Isopropylation of naphthalene (NP) was examined over H-mordenite (MOR), H-Y zeolite (FAU), and HBeta zeolite (BEA) in order to elucidate roles of isopropylnaphthalene (IPN) isomers during the catalysis. 2-IPN was the predominant isomer over MOR and works as a precursor for the selective formation of β,β-DIPN, particularly, 2,6-DIPN. In contrast, 1-IPN was predominant (with 2-IPN as a minor isomer) over FAU and BEA at low temperatures; dialkylation accompanied by the consumption of 1-and 2-IPN led to predominant formation of α,α-and α,β-DIPN. The formation of β,β-DIPN from 2-IPN was enhanced at higher temperatures. Bulky transition states of 1-IPN in IPN isomers and α,α-and α,β-DIPN among DIPN isomers were hindered by the interaction with MOR channels, resulting in the selective formation of β,β-DIPN, particularly 2,6-DIPN through the less bulky 2-IPN. FAU and BEA allow the formation of α,α-and α,β-DIPN from both of 1-and 2-IPN isomers because their channels are too large to exclude bulky transition states. The catalysis over FAU and BEA occurred under kinetic control at lower temperatures, and thermodynamic control also participates at higher temperatures.

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was examined for the deactivation of external acid sites and confirmed in the cracking of 1,3,5-triisopropylbenzene (TIPB) and cumene (IPB) and in the isopropylation of biphenyl (BP). The cracking of TIPB, which cannot enter the pores of MOR, shows that external acid sites were effectively deactivated by the modification of MOR with the lanthanide oxides in small amounts. Only the cracking of IPB over CeO 2 -modified MOR exhibited excellent catalytic activities, even at a 30 wt % metal loading, whereas the activities of other lanthanide oxide-modified MORs rapidly decreased as the loadings were increased because pore entrances became choked. The isomerization of 4,4′-diisopropylbiphenyl (4,4′-DIPB) during the isopropylation of BP at high temperatures such as 300 °C was also effectively prevented by the modification of MOR with the lanthanide oxides. Particularly, CeO 2 -modified MOR remained highly active even at a 30 wt % loading. Other lanthanide oxides can deactivate the isomerization of 4,4′-DIPB at 5−10 wt % loadings without significant loss of the activities at 300 °C, while the activity was rapidly lost as the loading amount was increased. The physicochemical properties of lanthanide oxide-modified MORs indicate that the lanthanide oxides modify the surface properties of MOR. The amounts of N 2 , o-xylene, and NH 3 adsorbed on MORs mostly remained high after CeO 2 modification; however, they rapidly decreased when loadings of the other oxides increased. These results show that CeO 2 remains the open pores at high loadings; however, the other oxides reduce the size of pore entrances as the loading is increased.

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Alkaline earth metal modification of H-mordenite (MOR) was examined in the isopropylation of biphenyl (BP). Of interest was the chemical and textural changes on catalytic properties as a result of the modification. At low loadings of 0.2− 0.5 mmol/g of the metals, the isomerization of 4,4′-diisopropybiphenyl (4,4′-DIPB) was effectively prevented at temperatures as high as 300 °C, resulting in high selectivities for 4,4′-DIPB. Metals reduce the acid amounts by low loadings, and deactivate external acid sites. At the loading of 2 mmol/g, only BaMOR was active with high selectivities for 4,4′-DIPB; however, other metals lost catalytic activity with the increase in the loading. These differences are ascribed to changes of acidity and pore size. The modification of barium with high loading formed moderate acidities, and kept pores open for the access of bulky molecules, resulting in the selective formation of 4,4′-DIPB; however, other metals declined the activities by choking pores for magnesium and calcium or by losing acidity for strontium.