1. Analysis methods and principles

The principle of laser Raman spectroscopy analysis technology is the Raman scattering effect.

Raman scattering: When excited photons interact with molecules as scattering centers, most of the photons only undergo directional scattering without changing the frequency of the light. Approximately 10-10-10-6% of the total scattered light undergoes scattering, which not only changes the propagation direction but also the frequency. This type of scattering with frequency changes is called Raman scattering.

Through years of research on the Raman effect, we have found that the Raman scattering effect can directly reflect the molecular structure of the analyzed substance. Moreover, compared with other traditional infrared, mid infrared, and near-infrared methods, Raman spectroscopy has strong anti-interference ability, no self absorption effect, and characteristic peaks for most molecules. Therefore, in the 1980s, laser Raman spectroscopy began to be applied in the field of medicine. After years of effort, the Raman spectra have become more refined, and laser Raman spectroscopy analysis has begun to be applied in the chemical and petrochemical fields.

2. Application of laser Raman spectroscopy in the petrochemical field.

Laser Raman spectroscopy analysis technology has been widely used in the petrochemical industry. The main uses are divided into two categories: a. Used in research fields, laser Raman spectroscopy is applied in the study of catalysts and the molecular structure of oil products. b. The application in industrial sites mainly involves the analysis of the content of benzene and aromatic hydrocarbons in PX units and the analysis of the comprehensive properties of oil products in oil blending units.

The content analysis of benzene and aromatic compounds in PX unit is the earliest application example of Raman spectroscopy analyzer in industrial field. Due to the mechanism of laser Raman spectroscopy, the influence of moisture and impurities in the sample on the analysis results is minimal. Meanwhile, benzene and its derivatives exhibit independent characteristic peaks in laser Raman spectra. Due to the inability of infrared to independently distinguish the characteristic peaks of various substances in the absorption spectra of benzene and its derivatives, infrared cannot qualitatively analyze benzene and its derivatives. Currently, laser Raman spectroscopy analyzers are used for quantitative analysis in PX facilities.

Please refer to the attached figure for the laser spectrum diagram:

As can be seen from the attached figure, in the Raman spectrum. The characteristic peaks of various substances such as benzene and its derivatives are very obvious. We have compared the analysis data of benzene with the laboratory analysis data multiple times and obtained the following figure:

The analysis results of benzene content using a laser Raman spectrometer as shown in the figure are very consistent with the laboratory analysis results, with a standard deviation of R=0.99886.

The analysis data comparison of aromatic compounds is as follows:

The standard deviation R is 0.98785. The laser Raman spectrometer provides excellent analysis results for the content of aromatic compounds.

At the same time, the principle of laser Raman analysis results in minimal influence of sample temperature, moisture, and impurities on the analysis results. Online laser Raman analyzers have low requirements for on-site conditions, so they are widely used in the analysis of benzene and aromatic compounds in PX plants