Catalysts based in cerium oxide for wet oxidation of acrylic acid in the prevention of environmental risks

• Type: Article in International Scientific Journal
• Date: 2004

Authors

Silva, Adrian (Author) Other; Marques, RRN (Author) Other; Quinta Ferreira, RM (Author) Other

Journal

Title: Applied Catalysis B: Environmental

Vol. 47

Pages: 269-279

ISSN: 0926-3373

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 94 Citations

Scopus - 108 Citations

Other information

Authenticus ID: P-000-BK8

DOI: 10.1016/j.apcatb.2003.09.019

Abstract (EN): Acrylic acid is a refractory compound for the non-catalytic wet oxidation (WO) process and can seriously damage the environment when released in industrial effluents. Oxidation of acrylic acid by catalytic wet oxidation (CWO) was studied in slurry conditions in a high-pressure batch reactor at 200 degreesC and 15 bar of oxygen partial pressure. Several solid cerium-based catalysts prepared in our laboratory were used (Ag/Ce, Co/Ce, Mn/Ce, CeO, MnO) and evaluated in terms of activity, selectivity and stability. Mn/Ce shows the higher activity in 2 h with 97.7% reduction of total organic carbon (TOC) followed by: MnO(95.5%) > Ag/Ce(85.0%) > Co/Ce(65.1%) > CeO(61.2%). Attempts were also carried out to analyze the influence of different Mn/Ce molar ratios. High percentages of Mn lead to practically total organic carbon concentration (TOC) abatements while low ratios lead to the formation of non-oxidizable compounds. Acrylic acid was readily degraded by all the catalysts pointing out the high importance of using a catalytic process. pH was an indicator of the reaction pathway and acetic acid was found as the major reaction intermediate compound; however it is completely oxidized after 2 h with exception for Co/Ce, CeO and MnO. Carbon adsorption and leaching of metals were poorly found for Mn/Ce indicating high stability. The catalyst microstructure after the reaction was analyzed and formation of whiskers of beta-MnO2 (or less probably MnOOH) were observed at the catalyst surface. Therefore, Mn/Ce revealed to be a promising catalyst for the treatment of effluents containing acrylic acid; nevertheless, its commercialization depends on further research.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11