An effective one-electron quantum chemical method was applied to enumerate the conformers of unbranched aliphatic alkanes. The results obtained for butane, pentane, hexane, and heptane were utilized to derive four rules with which the number and sequences of the existing conformers up to undecane could be reproduced. The validity of the rules was confirmed at Hartree-Fock and second-order Moeller-Plesset levels too. Full ab initio conformational analyses were performed for the butane, pentane, hexane, heptane, and octane molecules. The rules demonstrate that the most important factors governing the conformational behavior of unbranched aliphatic alkanes are the nonbonded repulsive-attractive (van der Waals) interactions between the hydrogen atoms attached to the carbon atoms at positions 1,4; 1,5; 1,6; and 1,7. The calculated gasphase standard heats of formation of the unbranched aliphatic alkanes closely matched the experimental values.
The effect of various reduced catalysts for the upgrading of bio-oil produced by fast pyrolysis in a small batch reactor was evaluated using reduced Ni/SiO 2 , Co/SiO 2 , Pt/SiO 2 , Pd/SiO 2 , and conventional sulfided CoMo/Al 2 O 3 catalysts. All of the reduced catalysts were prepared by incipient wetness impregnation. Hydrodeoxygenation (HDO) reactions carried out in the H 2 pressure range of 1-5 MPa and temperature range of 300-350 °C using guaiacol and woody tar as model compounds for fast pyrolysis oil demonstrated that at 300 °C, higher guaiacol conversion was achieved with the reduced Co/SiO 2 , Ni/SiO 2 , and Pd/SiO 2 catalysts compared with the conventional sulfide CoMo/Al 2 O 3 catalyst. However, only the reduced Co/SiO 2 catalyst exhibited high HDO activity and selectivity towards aromatics in the guaiacol HDO reaction. The reduced Co/SiO 2 catalyst also exhibited high HDO activity and selectivity towards aromatics in the HDO of woody tar, indicating that this catalyst may be active for direct deoxygenation of phenol yielding mostly benzene. Thus, the reduced catalysts, especially the Co/SiO 2 catalyst, can be considered to be potential candidates for use as HDO catalysts with improved activity and selectivity.
One-pot synthesized Ti-SBA-15 mesoporous materials with various Ti loadings of 0.808-6.78 mol% were applied as heterogeneous solid acid catalysts for simultaneous esterification and transesterification of vegetable oils with methanol into high-quality biodiesel fuel (BDF) at 200 o C under autogeneous pressure. According to the diffuse-reflectance (DR) UV-Vis spectra, diffuse-reflectance infrared Fourier transform (DRIFT) spectra and pulsed ammonia (NH 3 ) chemisorption studies combined with other conventional characterizations, the catalytically active site for high-quality BDF synthesis was mostly related to the tetrahedral Ti 4+ species with weak Lewis acid character, which differential heat of NH 3 adsorption was lower than 90 kJ mmol -1 . Due to that the tetrahedral Ti 4+ species were accessible on largely mesoporous framework, the Ti-SBA-15 catalyst gave much higher activity in transesterification of crude Jatropha oil (CJO) with methanol than microporous titanosilicate of TS-1 and commercial TiO 2 nanocrystallites. Among them, the 3Ti-SBA-15 catalyst with a Ti loading of 2.46 mol% showed a highest fatty acid methyl ester (FAME) content of 90 mass% at 200 o C for 3 h using a methanol-to-oil molar ratio of 27. When the reaction period and methanol-to-oil molar ratio were increased to 3-6 h and 108, respectively, a great variety of edible and non-edible vegetable oils with various acid values (0.06-190 3 mg KOH g -l ), including refined soybean oil (RSO), refined rapeseed oil (RRO), waste cooking oil (WCO), crude palm oil (CPO), CJO and palm fatty acid distillates (PFAD), was directly transformed into high-quality BDFs, which met with a European standard (EN 14214:2009), over 3Ti-SBA-15 catalyst at 200 o C. The used 3Ti-SBA-15 catalyst was easily regenerated by calcination and its high activity was maintained. Most importantly, the 3Ti-SBA-15 catalysts could resist 5 wt% of water or 30 wt% of free fatty acid (FFA), which tolerance levels were several ten times better than those of homogeneous and heterogeneous catalysts in the current BDF production technology.
A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-l-ol (ohyl + elaidyl alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst prepared by an improved sol, el method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9~Y~adecen-l-ol and total alcohol (9~ctadecen-l~l + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%. KEY WORDS: 9-Octadecen-l-al, oleie acid, ruthenium-tin-alumina catalyst, selective hydrogenation, sol-gel method.
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