金属掺杂TiO_2催化裂解稻壳直接液化产物制备液体油

Liquid oil produced by TiO_2 with dopant metals catalytic pyrolysis using direct liquefaction products of rice husk

以TiO2掺杂金属离子催化剂催化裂解稻壳直接液化生物油,研究了催化效果及催化剂重复利用后催化效果的变化。结果表明,直接液化产物中轻油1相的酸值最小,为22.23mg/g,羟值最大,为289.27mg/g,黏度较小,为2.0mPa·s,说明轻油1相酸性小,分子量小,流动性好,更有利于催化裂解。直接液化产物中轻油的黏度随时间变化不大,稳定在1.8mPa·s,而重油的黏度随时间延长迅速变大。Fe3+/TiO2催化效果最佳,轻油和重油随着时间延长黏度变化都很小,说明裂解产物性质很稳定。轻油1相和轻油2相裂解后分子量增加,可能是因为裂解产物由原来的不饱和醛、酮类化合物转化成了酯、醚、芳香族化合物,发生了环化反应,导致分子量增加,环化反应使得产物稳定性增加;重油相羟值增大,分子量变小,可能是大分子物质裂解成小分子物质。随着催化剂重复使用的次数增加,催化效果逐渐减弱,催化剂最好只重复使用1次。N2吸附脱附测定结果表明,Fe3+/TiO2比表面积最大;凝胶色谱分析表明,经过裂解之后,轻油1相的分子量增大,轻油2相分子量增大幅度比轻油1相小,而重油相的分子量减小。

TiO2catalyst was prepared through doping metal ion to directly carry the catalytic pyrolysis of bio-oil from rice husk.The catalytic efficiency of raw catalyst and reused catalyst were studied.Results showed that light oil phase 1in direct liquefaction product had the mimimum acid value（22.23 mg/g）and maximum hydroxyl value（289.27mg/g）,with small viscosity（2.0mPa·s）,indicating that light oil phase 1had low acidity,small molecular weight and good fluidity.In direct liquefaction product,the viscosity of light oil kept stable at 1.8mPa·s with time increasing,whereas the viscosity of heavy oil increased quickly with time prolonging.The catalytic efficiency of Fe3＋/TiO2 was the best.The viscosity of light oil and heavy oil catalyzed by Fe3＋/TiO2 had hardly changed with time extending because of the properties of products very stable.The molecular weights increased after light oil 1and light oil 2were pyrolyzed,probably inferring that pyrolysis process had converted unsaturated aldehyde or ketone compounds into esters,ethers or aromatic compounds due to cyclization,leading to molecular weight increased.Cyclization made the product more stable.However,the hydroxyl value of heavy oil phase increased while the molecular weight decreased because of molecular cracking.For repetitive use of the catalyst,catalytic efficiency decreased gradually.It was suggested that the catalyst should reuse for 1time.N2adsorption/desorption results showed that specific surface area of Fe3＋/TiO2 was the largest.Gel permeation chromatography analysis showed that molecular weight of light oil phase 1increased,but molecular weight of light oil phase 2increased slower than that of light oil 1,and molecular weight of heavy oil phase decreased sharply.