Impact of Precipitants on the Structure and Properties of Fe-Co-Ce Composite Catalysts

Yongli Zhang,Yanbo Zhou,Shujuan Dai,Kai Lin

doi:10.1155/2016/3797896

Abstract

Fe-Co-Ce composite catalysts were prepared by coprecipitation method using CO(NH2)2, NaOH, NH4HCO3, and NH3·H2O as precipitant agents. The effects of the precipitant agents on the physicochemical properties of the Fe-Co-Ce based catalysts were investigated by SEM, TEM, BET, TG-DTA, and XRD. It was found that the precipitant agents remarkably influenced the morphology and particle size of the catalysts and affected the COD removal efficiency, decolorization rate, and pH of methyl orange for catalytic wet air oxidation (CWAO). The specific surface area of the Fe-Co-Ce composite catalysts successively decreased in the order of NH3·H2O, NH4HCO3, NaOH, and CO(NH2)2, which correlated to an increasing particle size that increased for each catalyst. For the CWAO of a methyl orange aqueous solutions, the effects of precipitant agents NH3·H2O and NaOH were superior to those of CO(NH2)2and NH4HCO3. The catalyst prepared using NH3·H2O as the precipitant agent was mostly composed of Fe2O3, CoO, and CeO2. The COD removal efficiency of methyl orange aqueous solution for NH3·H2O reached 92.9% in the catalytic wet air oxidation. Such a catalytic property was maintained for six runs.

Highlights

A large amount of wastewater is produced worldwide every year from the ever-expanding printing and dyeing industries
The present study aims at investigating the effects of CO(NH2)2, NaOH, NH4HCO3, and NH3⋅H2O on the particle size and morphology and structure characteristic of the Fe-Co-Ce composite catalysts
The CAT-1 particles displayed obvious agglomeration and larger particle size, whereas the particles of CAT-2 mainly consisted of a flaky structure presumably because the formation of the crystalline grain was rapid under the strong alkalinity of NaOH [19]

Summary

Introduction

A large amount of wastewater is produced worldwide every year from the ever-expanding printing and dyeing industries. It is well known that the noble metal catalysts have excellent catalytic performance Owing to their high cost and low natural occurrence, their industrial production and applications are hindered [4]. Transition metals are widely used in industrial production and application due to their ubiquitous presence, relatively low cost, and outstanding catalytic performance [6]. The catalyst prepared by the NH3⋅H2O precipitant agent exhibited excellent catalytic performance. Prepared CuO catalysts using NH3⋅H2O, NaHCO3, Na2CO3, and NaOH as precipitant agents and found that HCO3− and. Building on the previous research, the Fe-Co-Ce composite catalysts were prepared by the coprecipitation method with iron nitrate, cobalt nitrate, and cerium nitrate as metal sources in the present study [15]. The influence of different precipitants on the chemical oxygen demand (COD) removal efficiency, decolorization rate, and pH of methyl orange in CWAO over the Fe-Co-Ce composite catalysts was investigated

Experimental

Results and Discussion

Physicochemical Properties of Catalyst Using the Ammonia

Conclusions