Carmen Mayoral

Polycyclic aromatic hydrocarbon emissions from fluidized bed combustion of coal

The most volatile polycyclic aromatic hydrocarbons remaining in the flue gas leaving cyclones placed at the exit of a fluidized bed coal combustor and classified by the US EPA as priority pollutants were trapped on filters and adsorbents, dissolved in dimethylformamide and analysed by synchronous fluorescence spectroscopy. The results are discussed.

Iron catalyzed hydrogenation of high sulphur content coals

Abstract Four high-sulphur low-rank coals have been trated at hydrogenation conditions with three iron-based catalyst precursors: Red Mud (Fe2O3), iron sulphide and iron pentacarbonyl. The obtained yields show a dependence with the sulphur content of the coals; the organic sulphur content correlates with the conversion and THF-solubles when Red Mud and iron sulphide are added. In spite of the high hydrogen sulphide partial pressure in the reaction, the addition of other sources of sulphur enhances the percentages in conversion products.

From coal to char

Abstract The evolution of coal into char through a hydroconversion process is studied in this paper. The coals used were Spanish low-rank and bituminous coals. The hydroconversion process was performed in the absence of solvent and at increasing severity conditions: pressure from 5 to 10 MPa, and temperatures from 300° to 400°C. When the hydrogenations were catalyzed, ammonium heptamolybdate was used as catalyst precursor, using the coal as catalytic support. Several analytical techniques were applied to the obtained chars to find some of the changes undergone by the unconverted part of the coal. According to the results, except for the most reactive coals, a development of microporosity is observed in the first stages of char formation in the absence of catalyst, up to 350°C for the subbituminous coals and 400°C for bituminous ones. In general, an increase in network crosslinking with increasing severity conditions is observed.

Coal structure : inferences from catalytic hydrogenation

Abstract The early stages of low-temperature catalytic hydrogenation were studied with the aim of following changes in the macromolecular network component of coal during catalysed hydropyrolysis/hydroliquefaction. Reactions were carried out using a subbituminous coal in the presence of MoS 2 at 15 MPa H 2 and 300–450 °C in a tubing bomb reactor and a swept fixed-bed reactor. The changes in the coal structural network were characterized by volumetric swelling ratios in pyridine, infrared spectroscopy and solid-state nuclear magnetic resonance and the mineral matter content was determined by low-temperature ashing. The oils were analysed by chromatography. The use of two different reactors allowed the effect of the hydrogenation system on the coal network structure to be assessed. To infer information on coal structure, the fixed-bed reactor is preferable because retrogressive reactions are minimized. However, in the tubing bomb the hydrogenation is deeper, and less severe conditions are needed to obtain high yields of conversion products.

COAL BEHAVIOUR IN DRY RAPID CATALYTIC HYDROGENATION

Publisher Summary This chapter discusses the coal behavior in dry rapid catalytic hydrogenation. According to the two-component structural model, coal contains weak bonds relatively easy to be broken and stronger bonds within the matrix that require more severe conditions to be degraded. The chapter highlights the less severe conditions in which a low rank coal can yield good conversion into liquids. The control of the coal hydrogenation requires getting a balance between the bond cleavage and the stabilization of the cleaved fragments. As consequence of the ZnCl2 pretreatment, the Zn content of the coal is increased, from 0.012% in the original coal to 1.05% in the treated coal, the incorporated Zn being found by scanning electron microscopy as highly dispersed into the coal matrix. In view of the obtained results in the hydrogenation procedure, the main effect of the ZnCl2 pretreatment is a lower oils/asphaltenes ratio in all cases and higher gases formation.

A female engineer in every school

This paper presents a novel initiative carried out in the Spanish region of Aragon in the last three years to promote engineering vocations among primary school children, especially among girls. Another objective is to make visible the role of women in the engineering field and to put into value their contributions. To do so, women working in this areas, both from the academic and professional fields, visit schools to sensitize teachers and give a talk and run a workshop with the kids. Workshops are creative, collaborative, without a final closed result, each group creates their designs or proposes their solutions. In this way, it is intended to offer girls a positive experience that promotes their self-perceived effectiveness, accompanied by women that can represent models for them. The initiative, which has evolved over its three years of existence, aims to reverse the decline of vocations in the field of STEM careers and increase the presence of women in these studies.

Char formation and release of liquids in catalysed hydropyrolysis

Abstract This paper presents the results on catalytic hydropyrolysis as used to explore the relationship between the release of tars and the formation of char from coal. A total of 19 low-rank coals and 6 bituminous coals, covering a wide range of variability in different characteristics, has been studied. The reaction was performed at 5 and 10 MPa H 2 cold, temperatures from 300 to 400°C and 30 minutes of reaction time. Molybdenum was used as catalyst using coal as catalytic support. Four of these coals were selected throughout a cluster experimental design to carry out the hydropyrolysis for several reaction times (5, 10, 15 and 60 min). Different analytical techniques were applied in order to characterise chars and tars from the hydropyrolysis. Results obtained from thin layer chromatography coupled with a flame ionization detector show that at 350°C and in the presence of Mo catalyst there is an important decrease in polar compounds in oils in comparison with the reaction carried out at the same temperature but in absence of catalyst, probing the interdependence of thermal and catalytic processes. At 300°C, results from both reactions were similar. From the characterisation of chars, it can be observed that at increasing temperatures there is an increase in char aromaticity and mesopore surface area accompanied by an increase of total pore volume of meso- and macropores and by a loss of aliphatic carbon content.

Relation between release of conversion products in coal liquefaction and cross-linking

Abstract A study was made of the relation between the release of coal conversion products and cross-linking, using catalytic solvent-free hydrogenation in order to avoid problems in data interpretation caused by the presence of solvent. Twenty-five subbituminous and bituminous coals were hydrogenated in the absence of solvent at 5 and 10 MPa H 2 (cold), temperatures of 300, 350 and 400 °C and reaction time 30 min, with molybdenum sulfide as catalyst supported on the coal. The low-rank coals selected were more reactive than the bituminous ones. The subbituminous coals gave a maximum liquids production at 350 °C. At 400 °C the liquids yield decreased but the oil yield increased. Liquids from the hydrogenation of subbituminous coals were less asphaltenic than those from the bituminous ones. The residual chars were characterized by the extent of swelling in pyridine. For the subbituminous coals the swelling decreased with increasing conversion, reaching maximum cross-linking at the most severe conditions in most instances. The bituminous coals showed a different behaviour at low conversion, but at higher conversion the relation between conversion and swelling appeared to be similar to that for the subbituminous coals.