Utilization of biomass: Conversion of model compounds to hydrocarbons over zeolite H-ZSM-5
Zeolite catalyzed deoxygenation of small oxygenates present in bio-oil or selected as model compounds was performed under Methanol-to-Hydrocarbons (MTH) like reaction conditions using H-ZSM-5 as the catalyst. Co-feeding of the oxygenates with methanol generally decreases catalyst lifetime due to coking and results in higher selectivity towards aromatics compared to conversion of pure methanol. The reaction pattern of the different oxygenates did not simply follow the effective H/C ratio of the additives since structural isomers with identical effective H/C ratios showed significant differences with respect to catalyst lifetime and product selectivity. A distinct positive effect on catalyst lifetime was observed for methanol dilution. Thus, the conversion capacity of the catalyst was up to 10 times higher when the reactant was diluted in methanol. We observe that in particular acid/ester functionalities favor oxygen removal through decarbonylation over dehydration which preserves hydrogen in the hydrocarbon product mixture. By employing 13C labeled substrates we confirmed the incorporation of carbon into the hydrocarbon products as well as a pronounced preference of the additive carbon towards incorporation into aromatic compounds.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (102 K)Download as PowerPoint slideResearch highlights► Different conversion capacities are seen when co-feeding structural isomers in MTH. ► Methanol dilution increases conversion capacity of the additive by up to 10 times. ► Acids and esters favor deoxygenation through CO/CO2 dissociation over dehydration. ► 13C labeling indicates that additives are incorporated via the aromatic products.
Journal: Applied Catalysis A: General - Volume 396, Issues 1–2, 15 April 2011, Pages 59–67