring crude oils using small angle neutron scattering (SANS). When two compatible oils are blended together, the asphaltenes remain dispersed as colloidal nanoparticles; however, when two incompatible oils are blended together, these asphaltene nanoparticles can aggregate to form microscale structures. We show that SANS directly probes asphaltene aggregation in unmodified (i.e., nondeuterated) crude oil mixtures due to a significant neutron scattering length density difference between the hydrogen-poor asphaltenes and the surrounding oil. Moreover, the small length scales probed by SANS are ideally suited for studying asphaltene aggregation: SANS simultaneously provides the average size and concentration of nanoscale asphaltene particles and also the volume fraction of microscale asphaltene aggregates. These discoveries yield a practical means for directly assessing the compatibility of crude oils and for diagnosing refinery fouling problems resulting from blending incompatible oils.
我们使用小角中子散射（SANS）研究了天然原油混合物中由大的多环芳烃分子组成的沥青质的结构和相行为。当两种相容的油混合在一起时，沥青质仍以胶体纳米颗粒的形式分散；然而，当两种不相容的油混合在一起时，这些沥青质纳米颗粒会聚集形成微观结构。我们表明，由于贫氢沥青质与周围油之间存在显著的中子散射长度密度差异，SANS可以直接探测未改性（即非氘代）原油混合物中的沥青质聚集。此外，SANS探测的小长度尺度非常适合研究沥青质聚集：SANS同时提供纳米级沥青质颗粒的平均尺寸和浓度，以及微米级沥青质聚集体的体积分数。这些发现为直接评估原油的相容性以及诊断因混合不相容油而导致的炼油厂结垢问题提供了一种实用方法。
