Photothermal characterization of biodiesel and petroleum diesel fuels—A review and perspective

Abstract

Alternative fuels hold considerable promise as substitutes for petroleum diesel fuel. As such, biodiesel is a promising renewable fuel that has been developed and tested by a number of research groups. Quality control of this transportation fuel is of great significance to its commercialization. Conventional chromatographic and spectroscopic analytical methods are most commonly used for biodiesel characterization, in some cases yielding information detail beyond that needed for the determination of biodiesel quality. By contrast, less common methods, such as photothermal techniques, are well suited to characterize a wide range of transportation fuels. The complexities of photothermal and chemical analytical techniques are roughly similar, as are the costs. Photothermal methods are based on spectroscopic and thermophysical properties of the sample, an advantage with respect to ordinary chromatography and spectroscopy techniques. Furthermore, some photothermal techniques can be adapted for remote signal detection, which can be used for in situ analysis in fuel production for inline biodiesel quality inspection and control. Therefore, an overview and outlook of the photothermal characterization is of considerable interest. In this paper, the applications of photothermal techniques in the characterization of biodiesel, petroleum diesel fuels, and their blends are reviewed. The review includes thermophysical properties and correlations for fuels, determination of blend levels, and biodiesel stability investigations. After the review, discussion and perspective are presented for future improvement of photothermal characterization and industrial applications.