Yuzo Imizu

3.17 Preparation of Silica-Deposited Alumina Catalyst by Utilizing Organosilicon Complexes as Building Blocks for the Synthesis of Acidic Sites

Abstract To elucidate the structural details of the interface and its catalytic properties of silica-alumina, we prepared three types of silica-alumina catalysts employing trimethylsiloxyaluminumdichloride ((CH 3 ) 3 SiOALCL 2 ) 1 , polyhedral oligosilsesquioxane ((c-C 5 H 9 ) 7 Si 7 O 9 (OH) 3 ) 2 and CH 3 Si(OCH 3 ) 3 . The simultaneous silica and alumina-deposited catalysts derived from 1 exhibited high activity for cyclopropane isomerization but not for 1-butene isomerization. The results of the variation of activity for ethanol dehydration on silica and alumina-deposited catalysts suggested that the deposited ALOx is also active for ethanol dehydration. The silica cluster-deposited alumina catalysts derived from 2 exhibited high activity for 1-butene isomerization upon deposition of a small amount of silica, indicating that the active sites for the 1-butene isomerization were formed more efficiently than those formed on the silica-deposited alumina derived from CH 3 Si(OCH 3 ) 3 . The nature of active sites on the several types of silica-alumina for these reaction are discussed in terms of the structure of deposited silica.

Catalytic behavior of Zn2+ or Cd2+ supported Y-zeolite for acetonitrile formation from ethene and ammonia

Abstract Zn/Y- and Cd/Y-zeolites were found to be much more active for the formation of acetonitrile from ethene and ammonia than Al 2 O 3 and H/Y-zeolite. Although Zn or Cd/Al 2 O 3 showed the higher activity than Al 2 O 3 itself, Y-zeolite was superior as a support to Al 2 O 3 . The partial pressure dependence of NH 3 on Zn/Y-zeolite was different from that on Cd/Y-zeolite. The reaction of ethylamine over Zn/Y and Cd/Y-zeolites was performed, since formation of a very small amount of ethylamine was observed during the reaction between ethene and ammonia. However, the amount of acetonitrile formed from ethylamine was very small on Zn/Y-zeolite. The amount of ethylamine rapidly decreased with reaction time. On the other hand, an induction period was observed on the formation of acetonitrile over Zn/Y-zeolite. The Cd/Y-zeolites were found to be almost inactive for the formation of acetonitrile from ethylamine. On the basis of the results obtained, the main reaction route for the acetonitrile formation is thought to be different from the route through the formation of ethylamine.

3.12 Grinding of Zirconium Pyrophosphate and its Catalytic Activity for 1-Butene Isomerization

Abstract Grinding zirconium pyrophosphate catalysts resulted in enhanced catalytic activities (weight basis), which were strongly influenced by their calcination temperatures before grinding as well as by evacuation temperatures prior to use for the titled reaction. The grinding effect on activity was also investigated.

Zinc oxide modified by alkylsilylation as an efficient catalyst for isomerization of hydrocarbon

Isomerization of 1-butene, 1-pentene, and cis -1,3-pentadiene was carried out on alkylsilylated ZnO catalyst. The alkylsilylation of ZnO exerts a promoting effect in the isomerization of olefin. The extents of enhancement by the silylation were depend on the type of alkylgroup of silane, especially upon silylation with Et3SiH, the activity for cis -1,3-pentadiene was remarkably enhanced by a factor of 89. The selectivity for 1-butene and 1-pentene isomerization were not changed before and after silylation. The silylation also did not change the kinetics as well as the activation energy for the isomerization of cis -1,3-pentadiene, suggesting that silylation did not alter the reaction mechanism. TPD study revealed that the silyl group prevents the strong adsorption of 1,3-pentadiene. Taken together, it was concluded that the alkylsilyl group served as a template to prevent irreversible adsorption of reactant and keep active sites free from the self poisoning.

3.14 Surface Properties and Catalytic Activities of Superconducting Bi-Pb-Sr-Ca-Cu Oxides for 1-Butene Isomerization

Abstract The isomerization of 1-butene was carried out in order to detect trace amounts of acidic and/or basic impurities which are supposed to localize on the surfaces of the titled superconducting oxides. In was found that the superconducting oxides containing almost only a high critical-temperature phase (Tc=110K) showed no catalytic activity, whereas precursor compounds of the high Tc phase showed considerable activities as well as the selectivity featured by the base-catalyzed reaction. On the basis of the catalytic properties and other data of XRD, SEM, and Tc-measurement, we have concluded that CaO as an impurity remains on the surface of imperfect Bi-based superconducting oxides.

4.13 Hydrogenation of 1,3-Dienes over Tetramethyltin-Promoted Zinc Oxide Catalyst

Abstract The catalytic properties of Sn(CH 3 ) 4 -modified ZnO for the hydrogenation of 1, 3-dienes were examined as a function of pretreatment temperature. Upon deposition of Sn(CH 3 ) 4 on ZnO, the activities for the hydrogenation of 1, 3-dienes increased by a factor of more than 10 at optimum pretreatment rature. especially, acceleration factor was observed to be 30 for 1, 3-pentadiene hydrogenation. The product for hydrogenation of 1, 3-butadiene was exclusively 1-butene, however, regioselectivity for 1, 2-hydrogen addition to the methyl substituted 1, 3-dienes were altered by variation of pretreatment temperature of Sn(CH 3 ) 4 . In sharp contrast to ZnO, Sn(CH 3 ) 4 failed to improve the activities of other basic oxides including MgO, La 2 O 3 , CdO, ZrO 2 , indicating Sn(CH 3 ) 4 acts as a sites blocking agent on these oxides. Moreover, no promoting effect was observed for ethylene, propylene, and 1-butene hydrogenation. It suggested that the partially demethylated Sn complexes are effective for improving the catalytic properties of ZnO for the 1,3-dienes hydrogenation and the interaction between the conjugated dienes and Sn complexes is responsible for promoting the activity. The methyl moieties attached to Sn complexes may also serve as a template to orient or align the reactant and the intermediate.

3.13 Preparation of Amorphous Metal-substituted Aluminum Phosphates and Their Acid-Base Properties

Abstract Metal(Ti, Fe, Zn, K) substituted aluminum phosphates (Me-Al-P-O, (Al+Me)/P=1) were prepared by a sol-gel method. As compared with the acid-base properties of AlPO 4 , the amounts of basic sites on Me-Al-P-O were significantly increased, while the amounts of acid sites slightly changed. For 1-butene isomerization, Me-Al-P-O showed higher activities than AlPO 4 . It was suggested that basic sites generated by metal substitution enhanced the activities of Me-Al-P-O.

1.13 Friedel-Crafts Polyalkylation of Mesitylene with Trichlorotoluene: A Synthesis of 1,3-Connected Polyarylmethanes as Precursors for Organic Magnets

Abstract Friedel-Crafts polyalkylation of mesitylene with trichlorotoluene was carried out to synthesize precursors of organic magnets without metal. More than twenty kinds of solid acid and base catalysts and inorganic salts are examined for this reaction. Among these, Zn(II)(OTf) 2 and Cu(II)(OTf) 2 were observed to be the excellent catalysts showing the highest catalytic performance in yield and efficiency. Also zinc(II) chloride displayed good catalytic performance showing the highest molecular weight from the economical point of view. Weak Lewis acid having high solubility properties in the organic media is concluded to be the best catalyst for this reaction. The reaction encountered significant extent of methyl dealkylation requiring further work in order to solve this structural deficiencies.