18970-30-4Relevant articles and documents
The isopropylation of biphenyl over transition metal substituted aluminophosphates: MAPO-5 (M: Co and Ni)
Zhang, Hui Xing,Chokkalingam, Anand,Subramaniam, Priya V.,Joseph, Stalin,Takeuchi, Seiji,Wei, Ming Deng,Al-Enizi, Abdullah M.,Jang, Hoi-Gu,Kim, Jong-Ho,Seo, Gon,Komura, Kenichi,Sugi, Yoshihiro,Vinu, Ajayan
, p. 117 - 124 (2016)
The isopropylation of biphenyl (BP) was examined over transition metal substituted aluminophosphates (MAPO-5; M: Co and Ni) with 12-membered (12-MR) oxygen ring pore-entrances of AFI topology. The MAPO-5 samples were synthesized by dry gel conversion method using trimethylamine as a structure directing agent, and their properties were characterized by XRD, XPS, SEM, N2 adsorption, NH3-TPD, pyridine adsorption, and o-xylene uptake. They are clear crystals without impurity phases and agglomerates, and found small amounts of Br?nsted acid sites which are expecting active for acid catalysis. The isopropylation of BP over both of Co(5)APO-5 and Ni(5)APO-5 at 250 °C gave the high selectivities for 4,4′-DIPB: 65-75%. 4-IPBP is almost exclusive precursor of 4,4′- and 3,4′-DIPB. 3-IPBP was not significantly concerned even though 3-IPBP was predominant among IPBP isomers at the late stages: the MAPO-5 channels allow preferential access of 4-IPBP, and prevent the access of 3-IPBP due to reactant selectivity mechanism. The selective formation of 4,4′-DIPB occurred by preferential exclusion of bulkier 3,4′-DIPB and other isomers through the steric interaction of transition states with the channels by the restricted transition state selectivity mechanism. MAPO-5 (M: Co and Ni) has the same level of the selectivities for 4,4′-DIPB to SSZ-24 and other MAPO-5 (M: Si, Mg, and Zn), and these selectivities were originated by the AFI channels. The selectivities for 4,4′-DIPB were kept 65-75% at low and moderate temperatures over MAPO-5 (M: Co and Ni); however, they were decreased by the isomerization to stable 3,4′-DIPB with the increase in temperature.
Shape-selective isopropylation of aromatic hydrocarbons over h-mordenite in supercritical carbon dioxide medium
Laha, Subhash Chandra,Naiki, Hiroaki,Komura, Kenichi,Sugi, Yoshihiro
, p. 1283 - 1290 (2011)
The isopropylation of aromatic hydrocarbons isobutylbenzene (IBB), naphthalene (NP), and biphenyl (BP) was examined over H-mordenite (MOR), H-β (BEA), and H-Y (FAU) zeolites in supercritical carbon dioxide (sc-CO2) medium. MOR was only selective for the formation of the least bulky 4-isobutylcumene (4-IBC) in the isopropylation of IBB. In particular, the catalytic activity and selectivity for 4-IBC were enhanced by the dealumination of MOR; MOR with 110 of SiO2/Al2O3 ratio rendered the highest performance; however, the catalytic activity was decreased by further dealumination. Thermogravimetric analyses confirmed the reduction of coke formation on the catalysts in sc-CO2 medium, preventing the deactivation of MOR. Shape-selective formation of the least bulky isomers, 2,6- diisopropylnaphthalene (2,6-DIPN) and 4,4′-diisopropylbiphenyl (4,4′-DIPB), was also observed in the isopropylation of NP and BP over MOR in sc-CO2. sc-CO2 works as an efficient medium to access and/or replace substrates and their products to/from acidic sites in the MOR channels. In particular, the removal of coke precursors from acidic sites on the zeolite is enhanced by the sc-CO2 medium, resulting in decreased coke formation.
Lanthanoid exchanged mordenites as catalysts for the isopropylation of biphenyl
Sugi, Yoshihiro,Watanabe, Seiji,Naiki, Hiroaki,Komura, Ken-Ichi,Kubota, Yoshihiro
, p. 660 - 666 (2011)
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 0.60-.8 exchange calculated from La/3Al molar ratio. Similar acidities appeared with all Ln,NaMORs. The resultant zeolites have Bronsted 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/Al 2O3 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.
Shape-selective alkylation of biphenyl with propylene using zeolite and amorphous silica-alumina catalysts
Pendyala, Venkat Ramana Rao,Jacobs, Gary,Shafer, Wilson D.,Keogh, Robert A.,Kang, Jungshik,Sparks, Dennis E.,Davis, Burtron H.
, p. 195 - 203 (2013/04/10)
The influence of zeolite structure for the alkylation of biphenyl with propylene was studied over various zeolites such as HY, HZSM-5, and dealuminated mordenite (DMOR), as well as amorphous SiO2/Al2O 3, in a stirred tank reactor. Biphenyl conversion was found to increase with reaction time for HZSM-5 and DMOR zeolites and reach a leveling off in 4 h, whereas for HY and amorphous SiO2/Al2O 3 a leveling off was reached within an hour. DMOR displayed the highest selectivity for 4,4′-diisopropylbiphenyl (4,4′-DIPB) even at temperatures as high as 300 °C, whereas for HY, HZSM-5 and amorphous SiO2/Al2O3 selectivities fell in the range of 10-35%; they were significantly lower than observed for DMOR. These differences in selectivity might be due to the structure and pore channels of the zeolites. DMOR was found to be an active catalyst, the selectivity for 4-isopropylbiphenyl (4-IPB) and (4,4′-DIPB) was high among isopropylbiphenyl (IPB) and diisopropylbiphenyl (DIPB) isomers, respectively, indicating DMOR possesses shape-selectivity. The selectivity of 4,4′-DIPB increased with time, while the corresponding selectivity of 4-IPB decreased for DMOR catalyst. Alkylation of biphenyl with propylene occurred with predominant formation of 4-IPB in the first step. 4-IPB is only a source in the second step of alkylation of biphenyl with propylene for the formation of 4,4′-DIPB, while 3-IPB does not participate in the formation of DIPB isomers.
