In-situ electro-deposition synthesis of MnOx-NiCo2O4 monolithic catalyst with rich phase interfaces

A hierarchically structured MnOx-NiCo2O4 monolithic catalyst with rich phase interfaces was designed by a simple, eco-friendly and time-saving in situ electro-deposition method. The abundance of active oxygen species due to this rich phase interfaces contributed to the excellent benzene combustion performance of MnOx-NiCo2O4 -2:2 sample, oxidizing about 90% of benzene (T-90) at 198 degrees C under 12000 h(-1) gaseous hourly space velocity. This work shed new light on the design of excellent monolithic catalysts, which might pave the way for the industrialization of benzene combustion. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved

In situ anchored NiCo2O4 on a nickel foam as a monolithic catalyst by electro-deposition for improved benzene combustion performance

In situ designed monolithic catalysts possess a bright prospect in practical industrial catalytic applications owing to their strong anchoring force and lower pressure drop. In this study, a series of NiCo2O4 nickel foam-based monolithic catalysts were successfully prepared via an in situ electro-deposition strategy. The active phase was strongly and vertically anchored on a nickel foam, leading to a catalyst with a stable structure, abundant surface areas and an excellent electronic transmission capacity. Moreover, the as-prepared catalysts exhibited abundant structural defects, which can be attributed to the violent reaction rate. All the samples assuredly possessed excellent benzene oxidation performance, and the CoNi-NF-2:1 sample exhibited a superior activity, oxidizing about 90% of benzene (T-90) at 198 degrees C under a gaseous hourly space velocity (GHSV) of 6000 h(-1). A conclusion can be rationally drawn that the superior catalytic performance and the stability of the catalysts are primarily attributable to the strong anchoring force, rich oxygen vacancies, and the higher Co3+/Co2+ ratio according to the relevant characterizations. Furthermore, the benzene combustion mechanism was summarized by adequately studying the above conclusions and previous studies. This work indicates a promising strategy to design highly active monolithic catalysts with abundant defects, which potentially pave the way for the thorough removal of industrial benzene

Hierarchical NiCo2O4-MnOx-NF monolithic catalyst synthesized by in-situ alternating anode and cathode electro-deposition strategy: Strong interfacial anchoring force promote catalytic performance

It is of great significance to explore and develop in-situ preparation strategies to improve the activity and service life of monolithic catalysts. In this work, the strategy of alternating anode and cathode electro-deposition was creatively proposed, a hierarchical monolithic catalyst that three-dimensional nickel foam with an open-pore structure at the bottom, structural flexible MnOx crystal in the middle layer, and vertically oriented small size NiCo2O4 spinel phase at the top was successfully prepared. Consequently, NiCo2O4-MnOx-NF-250 monolithic catalyst exhibits lowest T-90 of 196 degrees C, and T'(90) of 204 degrees C (after ultrasonic exfoliation experiment) at 6000 h(-1) gaseous hourly space velocity (GHSV) for 100 ppm benzene combustion. It has been convinced that a monolithic catalyst with high activity and strong anchoring force was successfully prepared by a simple strategy of alternating anode and cathode electro-deposition, which not only provides a strategy for designing monolithic catalyst but also paves the way for industrial benzene removal

Spherical Al2O3-coated mullite fibrous ceramic membrane and its applications to high-efficiency gas filtration

Porous ceramic membranes (PCMs) have been widely used in gas filtration to reduce the Particulate Matters (PMs) emission from industrial systems. Generally, the filter materials are composed of two parts: the support layer and filter layer. However, the typical PCMs prepared through accumulation of particles have existing problems like heavy self-weight, low porosity and high pressure drop, which limit their use in practical applications. In this paper, fibrous PCMs with three-dimensional structures were prepared and then coated with a layer of spherical alpha-Al2O3 membrane on the surface via spray-coating process. The effect of binder composition and sintering temperature on the porosity, phase composition, bulk density and mechanical strength of PCMs, as well as the effect of the coating thickness of spherical alpha-Al2O3 on PMs filtration efficiency and pressure drop were investigated. The results showed that samples with an added binder weight of 50 wt% and sintered at 1250 degrees C resulted to an optimal structure with material properties such as low bulk density (0.88 g/cm(3)), high porosity (70.36%), low linear shrinkage (0.40%), high mechanical strength (5.54 Mpa), and excellent corrosion resistance against both acid and alkali solutions. Furthermore, a spherical alpha-Al2O3 coating thickness of 150 mu m was found to effectively reduced the concentration of PMs from dust-laden air through the filtration tests, achieving enhanced dust removal efficiencies of almost 100% for 3-10 mu m, 99.2% for 1.0 mu m, 95.0% for 0.5 mu m and 91.6% for 0.3 mu m PMs with the pressure drop was only 280 Pa when the airflow linear velocity reached to 2.00 m min(-1). The membranes displayed a 10% increase efficiency in fine particles (d = 1.0-0.3 mu m) removal compared to those without alpha-Al2O3 coating layer

Highly porous fibrous mullite ceramic membrane with interconnected pores for high performance dust removal

Porous fibrous mullite ceramic membranes with different content of fibers were successfully fabricated by molding method for dust removal. The properties of the samples, such as microstructure, porosity, bulk density and mechanical behavior were analyzed. Owing to the highly porous three-dimensional structure of ceramic membranes, all the samples exhibited low density (lower than 0.64 g/cm(3)), high porosity (higher than 73%), low linear shrinkage (lower than 1.0%) and low thermal conductivity (lower than 0.165 W/mK). Significantly, the as-prepared porous ceramic membrane possessed of enhanced dust removal efficiency with almost 100% for 3-10 mu m, 97% for 1.0 mu m, 87% for 0.5 mu m and 82% for 0.3 mu m dust particles in diameter from dust-laden air passed through the test module. Moreover, the pressure drop was lower than 80 Pa when the airflow linear velocity reached 1.25 m min(-1). The results indicated that the ceramic membranes prepared in this work were promising high efficiency dedusting materials for the application in gas filtration field.</p

A Novel Porous Ceramic Membrane Supported Monolithic Cu-Doped Mn-Ce Catalysts for Benzene Combustion

Porous ceramic membranes (PCMs) are considered as an efficient hot gas filtration material in industrial systems. Functionalization of the PCMs with high-efficiency catalysts for the abatement of volatile organic compounds (VOCs) during dust elimination is a promising way to purify the industrial exhaust gases. In this work, we prepared PCMs (porosity: 70%) in a facile sintering process and integrated Cu-doped Mn-Ce oxides into the PCMs as monolithic catalysts by the sol-gel method for benzene oxidation. Through this method, the catalysts are dispersed evenly throughout the PCMs with excellent adhesion, and the catalytic PCMs provided more active sites for the reactant gases during the catalytic reaction process compared to the powder catalysts. The physicochemical properties of PCMs and catalytic PCMs were characterized systematically, and the catalytic activities were measured in total oxidation of benzene. As a result, all the prepared catalytic PCMs exhibited high catalytic activity for benzene oxidation. Significantly, the monolithic catalyst of Cu0.2Mn0.6Ce0.2/PCMs obtained the lowest temperature for benzene conversion efficiency of 90% (T-90) at 212 degrees C with a high gaseous hourly space velocity of 5000 h(-1) and showed strong resistance to high humidity (90 vol.%, 20 degrees C) with long-term stability in continuous benzene stream, which is caused by abundant active adsorbed oxygen, more surficial oxygen vacancy, and lower-temperature reducibility

Monolithic Mn/Ce-based catalyst of fibrous ceramic membrane for complete oxidation of benzene

Herein, a series of monolithic Mn/Ce-based catalyst of ceramic membranes (CMs) were prepared through impregnation method for volatile organic compounds (VOCs) removal. The porous fibrous CMs with a sinter-locked network structure were fabricated by molding method in a feasible sintering process. Then, the catalytic CMs were systematically analyzed by using specific analytical techniques. The results showed that the fibrous CMs possessed a unique interconnected and uniform pore structure, and MnOx-CeO2 active phases were homogenously dispersed into the porous CMs support. The catalytic activity of samples was measured by using benzene as target VOCs. The results revealed that all catalytic CMs were active for oxidation of benzene. Significantly, the catalytic performance was promoted by introducing Ce species into MnOx. Among all, MnOx-CeO2-3:1 catalyst exhibited the lowest 90% benzene conversion temperature (T-90) at 244 degrees C and high stability with continuous benzene stream in the presence of 90 vol.% (20 degrees C) water vapor under a gaseous hourly space velocity (GHSV) of 5000h(-1), owing to the lower-temperature reducibility and the abundant active oxygen (O-Ads.) with synergetic effect of MnOx and CeO2. The results indicated a promising way to design a high efficiency dual functional CMs for the industrial application of removal VOCs while controlling particulate matters (PMs) from hot gases.</p