Makoto Toba

Synthesis of alcohols and diols by hydrogenation of carboxylic acids and esters over Ru-Sn-Al2O3 catalysts

Abstract Ru–Sn–Al2O3 catalysts were prepared by sol–gel, impregnation and their combination methods and the relationship between catalyst properties and reaction profiles in the hydrogenation of dicarboxylic acids and saturated fatty acids were examined. The surface Sn contents of catalysts characterized by X-ray photoelectron spectroscopy (XPS) depended on the preparation method in spite of almost the same bulk Ru and Sn compositions measured by X-ray fluorescence analyses. Temperature programmed reduction (TPR) and CO adsorption of the catalysts also depended on preparation methods. The preparation method, Sn/Ru ratio, reaction temperature and the structure of substrate have influence on the yield of diol. Ru–Sn–Al2O3 catalysts gave fatty alcohols with good yield in the hydrogenation of the corresponding saturated fatty acids. The conversion of the acids increased with increase in their carbon number.

Selective hydrogenation of oleic acid to 9-octadecen-1-ol: Catalyst preparation and optimum reaction conditions

A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-1-ol (oleyl + 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-gel 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-octadecen-1-ol and total alcohol (9-octadecen-1-ol + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%.

Thermal behaviour of alumina from aluminium alkoxide reacted with complexing agent

Several aluminas were synthesized from aluminium isopropoxide using some organic complexing agents as solvents. The difference in the properties, especially specific surface area, of the aluminas obtained was investigated. The thermal behaviour of the aluminas depended on the complexing abilities of the solvents used. The transmission electron microscopic studies confirmed that size and shape of the gel particles were controlled by the complexing agents.

Effect of the type of preparation on the properties of titania/silicas

Abstract Titania/silicas were prepared by four methods: (i) complexing-agent assisted sol—gel, (ii) coprecipitation, (iii) hydrogel kneading and (iv) xerogel kneading. The properties of these titania/silicas were investigated by thermal gravimetry and differential thermal analysis (TG-DTA) X-ray powder diffraction, solid-state magic angle spinning nuclear magnetic resonance (MAS NMR), ammonia temperature programmed desorption (TPD) and nitrogen adsorption. Of the four methods, the complexing-agent assisted sol—gel method gave the most homogeneous titania/silicas. Their TiOSi bond formation, acidities, and specific surface areas depended on completing agents used in the preparations and the Ti/Si ratios of raw materials. In contrast, the kneading titania/silicas were heterogeneous and their properties did not depend on the Ti/Si ratio. The dependence of properties of coprecipitated titania/silicas on their Ti/Si ratio were intermediate between those of complexing-agent assisted sol—gel and kneading.

Effect of preparation methods on properties of alumina/titanias

Alumina/titanias have been prepared by three methods: complexing-agent-assisted sol–gel; coprecipitation; and hydrogel kneading. The relationship between the preparation methods and the properties of the alumina/titanias was investigated by thermal gravimetry and differential thermal analysis (TG–DTA), X-ray powder diffraction, laser Raman spectroscopy, solid-state magic-angle spinning nuclear magnetic resonance (MAS-NMR), ammonia temperature-programmed desorption (TPD) and nitrogen adsorption. Of the three preparation methods, the complexing-agent-assisted sol–gel method gave the most homogeneous alumina/titanias, and their acidities and specific surface areas depended on complexing agents used in the preparation and the Ti:Al ratios of the raw materials. In contrast, kneading alumina/titanias were relatively heterogeneous and their properties did not depend on the Ti:Al ratio. Regarding the dependences of properties of alumina/titanias on the Ti:Al ratio, coprecipitation alumina/titanias are intermediate between complexing-agent-assisted sol–gel and kneading ones.

Production of Jatropha biodiesel fuel over sulfonic acid-based solid acids.

Sulfonic acid-functionalized platelet SBA-15 mesoporous silica with an acid capacity of 2.44mmol H(+) g-cat(-1) (shortly termed 15SA-SBA-15-p) was one-pot synthesized by co-condensation method. When applied as solid acid catalyst in synthesis of Jatropha biodiesel fuel (BDF), the 15SA-SBA-15-p catalyst showed higher activity and resistances to water and free fatty acid (FFA) than commercial sulfonic resins of Amberlyst-15 and SAC-13. For the continuous Jatropha BDF production, a steady 75-78wt% of fatty acid methyl ester (FAME) content was obtained over 15SA-SBA-15-p catalyst at 150°C for 75h, whereas the Amberlyst-15 and SAC-13 catalysts were quickly deactivated due to the decomposition of thermally unstable framework and serious leaching of sulfonic acids. More importantly, the quality, stability and cold flow characteristic of Jatropha BDF synthesized by 15SA-SBA-15-p catalyst were better than those synthesized by Amberlyst-15 and SAC-13 catalysts, making the blending with petro-diesel an easy task.

Materials chemistry communications. New preparation method for highly siliceous zeolite films

Highly siliceous zeolite films of silicalite and ZSM-5 were prepared by a new preparation method using cellulose moulding.

Catalytic activity of a zeolite disc synthesized through solid-state reactions

Abstract ZSM-5 zeolite in a disc-shaped form was synthesized by a new method in which reactions occurred in the solid state. The proton form of the zeolite was prepared by ion exchange of the sodium ions of the disc-shaped pellet in hydrochloric acid solution. The catalyst prepared was characterized by SEM, thermogravimetry, nitrogen adsorption and ammonia TPD. High p -xylene selectivity was observed for the new disc-shaped ZSM-5 zeolite catalyst in the alkylation of toluene with methanol. This catalytic feature was attributed to the inherent character of the zeolite, since its structure consisted of inter-grown individual HZSM-5 crystals forming secondary mesopores which promote the high gas permeability of the zeolite disc.

Hydrogenation of 9-octadecenoic acid by Ru-Sn-Al2O3 catalysts : effects of catalyst preparation method

Evaluation of the method of preparation and the sequence of metal incorporation onto the catalyst showed that they had profound effects on the catalytic behavior of Ru−Sn−Al2O3 catalysts used in the selective hydrogenation of oleic acid to 9-octadecen-1-ol. When Ru was loaded first onto the support and then followed by Sn, the catalyst had lower activity but greater ability to preserve the unsaturated bond. On the other hand, when the sequence of loading was reversed, the behavior of the catalyst changed correspondingly, i.e., the catalyst showed higher activity but poorer ability to protect the unsaturated bond. The metal particles incorporatedvia the sol-gel method were finely and evenly distributed on the support. As such, they were more readily shielded by the second metal particles that were subsequently incorporatedvia the impregnation process. When both metals were loadedvia the sol-gel process, the best result was obtained with superior performance in activity, as well as selectivity in the preservation of double bond.

Preparation and Properties of the Catalysts by A Chemical Mixing Procedure

Various solid catalysts were prepared by a chemical mixing technique, composed of four steps (complexing, gelation, drying and activation) and characterized by the preparation of a homogeneous solution containing catalyst precursors and the uniform coagulation of the solution through hydrolysis. The mixed-oxides prepared by the technique were expected to be more homogeneous than those prepared by kneading and coprecipitation methods. The chemically mixed ruthenium catalysts were much more effective for the partial hydrogenation of benzene to cyclohexene without any assistance from poisons. Furthermore, the chemically mixed alumina-silicas showed much higher activities for the conversion of methanol to hydrocarbons than the kneaded alumina-silica.