Catalytic Co-Aromatization of Ethanol and Methane

This study demonstrates the technical feasibility of simultaneously converting ethanol and methane into liquid hydrocarbons at mild reaction conditions (400 °C and 1 atm) over silver and/or zinc modified zeolite catalysts. After GC-MS analysis, it is worth noting that aromatics are the major compounds contained in the liquid product collected from the run when 1%Ag/ZSM-5, particularly after H₂ pretreatment, is charged. Compared to the performance exhibited from the run with pure HZSM-5 support engaged, Ag addition into the HZSM-5 framework favors aromatics formation, which might be closely associated with better Ag dispersion and more abundance of strong surface acidic sites where aromatization might take place while Zn loading exerts a detrimental effect on the production of aromatics but promotes the ether generation possibly through dehydration reaction. Referred to that from its N₂ counterpart, the increased aromatics formation of the collected liquid product when methane is present indicates that methane existence might facilitate ethanol aromatization. Moreover, combined with the increased carbon number in the formed aromatics from CH₄ run when H₂ run is referred and zero liquid formation from CH₄-alone test as well as more prominent endothermic feature of methane run and more importantly the notably increased ¹³C signals in ¹³C NMR spectra of the liquid product collected during ethanol conversion under ¹³CH₄ environment, all the observations suggest that methane might be activated nonoxidatively and converted into higher hydrocarbons, preferentially into aromatics if suitable catalyst is charged under the assistance of co-existing oxygenated hydrocarbon. The reported synergetic effect could potentially lead to the more economic utilization of abundant natural gas and cellulosic ethanol.