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Characterization of zirconia-magnesia-yttria materials used as catalysts for esters and alcohols fractions transformations by ketonization

Klimkiewicz R., Teterycz H., Sikora E., Rakoczy J., Biskupski A., Trawczyński J.

Polish Journal of Chemical Technology

2005

Vol. 7, nr 1

29-32

In former publications the application of the monophase material Zr(0.89)-Mg(0.10)-Y(0.01)-O as a catalyst of the waste alcohol and ester fractions ketonization was described. In the present work various compositions of the Zr-Mg-Y-O type respecting the reaction group: Zr(0.89)-Mg(0.10)-Y(0.01)-O(CL) synthesized from chlorides, Zr-Mg-Y-O(SULPH) from zirconium sulfate, mixed oxide ZrO2+Y2O(3BOG) and its derivative Zr-Mg-Y-O(BOG) are characterized. The catalytic properties of the materials were characterized with the use of n-butanol test, isopropanol test, cyclohexene + H2 test as well as TPD NH3, and FT-IR (pyridine) spectroscopy. Zr-Mg-Y-O(SULPH) catalyst obtained from the sulfate precursor, as compared to Zr(0.89)-Mg(0.10)-Y(0.01)-O(CL), revealed a much lower selectivity of the reaction of the primary and secondary alcohols into ketones. The surfaces of Zr(0.89)-Mg(0.10)-Y(0.01)-O(CL) and ZrO2 + Y2O(3BOG) materials, although they contained comparable numbers of the Lewis acidic centers (164 and 126 žmol Py/g, respectively), differed considerably as for the selectivity in the reaction of n-butyl alcohol condensation: ZrO2,+Y2O(3BOG) was not a selective catalyst of the ketonization. Under the conditions of the cyclohexene + H2 test over ZrO2 + Y2O(3BOG) the reaction proceeded towards isomerization and cracking, while Zr(0.89)-Mg(0.10)-Y(0.01)-O(CL) catalyzed hydrogenation. The application of Zr-Mg-Y-O(BOG) material of the lower Lewis acidity (62 žmol Py/g) did not result in the higher selectivity of the ketonization. However, the result of the cyclohexene + H2 test changed. Thus, a considerable number of the Lewis acidic centers (such as ZrO2+Y2O(3BOG) was not the only necessary condition for the bimolecular condensation of the primary alcohols and/or aldehydes or for esters transformation. The search for materials should be conducted towards the syntheses of the catalysts of the dehydrogenation properties and containing in their structure oxygen vacancies which could form the Lewis acidic centers.

Some properties of MgO and catalytic performance in oxidative coupling of methane

Taniewski M., Kuś S.

Polish Journal of Applied Chemistry

2000

Vol. 44, nr 4

181-194

The catalytic performance of unpromoted MgO in oxidative coupling of methane to C(2)+ hydrocarbons (OCM) and a controversial question of possible MgO properties/performance relationship were studied. The properties and structure of several MgO samples of different origin (BET surface area and pore size distribution, surface morphology by electron scanning microscopy, phase characteristics by thermo-gravimetry, identification of impurities by AAS) were determined. Tests carried out in the small-scale laboratory unit with silica tubular reactor at 760°C, demonstrated the diversity of catalytic performance of applied MgO samples in OCM C(2) selectivity, in particular). It was shown that the surface area and the structure of MgO were not the main factors responsible for the diversity of catalytic performance. The content or absence of Ca compounds in applied MgO samples appeared to be the main factor. The presence of Ca compounds led to the increase in C(2) selectivity and activity of MgO. Similar effects were achieved by introduction of various alkalies, water, etc. to MgO. It was concluded that the variation in the basicity could be a decisive factor responsible for observed differences between MgO samples regarding their selectivity and activity in OCM.