Hydrogenolysis of 1,1a,6,10b-tetrahydro-1,6-methanodibenzo[a,e]cyclopropa[c] cycloheptene over Ru-zeolites

An UV-Visible study of the stability of the ruthenium hexaammine cation in BEA zeolites—comparison with NaY

“…[8][9][10][11] Supported-Ru catalysts also received considerable interest in the field of ammonia synthesis, [12][13][14][15][16][17][18] in particular the Ru/AC-K system (Ru deposited on activated carbon promoted by K), which was developed for industrial use. 19 Ru supported on oxides also behave, after sulfidation, as promising catalysts for the catalytic hydrogenation of aromatics in the presence of H 2 S. [20][21][22] Among the supports used to disperse ruthenium, special attention has been devoted to zeolites, in particular to X and Y 11,[14][15][16][22][23][24][25][26][27][28][29][30][31] that have the same faujasite structure (FAU). It was shown that the more acidic the faujasite, the higher the activity of supported Ru sulfide in the hydrogenation of tetralin and toluene.…”

“…22,27 In contrast, for ammonia synthesis, 14,16,28 faujasites with more basic character lead to more active Ru /zeolite catalysts. In most cases, [14][15][16]22,[24][25][26][27][28][29][30][31][32] ruthenium was introduced into FAU by cationic exchange of [Ru(NH 3 ) 6 ] 3þ in an aqueous solution. This complex is relatively stable in water at room temperature against hydrolysis, 33 but after exchange into FAU and storage in ambient conditions, it is readily transformed into the so-called Rured-wine [(NH 3 ) 5 Ru III O-Ru IV (NH 3 ) 4 -O-Ru III (NH 3 ) 5 ] 6þ and Ru-brown [(NH 3 ) 5 Ru IV -O-Ru III (NH 3 ) 4 -O-Ru IV (NH 3 ) 5 ] 7þ trimers.…”

“…23,34,35 Although high dispersions of Ru in FAU were usually reported after reduction, 5,[14][15][16]24 it was also noted that larger Ru particles could arise from the Ru trimers. 15 Few zeolitic supports with a structure different from FAU, 2,29,32,[36][37][38][39] and few mesoporous ones 38,40,41 were used to disperse Ru metal particles. In particular, acidic H-BEA was tested as a support for Ru in the reactions of hydrogenolysis of 1,1a,6,10b-tetrahydro-1,6-methanodibenzo[a,e]cyclopropa-[c]cycloheptene 29 and of hydrogenation of cinnamaldehyde.…”

“…15 Few zeolitic supports with a structure different from FAU, 2,29,32,[36][37][38][39] and few mesoporous ones 38,40,41 were used to disperse Ru metal particles. In particular, acidic H-BEA was tested as a support for Ru in the reactions of hydrogenolysis of 1,1a,6,10b-tetrahydro-1,6-methanodibenzo[a,e]cyclopropa-[c]cycloheptene 29 and of hydrogenation of cinnamaldehyde. 38 Since its discovery in 1967, 42 BEA zeolite has attracted strong interest, due to its large pore size (main channel system with diameter 6.6 Â 7.7 A ˚), [43][44][45] which allows easier diffusion of the reactants than in small pore zeolites, and to its activity in the transformation of many petrochemicals and fine chemicals, illustrated for instance by the development of the industrial BEA catalyst for the alkylation of benzene to cumene.…”