Preparation Of Acetol From Crude Glycerol Of Biodiesel Byproduct Via Catalytic Reactive Distillation

Nowadays biodiesel as a kind of most promising bioenergy has been winning more and more concern and vigorous development from all over the world. As a by-product of biodiesel production, glycerol has also been produced largely, so deeper exploiture of glycerol is a goal people focus on. Herein, two main achievements have been accomplished. Firstly, a KF/chitin solid base catalyst with high activity was prepared and applied in the esterification of vegetable oil for biodiesel. Secondly, catalyst preparation conditions on the hydration of glycerol to acetol was investigated and the reaction parameters was optimized. In the process of hydration of glycerol to acetol, for one thing, The Zn-modified copper-chromite catalyst was prepared by impregnation; for another, A series of three-components copper-chromite catalyst with the third component as modification additives were prepared by coprecipitation. The catalysts was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Further, major effect factors on the hydration of glycerol to acetol in the presence of various copper-chromite catalysts was investigated and the reaction parameters was optimized. In detail, three points about the achievement are listed as follows:1. The KF/chitin solid base catalysts was prepared and utilized in the synthesis of biodiesel. The catalysts was characterized. Results showed that KF could be highly loaded on chitin. Response Surface Method was adopted to optimize the catalyst preparation conditions. It was found that in the presence of the catalyst loaded with 38% (w/w)KF, activated at 210℃, and aged for 4h, the yield of biodiesel reached as high as 97.4%.2. The Zn-modified copper-chromite catalyst was prepared and used in the hydration of glycerol to acetol. The catalysts was characterized. It is discovered that the introduction of Zn can inhibit the deactivation of catalyst effectively, so that increas the activity of catalyst, and improve the yield of acetol, as well as prolong the lifetime of the catalyst significantly. Conditions of modification and reaction were further studied. In the presence of the catalyst with a dosage of 4% modified by 10% Zn in mass fraction, calcined at 350℃, with the reaction temperature at 350℃and a vacuum condition at 0.025 MPa, the selectivity toward acetol is up to 88.9%. 3. A series of three-components copper-chromite catalyst with the third component as modification additives were prepared for the hydration of glycerol to acetol. The catalysts was characterized. The Cu-Cr-Zn catalyst prepared by coprecipitation is advantageous in that it has high activity and good stability as well as superior regeneration capacity. Among all the catalysts, the Cu-Cr-Zn catalyst is the most highly active one. And its optimum preparation conditions are as follows: Cu/Cr/Zn ratio is 1:1:0.5, precipitation temperature is 70℃, precipitation pH is 8.0, calcination temperature is 400℃.