Process and apparatus for analysis of hydrocarbon species by near infrared spectroscopy

In addition to analysis in the infrared spectra of hydrocarbon group types, it has now been found that certain hydrocarbon species, including preferably aromatic species such as benzene, toluene, xylene, and alkyl benzenes such as ethyl benzene, can be determined by measuring absorption in certain selected wavelengths in the infrared spectra, then manipulating the data, e.g., preferably by taking the first or higher derivative, and applying statistical techniques, preferably multiple linear regression (MLR) to provide an output signal indicative of the concentration of the particular specie. The output signal can be used to control refinery and chemical processes, e.g., reforming, catalytic cracking, alkylation and isomerization. In manufacturing reformulated fuels, government regulations can be complied with by utilizing the invention to blend fuels which have a maximum of benzene or other regulated components.