Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Fundamentals and Catalytic Applications of CeO2-Based Materials

CO2 conversion covers a wide range of possible application areas from fuels to bulk and commodity chemicals and even to specialty products with biological activity such as pharmaceuticals. In the present review, we discuss selected examples in these areas in a combined analysis of the state-of-the-art of synthetic methodologies and processes with their life cycle assessment. Thereby, we attempted to assess the potential to reduce the environmental footprint in these application fields relative to the current petrochemical value chain. This analysis and discussion differs significantly from a viewpoint on CO2 utilization as a measure for global CO2 mitigation. Whereas the latter focuses on reducing the end-of-pipe problem “CO2 emissions” from todays’ industries, the approach taken here tries to identify opportunities by exploiting a novel feedstock that avoids the utilization of fossil resource in transition toward more sustainable future production. Thus, the motivation to develop CO2-based chemistry does...

Sustainable Conversion of Carbon Dioxide: An Integrated Review of Catalysis and Life Cycle Assessment

Over the last decade, significant effort has been devoted to the applications of hierarchically structured porous materials owing to their outstanding properties such as high surface area, excellent accessibility to active sites, and enhanced mass transport and diffusion. The hierarchy of porosity, structural, morphological and component levels in these materials is key for their high performance in all kinds of applications. The introduction of hierarchical porosity into materials has led to a significant improvement in the performance of materials. Herein, recent progress in the applications of hierarchically structured porous materials from energy conversion and storage, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine is reviewed. Their potential future applications are also highlighted. We particularly dwell on the relationship between hierarchically porous structures and properties, with examples of each type of hierarchically structured porous material according to its chemical composition and physical characteristics. The present review aims to open up a new avenue to guide the readers to quickly obtain in-depth knowledge of applications of hierarchically porous materials and to have a good idea about selecting and designing suitable hierarchically porous materials for a specific application. In addition to focusing on the applications of hierarchically porous materials, this comprehensive review could stimulate researchers to synthesize new advanced hierarchically porous solids.

Applications of hierarchically structured porous materials from energy storage and conversion, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine

Nitrogen-containing porous carbon materials are ubiquitous with a wide range of technologically important applications, including separation science, heterogeneous catalyst supports, water purification, electrochemistry, as well as the developing areas of energy generation and storage applications. To date, a variety of approaches has been developed and applied to introduce nitrogen into the carbon matrix. It is important and necessary to design and control a hierarchical porous structure and the surface chemical groups of nitrogen-containing porous carbons for their applications. In this work, we summarize and compare recently reported routes for the preparation of nitrogen-containing porous carbon materials and the effect of nitrogen groups on its applications in adsorption, electrochemistry, catalysis/catalyst supports and hydrogen storage properties.

Nitrogen-containing porous carbons: synthesis and application

The textile industry presents a global pollution problem owing to the dumping or accidental discharge of dye waste-water into waterways, which is having a major impact on the quality and aesthetics of water resources. The World Bank estimates that 17 to 20% of industrial water pollution comes from textile dyeing and treatment. This percentage represents an appalling environmental challenge for clothing designers and other textile manufacturers. Recently, the application of metal oxide semiconductors in the advanced oxidation process (AOP) has gained wide interest for the treatment of dye waste-water owing to its good degradation efficiency, low toxicity and physical and chemical properties. AOP refers to a set of chemical treatment procedures designed to remove organic and inorganic materials from waste-water by oxidation. In this paper, recently developed metal oxide semiconductors are discussed, in which the semiconductors are generally divided into three categories: (i) titanium dioxide; (ii) zinc oxide; and (iii) other metal oxides (such as vanadium oxide, tungsten oxide, molybdenum oxide, indium oxide and cerium oxide). The syntheses and modification methods as well as the efficiency of each category are discussed and analyzed. Copyright © 2011 Society of Chemical Industry

Recent developments of metal oxide semiconductors as photocatalysts in advanced oxidation processes (AOPs) for treatment of dye waste‐water

Photocatalytic degradation for methylene blue using zinc oxide prepared by codeposition and sol–gel methods

Deactivation of a Au/CeO2–Co3O4 catalyst during CO preferential oxidation in H2-rich stream

Selective oxidation of alcohols to aldehydes/ketones over copper oxide-supported gold catalysts

Synthesis of polyoxymethylene dimethyl ethers from methanol and trioxymethylene with molecular sieves as catalysts

CuO/Ce 1− x Ti x O 2 prepared by sol–gel impregnation was used as catalysts for the preferential oxidation (PROX) of CO in H 2 -rich stream. The effects of support composition, catalyst calcination temperature as well as the presence of H 2 O and CO 2 in the reaction stream on the catalytic performance of CuO/Ce 1− x Ti x O 2 were investigated. The results indicated that the catalyst CuO/Ce 0.8 Ti 0.2 O 2 exhibits the highest activity and the optimal temperature for the catalyst calcination is 500 °C. The presence of H 2 O and CO 2 in the reaction stream has a negative effect on the catalytic activity and stability of CuO/Ce 0.8 Ti 0.2 O 2 . The negative effect of CO 2 on the catalyst stability is stronger than that of H 2 O, suggesting that the accumulation of carbonate species may be the main reason for catalyst deactivation. The characterization by means of XRD, HRTEM, and H 2 -TPR indicated that the doping of TiO 2 in CeO 2 enhances the surface area of the composite oxide support, decreases its particle size, and promotes the dispersion of active copper species. The strong interaction between TiO 2 and CeO 2 in the support as well as the interfacial interaction between CuO and the support may also contribute to the high catalytic activity of CuO/Ce 0.8 Ti 0.2 O 2 .

Hui Wang

Papers

Photocatalytic degradation for methylene blue using zinc oxide prepared by codeposition and sol–gel methods

Deactivation of a Au/CeO2–Co3O4 catalyst during CO preferential oxidation in H2-rich stream

Selective oxidation of alcohols to aldehydes/ketones over copper oxide-supported gold catalysts

Synthesis of polyoxymethylene dimethyl ethers from methanol and trioxymethylene with molecular sieves as catalysts

Preferential oxidation of CO in H2-rich stream over CuO/Ce1−xTixO2 catalysts