硅胶负载碱金属磷酸二氢盐催化乳酸甲酯转化反应的研究  

Conversion of methyl lactate over silica-supported mono-alkali metal phosphates

作　　者：彭少君[1] 张志强[1] 屈一新[1] 王水[1] 王际东[1] 

机构地区：[1]北京化工大学化学工程学院,北京100029

出　　处：《北京化工大学学报（自然科学版）》2010年第2期11-15,共5页Journal of Beijing University of Chemical Technology(Natural Science Edition)

基　　金：国家"973"计划(2007CB714300)

摘　　要：以硅胶为载体,碱金属磷酸二氢盐MH2PO4(M=Li,Na,K)为原料,利用浸渍法制备了3种硅胶负载的含有不同碱金属阳离子的聚合磷酸盐催化剂MH2PO4/S iO2。在固定床连续流动反应器上考察了不同碱金属阳离子对聚合磷酸盐催化乳酸甲酯转化生成丙烯酸和丙烯酸甲酯的影响。3种催化剂中,NaH2PO4/S iO2催化生成丙烯酸和丙烯酸甲酯的总选择性最高,380℃时,乳酸甲酯转化率为99.5%,目标产物选择性可达52.0%。催化剂表征及量子化学计算的结果表明,碱金属阳离子的性质影响聚合磷酸盐链末端P—OH的酸性和催化剂的表面酸量,导致3种催化剂上乳酸甲酯转化成丙烯酸和丙烯酸甲酯的选择性的差异。Using silica as a support and mono-alkali metal phosphates MH2PO＋ （M = Li, Na, K） as starting materials, catalysts of silica-supported polyphosphates with different mono-alkali metal cations were prepared via an im- pregnation method. The influence of the alkali metal cations contained in the polyphosphates on the conversion of methyl lactate to acrylic acid and methyl acrylate was investigated using a continuous flow fixed-bed reactor. Of the three catalysts, NaH2PO4/SiO2 gave the highest total selectivity to acrylic acid plus methyl acrylate. At 380 ℃, the conversion of methyl lactate was 99.5% and the selectivity to acrylic acid plus methyl acrylate amounted to 52. 0%. Results of catalyst characterization and quantum chemistry calculations indicated that the alkali cations in the polyphosphates supported on silica influenced both the acidity of the P--OH groups located at the termini of the polyphosphate chains and the amount of surface acidic sites, leading to the observed differences in the selectivity for the conversion of methyl lactate to acrylic acid and methyl acrylate for these three catalysts.

关 键 词：丙烯酸酯 聚合磷酸盐 酸性 乳酸甲酯 选择性 

分 类 号：TQ032.41[化学工程]