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-Spectral characterization of the key parameters and elements in coal using terahertz spectroscopy

• Honglei Zhan^a, b, 
• Kun Zhao^b, , , 
• Lizhi Xiao^a
• 
  
• http://www.sciencedirect.com/science/article/pii/S0360544215013390

The augmenting necessity of energy saving and environmental protection has led to the increasing technical requirements about on-line monitoring of key parameters and elements in coal. In this study, terahertz spectroscopy combined with PCA (principal components analysis) was employed to analyze nine kinds of coal materials. Due to the strong absorption of the organics with the relatively high C/H ratio, such as aromatic compounds, coals with lower hydrogen content show higher absorption effects in terahertz range. Based on PC1 score calculated by PCA, the anthracite and bituminous coal can be clearly classified, and the clean as well as meagre coals were also distinguished by opposite trends. All the critical points in PCA system are in agreement with those (volatile matter and ash, respectively) classified in international standard of coal classification. In addition, significant elements, including carbon, hydrogen, nitrogen and sulfur, can be directly characterized using PC1 score with linear and non-linear models. This research indicates that the terahertz spectral analysis of key parameters and elements of coal is a promising tool for improving the detection method and advancing the technical innovation in coal processing industry.

Abstract-Optical characterization of the principal hydrocarbon components in natural gas using terahertz spectroscopy

Lina Ge , Honglei Zhan , Wenxiu Leng , Kun Zhao , and Lizhi Xiao

Energy Fuels, Just Accepted Manuscript

DOI: 10.1021/ef5028235

Publication Date (Web): March 2, 2015

Copyright © 2015 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/ef5028235?journalCode=enfuem
A rapid technique is necessary to detect the natural gas which is a more and more significant fuel resource in modern industry. Terahertz (THz) technique was employed in this research to detect the principal hydrocarbon components of natural gas including methane, ethane and propane. Two- and three-component mixtures were measured by THz setup, respectively. The amplitude ratio and time delay deviation of THz peaks between samples and reference were calculated. Phase projection pictures were obtained between the component concentrations and the amplitude ratio as well as time deviation. The phase figures evidently reflected the concentration dependent THz response and a greatly different distribution was located in the whole phase projection area. In addition, back propagation artificial neural networks method was utilized for the quantitative determination of components concentration and total pressure, and the correlation coefficient of prediction set was proved to be 0.9859. Therefore, THz technique can satisfy the increasing need of the rapid and efficient detection in natural gas industry.

Abstract-Water adsorption dynamics into active carbon probed by terahertz spectroscopy

Honglei Zhan,   Shixiang Wu,   Rima Bao,   Kun Zhao,   Lizhi Xiao,  Lina Ge and   Hongjie Shi  

RSC Adv., 2015, Accepted Manuscript

DOI: 10.1039/C4RA14730H
Received 17 Nov 2014, Accepted 12 Jan 2015
First published online 12 Jan 2015
http://pubs.rsc.org/en/content/articlelanding/2015/ra/c4ra14730h#!divAbstract


It is vital to characterize the adsorption dynamics in oil-gas reservoirs and pollution control industry. Terahertz (THz) spectroscopy was used to study the adsorption of the water molecules into active carbons. The absorbance at selected frequencies and the first principal component scores over the whole THz range were related to the corresponding time lengths. The collective tendency expressly tracked the dynamics of water adsorbed into active carbon pores. Therefore, THz technique can be used as a promising tool to monitor the adsorption issue in petroleum and environment fields.