Guy Reggers

A study of the reductive pyrolysis behaviour of sulphur model compounds

Abstract The difficulties inherent in the direct determination of sulphur functionalities in complex solid matrices by various techniques often make the need for reference compounds indispensable. One of the pyrolysis techniques used for sulphur determination is atmospheric pressure–temperature programmed reduction (AP-TPR). Experiments on sulphur model compounds have served successfully as a reference for both the temperature region in which the reduction or hydrogenation occurs and the efficiency of the reduction reaction. In this study, the pyrolysis behaviour of several organic and inorganic sulphur model compounds is investigated by AP-TPR using a mass spectrometer detector interfaced with the pyrolysis reactor (AP-TPR-MS). This technique permits a more complete description of the competitive and successive reactions that are occurring during the pyrolysis of the model compounds, providing new information regarding the reduction efficiency of oxidised and non-oxidised sulphur compounds.

TG-GC-MS, TG-MS and TG-FTIR applications on polymers and waste products

Abstract A latex is studied using the off-line combination, TG-GC-MS. A mixture, CuSO 4 ·5H 2 O-cellulose, is studied using the online combination, TG-MS, and the amount of HCN in gases released by heating of a waste product is determined using the online combination of TG-FTIR, successive sampling, FIA and photometry.

Characterization of organic sulfur functional groups in coal by means of temperature programmed reduction

Abstract An experimental set-up is described for the characterization of organic sulfur-containing functional groups with a temperature programmed reduction method (TPR). Both a low sulfur and a high sulfur coal have been analysed. The influence of pyrite on the measurements has been studied. The results show that most of the types of sulfur functional groups could be tentatively assigned in the coals. Removal of pyrite slightly improves the resolution. It is shown for the low sulfur coal that thiophenic sulfur constitutes most of the organic sulfur and that the thiolic sulfur does not contribute significantly to the total organic sulfur.

Description of the nanostructured morphology of [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) by XRD, DSC and solid‐state NMR

PCBM or [6,6]‐phenyl‐C61‐butyric acid methyl ester is nowadays still one of the most successful electron acceptors for plastic bulk heterojunction (BHJ) photovoltaic devices. In this study, a set of complementary techniques, i.e. solid‐state NMR, XRD and DSC, is proposed as a fast and sensitive tool to screen the morphology of PCBM specimens with different preparation histories. Based on proton NMR relaxation decay time values, an interval can be derived that situates the average crystal dimensions and which can further be refined on the basis of XRD patterns and DSC thermograms. Copyright

The determination of the gases released during heating of a flame retardant for polymers

The oxidative degradation of HET-acid (1,4,5,6,7,7-hexachlorobicyclo [2.2.1] hept-5-en-2, 3-dicarboxylic acid) is studied by the combination of TG, FTIR, MS and GC-MS. The gases evolved during the decomposition of this flame retardant are investigated on-line by FTIR and by MS. Simultaneously the evolved gases are collected by an adsorbent and, after the thermal experiment, desorbed to release the volatile products for identification using GC-MS. The combination of these techniques offers the unambiguous identification of the evolved products as a function of temperature. The main identified products are CO2, H2O, Cl2, HCl, C2Cl4, maleic acid anhydride, HET-acid anhydride, chlorinated cyclic hydrocarbons and chlorinated unsaturated linear hydrocarbons.

Coupling between FTIR (Bruker IFS 66) and TG (Du Pont TGA 951–2000)

Abstract In our laboratory for the first time a combination between the Bruker IFS 66 FTIR spectrometer and the Du Pont TGA 951–2000 was realized. The interface allows the spectral monitoring of gases evolving from heated samples in the TGA system. The purpose of this paper is to demonstrate the capabilities of the instrumentation and the software.

An investigation into the changes of structure and reactivity during desulphurization of a bituminous coal

Abstract A bituminous coal has been treated with molten (non-aqueous) caustic using several reaction temperatures and times. The caustic treatment removed all the pyritic sulphur and up to 80% of the organic sulphur. The extent of organic sulphur removed, as determined directly by scanning electron microscopy and energy-dispersive X-ray analysis (SEM-EDX), was linearly dependent on temperature. Optimal desulphurization conditions were investigated and correlated with losses in calorific value. The fate of pyrite and the organic sulphur functional groups during the desulphurization procedure was followed by the recently developed technique of temperature programmed reduction (TPR). Pyrite and the thermally labile sulphur compounds were removed, and with increasing desulphurization temperatures and times the thiophenic compounds were also removed. It has also been possible to follow the desulphurization quantitatively with TPR, i.e. the amount of aliphatic sulphur removed as indicated by the elemental analysis was the same as the amount obtained from the integrated TPR signals. These results underline the value of the TPR method as a technique for following sulphur functional group distribution during coal processing. The effect of the caustic treatment on the microstructure was clearly noticeable on the SEM micrographs showing the formation of depressions and microfissures and fragmentation into smaller particles. At higher reaction temperatures solid state 13 C cross-polarization and magic angle spinning nuclear magnetic resonance ( 13 C CP/MAS) indicated an increased carbon aromaticity ( f C a ) and an increase of the non-protonated aromatic fraction ( f NP a ).

Thermogravimetric desorption and de novo tests I: method development and validation.

Thermogravimetric analysis (TGA) has been combined with evolved gas analysis (EGA) with the purpose of simulating the thermal behaviour of filter dust samples under inert (desorption) and de novo test oxidising conditions. Emphasis is on studying de novo formation of dioxins, surrogates and precursors arising from filter dust derived from thermal processes, such as municipal solid waste incineration and metallurgy. A new method is tested for sampling and analysing dioxin surrogates and precursors in the TGA effluent, which are collected on sampling tubes; the adsorbed compounds are eventually desorbed and quantified by TD-GC-MS. The major sources of error and losses are considered, including potential sorbent artefacts, possible breakthrough of volatiles through sampling tubes, or eventual losses of semi-volatiles due to their incomplete desorption or re-condensation inside the TG Analyser. The method is optimised and validated for di- to hexa-chlorinated benzenes in a range of 10-1000 ppb with average recovery exceeding 85%. The results are compared with data obtained in similar studies, performed by other research groups. As a result, the method provides the means for simulating de novo synthesis of dioxins in fly-ash and facilitates reliable and easy estimation of de novo activity, comparable with results of other studies, in combination with wide flexibility of testing conditions.

TG-MS analysis as tool for the evaluation of clay mixtures

The evolved gases after thermal treatment of a series of clay samples are studied using on-line TG-MS and off-line TGA-GC-MS.

Atmospheric Pressure Temperature Programmed Reduction (AP-TPR) as a tool to investigate the changes in sulphur functionalities in solid fuels

This research contribution reports the preliminary interpretation of the results of selective desulphurization procedures of a Bulgarian lignite, Maritza-Iztok. The AP-TPR profiles can be explained in view of the selective treatments used. In addition, the importance of heat recovery for the products obtained is discussed.