Luz Amparo Palacio

Total oxidation of toluene over calcined trimetallic hydrotalcites type catalysts.

Two trimetallic ZnCuAl and MnCuAl hydrotalcites have been successfully synthesized by a co-precipitation method. The manganese based material was identified as a new hydrotalcite phase. Both lamellar precursors were calcined at 450 and 600 degrees C and the resulting catalysts were tested on reaction of total oxidation of toluene. The solids were characterized by X-ray diffraction, thermal analysis, atomic absorption spectroscopy, Fourier transformed infrared spectroscopy, N(2) adsorption and H(2) temperature-programmed reduction. It was found that ZnCuAl materials are composed of copper and zinc oxides supported on alumina; while MnCuAl ones comprise basically spinel phases, which were not completely identified. The catalytic behavior of the calcined samples showed that Mn hydrotalcite calcined at 450 degrees C exhibited the best catalytic performance that corresponds to 100% toluene conversion into CO(2) at about 300 degrees C.

Crystal structure a cobalt molybdate type φx: NaCo2OH(H2O)(MoO4)2

A cobalt molybdate with the formula NaCo2OH(H2O)(MoO4)2 was synthesized by hydrothermal reaction at 200°C in 3 days. The structure was determined from powder data by means of the EXPO direct methods program and refined with GSAS. The purple solid crystallizes in the monoclinic space group C2/m with a=9.3789(3), b=6.3330(1), c=7.6280(2) A, and β=115.833(2)a. Octahedral cobalt atoms, centered at 1/4b and 3/4b, share edges to create endless chains running parallel to the b axis. The chains are connected through molybdenum tetrahedra, which share two vertices with consecutive octahedra in one chain and extend the third vertex to an adjacent chain; the fourth vertex protrudes into the interlayer space. This arrangement repeats itself indefinitely in the ab plane to create a layered structure.

A zinc chromate of type ΦY : synthesis and structure

Abstract A zinc chromate with the formula (NH 4 OH) 3/2 (ZnCrO 4 ) 2 was synthesized by hydrothermal reaction at 100°C in 24 h. The structure was solved from powder data and refined with GSAS. The yellow solid crystallizes in the hexagonal space group R−3m with a =5.99634(7) A and c =21.5117(3) A. Two types of adjacent rows of zinc octahedra, one of which is full while its neighbor has a vacant site between successive octahedra, are linked through chromate groups which extend two vertices to consecutive edge sharing octahedra in one row and a third vertex which serves as bridge to the contiguous row. The fourth tetrahedral vertex protrudes into the interlayer space. This arrangement repeats itself indefinitely in the ab plane to create a layered structure.

Synthesis and crystallographic data of a new copper phosphate CuPO 4 H⋅0.5H 2 O

A new copper phosphate, CuPO 4 H⋅0.5H 2 O, was synthesized using a low temperature hydrothermal method and characterized by powder X-ray diffraction, thermogravimetric analysis, and chemical analysis. The material is monoclinic, space group P 2 1 / c , with a =10.6524(2), b =8.4730(2), c =9.2204(2), β=92.43(0), and V =831.47 A 3 .

Structural characterization of a porous zinc vanadate: Zn 3 (VO 4 ) 2 ⋅3H 2 O

A novel porous material of composition Zn 3 (VO 4 ) 2 ⋅3H 2 O was prepared hydrothermally. The solid crystallizes in the hexagonal space group P 6 , with a =6.078 77(8), c =7.1827(2) A, and V =229.857 A 3 .

Structural characterization of a new zinc phosphate: (ZnPO4)4(H3PO4)2(C4N2H14)2

A new zinc phosphate was synthesized by the hydrothermal reaction of zinc oxide and phosphoric acid in the presence of 1,4-diaminebutane. The formula of the product is (ZnPO 4 ) 4 (H 3 PO 4 ) 2 (C 4 N 2 H 14 ) 2 and crystallizes in the triclinic system with a =8.6590(3) A, b =10.3467(3) A, c =8.3910(3) A, α=102.180(2)°, β=93.676(2)°, and γ=88.203(2)°.