Neil R. Foster

Direct catalytic oxidation of methane to methanol — a review

Abstract There is considerable incentive for the development of a process for onsite conversion of large uncommitted reserves of natural gas into a product which can be transported more cheaply than liquefied natural gas (LNG). A prime candidate for this purpose is methanol, a liquid which can either be used as a transport fuel itself or be converted to gasoline using the Mobil methane-to-gasoline (MTG) process. A potential route is the direct catalytic partial oxidation (CPO) of natural gas to methanol. Considerable research has been undertaken in this area using both atmospheric and elevated pressures. The potential advantage of this route is that it eliminates the steam reforming step. Whilst it has been demonstrated that the CPO reaction is technically feasible, a reaction system which gives commercially viable per pass conversion and selectivity has not yet been developed. However, more recent results show significant promise.

Tetralin decomposition in short contact time coal liquefaction

Abstract Tetralin was passed through a fixed-bed continuous microreactor in the presence and absence of Liddell vitrinite concentrate at 13.8 MPa nitrogen pressure. Temperatures ranged from 350 to 460 °C, with a 5 min liquid contact time. The liquid products were examined by capillary g.c. and g.c.-m.s. It was noted that naphthalene formation was catalysed by the vitrinite concentrate at these temperatures and that the reaction was limited by the rate of mass transfer of tetralin to the catalyst surface. The formation of 1-methylindan was also influenced by the addition of coal and it is inferred that the mechanism of tetralin isomerization must include a multimolecular step.

Initial solvation of coal with tetralin under liquefaction conditions

Abstract Secondary vitroplast, produced by treating a Liddell vitrinite concentrate with tetralin in a continuous flow, packed-bed microreactor under a nitrogen pressure of 13.8 MPa at 360, 410 and 460 °C, has been analysed by i.r. spectroscopy, gel permeation chromatography, solid state 13C n.m.r. and reflectance microscopy. Results showed that this intermediate in the liquefaction process had the same carbon aromaticity as the untreated vitrinite concentrate and that both its aromaticity and reflectance were independent of the temperature of formation. It was concluded that the initial solution of the vitrinite concentrate in tetralin involved no significant hydrogenation of the vitrinite.

Formation of pyrolytic carbon in a continuous reactor for coal hydrogenation

Abstract Microscopic examination of blockage material from the CSIRO laboratory-scale continuous reactor for coal hydrogenation has indicated the presence of pyrolytic carbon. Both the morphology and abundance of pyrolytic carbon were variable. In some samples pyrolytic carbon spheres (≈ 1 μm) formed large deposits with clear zonal texture. Spherical agglomerates (up to 70 μm) of these particles, and large particles were also observed. In some cases spherulitic pyrolytic carbon was embedded in vitroplast and/or mesophase. The occurrence of pyrolytic carbon in continuous reactors for coal hydrogenation is significant as it can provide, in the absence of other information, a posteriori indication of undesirable reaction conditions, i.e. large gas hold-ups and localized overheating.

Surface changes in coal hydrogenation autoclaves that affect autoclave reactions

Abstract The morphology and chemical composition of the internal wall of a batch autoclave reaction vessel, which had been extensively used for coal hydrogenation studies, have been investigated. Pits resulting from corrosion of the vessel wall were found to contain three types of deposit. Two of the deposits are of carbonaceous and siliceous matter and can be regarded as non-catalytic. The third type of deposit consists of mixed sulphides. These are known to exert a catalytic effect in coal hydrogenation. The results show that a steel reaction vessel used for coal hydrogenation can retain ‘memory effects’ from previous experiments.

Short contact time dissolution of Liddell coal

Abstract The thermal dissolution of Liddell coal in tetralin at 400 °C proceeds rapidly. The addition of hydrogen to coal under moderate, uncatalysed conditions is significant and initially proceeds without the elimination of nitrogen, oxygen or sulphur. At extended reaction times, however, oxygen is eliminated via hydrogenolysis reactions. The simulation of product distributions from the thermal dissolution of Liddell coal at 400 °C, and short contact times, has been undertaken using a system of second-order pseudo-kinetic equations. Excellent agreement between the experimental data and the calculated conversions has been obtained.

Simulation of chemical rate processes in short contact time coal liquefaction

Abstract Conversions and product distributions from the thermal dissolution of Liddell coal in the presence of tetralin have been simulated by a system of second-order rate equations. Satisfactory correlation with experimental data is obtained over the range of temperatures studied, i.e. 380–420 °C.

Application of neutron techniques to studies of reactor fluid dynamics

Abstract Techniques have been developed for determining residence time distributions, flow rates and levels or distributions of materials contained inside reactor vessels with metal walls. The techniques, which utilize the scattering and absorption of neutrons emitted from a small encapsulated neutron source, are non-intrusive, suitable for use on thick-walled vessels, do not require radioactive tracers to be used and are especially suited to the study of systems containing hydrogen. The results of studies of flow and phase distributions in a variety of laboratory bubble column reactors show that the techniques are suitable for detecting liquids in vessels with wall thicknesses of up to 100 mm and for detecting tracer concentrations as low as 0.005 wt. %.

Donor interactions of 1-methylindan in coal liquefaction

Abstract Liddell vitrinite concentrate was treated at 380 and 420 °C for 30 min in a batch autoclave pressurized to 13.8 MPa with either nitrogen or hydrogen. Tetralin or 1-methylindan was used as the donor solvent and comparative analysis of the products was carried out. The results indicate that at 380 °C 1-methylindan is a poor donor when compared to tetralin and at 420 °C these differences become significant. It is concluded that 1-methylindan forms adductive and polymeric materials, formation of the latter being suppressed by gaseous hydrogen.

Short contact time dissolution of vitrinite and inertinite concentrates

Abstract The short contact time dissolution of vitrinite and inertinite concentrates of an Australian bituminous coal was studied under isothermal conditions with tetralin as solvent. The reactivity of the two maceral types and the yields and nature of the products were determined for a range of reaction temperatures (400, 420 and 440 °C) and reaction times (2–20 min). The dissolution of vitrinite proceeded at a significantly greater rate than for inertinite and was associated with greater selectivity to soluble non-gaseous products. At very short reaction times (2 min), the vitrinite underwent solubilizing reactions to yield products of higher molecular weight and greater oxygen functionality than was the case for inertinite, for which changes in the chemical nature of the products were negligible over the range of conditions studied. At longer reaction times (5 min), the composition of the vitrinite-derived products was similar to that of the inertinite-derived products.