Abstract:

Hierarchical porous Hβ molecular sieve with different structure and acidity were prepared by alkali treatment. XRD, SEM, N₂ physical adsorption and NH₃?TPD characterization methods were used to characterize molecular sieves before and after alkali treatment. With hierarchical porous Hβ molecular sieve as the carrier, the Ru?Hβ bifunctional catalysts were prepared by an equal volume impregnation method, and the benzene hydroalkylation reaction activity and stability were evaluated in a fixed bed reactor.The results show that Hβ molecular sieve can effectively increase the proportion of mesopores after being treated with a proper concentration of alkali, which is beneficial to improve the hydroalkylation activity and stability. At 2 MPa, 210 ℃ and a liquid hourly space velocity of 1 h^-1, when the Ru mass fraction is 0.2% (based on the mass of hierarchical porous Hβ molecular sieve), the dual?functional catalyst composed of hierarchical porous Hβ can achieve effective and stable operation. At the same time, the conversion rate of benzene is 54.32%, the selectivity of cyclohexyl benzene is 71.47%, and the stability of the catalyst does not decrease significantly within 280 h.

Key words: Hierarchical porous Hβ, Bifunctional catalyst, Benzene, Hydroalkylation, Cyclohexyl benzene

摘要：

通过碱处理方法制备了具有不同结构和酸性的梯度孔Hβ分子筛，采用XRD、SEM、N₂物理吸附和NH₃?TPD表征方法对碱处理前后分子筛进行表征。以梯度孔Hβ分子筛为载体，采用等体积浸渍法制备Ru?Hβ双功能催化剂，并在固定床反应器上进行苯加氢烷基化反应活性以及稳定性评价。结果表明，经适量浓度碱处理后，提高了Hβ分子筛的介孔占比，有利于提高加氢烷基化活性以及稳定性。在氢气压力为2 MPa、反应温度为210 ℃、体积空速为1 h^-1的条件下，Ru质量分数为0.2%时（以梯度孔Hβ分子筛质量为基准），与梯度孔Hβ组成的双功能催化剂可实现有效、稳定运行，苯的转化率达到54.32%，环己基苯选择性达到71.47%，催化剂稳定性在280 h内无明显下降。

关键词: 梯度孔Hβ, 双功能催化剂, 苯, 加氢烷基化, 环己基苯