and Fuels Changzhi Li,† Xiaochen Zhao,† Aiqin Wang,† George W. Huber,†,‡ and Tao Zhang*,† †State Key Laborotary of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China ‡Department of Chemical and Biological Engineering, University of WisconsinMadison, Madison, Wisconsin 53706, United States

Catalytic Transformation of Lignin for the Production of Chemicals and Fuels

Spinels with the formula of AB2O4 (where A and B are metal ions) and the properties of magnetism, optics, electricity, and catalysis have taken significant roles in applications of data storage, biotechnology, electronics, laser, sensor, conversion reaction, and energy storage/conversion, which largely depend on their precise structures and compositions. In this review, various spinels with controlled preparations and their applications in oxygen reduction/evolution reaction (ORR/OER) and beyond are summarized. First, the composition and structure of spinels are introduced. Then, recent advances in the preparation of spinels with solid-, solution-, and vapor-phase methods are summarized, and new methods are particularly highlighted. The physicochemical characteristics of spinels such as their compositions, structures, morphologies, defects, and substrates have been rationally regulated through various approaches. This regulation can yield spinels with improved ORR/OER catalytic activities, which can furth...

Spinels: Controlled Preparation, Oxygen Reduction/Evolution Reaction Application, and Beyond

Catalysts for chemical and electrochemical reactions underpin many aspects of modern technology and industry, from energy storage and conversion to toxic emissions abatement to chemical and materials synthesis. This role necessitates the design of highly active, stable, yet earth-abundant heterogeneous catalysts. In this Review, we present the perovskite oxide family as a basis for developing such catalysts for (electro)chemical conversions spanning carbon, nitrogen, and oxygen chemistries. A framework for rationalizing activity trends and guiding perovskite oxide catalyst design is described, followed by illustrations of how a robust understanding of perovskite electronic structure provides fundamental insights into activity, stability, and mechanism in oxygen electrocatalysis. We conclude by outlining how these insights open experimental and computational opportunities to expand the compositional and chemical reaction space for next-generation perovskite catalysts.

http://science.sciencemag.org/content/sci/358/6364/751.full.pdf

Perovskites in catalysis and electrocatalysis

Polymer nanocomposites possess promising high performances as engineering materials, if they are prepared and fabricated properly. Some work has been recently done on such polymer nanocomposites as dielectrics and electrical insulation. This was reviewed in 2004 based on the literatures published up to 2003. New significant findings have been added since then. Furthermore, a multi-core model with the far-distance effect, which is closely related to an "interaction zones", has been proposed from consideration of mesoscopic analysis of electrical and chemical structures of an existing interface with finite thickness. It is speculatively examined in the paper how the model works for various properties and phenomena already found in nanocomposites as dielectrics focusing on electrical characteristics, resistance to high voltage environment, and thermal properties.

Dielectric nanocomposites with insulating properties

Polymer nanocomposites are defined as polymers in which small amounts of nanometer size fillers are homogeneously dispersed by only several weight percentages. Addition of just a few weight percent of the nanofillers has profound impact on the physical, chemical, mechanical and electrical properties of polymers. Such change is often favorable for engineering purpose. This nanocomposite technology has emerged from the field of engineering plastics, and potentially expanded its application to structural materials, coatings, and packaging to medical/biomedical products, and electronic and photonic devices. Recently these 'hi-tech' materials with excellent properties have begun to attract research people in the field of dielectrics and electrical insulation. Since new properties are brought about from the interactions of nanofillers with polymer matrices, mesoscopic properties are expected to come out, which would be interesting to both scientists and engineers. Improved characteristics are. expected as dielectrics and electrical insulation. Several interesting results to indicate the foreseeable future have been revealed, some of which are described on materials and processing in the paper together with basic concepts and future direction.

Polymer nanocomposites as dielectrics and electrical insulation-perspectives for processing technologies, material characterization and future applications

There is provided a process for manufacturing a carbonaceous anode for an electrolysis cell for the production of aluminium. The process comprises contacting coke particles with a boron-containing solution to obtain boron-impregnated coke particles, mixing the boron- impregnated coke particles with coal tar pitch to form an anode paste, and forming a green anode with the anode paste. A carbonaceous anode for an electrolysis cell for the production of aluminium is also provided, which comprises at least a first fraction of coke particle, a second fraction of coke particles and coal tar pitch, wherein at least the first faction of coke particles comprises boron-impregnated coke particles, the boron- impregnated coke particles being distributed throughout the carbonaceous anode. The carbonaceous anode presents good resistivity towards air and CO 2 oxidation, which translates into less dusting of the anode, thus improving its integrity throughout its lifetime.

Process for manufacturing carbon anodes for aluminium production cells and carbon anodes obtained from the same

To simulate the thermo-mechanical behaviour of ramming paste in aluminium electrolysis cells, experimental data are required to feed 3D constitutive models. Both axial and radial strain measurements are necessary to design constitutive laws and to identify the parameters. However, radial strains are difficult to obtain at high temperature due to limitations of measuring devices. Moreover, samples need to be sufficiently large to acquire significant radial strain amplitude. Hence, the creep behaviour of ramming paste was studied at room temperature so the radial behaviour could then be extrapolated for the high temperature case using the axial strain evolution as a function of the temperature. Mechanical properties of ramming paste, baked at temperatures ranging from 250 °C to 1000 °C, were measured at room temperature. Uniaxial creep tests were performed at three different stress levels for each baking temperature.

Room Temperature Creep Behaviour of Ramming Paste Baked at Different Temperatures

A panacea for solving all electrical insulations problems

The Hall-Heroult process uses prebaked carbon anodes as electrodes. The anode’s quality plays a crucial role in the efficiency of the aluminium production process. During the baking process, the anode undergoes complex physicochemical transformations. Thus, the production of high-quality anodes depends, among others, on the efficient control of their baking process. This paper aims to investigate the evolution of some physical properties of the anode paste mixture during the baking process. These properties include the mass loss fraction, real and apparent densities, the ratio of apparent volume, the permeability, and porosities. For this purpose, experiments consisting of thermogravimetric analysis, dilatometry, air permeability, and helium-pycnometric measurements were carried out. The anode permeability at high temperatures was linked to the air permeability through a permeability correlator due to experimental limitations. Moreover, the real density at high temperatures was estimated by combining real densities of the coal tar pitch and coke aggregates. Different porosities, such as the open porosity and the closed porosity related to the pitch binder, were estimated by taking the permeability at high temperatures into account. In this context, the effect of the permeability correlator, which was introduced to link the permeability at high temperatures to the air permeability, was investigated through a sensitivity analysis. These results allow an estimation of the shrinking index, a new variable introduced to reflect the baking level of the anode mixture, which is linked to the volatile that is released in both open and closed pores. Afterwards, the pore pressure inside closed pores in the coal tar pitch was estimated. The obtained results highlight some new insights related to the baking process of the anode mixture. Moreover, they pave the way for better modeling of the thermo-chemo-mechanical behavior of anodes at high temperatures.

/pdf/physical-property-evolution-of-the-anode-mixture-during-the-e893mqno8f.pdf

Physical Property Evolution of the Anode Mixture during the Baking Process.

To assess the mechanical behavior of ramming paste, representative laboratory samples must be produced for experimental characterization. Experimental data are necessary to feed three-dimensional creep model where radial strain measurements are required. It is thus imperative to perform measurements on a sample large enough to get significant radial strain amplitude. However, the ISO standard fabrication method is restricted to small-size samples. In the present paper, a different compaction process, adapted from the Proctor method, is proposed in order to get larger cylindrical samples of 100 mm diameter and 200 mm height. The ramming paste samples are produced in multilayer by dynamic compaction, using a falling weight in a circular pattern over the tamped surface. The baked apparent density obtained by X-Ray computed tomography, or CT scan, and the baked mechanical properties such as compressive strength, have been characterized as a function of the number of layers and the number of impacts.

/pdf/new-compaction-method-for-the-production-of-large-ramming-6uhzklsc5h.pdf

Houshang Alamdari

Papers

Process for manufacturing carbon anodes for aluminium production cells and carbon anodes obtained from the same

Room Temperature Creep Behaviour of Ramming Paste Baked at Different Temperatures

A panacea for solving all electrical insulations problems

Physical Property Evolution of the Anode Mixture during the Baking Process.

New Compaction Method for the Production of Large Ramming Paste Samples for 3D Mechanical Characterization