Study On Lactic Acid Dehydration To Acrylic Acid By New Catalyst

Acrylic acid and its ester derivatives are important raw materials for the chemistry industry, as monomer, via homopolymerization and copolymerization, it can synthetic thousands of polymers. The polymers made of acrylic acid and its derivatives are characterized by color lasting, stability to light, moderate heat as well as weathering. And they are widely applied in surface coatings, textiles, adhesives, paper treatment, polishes, leather, fibers, and super-absorbent polymer, etc. However, the traditonal route of producing acrylic acid is oil route, the disadvantage of which is over-depending on the oil/petroleum. With the reduction of oil reserves and the rise of oil price, it is desirable and exigent to find the oil substitute, that is, the non-oil route, to reduce the stress from the scarcity of acrylic acid. Lactic acid to acrylic acid from biomass via fermentation is a significant chemical technology that is remarkable and promising.Based on detailed investigation of related literature, first, to prepare NaY zeolite by convenient method, then mix with MMT, use it as catalyst, via optimum technological conditions, achieve the reaction lactic acid dehydration to acrylic acid's high yeild.1. Mix sodium hydroxide, silica gel, sodium aluminate and water as following molar ratio:Na2O:Al2O3:SiO2:H2O=98:12.5:100:4753. The mixture is added into stainless steel autoclave with teflon. After 48h of reaction, the solid product is removed from the autoclave, separated from the slurry by filtration and washed with deionized water, dry at 100℃for 2h, calcined at 500℃for 2h. The product is characterized by XRD, BET, SEM. The result showed that the NaY zeolite s favorable crystallization temperature is 105℃, the crystal system is cube, the particles diameter is 5-17μm. The NaY zeolite is mixed with Montmorillonite with the weight ratio 5-30%, which is the catalyst.2. In the experiments, the effects of catalyst ratio and reaction temperature is investigated. The results showed that the optimum conditions are:the mass ratio of lactic acid/water in feeding stock 45%(contain 0.5% p-hydroxyanisole), flow rate of feeding stock 9mL/h, vaporizing chamber temperature 250℃, reaction temperature 300℃, the weight ratio 20% Li Montmorillonite have the optimum catalytic activity, the yield of acrylic acid reach 90%.3. Add cleaning agent. In the reaction, the catalyst's basic decay, and lose catalyst activaty. Adding base as cleaning agent to solve the problem, the result show that pyridine is a good cleaning agent, the reaction run 48h, and the catalyst also have high activity.4. Discuss the mechanism with basic catalyst at the first time, it is conform to the result.