Catalytic co-aromatization of ethanol and methane

• A novel catalytic process is developed to aromatize ethanol under methane.
• Ethanol aromatization is enhanced when methane is present over 1%Ag/ZSM-5.
• H2 pretreatment of charged Ag/ZSM-5 catalyst has a positive effect on aromatization.
• Aromatization performance is closely associated with catalyst’s surface acid sites.
• H2 pretreatment improves catalyst’s coke resistance capability.

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.

Bioethanol produced from biomass fermentation can be effectively valorized into aromatics under the assistance of methane at mild conditions (400 °C and 1 atm) when Ag modified HZSM-5 catalyst is charged.Figure optionsDownload as PowerPoint slide