High surface area La₂Sn₂O₇ pyrochlore as a novel, active and stable support for Pd for CO oxidation

Abstract

A high surface area mesoporous La 2 Sn 2 O 7 compound with a well crystallized pyrochlore structure has been successfully prepared by a simple low temperature hydrothermal IJLa 2 Sn 2 O 7 -HT) method. As a support for Pd, a catalyst with a significantly higher activity for CO oxidation has been achieved in comparison with the other two non-mesoporous pyrochlores prepared by co-precipitation IJLa 2 Sn 2 O 7 -CP) and sol-gel IJLa 2 Sn 2 O 7 -SG) methods. The CO adsorption-desorption and STEM results demonstrate that on Pd/La 2 Sn 2 O 7 -HT, the highest Pd dispersion can be achieved among all of the catalysts. Moreover, compared with Pd/La 2 Sn 2 O 7 -CP and Pd/La 2 Sn 2 O 7 -SG, more active oxygen species were formed on Pd/La 2 Sn 2 O 7 -HT. It is believed that these are the two major reasons accounting for the superior CO oxidation activity of Pd/La 2 Sn 2 O 7 -HT. Furthermore, this catalyst also shows a stable reaction performance in the presence of water vapour. In conclusion, the mesoporous La 2 Sn 2 O 7 -HT pyrochlore is an excellent support for Pd, and has the potential to be applied in some real exhaust control processes.Catal. Sci. Technol. This journal is Fig. 10 Water resistance (a) and durability test (b) of the 1% Pd/La 2 Sn 2 O 7 -HT catalyst for CO oxidation.

Catalytic Oxidation of Soot on a Novel Active Ca-Co Dually-Doped Lanthanum Tin Pyrochlore Oxide

“…Figure S2b depicts the Sn 3d spectra of different catalysts, which has the typical position (485.5–486.0 eV) and band shape of Sn (IV) compounds [29]. It can be seen that the change of dominant position is similar to La 3d, which proves that the introduction of calcium made the lattice internal environment undergo great changes.…”

Catalytic combustion of soot particulates over rare-earth substituted Ln2Sn2O7 pyrochlores (Ln = La, Nd and Sm)

“…S3(d) that Sn 3d energy level is composed of a doublet corresponding to Sn 3d 3/2 and Sn 3d 5/2 at $495 eV and $486 eV, respectively. Compared with pure SnO 2 [21], both of Sn 3d 3/2 and Sn 3d 5/2 peaks in the pyrochlore structure obviously shifts to lower binding energies, indicating a change of the chemical environment of the Sn cations. The peak separation in other words the spin-orbit splitting between these two photoemission peaks (Sn 3d 3/2 and Sn 3d 5/2 ) is determined to be $8.4 eV.…”

“…When criteria of the ionic radius and charge neutrality are satisfied, the partial substitution at A and B cationic sites as well as oxygen sites are possible. Recently, they have been well investigated in various environment-related catalytic reactions such as NO reduction [17], NO decomposition [18,19], CO and VOCs oxidation [20,21], and catalytic combustion of methane [22,23]. In our previous works [24,25], transition metal doped lanthanum stannate oxides with pyrochlore structure prepared by co-precipitation exhibited moderate catalytic activity for soot combustion in the presence of NO + O 2 .…”

Highly active and stable Ni/Y2Zr2O7 catalysts for methane steam reforming: On the nature and effective preparation method of the pyrochlore support

“…Apparently, with hydrothermal method, a high surface area Y 2 Zr 2 O 7 pyrochlore support can be achieved [30].…”