Selective Deoxygenation of Waste Cooking Oil to Diesel-Like Hydrocarbons Using Supported and Unsupported NiMoS2 Catalysts.

This work aimed to study the deoxygenation of two different waste cooking oils (WCOs; palm oil and soybean oil) using alumina (γ-Al2O3)-supported and unsupported NiMoS2 catalysts prepared by the hydrothermal method. The variables evaluated in this study were the reactant concentration, reaction time, and nickel (Ni)/[Ni + molybdenum (Mo)] atomic ratio (0.2 and 0.3) affecting the yield and selectivity of alkane products. The supported NiMo sulfide (NiMoS2)/γ-Al2O3 catalyst prepared by impregnation had the drawback of a lack of layers and stacks, so combining the γ-Al2O3 with unsupported NiMoS2 catalysts using a hydrothermal method was evaluated. The main products obtained from the deoxygenation of the two WCOs were normal (n-)alkane compounds (C15, C16, C17, and C18). The catalyst efficiency was ranked as 0.2-NiMoS2/γ-Al2O3 ≈ 0.2-NiMoS2 > 0.3-NiMoS2/γ-Al2O3 ≈ 0.3-NiMoS2. The catalyst that gave the high n-C15-C18 yield was 0.2-NiMoS2/γ-Al2O3 under a reaction condition of 300 °C, 40 bar initial H2 pressure, and oil concentration of 5 wt %. For the hydrodeoxygenation (HDO) of waste palm oil, the n-C14-C18 yield was 56.4% (C14, C15, C16, C17, and C18 at 1.3, 6.7, 14.5, 11.8, and 22.1%, respectively), while that for the waste soybean oil was 58% (C14, C15, C16, C17, and C18 at 1.1, 3.8, 6.7, 17.2, and 29.2%, respectively). The n-C18/n-C17 and n-C16/n-C15 ratios were both greater than 1 for both types of WCO, revealing that the deoxygenation mainly proceeded via HDO rather than decarbonylation and decarboxylation. The 5-10% lower n-C14-C18 yield from the waste oil compared with the fresh oil was acceptable, implying the effective oil treatment and some impurity removal.

Economical and green biodiesel production process using river snail shells-derived heterogeneous catalyst and co-solvent method.

River snail shells-derived CaO was used as a heterogeneous catalyst to synthesize biodiesel via transesterification of palm oil with methanol. The shell materials were calcined in air at 600-1000°C for 3h. Physicochemical properties of the resulting catalysts were characterized by TGA-DTG, XRD, SEM, BET, XRF, FT-IR and TPD. CaO catalyzed transesterification mechanism of palm oil into biodiesel was verified. The effects of adding a co-solvent on kinetic of the reaction and %FAME yield were investigated. %FAME yield of 98.5%±1.5 was achieved under the optimal conditions of catalyst/oil ratio of 5wt.%; methanol/oil molar ratio of 12:1; reaction temperature of 65°C; 10%v/v of THF in methanol and reaction time of 90min. The results ascertained that river snail shells is a novel raw material for preparation of CaO catalyst and the co-solvent method successfully decreases the reaction time and biodiesel production cost.

Improving transesterification acitvity of CaO with hydration technique.

An efficient technique for increasing the transesterification activity of CaO obtained from calcination of CaCO(3) was proposed in order to make them highly suitable for use as heterogeneous catalysts for biodiesel production. CaO was refluxed in water followed by the synthesis of the oxide from hydroxide species. The characterization results indicate that this procedure substantially increases both the specific surface area and the amount of basic site. Hydration and subsequent calcination also generates a new calcium oxide with less crystalline. Transesterification of palm olein was used to determine the activity of catalysts to show that the decomposed-hydrated CaO exhibits higher catalytic activity than CaO generated from calcination of CaCO(3). The methyl ester content was enhanced 18.4 wt.%.