Influence of Hydrogen in Catalytic Deoxygenation of Fatty Acids and Their Derivatives over Pd/C

Abstract

The influence of hydrogen on the catalytic deoxygenation of fatty acids was investigated in the semibatch reactor over a mesoporous 5 wt % Pd/C (Sibunit) catalyst. Transformations of a model fatty acid (lauric acid) and reaction intermediates (lauric aldehyde and lauryl alcohol) were performed under inert and hydrogen rich atmosphere. Analysis of the liquid and gas phases of the reaction mixture revealed that different reactions occurred depending on hydrogen content in the reaction atmosphere. A higher yield of hydrocarbons (59 mol %) was obtained in the fatty acid deoxygenation under hydrogen pressure compared to an experiment under argon where the yield of hydrocarbons reached 39 mol % after 300 min of the reaction. Different product distributions, intermediates and reaction pathways depending on hydrogen content in the reaction atmosphere, are discussed.

Selective hydrogenation of fatty acids to alcohols over highly dispersed ReO /TiO2 catalyst

“…Octadecane and octadecene were formed by dehydration and subsequent hydrogenation (only octadecane) of octadecanol, while heptadecane and heptadecene were the products of stearic acid decarboxylation or octadecanal decarbonylation/dehydroformylation. Similar reaction pathways have been proposed for deoxygenation of fatty acid over noble-metal-supported catalysts at higher temperatures [14]. Furthermore, the formation of a wax ester (stearyl stearate) was observed, which appears after $10% of stearic acid conversion from the reaction of stearic acid with 1-octadecanol.…”

A comprehensive review on biodiesel purification and upgrading

“…Comparing deoxygenation processes in the absence and presence of hydrogen indicates the superiority of the latter. Even in the case of Pd/C catalysts (initially believed to work identical under Ar/He and H2 environments), hydrogen has been proven beneficial (Immer et al, 2010;Rozmysłowicz et al, 2012). For instance, higher catalyst stability and quicker kinetics were reported for stearic acid deoxygenation under 10% H2 compared with He atmosphere using a 5% Pd/C catalyst (Immer et al, 2010).…”

“…In the context of biodiesel upgrading, higher hydrogen pressures heavily favor HDO over DCO by facilitating hydrogenolysis and hydrogenation reactions (Madsen et al, 2011;. Even in the case of Pd/C catalysts that remove oxygen exclusively through DCO under either inert or hydrogen atmospheres Lestari et al, 2009b), hydrogen has been shown to influence the kinetics of deoxygenation and improve the activity and stability of the catalyst (Immer et al, 2010;Rozmysłowicz et al, 2012). Elevated hydrogen pressures ensure higher carbon yields in the diesel range by suppressing side reactions such as cracking and decarboxylation (Kandel et al, 2014).…”

Effect of support on the NiMo phase and its catalytic hydrodeoxygenation of triglycerides

“…This conversion includes the following three reaction pathways: (1) hydrodeoxygenation (HDO), (2) decarbonylation (DCO) and (3) decarboxylation (DCO 2 ) [7,8]. Large amount of previous studies have focused on tailoring selectivity for certain reaction pathway [9][10][11][12][13][14]. It has been shown that the support plays an important role not only for cracking and isomerization but also for selectivity in the deoxygenation pathways.…”