Filomena Pinto

Effect of coal pre-treatment with swelling solvents on coal liquefaction

Pre-treatment of coal with swelling solvents may enhance coal porosity and thus facilitate catalyst action. The yields of products obtained by coal liquefaction were very much dependent on the type of swelling solvent used. Those studied included ethanol, tetrahydrofurane (THF) and tetrabutylammonium hydroxide (TBAH). After this treatment coal was liquefied using ZnCl2 as catalyst, both alone and mixed with Fe2O3 or ICI 41-6 (Co–Mo). When ethanol was used, the highest coal conversion was obtained, although this solvent had the lowest swelling ratio, probably because a better catalyst impregnation was achieved. On the other hand, although the swelling ratio of TBAH was the greatest, lower overall coal conversions and higher oils yields were observed. In an attempt to interpret these results, coal structure before and after swelling pre-treatment was also studied using SEM.

Determination of aromatic compounds in eluates of pyrolysis solid residues using HS-GC–MS and DLLME–GC–MS

A method for the determination of 15 aromatic hydrocarbons in eluates from solid residues produced during the co-pyrolysis of plastics and pine biomass was developed. In a first step, several sampling techniques (headspace solid phase microextraction (HS-SPME), static headspace sampling (HS), and dispersive liquid-liquid microextraction (DLLME) were compared in order to evaluate their sensitivity towards these analytes. HS-SPME and HS sampling had the better performance, but DLLME was itself as a technique able to extract volatiles with a significant enrichment factor. HS sampling coupled with GC-MS was chosen for method validation for the analytes tested. Calibration curves were constructed for each analyte with correlation coefficients higher than 0.999. The limits of detection were in the range of 0.66-37.85 ng/L. The precision of the HS method was evaluated and good repeatability was achieved with relative standard deviations of 4.8-13.2%. The recoveries of the analytes were evaluated by analysing fortified real eluate samples and were in the range of 60.6-113.9%. The validated method was applied in real eluate samples. Benzene, toluene, ethylbenzene and xylenes (BTEX) were the compounds in higher concentrations. The DLLME technique coupled with GC-MS was used to investigate the presence of less volatile contaminants in eluate samples. This analysis revealed the presence of significant amounts of alkyl phenols and other aromatic compounds with appreciable water solubility.

Gasification Technology and Its Contribution to Deal with Global Warming

It is predictable that energy demand will greatly increase in years to come, due to the continuous growth of world population, together with the quest to improve living standards. CO2 emissions are hence expected to increase significantly. Gasification is a mature technology for energy production that permits an easier separation of CO2 for its storage. As modern societies are producing everincreasing amounts of wastes with negative impact on the environment, new technologies have been developed to co-gasify these wastes either with coal or alone, thus resolving a serious problem of waste disposal. Wastes gasification reduces the dependence on fossil fuels and co-gasification with coal could provide the benefit of security in fuel supply, as the availability of wastes and biomass fuels could vary from region to region and show seasonal changes. Gasification experimental conditions and technologies and syngas cleaning methods are key issues for the production of a clean gas that could find a wide range of applications. This chapter will concentrate on syngas end-uses, focusing on new ones, like gas turbines or engines in IGCC, synthesis of methanol, ethanol and dimethyl ether, Fischer–Tropsch synthesis, and hydrogen production. The role of gasification in CO2 sequestration will also be discussed.

NH3 Abatement in Fluidized Bed Co-Gasification of RDF and Coal

Gasification of wastes may come out as an alternative technology to produce a gas with many potential applications, from direct burning in a boiler or motor to the production of synthetic chemicals and hydrogen. High tar production and high operational costs are preventing gasification wider dissemination. Besides these problems, the presence of NH3 in the syngas may have a negative impact as it can be converted into nitrogen oxides if the gas is further burnt. To reduce NH3 formation it is required a full understanding of how operational parameters contribute to the formation/reduction of this pollutant. A full studyon the effect of fuel composition, temperature and equivalence ratio on the formation of NH3 is given. Experimental results are compared to theoretical ones obtained with FactSage software. It is also analyzed the effect of feedstock mineral matterin NH3 release during gasification. Toaccomplish a significant decrease in the release of NH3, different catalysts and sorbents were tested with the aim of achieving high energy conversions and low environmental impact.

Thermal Improvement of Coal and Cooking Oil Wastes Mixtures in a Fluidised-Bed Gasifier

The objective of co-gasiication of edible oil wastes with coal or biomass, could, on one hand, lead to improvement of characteristics of final product, benefiting from complementary natures of different fuels and could simultaneously contribute to resolving the environmental problem of disposing used edible oils. This work also aims at providing potential new applications for law rank coals including those from marginal reserves. Co-gasification studies of mixtures of coal or biomass wastes with small amounts of waste edible oils (WEO) were carried out in an atmospheric bench-scale fluidised bed gasifier. The gasification medium was both steam and air-steam mixtures. The experimental trials were undertaken to understand the behaviour of these mixtures and to optimize the range of operating conditions, like gasification temperature, air-steam/fuel ratio and oil content in the feedstock.Copyright