Studies in Methane activation using Natural Gasoline as co-reactant over Zn/HZSM-11 zeolites

GRISELDA GONZÁLEZ MERCADO; LILIANA B. PIERELLA; OSCAR A. ANUNZIATA

Río de Janeiro

Congreso; Enpromer 2005-2nd Mercosur Congress on Chemical Engineering and 4th Mercosur Congress on Process Systems Engineering; 2005

UFRJ-UFRRJ-IME-UFF-UERJ-PLAPIQUI-UNL

Abstract A significant improvement in conversion of methane (C1) to more valuable compounds such as aromatics (benzene, toluene, xylenes) is obtained using natural gasoline as co-reactant in non-oxidizing reaction conditions. Natural gasoline is a low valued refinery cut rich in straight chain paraffinc hydrocarbons, mainly n-pentane (C5) and n-hexane (C6) (approximately 67 % w/w and 25% w/w, respectively). The catalytic C1 conversion to aromatic hydrocarbons (AH) was studied over a H-ZSM-11 catalyst with different content of Zn loaded as counter ion. AH yields were as high as 30 %mol C at 500ºC, w/f=40g.h.mol-1 and a C1 molar fraction, XC1 (C1/C1+C6) = 0.20. Reaction time, contact time and different feed molar fraction effects were carefully analyzed to obtain information about different intermediate species evolution during reaction development. The Zn loaded catalyst act as a hydride acceptor generating C2=, C3, C4= and carbenium species (high reactive intermediates) over the strong Lewis acid sites (SLS), through an EDA adduct which would we responsible to C1 activation. SLS presents into the catalyst suggest that higher concentrations of accepting species of hydrogen lead to higher levels of feed conversion towards AH. A Rideal-Eley model would control the bimolecular reaction of C1 with the adsorbed intermediates. The C1 conversion reached at 50 mol% C using Zn/HZSM-11 with 2.13 mol of Zn2+ per cell unit. These results considerably improve our previously reported ones.