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Abstract: Vanillin hydrodeoxygenation was investigated using Pt/C catalyst in the temperature and total pressure ranges of 80-200 °C and 20-30 bar in several solvents, such as tetrahydrofuran, 2-propanol, water and in solventless conditions using 1:1 mass ratio of vanillin to guaiacol. The results revealed that the rate increased with increasing solvent polarity as follows: tetrahydrofuran < 2-propanol < water. The main product was p-creosol with 66% selectivity at complete vanillin conversion in HDO under 30 bar total pressure at 100 °C after 4 h using water as a solvent. In a solventless experiment with 1:1 mass ratio of vanillin-guaiacol as a feedstock only vanillin was transformed to p-creosol with 91% conversion in 4 h at 200 °C under 30 bar total pressure, while guaiacol did not produce any HDO products. Both thermodynamic analysis and kinetic modelling were performed. Vanillin hydrodeoxygenation resulted in formation of p-creosol over Pt/C catalyst using an optimum vanillin initial concentration in water solution. From the industrial point of view vanillin hydrodeoxygenation proceeded rapidly giving high yields of p-creosol in solventless hydrodeoxygenation of vanillin-guaiacol mixture, while guaiacol was not deoxygenated.Graphical Abstract: [ABSTRACT FROM AUTHOR]

BACKGROUND Hydrodeoxygenation ( HDO) of Chlorella algal oil extracted with supercritical hexane and stearic acid as a model compound was investigated over several supported Ni and Mo2N-MoO2 catalysts in a semibatch reactor at 300 °C under 30 bar in the presence of hydrogen. RESULTS The results showed that all catalysts were very active in HDO of stearic acid. With crude algal oil, a maximum conversion of lipids of 35% was found with an acidic Ni- HY-80 zeolite catalyst after 360 min. The main products in algal oil HDO were fatty acids; whereas maximally only 7% hydrocarbons were formed with Ni- HY-80. The main hydrocarbon products were formed via decarbonylation, as the hydrogenation/dehydration route was suppressed. CONCLUSIONS Hydrodeoxygenation of crude Chlorella algal oil was demonstrated over nickel supported on beta zeolite and with a molybdenum oxide-nitride catalyst. Strong catalyst deactivation occurred for the former catalyst, whereas the latter retained its activity. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Sulfur-free Ni supported on H-Y zeolites, γ-Al 2 O 3 and SiO 2 synthesized by the wet impregnation method, and Pd/C were tested in hydrodeoxygenation (HDO) of stearic acid. The catalysts were forming n- heptadecane except Ni/H-Y-80, which was producing n- heptadecane and n- octadecane. Ni/H-Y 80 and Pd/C were tested on HDO of fatty acid methyl esters from chlorella, tall oil fatty acids, and animal fat. The reactions converting the substrates to the final products followed the path from unsaturated esters to acids, with hydrogenation of the latter into alcohols (i.e., stearyl alcohol), and finally formation of hydrocarbons. Ni/H-Y-80 permitted rapid and complete conversion into hydrocarbons, while Pd/C displayed 5–20 times lower turnover frequency, producing saturated intermediates along with hydrocarbons. The catalyst reusability of Ni supported on Y zeolites was studied by recycling and regenerating the spent catalyst from fatty acid HDO. The catalysts demonstrated the possibility of restoring the rates per unit of surface area after regeneration. Catalysts used in HDO of different feedstocks were investigated by thermogravimetric analysis, inductively coupled plasma-optical emission spectroscopy, transmission electron microscopy, surface area measurements, and pore size analysis. [ABSTRACT FROM AUTHOR]

Extraction of lipids from Chlorella algae with supercritical hexane resulted in the high lipids yield of approximately 10% obtained at optimum conditions in terms of extraction time and agitation compared to the total content of lipids being 12%. Furthermore, an easiness of hexane recovery may be considered as economically and ecologically attractive. For the first time, in the current work catalytic hydrodeoxygenation (HDO) of Chlorella algal lipids was studied over 5 wt % Ni/SiO2 at 300 °C and under 30 bar total pressure in H2. The conversion of lipids was about 15% as the catalyst was totally deactivated after 60 min. The transformation of lipids proceeded mostly via hydrogenation and hydrogenolysis with formation of free fatty acid (FFA). Lower activity might be attributed to deactivation of catalysts caused by chlorophylls and carotenoids. Even though the conversion is low, future studies in HDO of lipids extracted from other algae species having higher lipid content could be proposed. A coke resistant catalyst might be considered to improve catalytic activity. [ABSTRACT FROM AUTHOR]

In situ transesterification of Chlorella alga was performed using 5–20 wt% sulfuric acid as a catalyst at either 60 or 100 °C. The maximum ester yield in the range of 96–98% is comparative to the specification of ester content in biodiesel, 96%. A high excess of methanol was used in transesterification ensured also a high ester yield. The FAME was purified via adsorption of chlorophyll and carotenoids onto a clay. Properties of the purified biodiesel were investigated with several methods. The results showed that the Chlorella based biodiesel exhibits slightly lower oxidative and thermal stability compared to soybean based biodiesel due to the presence of polyunsaturated FAMEs. In addition to biodiesel, also the residual biomass was characterized showing that it contained sugars and proteins. An additional hydrogenation would increase the oxidative stability. Hydrodeoxygenation of Chlorella based biodiesel was also demonstrated over 5 wt% Ni–HY-80 zeolite with SiO 2 /Al 2 O 3 ratio of 80 and with 5 wt% Pd/C at 300 °C and 30 bar in dodecane as a solvent. Ni–HY-80 was superior to Pd/C catalyst giving more than 95% yield of hydrocarbons. [ABSTRACT FROM AUTHOR]