Jillian M. Thompson

Highly selective and efficient hydrogenation of carboxylic acids to alcohols using titania supported Pt catalysts

Selective hydrogenation of carboxylic acids to alcohols and alkanes has been achieved under remarkably mild reaction temperatures and H(2) pressures (333 K, 0.5 MPa) using Pt/TiO(2) catalyst.

Dramatic solvent effects on ring-opening metathesis polymerization of cycloalkenes

Abstract A series of metathesis polymers and copolymers have been formed and their structures were analysed by 13 C NMR spectroscopy. Noble metal and non-noble metal salt catalysts are distinguished by their behaviour in various solvents. Thus, in phenolic solvents, the former class produce alternating copolymers from cyclopentene and norbornene, while the latter are unaffected and produce random copolymers. In contrast, ether solvents have the effect of markedly increasing the cis content of polymers from the latter catalysts while the former are unaffected. The tacticity of various polymers are correlated through their hydrogenated derivatives and found to depend on the type of monomer as well as the catalysts.

Doubly dual nature of ammonium-based ionic liquids for methane hydrates probed by rocking-rig assembly

This work presents a systematic study of methane hydrate inhibition in the presence of five structurally variable ionic liquids (ILs) belonging to the ammonium family—viz., tetra-alkylammonium acetate (TMAA), choline butyrate (Ch-But), choline iso-butyrate (Ch-iB), choline hexanoate (Ch-Hex) and choline octanoate (Ch-Oct). For this purpose, hydrate equilibrium curves have been obtained for methane in pure water and in 1 and 5 wt% aqueous solutions of ILs using a rocking cell apparatus (RC-5). Thermodynamic hydrate inhibition and promotion efficiency in each IL has been thoroughly investigated by observing the shifts in the hydrate equilibrium curves and trends of the calculated hydrate suppression temperatures (ΔT). The results were also obtained for methanol to validate the apparatus and compare the inhibition efficiency of ILs. Molar hydrate dissociation enthalpies (ΔHdiss) were obtained for the studied systems using the Clausius–Clapeyron equation and showed that ILs do not participate in forming the hydrate cages. The induction time (tind) data reveal that some of the studied ILs delay the time of hydrate formation, thereby indicating a potential kinetic inhibitor effect. The tested ILs exhibited a variety of phenomena, such as hydrate inhibition, hydrate stabilization, kinetic effect and surfactant-like behavior, which emphasize the use of ILs as potential gas hydrate inhibitors.

Improved Efficiency for Partial Oxidation of Methane by Controlled Copper Deposition on Surface‐Modified ZSM‐5

The mono(μ‐oxo) dicopper cores present in the pores of Cu‐ZSM‐5 are active for the partial oxidation of methane to methanol. However, copper on the external surface reduces the ratio of active, selective sites to unselective sites. More efficient catalysts are obtained by controlling the copper deposition during synthesis. Herein, the external exchange sites of ZSM‐5 samples were passivated by bis(trimethylsilyl) trifluoroacetamide (BSTFA) followed by calcination, promoting selective deposition of intraporous copper during aqueous copper ion exchange. At an optimum level of 1–2 wt % SiO2, IR studies showed a 64 % relative reduction in external copper species and temperature‐programmed oxidation analysis showed an associated increase in the formation of methanol compared with unmodified Cu‐ZSM‐5 samples. It is, therefore, reported that the modified zeolites contained a significantly higher proportion of active, selective copper species than their unmodified counterparts with activity for partial methane oxidation to methanol.

Alternating ring-opening metathesis copolymerization of bicyclo[2.2.1]hept-2-ene and cyclopentene

Almost alternating copolymers of bicyclo[2.2.1]hept-2-ene and cyclopentene have been formed by ring-opening metathesis polymerization using a RuCl3–phenol catalyst system; this highly novel result is attributed to differential steric influences exerted by a hydrogen-bonded solvent cage which encloses the catalyst site.

First evidence for radical anions in metathesis catalysis

The Grubbs’ catalyst, (PCy3)2RuCl2(CHPh), generates persistent radical anions on treatment with π-acceptors such as p-benzoquinones and a remarkably wide range of dienes and even simple alkenes.

Surface hydrophobicity and acidity effect on alumina catalyst in catalytic methanol dehydration reaction

Abstract BACKGROUND Methanol to dimethyl ether (MTD) is considered one of the main routes for the production of clean bio‐fuel. The effect of copper loading on the catalytic performance of different phases of alumina that formed by calcination at two different temperatures was examined for the dehydration of methanol to dimethyl ether (DME). RESULTS A range of Cu loadings of (1, 2, 4, 6, 10 and 15% Cu wt/wt) on Al2O3 calcined at 350 and 550 °C were prepared and characterized by TGA, XRD, BET, NH3‐TPD, TEM, H2‐TPR, SEM, EDX, XPS and DRIFT‐Pyridine techniques. The prepared catalysts were used in a fixed bed reactor under reaction conditions in which the temperature ranged from 180–300 °C with weight hourly space velocity (WHSV) = 12.1 h‐1. It was observed that all catalysts calcined at 550 °C (γ‐Al2O3 support phase) exhibited higher activity than those calcined at 350 °C (γ‐AlOOH), and this is due to the phase support change. Furthermore, the optimum Cu loading was found to be 6% Cu/γ‐Al2O3 with this catalyst also showing a high degree of stability under steady state conditions and this is attributed to the enhancement in surface acidity and hydrophobicity. CONCLUSION The addition of copper to the support improved the catalyst properties and activity. For all the copper modified catalysts, the optimum catalyst with high degree of activity and stability was 6% copper loaded on gamma alumina.

Olefin / Paraffin separation using Task-Specific Materials based on Ionic Liquids: Advances in Gas Processing

Abstract In this work, 1-hexene was extracted from its mixtures with n-hexane in varying ratios using a task specific ionic liquid. Herein, the ionic liquid (IL) 1-butyl-3-methylimidazolium nitrate, [BMIM][NO3], was used and examined with and without the addition of a metal salt. The impact of water on both selectivity and distribution coefficient was also tested. Four potential metal salts were investigated, the results of which demonstrate that the dissolution of transition-metal salts in the IL improves the separation of 1-hexene from n-hexane through metal-olefin complexation. Additionally, the presence of water in IL solutions containing metal salt enhances this selectivity. Finally, UNIFAC was used to correlate the experimental LLE data with good accuracy.