Selective Catalytic Reduction of NOx by CO over Doubly Promoted MeMo/Nb2O5 Catalysts (Me = Pt, Ni, or Co)

Catalysts

AlcineiaC. Oliveira¹  LaisF. Oton¹  JoãoPedro S. Nascimento¹  Enrique Rodríguez-Castellón²  Elena Rodríguez-Aguado²  MoniqueS. Souza³  RinaldoS. Araujo³  Rossano Lang⁴ 

[1] Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará, Campus do Pici, Bloco 940, Fortaleza 60455-760, Ceará, Brazil;Departamento de Química Inorgánica, Universidad de Málaga, Facultad de Ciencias, 29071 Málaga, Spain;Instituto Federal de Educação-IFCE, Campus de Fortaleza, Av. 13 de Maio 2081, Fortaleza 60455-760, Ceará, Brazil;Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo-UNIFESP, São José dos Campos-SP 12231-280, Brazil;

关键词: Nb₂O₅;    catalyst;    synergistic effect;    NO_x;    CO-SCR;   

DOI  :  10.3390/catal10091048

来源: DOAJ

【 摘 要 】

Doubly promoted MeMo/Nb₂O₅ catalysts, in which Me = Pt, Ni, or Co oxides were prepared for the selective catalytic reduction of NO_x by CO reaction (CO-SCR). Comparable chemical, textural, and structural analyses revealed similarities between NiMo and CoMo impregnated on Nb₂O₅, in contrast to PtMo sites, which were not homogeneously dispersed on the support surface. Both the acid function and metal dispersion gave a synergistic effect for CO-SCR at moderate temperatures. The reactivity of PtMo catalysts towards NO_x and CO chemisorption was at low reaction temperatures, whereas the NO_x conversion over CoMo was greatly improved at relatively high temperatures. Careful XPS, NH₃-TPD, and HRTEM analyses confirmed that the large amounts of strong and moderate acid sites from PtO_x entrapped on MoO₃ sites induced high NO_x conversions. NiMo/Nb₂O₅ showed poor performance in all conditions. Poisoning of the MeMo sites with water vapor or SO₂ (or both) provoked the decline of the NO_x conversions over NiMo and PtMo sites, whereas the structure of CoMo ones remained very active with a maximum NO_x conversion of 70% at 350 °C for 24 h of reaction. This was due to the interaction of the Co³⁺/Co²⁺ and Mo⁶⁺ actives sites and the weak strength Lewis acid Nb⁵⁺ ones, as well.

【 授权许可】

Unknown