Dehydrogenation processes on nickel and platinum surfaces. Conversion of cyclohexane, cyclohexene, and cyclohexadiene to benzene

Abstract

Described is the surface coordination chemistry of cyclohexane, 1,3 and 1,4-cyclohexadiene and cyclohexene on the low Miller index planesand a stepped surface of nickel and on the platinum (111) (111) at 20-70°C. A similar behavior was observed for Pt(lll) at -35 to +135°C although a small degree of dehydrogenation was evident on this surface.

Calorimetric Measurement of the Heat of Adsorption of Benzene on Pt(111)

“…Thus, its adsorption energy is of substantial fundamental importance. At 300 K, benzene adsorbs molecularly on Pt(111) 30,33,36,43 with its molecular plane parallel to the surface, interacting with the Pt through its aromatic π electron system. 28,29,33,37,51 Thus, its heat of adsorption is 6 times the C-Pt(111) bond energy for a carbon atom in an aromatic ring parallel to the surface.…”

Dehydrogenation of Cyclohexene on Platinum Nanoclusters on a Thin Film of Al2O3/NiAl(100)

“…There, adsorbed cyclohexene loses H atoms stepwise to form a cycloallylic species (c-C 6 H 9 ), cyclohexadiene (c-C 6 H 8 ), cyclohexadienyl (c-C 6 H 7 ) and then benzene (C 6 H 6 ). The dehydrogenation notably begins at 150 K, much lower than the temperature for a single-crystal surface [1][2][3][4][5][6][7][8][9][10][11]. The dissociation of benzene, evident through the shift of the C 1s signal to the elemental carbon position about 284.5-285 eV, occurs between 300 and 400 K, also a lower temperature than expected for Pt single crystals [9].…”

“…Because of the relevance to petroleum processing [1][2][3][4][5][6][7][8][9][10][11], the dehydrogenation of cyclic hydrocarbons such as cyclohexane (C 6 H 12 ) and cyclohexene (C 6 H 10 ) over singlecrystal Pt(100) and Pt(111) surfaces has been extensively investigated with various techniques. Cyclohexene, a possible intermediate in the dehydrogenation of cyclohexane into benzene, can be hydrogenated to cyclohexane or dehydrogenated to benzene (C 6 H 6 ).…”

Iridium/H-ZSM-5 zeolite catalyst promoted via hydrochlorination or hydrofluorination for the hydroconversion of cyclohexene

“…Su et al [47] and Tsai et al [48] find that CHE is converted to benzene on all Pt planes. Gland et al [49] observe that CHE dehydrogenation on Pt (1 1 1) should occur at some intermediate state before chemisorbed benzene is generated.…”