No abstract

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

No abstract

No abstract

RESUMEN Muchos sistemas describen la reacción de carbocloración de materiales de importancia industrial mediante técnicas gravimétricas y termogravimétricas. Estos estudios se focalizan en la reacción global basándose en la identificación de los productos condensados, los cálculos termodinámicos y el cambio de masa generado durante la reacción. En un proceso de carbocloración, la composición de la fase gaseosa es compleja, pudiendo contener CO, CO2, y COCl2 además de cloruros y/u oxicloruros del metal estudiado. En el presente estudio se desarrolló un sistema que permite estudiar una reacción de carbocloración siguiendo la formación de productos gaseosos del carbono por espectroscopía de IR. Nuestros resultados indicaron que la carbocloración del MoO3 en presencia de carbón de sucrosa, no sólo ocurre con la formación del oxicloruro y CO2, también fueron detectados CO y HClO. Los resultados demostraron la formación de un intermediario entre el Cl2(g) y el carbón superficial, constituyendo la etapa determinante de la velocidad de reacción.

Uranium tetrafluoride was synthesized using a novel method, which consists of a combination of carbochlorination reaction between a mixture of U3O8 and sucrose carbon with chlorine, and a solid-state halogen exchange reaction between the products of the carbochlorination reaction and sodium fluoride. The thermodynamic feasibility to produce the halogen exchange reaction between UCl4 and NaF was analyzed. Reactions are favorable in standard conditions, even at low temperature. We have prepared a mixture of UCl4 and UCl2O2 by U3O8 treatment in Cl2 atmosphere with presence of sucrose carbon at 900 °C. UCl4 and UCl2O2 were obtained as a condensed product, which was collected in a quartz capsule containing NaF. The capsules were sealed after several repeated stages of argon purges and mechanic vacuum. Subsequently, they were treated at 300–350 °C for 2 h. We obtained that when NaF is the limiting reagent, the solid product of the thermal treatment of the capsules consists in a mixture of UF4 and NaCl. Solid products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy, and energy dispersive X-ray spectroscopy. Gaseous products were identified by Fourier-transform infrared spectroscopy.

Ruthenium, as well as the rest of the platinum-group metals, is of crucial importance for industry due to its extraordinary catalytic activity and high-tech applications. Because of its scarcity and high value, there is an increasing interest towards its recovery from wastes. Chlorination metallurgy arises as one possible recovery method. The intrinsic kinetics of the chlorination of ruthenium oxide was studied with the aim of applying this process in a suitable recovery technology. Chlorination of RuO 2 was investigated for temperatures between 973 K and 1073 K (700 °C and 800 °C) and chlorine partial pressure from 50 to 90 kPa. The reaction rate was measured by gravimetry and the rate equation was obtained. An activation energy of 259 ± 6 kJ mol À1 and a reaction order of 0.5 with respect of chlorine partial pressure were determined. The reaction product is unstable at atmospheric conditions. Formation of RuO 2 Cl 2 is proposed based on experimental evidence; however, such product has not been confirmed yet.

This work presents the apatite fission track (AFT) age and multielement analysis of four samples performed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The central ages calculated range between 15.4...