Sulfur analysis of Bolu-Mengen lignite before and after microbiological treatment using reductive pyrolysis and gas chromatography/mass spectrometry

Atmospheric pressure-temperature programmed reduction coupled with on-line mass spectrometry (AP-TPR/MS) is used for the first time on microbiologically treated coal samples as a technique to monitor the degree of desulfurization of the various sulfur functionalities. The experimental procedure enables the identification of both organic and inorganic sulfur species present in the coal matrix. A better insight in the degradation of the coal matrix and the accompanying processes during the AP-TPR experiment is obtained by a quantitative differentiation of the sulfur. The determination of the sulfur balance for the reductive pyrolysis gives an overview of the side reactions and their relative contribution in the total process. The volatile sulfur species are unambiguously identified using AP-TPR off-line coupled with gas chromatography/mass spectrometry (GC/MS). In this way, fundamental mechanisms and reactions that occur during the reductive pyrolysis could be quantified, explaining the differences in AP-TPR recoveries. Therefore, this study gives a clearer view on the possibilities and limitations of AP-TPR as a technique to monitor sulfur functionalities in coal

Microwave heating as a novel route for obtaining carbon precursors from anthracene oil

This work describes a novel route for the preparation of pitches by oxidative polymerization of an industrial anthracene oil (AO) in a microwave semi-pilot equipment consisting in a multimode applicator having a 2.45 GHz magnetron with variable microwave power. The experimental five variables of microwave heating of AO air-blowing range between 320-380 ˚C (temperature), 0.2 - 3.9 ˚C min-1 (heating rate), 1.5 - 5 h (soaking time), 16 – 20.5 % (air/AO ratio ) and 200 – 1500 g (initial weight). Their effect on the overall microwave air-blowing process is evaluated by means of a statistical analysis. A detailed characterization of the pitches has been carried out in terms of ultimate analysis, softening point, solubility parameters (toluene insolubles (TI) and quinoline insolubles (QI)) and thermogravimetric analysis. The experiments were also carried out by using conventional heating for comparative purposes. The detailed study of the electric energy consumption of the overall microwave treatment allows estimating a significant electric energy saving of about 20 % when compared to conventional heating thus representing an excellent result in the production of carbon precursors

Carbon materials from conventional/unconventional technologies for electrochemical energy storage devices

In the last years our society has shown a growing interest on the development of both new sources of clean energy and advanced devices able to store it. In this context supercapacitors (SCs) and hybrid systems have emerged to cover the power and energy demands. Most of these electrochemical devices use carbon materials as electrodes being the activated carbons (ACs) the most commonly ones. Nonetheless graphene (G) has emerged as a promising electrode either by itself or combined with ACs in composites. This work investigates the use of a low added value coal-derived liquid (anthracene oil, AO) for the production of pitch-like carbon precursors to synthesize suitable active electrode materials (ACs, G, AC/G) in SCs and hybrid systems. In addition to the well-known oxidative thermal polymerization of AO, a new alternative based on the use of microwave heating is presented as a promising clean route to obtain such carbon precursors resulting in energy saving, shortening time and specific nonthermal effects. The characteristics of the carbon materials obtained from both conventional/ unconventional technologies are compared mainly in terms of their specific surface area, surface chemistry and electrical conductivity which would allow the design of energy storage devices with an improved electrochemical performance

Precursors of volatile organic compounds emitted during phosphorite processing

The composition of solvent-soluble organic matter of phosphorite, which is a precursor of volatile organic compounds emitted by the fertilizer industry, was studied. A benzene-methanol mixture and chloroform were used for the extraction of free and bound bitumen from phosphorites, respectively. The separated bitumen fractions were characterized qualitatively by GC-MS and quantitatively by GC-FID. n-Alkanes, n-alkenes, fatty acids and isoprenoids were identified in the extracts. The main components were n-alkanes and n-alkenes, constituting over 80% of the total bitumen determined. An unexpected presence of n-alkenes only in the free bitumen fraction was found. The possible source of ill-smelling substances evolved during treatment of phosphorite with H2SO4 was discussed