作者:Yoshihiro Sugi、Seiji Watanabe、Hiroaki Naiki、Ken-ichi Komura、Yoshihiro Kubota
DOI:10.1246/bcsj.20110022
日期:2011.6.15
Liquid-phase isopropylation of biphenyl (BP) with propene was studied to understand the acidities resulting from lanthanoid exchanged sodium mordenite (Ln,NaMOR; Ln: La, Ce, Pr, Sm, Dy, and Yb). The acidities of La3+ exchanged sodium mordenite (La,NaMOR) appeared at around 0.6–0.8 exchange calculated from La/3Al molar ratio. Similar acidities appeared with all Ln,NaMORs. The resultant zeolites have Brønsted acidic sites appearing near unsaturated lanthanoid cations. The isopropylation of BP predominantly afforded 4,4′-diisopropylbiphenyl (4,4′-DIPB) among DIPB isomers over all Ln,NaMORs. These catalyses occur on the acidic sites in the channels. The exchanged catalysts had high selectivities for 4,4′-DIPB even at temperatures as high as 300 °C although the selectivities decreased by the isomerization of 4,4′-DIPB over H-mordenite (HMOR) with similar SiO2/Al2O3 ratio. These results indicate the external acid sites are lowly active for the isopropylation of BP and the isomerization of 4,4′-DIPB. The combustion of coke-deposits on Ln,NaMORs, particularly Ce,NaMOR, used for the isopropylation occurred at lower temperatures than that on HMOR because the lanthanoids dispersed in MOR channels work as an oxidation catalyst.
为了了解镧系元素交换莫代森钠(Ln,NaMOR;Ln:La、Ce、Pr、Sm、Dy 和 Yb)产生的酸性,对联苯(BP)与丙烯的液相异丙基化进行了研究。根据 La/3Al 摩尔比计算,La3+ 交换莫来石钠(La,NaMOR)的酸度出现在 0.6-0.8 左右。所有 Ln,NaMOR 的酸度都相似。由此产生的沸石具有布氏酸性位点,出现在不饱和镧系阳离子附近。在所有 Ln、NaMORs 上,BP 的异丙基化反应主要产生 DIPB 异构体中的 4,4′-二异丙基联苯(4,4′-DIPB)。这些催化作用发生在通道中的酸性位点上。交换催化剂对 4,4′-DIPB 的选择性很高,即使在高达 300 °C 的温度下也是如此,尽管在具有相似 SiO2/Al2O3 比率的 H-莫代石(HMOR)上异构化 4,4′-DIPB 时选择性会降低。这些结果表明,外部酸性位点对 BP 的异丙基化和 4,4′-DIPB 的异构化活性较低。用于异丙基化的 Ln、NaMOR(尤其是 Ce、NaMOR)上的焦炭沉积物的燃烧温度低于 HMOR,这是因为分散在 MOR 通道中的镧系元素起到了氧化催化剂的作用。