Reactions of methyl heptanoate hydrodeoxygenation on sulphided catalysts

Reactions of methyl heptanoate on sulphided NiMo/γ-Al2O3 and CoMo/γ-Al2O3 catalysts in gas and liquid phases were investigated in detail. Experiments with heptanol and heptanoic acid were carried out in support of the conclusions. Hydrodeoxygenation (HDO) of the ester produced C7 and C6 hydrocarbons. Alcohols, aldehyde, carboxylic acid and ethers were formed as intermediates. In addition, a few sulphur-containing compounds were formed as intermediates and they led to desulphurisation of the catalysts. The reactions of the ester and the intermediates are explained in terms of hydrogenation and acid-catalysed reactions such as hydrolysis, esterification and dehydration. The E2 elimination and SN2 nucleophilic substitution mechanisms are proposed to play a role in the reactions. HDO and hydrogenation activities were higher on the NiMo catalyst than the CoMo catalyst. The NiMo catalyst might thus seem to be preferred for the conversion of aliphatic esters, alcohols and carboxylic acids. According to the proposed reaction scheme, however, hydrogen consumption will be greater with this catalyst.

Graphical abstractHydrodeoxygenation (HDO) of methyl heptanoate produced hydrocarbons from intermediate oxygen-containing and sulphur-containing compounds on sulphided NiMo/γ-Al2O3 and CoMo/γ-Al2O3 catalysts by hydrogenation and acid-catalysed reactions such as hydrolysis, esterification and dehydration. Use of the NiMo catalyst is favourable for the HDO of aliphatic oxygen-containing compounds such as esters, alcohols and acids, but at the cost of increased hydrogen consumption. Figure optionsDownload full-size imageDownload as PowerPoint slide