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烃类汽转化催化剂Ni/α—Al_2O_3的抗积碳性能随镍晶粒分布有显著变化。本文用X—射线小角散射法对镍晶粒分布进行了测定,用正庚烷蒸汽转化反应测定了催化剂抗积碳性能。结果表明,镍催化剂的积碳速率随大晶粒比率的增加而加快。用适量稀土氧化物(La_2O_3)将载体进行改性,能增强金属—载体之间的相互作用,镍的分散度显著增加,从而可提高镍催化剂的抗结碳性能。考察了高温(987K)水热处理后不同镧含量催化剂的抗积碳性能。结果表明,随着水热处理时间的延长,镍晶粒先熔结变大,到一定程度后再分散变小。与其对应,积碳速率先增大到一个峰值,然后下降。
The carbon deposition resistance of Ni / α-Al_2O_3 catalysts for hydrocarbon steam reforming significantly changes with the distribution of Ni grains. In this paper, the distribution of nickel grains was determined by X-ray small-angle scattering method. The anti-carbon deposition performance of the catalyst was measured by the n-heptane steam reforming reaction. The results show that the carbon deposition rate of nickel catalyst increases with the increase of the large grain ratio. Modification of the carrier with an appropriate amount of rare earth oxide (La 2 O 3) can enhance the interaction between the metal and the carrier and the dispersion of nickel significantly increases, thereby improving the anti-caking performance of the nickel catalyst. The anti-carbon performance of catalysts with different contents of lanthanum after high temperature (987K) hydrothermal treatment was investigated. The results show that with the extension of hydrothermal treatment time, the nickel grains first fuse and become larger, and then disperse and then decrease to a certain extent. Correspondingly, the carbon deposition rate first increases to a peak, then decreases.