Patent MX-2017005587-A (MX)
Title: Vanadates of lanthanum and cerium supported in titanates and gamma alumina: super-claus catalysts.
Inventor: ROBERTO GARCÍA DE LEÓN
IPC: B01J21/06
Filed: 2017-04-28
Abstract: The present invention relates to a catalyst for the oxidation of hydrogen sulfide. In particular, it reports catalysts for the partial oxidation of H2S to elemental sulfur and water. Said catalyst comprises a support of lanthanum or alumina titanates and a catalytically active component. The active phase used is a metal oxide, one or more mixtures of metal oxides. Said metal oxides composing the catalyst are selected from the group of metal oxides of the transition metals or lanthanides. The metal oxides for use in the catalyst of this invention are those which are not poisoned by the hydrogen sulfide and/or undergo a phase transformation which is inactive in the selective oxidation reaction. The preferred supports are the lanthanum and alumina titanates, while the metal oxides integrated into the said catalyst are the oxides of V, Fe, La, Ce, Zn, Sb, demonstrating an increase in selectivity when integrating a promoter agent to the catalyst. Said promoters are incorporated during the initial stage of preparation of the support by co-precipitation/precipitation by combining the required amount of Ti / Al with the corresponding metal precursor salt. The precursor metal oxides are integrated by the standard technique of incipient wet impregnation when using solutions of the selected metal salts or metal complexes. In the reaction of the catalyst with hydrogen sulfide, the activity and selectivity for sulfur production of the lanthanum and cerium vanadate species indicate differences in the dry and wet conditions of the Super Claus process. The conversion levels of H2S at a reaction temperature between 150°C and 300°C are higher than 95% for vanadates deposited in lanthanum titanates under the dry and wet reaction conditions. The vanadate species of the alumina range catalyst demonstrates a 95% activity level in dry Super Claus reaction but a deactivation when carrying out the reaction in wet Super Claus decreasing the conversion of H2S from >90% to 70%. The catalytic component of vanadate deposited in lanthanum titanates indicates a selectivity value of elemental sulfur between 65-70% under the wet reaction conditions and having a level higher than 90% selectivity to elemental sulfur in Super Dry Claus reaction. The catalyst with alumina range support demonstrates a selectivity level of more than 90% under the Super Claus wet and dry reaction. The catalysts that relate the active phase of iron with Ce or Zn promoters in the alumina range support demonstrate selectivity values ??higher than 80%. In particular, the ferrous iron and iron catalyst component with cerium promoter have values ??of approximately 95% in selectivity of elemental sulfur, and with a decrease from 85% to 80% in sulfur selectivity when used as a promoter to zinc. The catalyst with metal oxides of iron and zinc has a conversion of H2S of 90%, and deactivation for the active phase of iron and iron with cerium demonstrating low levels of 50% and 30% in catalytic activity, respect ively. In another series of catalysts, the effect of the active phase of iron and iron with promoters supported on lanthanum titanates is investigated. The iron catalytic material in lanthanum titanates shows an H2S conversion of 85% and 90% in the reaction with water and without water, respectively. Said catalyst indicates a selectivity to elemental sulfur of 85% under reaction conditions without water and a value of 90-95% in the presence of water. When the promoters of Ce, Sb, and Zn added to the active phase of iron, the conversion of H2S decreases to values ??of 80%, 70%, and 45%, respectively. Elemental sulfur selectivity increased from 90% to 96% with the addition of the Ce, Sb and Zn promoters.