CuNiAl类水滑石的合成及其在催化氧化苯甲醇中的应用

Synthesis of CuNiAl Hydrotalcites and Its Application in Catalytic Oxidation of Benzyl Alcohol

采用水热法制备了CuNiAl类水滑石催化剂;运用电感耦合等离子体原子发射光谱、X射线衍射、傅里叶变换红外光谱和透射电子显微镜等方法对其进行表征,并用于催化苯甲醇氧化合成苯甲醛。表征结果显示,催化剂中Cu,Ni,Al的配比明显影响类水滑石的晶型结构,层间阴离子的结构决定着层间通道的大小和空间位阻。在催化苯甲醇氧化合成苯甲醛反应中,以层间阴离子为CO_3^(2-)的CuNiAl类水滑石为催化剂,且催化剂中n(Cu):n(Nj):n(Al)=0.86:0.84:1.00,在催化剂用量(占苯甲醇的质量分数)0.46%、反应温度50℃、n(H_2O_2):n(苯甲醇)=2.6、反应时间1 h的适宜条件下,苯甲醇的转化率为55.6%,苯甲醛的选择性为98.0%。该催化剂重复使用6次后仍保持较优的催化性能。

CuNiAl hydrotalcite-like compounds （CuNiAl-HT） were synthesized by hydrothermal method and were characterized by the means of ICP-AES, XRD, FTIR and TEM. CuNiAl-HTs were used as catalysts in selective oxidation of benzyl alcohol to benzaldehyde. The crystalline structures of the catalysts varied obviously according to n （Cu） ： n （Ni） ： n （Al） ratios of the catalysts. The size of interlayer space and related steric hindrance in reaction significantly depended on the structure of intercalated anions. In catalytic oxidation of benzyl alcohol to benzaldehyde, when n （Cu） ： n （Ni） ： n（Al1） ratio of CuNiAl-HTs catalyst was 0. 86 ： 0.84 ： 1.00 with CO3^2- as intercalated anions and reaction was carried out under optimal conditions ： catalyst dosage 0.46% （ based on mass of benzyl alcohol）, mole ratio of H2 02 to benzyl alcohol 2.6, reaction temperature 50℃ and reaction time 1 h, conversion of benzyl alcohol was 55.6% and selectivity to benzaldehyde was 98.0%. The catalytic activity remained after being reused 6 times.