Abstract-Characterization of morphology and structure of wax crystals in waxy crude oils by terahertz time-domain spectroscopy

Chen Jiang, Kun Zhao, Cheng Fu, and Lizhi Xiao

Energy Fuels, Just Accepted Manuscript

DOI: 10.1021/acs.energyfuels.6b02900

Publication Date (Web): January 8, 2017

Copyright © 2017 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.6b02900?journalCode=enfuem

Abstract: The content, morphology and structure of precipitated wax crystals are major factors affecting crude oil rheology. In this paper, model oils obtained by dissolving a realistic mixture of long-chain n-octacosane in diesel fuels were studied using terahertz time-domain spectroscopy (THz-TDS) and microscopy to gain insight into clusters composed of asphaltene and wax with increasing wax content. The fractal dimension was used for quantitative characterization of the morphology and structure of clusters in the model oils. From the measured absorption and extinction coefficients in the THz region, dynamic processes of the clusters in the model oils were analyzed and identified. The extinction coefficient in the THz region strongly depended on the dispersed and aggregated states of the asphaltene and wax crystals. These observations suggest that the aggregation state of the particles in model oils can be monitored with THz-TDS. In the future, THz-TDS technology may be used to effectively analyze particle dispersion or the aggregation state in crude oil, and may thus be useful for rapid assessment of the effect of pour-point depressant on wax crystal aggregates..

Abstract-Probing disaggregation of crude oil in magnetic field with terahertz time-domain spectroscopy

Chen Jiang , Kun Zhao , Li J. Zhao , Wu J. Jin ,

Yuping Yang , and Shao H. Chen

Energy Fuels, Just Accepted Manuscript

DOI: 10.1021/ef401984u

Publication Date (Web): January 3, 2014

Copyright © 2014 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/ef401984u

The magnetic technology can significantly change the characteristics of crude oil, and the physical mechanism has received much attention for several years. To date, there is no accurate conclusion yet. Terahertz time domain spectroscopy is employed in this paper to characterize the optical parameters of selected wax-bearing crude oil under the action of a magnetic field. The corresponding absorption coefficient and extinction coefficient of samples are obtained by fast Fourier transform frequency-domain spectrum, and the aggregation characteristics of particles are analyzed in crude oil under magnetic field. The decrease of extinction coefficient may be suggested as a qualitative proof of a magnetic-field-induced disaggregation of the suspended colloidal particles. Terahertz time domain spectroscopy may be a powerful tool to characterize the particle disaggregation state in crude oil.