The observation of high-resolution transmission electron microscopy (HRTEM) lattice fringe images for coals has aided the rationalization of structure and order. Within the hundreds of lattice fringes (edge-on view of the aromatic structures) in a typical micrograph, apparent curvature is common. Traditional image analysis approaches do not appropriately quantify curvature. Tortuosity is functional for the quantification of single-inflection-point smooth lines but poor for complex or undulating lines. Here we present an image analysis method that can identify the points of inflection, angles, and segment lengths that constitute curved lattice fringes. Four coals from the Argonne Premium suite (Pocahontas No. 3, Upper Freeport, Illinois No. 6, and Beulah-Zap) and example anthracites were examined, and curvature was present in 17−24% of the fringes. These curved fringes were further classified as having low (<45°), medium (45−90°), or high curvature (>90°) on the basis of cumulative angle changes. For the Argonne Premium coals, Pocahontas had the greatest portion of fringes with low curvature (74%), with the other coals being between 55 and 65%. In all cases, low curvature was the predominant class. High curvature contributed between 8 and 19%. The majority of the curved fringes (84 to 87%) were located in the range defined by fringes with lengths of 6.0−12.5 Å and cumulative angles of 4−125°. The Argonne Premium coals examined have similar distributions of angle change between adjacent segments. Angle changes of 10−20°account for the largest contribution. The coals had similar tortuosity distributions with fringe length. The majority of curved fringes for Argonne Premium coals (>90%) were defined by fringes with lengths of 6.0−22.5 Å and tortuosities of 1.001−2.0, while the curved fringes of anthracite with lengths of 6−52.5 Å and tortuosities of 1.001−1.5 accounted for 90%. These observations have implications for the frequency and placement of nonsix-membered rings in aromatic structures.

No abstract

The work carried out in this paper assessed how processing conditions and feedstock affect the quality of the coke produced during microwave coke making. The aim was to gather information that would support the development of an optimised microwave coke making oven. Experiments were carried out in a non-optimised 2450 MHz cylindrical cavity. The effect of treatment time (15 -120 min), power input (750 W -4.5 kW) and overall power input (1,700 -27,200 kWh/t) on a range of coals (semi-bituminous -anthracite) was investigated. Intrinsic reactivity, random reflectance, strength index and dielectric properties of the produced cokes were compared with those of two commercial cokes to assess the degree of coking produced in the microwave system.Overall energy input and coal rank were found to be the major factors determining the degree of coking following microwave treatment. The dependency on coal rank was attributed to the larger amount of volatiles that had to be removed from the lower ranked coals, and the increasing dielectric loss of the organic component of the coal with rank due to increased structural ordering. Longer treatment times at lower powers or shorter treatment times at higher powers are expected to produce the same degree of coking.It was concluded that microwave coke making represents a potential step-change in the coking industry by reducing treatment times by an order of magnitude, introducing flexibility and potentially decreasing the sensitivity to quality requirement in the feedstock. The main challenges to development are the energy requirements (which will need to be significantly reduced in an optimised process) and penetration depth (which will require an innovative reactor design to

(2016) Understanding bottom-up continuous hydrothermal synthesis of nanoparticles using empirical measurement and computational simulation. Nano Research, 9 (11). pp. 3377-3387. ISSN 1998-0000 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/41016/1/1215_proof.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. ABSTRACTContinuous hydrothermal synthesis was highlighted in a recent review as an enabling technology for the production of nanoparticles. In recent years, it has been shown to be a suitable reaction medium for the synthesis of a wide range of nanomaterials. Many single and complex nanomaterials such as metals, metal oxides, doped oxides, carbonates, sulfides, hydroxides, phosphates, and metal organic frameworks can be formed using continuous hydrothermal synthesis techniques. This work presents a methodology to characterize continuous hydrothermal flow systems both experimentally and numerically, and to determine the scalability of a counter current supercritical water reactor for the large scale production (>1,000 T•year -1 ) of nanomaterials. Experiments were performed using a purpose-built continuous flow rig, featuring an injection loop on a metal salt feed line, which allowed the injection of a chromophoric tracer. At the system outlet, the tracer was detected using UV/Vis absorption, which could be used to measure the residence time distribution within the reactor volume. Computational fluid dynamics (CFD) calculations were also conducted using a modeled geometry to represent the experimental apparatus. The performance of the CFD model was tested against experimental data, verifying that the CFD model accurately predicted the nucleation and growth of the nanomaterials inside the reactor.

A techno-economic assessment of the potential for combining supercritical water oxidation with 'insitu' hydrothermal synthesis of nanocatalysts using a counter current mixing reactor, Chemical Engineering

No abstract

No abstract

No abstract