基于杨梅单宁制备Pt/SiO_2-C催化剂及其对肉桂醛选择性催化加氢性能

Using Bayberry Tannin to Construct Novel Pt/SiO_2-C Catalyst and Its Catalytic Properties in Selective Hydrogenation of Cinnamaldehyde

以天然植物多酚杨梅单宁(BT)改性的SiO2为载体,经吸附Pt4+、Na BH4还原和碳化处理制得Pt/SiO2-C催化剂.对所制备的催化剂进行了表征,并考察了催化剂对肉桂醛液相选择性催化加氢的性能.结果表明,由于杨梅单宁分子的分散稳定作用,使碳化过程中纳米Pt粒子粒径适度增长且保持高度分散.碳化温度影响杨梅单宁的脱除效果、纳米Pt粒子晶型与粒径,以及载体的比表面积与孔径,最终影响肉桂醛催化加氢性能.500℃碳化处理得到的Pt/SiO2-C-500催化剂的催化性能最佳,在乙醇为溶剂,323.25 K和2MPa氢压条件下,肉桂醛6 h转化率为82.98%,生成肉桂醇的选择性达到91.33%,表现出较高的催化活性和选择性.同时,该催化剂重复使用5次后其催化活性仍为第一次反应活性的81.18%,体现出优良的重复使用性.

A novel heterogeneous Pt/SiO2 -C catalyst was prepared by loading Pt4＋on modified SiO2 with bay- berry tannin（ BT） , followed with reduction of NaBH4 and carbonization. The as-prepared catalyst was charac- terized by TEM, XPS, XRD, FTIR and so on. Subsequently, the Pt/SiO2 -C catalyst was utilized in selective hydrogenation of cinnamaldehyde. Since the dispersion and stabilization function of BT molecular, which could efficiently growth of Pt nanoparticles and remain highly dispersion in carbonization process. The removal effi- ciency of BT, crystal type and size of Pt nanoparticles, specific surface area of SiO2 and the performance of catalytic hydrogenation of cinnamaldehyde could be influenced by carbonization temperature. Pt/SiO2 -C-500 catalyst showed the best catalytic performance when the carbonization temperature was 500 ℃. The conversion of cinnamaldehyde was 82. 98% and the selectivity to cinnamic alcohol was 91. 33%（ reaction conditions：323. 25 K, 2 MPa H2 pressure and ethanol as solvent ） . After 5 cycles, the catalyst activity was about 81. 18% of that in the first run, exhibiting excellent reusability.