Dehydrogenation of Cyclohexanol to Cyclohexanone Over Nitrogen-doped Graphene supported Cu catalyst

In this study, the dehydrogenation of cyclohexanol to cyclohexanone over nitrogen-doped reduced graphene oxide (N-rGO) Cu catalyst has been reported. The N-rGO support was synthesized by chemical reduction of graphite oxide (GO). The synthesized N-rGO was used as a support to prepare the Cu/N-rGO catalyst via an incipient wet impregnation method. The as-prepared support and the Cu/N-rGO catalyst were characterized by FESEM, EDX, XRD, TEM, TGA, and Raman spectroscopy. The various characterization analysis revealed the suitability of the Cu/N-rGO as a heterogeneous catalyst that can be employed for the dehydrogenation of cyclohexanol to cyclohexanone. The catalytic activity of the Cu/N-rGO catalyst was tested in non-oxidative dehydrogenation of cyclohexanol to cyclohexanone using a stainless-steel fixed bed reactor. The effects of temperature, reactant flow rate, and time-on-stream on the activity of the Cu/N-rGO catalyst were examined. The Cu/N-rGO nanosheets show excellent catalytic activity and selectivity to cyclohexanone. The formation of stable Cu nanoparticles on N-rGO support interaction and segregation of Cu were crucial factors for the catalytic activity. The highest cyclohexanol conversion and selectivity of 93.3% and 82.7%, respectively, were obtained at a reaction temperature of 270 °C and cyclohexanol feed rate of 0.1 ml/min. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A computer simulation and experimental study of the difference between krypton adsorption on a graphite surface and in a graphitic hexagonal pore

Adsorption isotherms and isosteric heats have been studied experimentally and by computer simulation for the krypton-graphitic hexagonal pore and krypton-graphite planar surface systems in the 60-109 K temperature range. The existence of a 2D transition in the sub-monolayer film on the basal plane of graphite that is observed experimentally is confirmed by the computer simulation results, but this transition is not observed in graphitic hexagonal pores because the onset of adsorption occurs at the junctions of adjacent pore walls, and the mechanism of surface adsorption is the spreading of adsorbate from the junction towards the basal planes until the first layer is completed. This is followed by molecular layering of higher layers, and then by capillary condensation when the empty core is small enough

A review on supervised machine learning for accident risk analysis: challenges in Malaysia

The new Fourth Industrial Revolution (IR 4.0) trend is driven by the concept of automation and artificial intelligence (AI). However, Malaysia is slightly behind Singapore in terms of adopting AI innovation among ASEAN countries. This paper aims to conduct a literature review of machine learning to overcome subjectivity and bias in risk ranking decision-making. An introduction to machine learning concerning accident risk analysis is presented, and the challenges of its application in Malaysia are discussed. Existing machine learning features were evaluated to identify the feasible application in industrial accident analysis and ensure safety decision-making consistency. This review observed how the IR 4.0 approaches were used in the risk analysis, especially on supervised machine learning. This study also highlights the finding from the previous works on challenges in utilizing supervised machine learning, which is the need to have publicly accessible large database from industries and agencies such as the Department of Occupational Safety and Health (DOSH) Malaysia for the development of algorithms, which can potentially improve accident risk analysis and safety, especially for Malaysian industries

Fire-resistant and flame-retardant surface finishing of polymers and textiles: a state-of-the-art review

Polymers and textiles can be found in every facet of human everyday life particularly as household items and apparels though most of them are inherently flammable. Surface finishing is a convenient approach to endow polymers and textiles with flame retardancy without sacrificing intrinsic properties of the bulk materials. In this contribution, we present a state-of-the-art review of a variety of surface finishing approaches to provide polymers and textiles with fire-resistance. The reviewed works are organized as follows: layer-by-layer assembly, dip coating, in-situ solution-based synthesis, and brushing/spray coating. The discussion then continues with a thorough assessment of the materials' flame-retardant performances. We also attempt to shed lights on key aspects of high-performance coatings including applications of bio-based or advanced materials, synergistic combinations, microstructure and interface evaluations, multifunctional coating, and many more. We hope that this contribution provides meaningful insights for researchers to better formulate and develop new synthesis protocol to fabricate high-performance flame-retardant coating

On the identification of the sharp spike in the heat curve for Argon, Nitrogen, and Methane Adsorption on Graphite: Reconciliation between computer simulation and experiments

Experimental data for the adsorption of argon, nitrogen, and methane on a planar graphite surface under subcritical conditions exhibit a very sharp peak in the isosteric heat curve at loadings close to the monolayer concentration. The magnitude of this peak is much greater than the value expected from the extrapolation of the isosteric heat in the submonolayer region to the monolayer loading. This sharp and large peak has been interpreted as the transition of the first layer from a hypercritical fluid phase to a solid phase. Here, we argue that volumetric or calorimetric experiments are in fact carried out in a canonical system, where a dose of known mass of adsorptive is introduced into the system, rather than in an open system exposed to an infinite supply reservoir as assumed in GCMC simulations. We have carried out canonical simulations with the new Mu-CMC scheme proposed recently by Fan et al. (J. Phys. Chem. B2011, 115 (35), 10509-10517) and have reproduced the sharp peak in the heat curve. We show that this sharp spike is observed in a canonical ensemble (and in some cases grand canonical ensemble), whether the surface is unstructured or structured and no matter whether nitrogen is modeled as a 1CLJ or 2CLJ+3q or methane is treated as a 1CLJ or 5CLJ+5q model, suggesting that the heat spike is an intrinsic characteristic of the gas-solid pair