Chemiluminescent control of the oxidation of a mixture of aluminum trialkyls to aluminum trialkoxides atthe key stage of the Alfol process for the synthesis of higher fatty alcohols

Abstract

An efficient chemiluminescent method has been developed for control the process of oxidation of aluminum alkyls (C2–22H5–45)3Al to aluminum alkoxides (C2–22H5–45O)3Al in the Alfol process chain of the production of higher fatty alcohols. Chemiluminescence occurs when aluminum alkyls are oxidized with air oxygen in kerosene to form a triplet-excited aldehyde (an oxidation by-product). To enhance CL, the Ru(bpy)3Cl2 complex is used, which accepts energy from the aldehyde triplet and emits red CL with a maximum at 580 nm.Compared to the control methods used (infrared spectrophotometry and gas liquid chromatography), the chemiluminescent method has a number of important advantages. Among them: higher accuracy of control, reproducibility, expressiveness, the use of a small number of reagents, simpler equipment. So, when using the chemiluminescent method, the controlled value - the glow intensity - decreases from 1.5 to 2 orders of magnitude; whereas in the IR control method used, the difference between the intensities of the bands before and after oxidation does not exceed 10 %. The reproducibility of the chemiluminescent method is characterized by a relative standard deviation not exceeding 0.1 %, which is quite sufficient for the purposes of technological control. While the relative error of the spectrophotometric method is much larger and equal to 7.9 %. The higher expressiveness of the chemiluminescent method makes it possible to improve the quality of target higher fatty alcohols by preventing underoxidation or overoxidation of aluminum alkyls. The present work also demonstrates the possibility of developing the CL method to the creation of a continuous control of the industrial process of aluminum alkyl oxidation.