Base-catalyzed Preparation Of Medium Polymerization Degree Of Polyglycerol Process

Polyglycerol, an important chemical raw materials and intermediates in industrial production, was widely used as surface active agents, food additives, emulsifiers and defoamers. As one of important derivative, medium chain fatty acid polyglycerol ester has played a significant role in food industry considering itsgood emulsification. Its emulsification properties largely depend on the polymerization degree of polyglycerol. Polyglycerol of high polymerization degree whose esters have better emulsification has not only higher hydroxyl number, better hydrophilic effect but also poor mobility and deep color of its product. On the contrary,polyglycerol of low polymerization degree has a good fluidity, but the emulsification far from satisfactory. Comprehensively, the informed choices have been made when we choose polyglycerol of medium polymerization degree (4-6) as the material in synthetizing of medium chain fatty acid polyglycerol ester. In this paper, the base-catalyzed preparation of medium polymerization degree of the polyglycerol process has been studied, the main experimental study are as follows.The four existing methods in testing Polymerization degree of polyglycerol as GB(national standard)Method、Acetic anhydride method、Refractive Index Method and Water-generating amount method have been compared with experiments. The result shows that GB Method and Acetic anhydride method the data results’ trend are likely and have a little difference. Compared with GB Method, Acetic anhydride method has simpler operation with less error, which uses inexpensive drugs and requirs shorter time. moreover, due to the characteristics of Polyglycerol and experimental operation etc, the data in experiments of Refractive Index Method and Water-generating amount method has large error. Hence the data of polymerization degree from these two methods are unreliable. Acetic anhydride method can be chosen in testing Polyglycerol average polymerization degree, which is quite normal in scientific research and industrial productionContrast as alkali metal hydroxides (NaOH, KOH),and alkali metal carbonates (Na2CO3, K2CO3) on the catalytic effect of glycerol polymerization under the same conditions, polymerization degree as the evaluation index found that, The effect of catalytic glycerin that alkali metal hydroxide (NaOH, KOH) is better than the alkali metal carbonates (Na2CO3, K2CO3), and because the greater of alkaline catalyst the better catalytic synthesis of polyglycerol. NaOH as catalyst synthesize polyglycerol that their products’ color and odor is lighter and detected by mass spectrometry the straight chain relative content of polyglycerol more than KOH. NaOH chosen as catalyst to synthesize polyglycerin. At the same time, single factor test method had discussed of the catalyst concentration, reaction time and reaction temperature on the synthesis of polyglycerol, and polymerization degree results as evaluation index:Higher catalyst concentration and longer reaction time will acquire higher polymerization degree of polyglycerol, but little impact on the kind of the polyglycerol, there are oligomeric and high polymer product existence. The influence of temperature on the reaction, under low temperature conditions main synthesize oligo-glycerol, while the temperature rises, the kind and polymerization degree of the polyglycerol are significantly increased, and the higher the temperature of the synthetic polyglycerol, the worse the color and odor thicker, high-temperature occur side reactions easily. Through orthogonal test method to determine the optimal experimental conditions:temperature of260℃,3%of the catalyst concentrationand reaction time of4hours. Under the best experimental conditions of polymerization reaction, polyglycerol’s polymerization degree is8.92.Different catalytically active component, the type of carrier solid base catalyst and the type of load prepared by impregnation method,then synthesis of polyglycerol,and polymerization degree as the evaluation index, Hammett indicator method and the CO2-TPD catalysts were characterized,the results show that, NaOH as catalytic active component prepared solid alkali synthesize polyglycerol better than Na2CO3.The smaller surface area of γ-Al2O3as carrier catalytic effect is better.The type of load NaOH supported on γ-Al2O3and prepared solid base catalyst, the best catalytic effect is40%load.Compared solid base with liquid alkali under the same conditions, the effect that solid base is lower than the liquid base synthesize polyglycerol. But the polymerization degree of solid base polyglycerin can reach more than6,while of polyglycerol carbon chain fatty acid polyglycerol esters need polymerization degree between4-6, the synthesis of solid base meet the requirements, solid base can instead of the liquid base for synthesizing polyglycerol.