Professor Michael Stockenhuber

© 2017 Elsevier Ltd A new coupled thin layer chromatography-imaging mass spectrometry method was developed to investigate solvent extracts from a coal. The technique was used to assess the separation of complex molecular structures in a tetrahydrofuran (THF) soluble extract taken from a semi-coke (the solid residue obtained after thermal pre-treatment of coal at 430¿°C). Thin layer chromatography (TLC) was then used with acetone as a mobile phase and silica as a stationary phase. The component separation was determined by laser desorption/ionisation time-of-flight imaging mass spectrometry (i.e. TLC-LDI-IMS). This provided the molecular weight distributions and spatial concentrations of coal derived structures observed over the TLC plate. In general, acetone lifted and concentrated lighter molecular species in the range of 200¿500¿Da by up to 55% compared to the THF extract. Structures of 500¿1000¿Da in molecular weight were lifted, but to lesser extent, distributing these more evenly across the TLC plate. The structures observed in the acetone-concentrate repeated every 12¿14¿Da as in a homologous series, similar to previous studies. Residual material remaining in the sample (unascended by the mobile phase) showed repeating structures every 24¿Da from 600¿3000¿Da, also similar to previous work. A novel methodology was also evaluated using the TLC plate as a heated substrate for inducing and studying cross-linking reactions. Acetone soluble material between 200¿500¿Da was loaded onto the TLC plate and heated to 250¿°C. This was found to convert the low molecular weight compounds into more complex structures between 1500 and 4000¿Da. Direct use of a MALDI-suitable TLC plate as a reaction surface provided a means of characterising the high molecular weight products without the need for a solvent to transfer material onto a second MALDI analysis plate. This avoided limitations in molecular weight with solvent solubility. Overall, the TLC-LDI-IMS method was shown to be a suitable method for tracking the separation and potential cross-linking mechanisms involved in coal derived extracts.

© 2016 Elsevier B.V. This paper presents the results of dichloromethane (DCM) decomposition to polymers utilising dielectric barrier discharge under non-oxidative reaction conditions. The conversion levels, mass balance, reaction mechanism and polymer characterisation in relation to DCM reaction are presented in this paper. Reaction pathways describing the decomposition of DCM and subsequent formation of the major products are outlined. Speculation of the mechanism of formation of CHCl 3 and C 2 HCl 3 are supported by quantum chemical calculations. In addition, the effect of introducing methane in the reaction feed on the conversion level of DCM and the polymer structure is also examined in this paper.

© 2015 Elsevier Ltd. This work has used high range imaging mass spectrometry to study a coal sample that has undergone heating with a temperature gradient. A custom made hotplate was heated to 1000°C and the coal was allowed to heat naturally through conduction to produce a large thermal gradient typical of conditions in a coke oven. The sample was quenched, sectioned and analysed using laser desorption time of flight imaging mass spectrometry (LDI-TOF-IMS) to study the molecular changes that occur within the plastic layer and in the semi-coke. The raw coal was observed to have a molecular weight range between 500 and 20,000 Da with a peak occurring at 2000 Da. The plastic layer was observed to have a prevalence for increasing 500-1000 Da structures though this formed part of the larger molecular weight range. Resolidification of the plastic layer coincided with a rise in 4000 Da structures. The semi-coke spectrum had a series of repeating peaks separated by 24 Da extending from 1000 Da to 3000 Da. This was considered evidence of broad molecular ordering. A second phenomenon was observed in the semi-coke associated with low range molecular weights (50-300 Da). This appeared as high intensity signals in a molecular range typically considered as ion fragments (being too low in size to remain in the high vacuum environment). It was speculated that these low range structures may be associated with the coking of volatile tars exiting the hot-side of the plastic layer through high temperature semi-coke. Overall, this preliminary work provides a novel methodology to study the heating impacts during coking on a molecular level.

© the Owner Societies 2016. A novel Pd supported on TS-1 combustion catalyst was synthesized and tested in methane combustion under very lean and under highly humid conditions ( < 1%). A notable increase in hydrothermal stability was observed over 1900 h time-on-stream experiments, where an almost constant, steady state activity obtaining 90% methane conversion was achieved below 500 °C. Surface oxygen mobility and coverage plays a major role in the activity and stability of the lean methane combustion in the presence of large excess of water vapour. We identified water adsorption and in turn the hydrophobicity of the catalyst support as the major factor influencing the long term stability of combustion catalysts. While Pd/Al 2 O 3 catalyst shows a higher turn-over frequency than that of Pd/TS-1 catalyst, the situation reversed after ca. 1900 h on stream. Two linear regions, with different activation energies in the Arrhenius plot for the equilibrium Pd/TS-1 catalys t, were observed. The conclusions were supported by catalyst characterization using H 2 -chemisorption, TPD, XPS analyses as well as N 2 -adsorption-desorption, XRD, SEM, TEM. The hydrophobicity and competitive adsorption of water with oxygen is suggested to influence oxygen surface coverage and in turn the apparent activation energy for the oxidation reaction.

© 2017. The effect of transition metals on the activity and selectivity of a Ni/Al 2 O 3 catalyst for carbon oxides hydrogenation was studied. It is found that each transition metal has different and distinct promoting or inhibiting influence. Nitric oxide was used as a probe molecule to study the electronic structure of a primary and two bi-metallic catalysts. Based on a series of catalyst activity and selectivity experiments, promoted bimetallic catalysts which enhanced and inhibited the activity and selectivity of the primary Ni/Al 2 O 3 catalyst were analysed by NO-FTIR experiments. The presence of multiple sites, with different electronic properties, were observed. It is concluded that the addition of transition metals to Ni/Al 2 O 3 markedly changed the electronic structure of the primary catalyst. Hydrogen and carbon monoxide chemisorption experiments showed that the ratio of CO/H chemisorbed species was affected by addition of Mn and Cu to Ni/Al 2 O 3 . Temperature programmed desorption of H 2 and CO confirmed the presence of different active sites on Ni/Al 2 O 3 .

© 2016 Elsevier B.V. In this contribution, the development of a process for the synthesis of potentially highly valuable polymeric products from the reaction of waste glycerol with ammonia is reported for the first time. The polymers were the result of a single step, continuous gas phase process, catalysed by an alumina-supported iron catalyst, operating under relatively mild reaction conditions. The solid product was characterised using 1D and 2D NMR spectroscopy, FTIR spectroscopy, qualitative chemical tests and elemental analysis. Characterisation revealed building blocks with unsaturated, amido and ester functionalities shaping a mixture of polymers. Nitrogen atoms were present in the main chain of the resultant polymers. NMR analyses of the polymer denotes the formation of structural defects such as unsaturation and branching; whilst the partial solubility of the polymer in solvents such as CDCl 3 and THF is indicative of the formation of cross-linked structures. Insights into the mechanism of formation of these functional groups were based on the liquid and gas phase product distribution. Polymers with chain structures similar to those synthesised in this work are currently manufactured from fossil fuels and are widely used in biomedical applications not only because of their architecture but also due to their response to changes in pH and temperature.

© 2015 The Institution of Chemical Engineers. An increased interest in using hydrocarbons in solid oxide fuel cells for the production of power has led to research into operation on synthesis (syn) gas, a mixture of hydrogen and carbon monoxide. Hydrocarbons are typically reformed, either internally or in an external reformer prior to the fuel cell, producing syngas with various H < inf > 2 < /inf > :CO ratios depending on the hydrocarbon used. This paper examines the effect of varying the H < inf > 2 < /inf > :CO ratio with respect to C < inf > 1 < /inf > to C < inf > 4 < /inf > steam reforming reactions and additionally a mixture containing a higher ratio of carbon monoxide. It was found that there was no significant relationship between cell performance and H < inf > 2 < /inf > :CO ratio when a high feed rate was employed. For low flow rates, however, the high carbon monoxide concentration resulted in a significant decrease in cell performance. It was determined that this was caused by reversible carbon deposition as opposed to a decrease in carbon monoxide reactivity.

© 2014 Elsevier B.V. All rights reserved. Nano-sized Co 3 O 4 , Fe 2 O 3 , Au/Co 3 O 4 and Au/Fe 2 O 3 catalysts were prepared and evaluated for catalytic combustion of lean methane-air mixtures. Characteristics and catalytic activities under dry and wet feed conditions were investigated at gas hourly space velocities up to 100 000 h -1 mimicking the typical flow and conversion requirements of a catalytic system designed to treat a ventilation air methane stream. In order to gain a better understanding of the interaction between H 2 O and the catalyst surface, temperature-programmed desorption of water over fresh and used samples were studied, and supported by other catalyst characterization techniques such as N 2 -adsorption desorption, XRD, TEM, SEM and XPS analyses. The activity measurements of the catalysts studied identify Co 3 O 4 as the most active material. Co-precipitating gold particles with cobalt oxide or iron oxide do not enhance the activity of the catalyst, which is most likely due to blocking the active site of support by the gold particle. The presence of strong hydroxyl bonds on the catalyst surface is substantiated by TPD and XPS analyses, and is suggested to be responsible for the rapid deactivation of Fe 2 O 3 and Au/Fe 2 O 3 catalysts.

© 2014 Elsevier B.V. All rights reserved. Reagents from a base catalysed condensation reaction (Knoevenagel condensation reaction between ethyl cyanoacetate and benzaldehyde), were adsorbed on ZnO and Al < inf > 2 < /inf > O < inf > 3 < /inf > catalyst surfaces and subject to temperature programmed desorption experiments, monitored using mass spectrometry. Ethyl formate, ketenimine species, carbon dioxide and carbon monoxide were desorption products from ethyl cyanoacetate, while benzene, carbon dioxide and carbon monoxide were desorbed from the catalysts loaded with benzaldehyde. The formation of the ketenimine species was confirmed by in situ FTIR experiments. The observation of the decomposition species further substantiates a proposed reaction mechanism for the Knoevenagel condensation reaction on the catalyst surface of some oxide catalysts.

Reaction of phenol with hydrogen peroxide over H-MFI, Fe-MFI, H-BEA, Fe-BEA and TS-1 zeolite catalysts was investigated. Over H-BEA, biphenyl product was observed. It is suggested, that the larger pore size of H-BEA facilitates coupling of two phenol molecules. Two distinct reaction mechanisms are proposed for acid and redox catalysts. © 2013 Springer Science+Business Media New York.

In this paper we focus on the development of a methodology for treatment of carbon tetrachloride utilising a non-equilibrium plasma operating at atmospheric pressure, which is not singularly aimed at destroying carbon tetrachloride but rather at converting it to a non-hazardous, potentially valuable commodity. This method encompasses the reaction of carbon tetrachloride and methane, with argon as a carrier gas, in a quartz dielectric barrier discharge reactor. The reaction is performed under non-oxidative conditions. Possible pathways for formation of major products based on experimental results and supported by quantum chemical calculations are outlined in the paper. We elucidate important parameters such as carbon tetrachloride conversion, product distribution, mass balance and characterise the chlorinated polymer formed in the process. © 2014 Elsevier B.V.

Conversion of glycerol to allyl alcohol was carried out over an iron on alumina catalyst. With the aim of enhancing selectivity towards the desired product and to reduce acrolein formation (a detrimental impurity in the subsequent epoxidation of allyl alcohol) the supported iron catalyst was modified using alkali metals. It was found that lithium, sodium, potassium, rubidium and caesium deposition on the catalyst surface increased allyl alcohol yield and reduced the rate of catalyst deactivation. Coincidently, acrolein selectivity decreased by up to 75% following treatment with the alkali salt.Changes in the product distribution were determined to be associated with altering the acid/base properties of the catalyst, as confirmed by isopropanol dehydration/dehydrogenation, ammonia and carbon dioxide temperature programmed desorption. The treatment was also found to influence the physical properties of the catalyst surface. A correlation between acid to basic site concentration and allyl alcohol selectivity was established. A reduction in the former value results in an enhancement in the rate of allyl alcohol formation. A reaction mechanism was developed based on the effect of iron and alkali metals catalysing the conversion of glycerol into allyl alcohol. The proposed catalyst modification technique is a straightforward method, readily applicable at a larger scale due to the simplicity of the alkali inclusion and its striking influence on the reaction selectivity. © 2014.

In this paper, we report new insights into the deactivation phenomenon of palladium based catalysts for catalytic combustion of ventilation air methane (VAM). It was found that the primary factor responsible for low temperature catalyst deactivation is the water vapour present in the feed stream. The influence of water vapour on VAM was examined by comparing the properties of fresh catalysts with catalysts following over 1000 h reaction time-on-stream. The techniques applied to characterize the catalysts included TPD, XRD, N 2 -isotherm adsorption, H 2 -chemisorption and XPS analyses. Alternating between dry and water vapour-saturated VAM feed disclosed ca. 50% reversible drop in activity. XPS analysis suggests an absence of a palladium hydroxide phase during the initial 2 h on stream, although prolonged exposure to the reactant leads to the formation of palladium hydroxide, which appears to match the progressive deactivation of the Pd/Al 2 O 3 catalyst. Introduction of VAM dust (a mixture of fine coal, CaCO 3 and aluminosilicate particles) causes a variation in catalytic activity originating from coal-dust ignition and the effect of chloride on the surface of the catalyst. In the presence of these inhibiting agents, an average methane conversion of higher than 75% over 1100 h was achieved at reaction temperatures below 600°C. This journal is © the Partner Organisations 2014.

A continuous process for the conversion of glycerol to allyl alcohol, where ammonia or organic acids are added to the feed as sacrificial reductants, was investigated. Significant enhancement on the rate of formation and yield of the allyl alcohol is observed with some of the reducing agents examined over an alumina-supported iron catalyst. Optimising the molar ratio of the reductant relative to feed glycerol results in an increase in the yield of allyl alcohol from 9% (in the absence of additives) to 11.3% with ammonia, 15.1% with ammonium hydroxide, 17.8% with oxalic acid and 19.5% with formic acid. Moreover, the addition of other organic acids, which are produced in a typical glycerol conversion experiment, was studied. However, acetic and propanoic acids had little effect on the rate of formation of allyl alcohol. Analysis of the product distribution in the liquid and gas phases when oxalic and formic acids were added suggests a two-step process for the formation of allyl alcohol under the operating conditions of the reaction; the initial step involves the dehydration of glycerol while the second comprises the reduction of the species produced in step one. © the Partner Organisations 2014.

The adsorption complex of hydrogen chloride on copper-modified ZSM-5 was studied by FTIR and theoretical calculations. The results indicate that the Cl atom of hydrogen chloride is bound to the Cu cations when adsorbed at low pressures ( < 1 µbar). At higher pressures, HCl adsorbs on the zeolite Brønsted acid sites as well as is hydrogen bonded to the Cu in a larger cluster. Using in situ infrared spectroscopy, we observed a sharp decrease in stretching vibrational frequency of HCl of about 700 cm -1 compared with the H-Cl stretching vibration of gaseous hydrochloric acid. The findings were supported by density functional theory cluster quantum chemical calculations. © 2013 American Chemical Society.