磷钨酸盐催化转化葡萄糖合成乙酰丙酸

制备了一系列金属离子修饰的磷钨酸盐(M_XH_3-2XPW₁₂O₄₀,M=Zn,Cu,Cs,Ag)催化剂,并将磷钨酸银盐(Ag₃PW₁₂O₄₀)用于水解葡萄糖制备乙酰丙酸的实验中。采用FTIR、XRD、SEM和EPMA等技术对磷钨酸盐性能进行了表征,并分析了磷钨酸银盐催化剂在反应前后结构和表面元素相对含量的变化。考察了反应温度、反应时间、催化剂用量和葡萄糖浓度等对乙酰丙酸得率的影响。结果表明:合成的磷钨酸盐具有磷钨酸的Keggin结构,并且Ag₃PW₁₂O₄₀催化剂在多次使用后Keggin结构没有被破坏。在催化合成反应中,在反应温度200℃、反应时间2 h、Ag₃PW₁₂O₄₀催化剂用量0.7 g和葡萄糖浓度40 g·L^-1的条件下,乙酰丙酸的最大得率可达到81.61%,催化剂可重复利用。

Catalytic conversion of glucose to levulinic acid by solid heteropolyacid salts

A series of metal-modified heteropolyacid salt catalysts(M_XH_3-2XPW₁₂O₄₀,M=Zn,Cu,Cs,Ag)were prepared,and the solid heteropolyacid salt Ag₃W₁₂O₄₀ was used in hydrolysis of glucose to produce levulinic acid.The surface structures of different heteropolyacid salt catalysts were characterized by means of FTIR,XRD.The surface structures and element relative mass content change of the fresh and used Ag₃W₁₂O₄₀ catalyst were also analyzed by means of FTIR,XRD,SEM and EPMA.The effects of such factors as reaction temperature,reaction time,amount of catalyst and glucose concentration on the yield of levulinic acid were investigated.Experimental results showed that the M_XH_3-2XPW₁₂O₄₀ heteropolyacid salt catalysts kept primary Keggin structure,and Ag₃W₁₂O₄₀ catalyst had the structure of Keggin after reuse for several times.It was found that the highest yield of levulinic acid was 81.61%(mole) under the conditions of reaction temperature 200℃,reaction time 2 h,Ag₃PW₁₂O₄₀ catalyst dosage 0.7 g and glucose concentration 40 g·L^-1.The catalyst could be used repeatedly.