“THE PROMOTING EFFECT OF LANTHANUM IN HETEROGENEOUS CATALYSTS”.

MARIA DO CARMO RANGEL; MANUELA DE SANTANA SANTOD; SERGIO GUSTAVO MARCHETTI

"Lanthanum: Compounds, Production and Applications"

Nova Science Publishers, Inc.

Lugar: New York; Año: 2011; p. 191 - 212

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:PT-BR; mso-fareast-language:PT-BR;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> The interest for studying lanthanum compounds has been growing in recent years, due to their attractive properties for industrial and technological purposes. They found several applications in different fields, such as component in various optical, electrical and magnetic applications, as well as catalytic materials. In this case, they are widely used as catalysts, supports and dopants. As a dopant, lanthanum is often used for stabilizing the gamma phase of alumina, in catalysts designed for high temperature applications, such as in automotive three-way catalytic process, in combustion for gas turbines and boilers and in hydrocarbon reforming. Besides alumina, other supports and catalysts have been improved by lanthanum, such as Ni/BaTiO3, silica, ceria, titania, HCa2Nb3O10, K1-xLaxCa2-xNb3O10 and iron oxides, for different reactions. The lanthanum addition to hematite, for instance, changes the specific surface area, the resistance against reduction and also the activity, selectivity and resistance against coke deposition of the catalysts during ethylbenzene dehydrogenation. However, these effects largely depend on the amount of the dopant, on the  preparation method as well as on the kind of precipitant. Lanthanum also improves catalysts for applications at low temperature such as nickel and copper-based solids or titania-supported gold for carbon monoxide oxidation, zirconia-supported platinum and tungstophosphoric acid for n-pentane isomerization, lanthanum and nickel supported on sepiolite for styrene hydrogenation and La-MCM-41 catalysts for styrene oxidation. These examples, and many others, make lanthanum a very promising dopant for heterogeneous catalysts for different applications