Decarboxylation of stearic acid over Ni/MOR catalysts

Abstract

BACKGROUND: Oils derived from plants, animal fats, and algae contain both saturated and unsaturated fatty acids. These fatty acids can be converted into liquid fuels and chemicals in the presence of active solid catalysts. RESULTS: Nickel-based catalysts were supported on mordenite via ion exchange synthesis and evaluated for the deoxygenation of stearic acid to diesel fuels. By tuning the synthesis pH, loadings of over 20 wt% Ni were obtained. Catalysts synthesized at pH 8.5 displayed the highest Ni loading and the highest activity for the decarboxylation/decarbonylation of stearic acid under inert nitrogen gas atmospheres, yielding 47% heptadecane. Characterization included scanning transmission electron microscopy-energy-dispersive spectroscopy (STEM-EDS), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), inductively coupled plasma atomic emission spectroscopy (ICP-AES), N 2 physisorption and thermogravimetric analysis (TGA), providing new insights into the recyclability of the catalyst. The observed loss of catalytic activity upon recycling was attributed to the agglomeration of Ni nanoparticles and the accumulation of carbonaceous coke.CONCLUSION: This work demonstrates that Ni-based catalysts supported on mordenite zeolite can effectively convert stearic acid into heptadecane. Yields to heptadecane were as high as 47%. Mechanistically, the reaction proceeds by decarboxylation and decarbonylation pathways. Industry experiments were performed using a Micromeritics AutoChem II 2920 chemisorption analyzer fitted with a thermal conductivity detector (TCD). Samples were placed in flow-through glass U-tubes packed atop quartz wool. Approximately 50 mg samples J Chem Technol Biotechnol 2020; 95: 102-110 Catalyst recyclabilityThe recycled Ni/MOR-8.5 catalyst displayed a decay in catalytic activity, suffering a 24% decrease in conversion. Typically, loss J Chem Technol Biotechnol 2020; 95: 102-110

Selective Decarboxylation of Fatty Acids Catalyzed by Pd-Supported Hierarchical ZSM-5 Zeolite

“…65 On the other hand, Ni supported over mordenite zeolite promoted the deoxygenation of stearic acid, yielding 47% heptadecane. 66 Finally, Co supported on zeolite NaX showed high conversion (83.7%) in the DC of stearic acid, although with a relatively low heptadecane yield (28%). 67 In this way, an important issue to be addressed is the role played by the acid sites present in zeolites because they may reinforce the catalytic activity of the metal centers but, at the same time, could promote undesired secondary reactions.…”

“…Likewise, Pt-SAPO-34 led to a high heptadecane selectivity in the conversion of oleic acid, whereas K-based faujasite (FAU) showed activity in the DC/decarbonylation of methyl laurate . On the other hand, Ni supported over mordenite zeolite promoted the deoxygenation of stearic acid, yielding 47% heptadecane . Finally, Co supported on zeolite NaX showed high conversion (83.7%) in the DC of stearic acid, although with a relatively low heptadecane yield (28%) .…”

Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites

“…The 8 wt% Ni/SAPO-11 catalyst exhibited superior activity with high selectivity towards isomerized product due to moderate acidity and balanced meso-micropore channels. Diesel-range alkanes production was performed over Ni/zeolite from different feedstock for example, Ni/Hβ used for fatty acid methyl esters ( Chen et al, 2014 ), Ni/micro-mesoporous β for methyl palmitate ( Papanikolaou et al, 2020 ), Ni/β for vegetable oil ( Wang et al, 2014 ), Ni/ZSM-5 for palmitic acid ( Ojeda et al, 2018 ) and Ni/MOR for stearic acid ( Crawford et al, 2020 ), etc. For hydrogenation of waste cooking oil into jet fuels, multicomponent Ni-contained zeolite-based materials like NiMo core-shell supported on hierarchical USY@Al-SBA-15 ( Zhang et al, 2018 ) and NiCoMo oxides supported on an A-type zeolite ( Asiedu and Kumar, 2019 ).…”