Anthony V. Cugini

Clean liquid fuels from direct coal liquefaction: chemistry, catalysis, technological status and challenges

Increased demand for liquid transportation fuels coupled with gradual depletion of oil reserves and volatile petroleum prices have recently renewed interest in coal-to-liquids (CTL) technologies. Large recoverable global coal reserves can provide liquid fuels and significantly reduce dependence on oil imports. Direct coal liquefaction (DCL) converts solid coal (H/C ratio ≈ 0.8) to liquid fuels (H/C ratio ≈ 2) by adding hydrogen at high temperature and pressures in the presence or absence of catalyst. This review provides a comprehensive literature survey of the coal structure, chemistry and catalysis involved in direct liquefaction of coal. This report also touches briefly on the historical development and current status of DCL technologies. Key issues, challenges involved in DCL process and directions for the future research are also addressed.

Modeling clathrate hydrate formation during carbon dioxide injection into the ocean

Because of carbon dioxides potential role in global warming, there is considerable interest in methods of long-term sequestering of anthropogenic emissions of CO[sub 2] outside of the atmosphere. The work reported here predicts the effect of hydrate formation on the fate of CO[sub 2] droplets discharged into the ocean under hydrate-forming conditions. New information on hydrate growth rates recently determined by one of the authors is incorporated into the model. It is seen that hydrate film formation on CO[sub 2] droplets into the deep ocean will increase estimates of required injection depths and decrease the maximum allowable droplet size suitable for effective sequestration to occur. 13 refs., 2 figs.

Development of a dispersed iron catalyst for first stage coal liquefication

Abstract A procedure yielding a very small particle size iron catalyst for coal liquefaction has been developed at the Pittsburgh Energy Technology Center. This procedure has two important components. The first is incipient wetness impregnation of coal with an aqueous solution of ferric nitrate (subsequently converted to hydrated iron oxide by contact with ammonium hydroxide). The second is proper time/temperature activation of the iron under a gaseous atmosphere of H2/H2S to produce pyrrhotite. In continuous operations, an optimum preliquefaction temperature of 275° C was observed for the activation of hydrated iron oxide in the presence of Illinois No. 6 coal. The net effect of proper implementation of this procedure was the development of a finely divided iron catalyst that exhibited high levels of activity in comparisons with molybdenum catalysts.

Observations of CO2 clathrate hydrate formation and dissolution under deep-ocean disposal conditions

Publisher Summary This chapter discusses the observations and implications for the effective disposal of carbon dioxide (CO 2 ) in the ocean. Simply discharging the CO 2 at great depths may be insufficient if hydrate coatings form on liquid droplets of CO 2 . Observations of single droplets indicate that the coating may impede the dissolution and permit the CO 2 droplet to rise to unacceptably shallow depths. The possibility of growth of the hydrate shell cannot be ruled out based on the observations of single droplets. If CO 2 is not dissolved, then the growth of the hydrate coatings becomes more likely, especially as droplets collide and fresh CO 2 is released. Density observations indicate that pure hydrates formed in the first case are negatively buoyant and sink. Problems with plugging in the event of a flow interruption in such systems may be avoided by operating at slightly under saturated conditions with respect to CO 2 . Observations indicate that these conditions favor the formation of a semi-solid mass rather than a solid hydrate plug.

Polyolefin Degradation in a Continuous Coal Liquefaction Reactor

A novel solvent extraction method to isolate and recover polyolefin materials from coal-plastics coprocessing product streams is reported. The method was applied to samples obtained from a bench-scale continuous unit, coprocessing coal with polyethylene (PE), polypropylene (PP), and polystyrene (PS) feed. Recovered PE and PP have been characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies, and gel permeation chromatography (GPC); PS is completely converted to distillable product. The results indicate that PP undergoes fairly rapid and essentially quantitative reaction and its conversion is complete before reaching the downstream portion of the process. On the other hand, PE undergoes some degradation in the coal liquefaction reactor, with an average reduction in molecular weight distribution for the unconverted material by a factor of 10 to 30. GPC can definitively distinguish between fresh (feed) and recycled PE in the process stream and has established that most of the PE degradation occurs in the first-stage liquefaction reactor. This partially converted, but undistillable material then passes into the atmospheric still bottoms stream. The two solid separation methods examined had very different effects on the incompletely reacted PE. Vacuum distillation sequesters the PE in the unconvertable (ashy) fraction, whereas pressure filtration allows most of it to pass through into the recycle stream. A qualitative mechanism for PE breakdown is proposed in which rapid scission occurs at the branching points of the paraffin backbone, followed by eventual breakdown to distillable products.

The effect of pressure on first stage coal liquefaction and solvent hydrogenation with supported catalysts

Publisher Summary This chapter discusses the hydrogenation activity of supported and unsupported catalysts in the presence and absence of coal. Coal inhibits the hydrogenation of naphthalene solvent by both supported and unsupported catalysts, the greater effect being observed for supported catalysts. Coal conversions are similar for two types of catalysts. The supported catalysts appear to be much more effective than the unsupported catalyst employed for 1-methylnaphthalene hydrogenation and tetralin dehydrogenation. In the presence of coal, solvent hydrogenation is inhibited, and both the supported and unsupported catalysts appear to approach a similar level of solvent hydrogenation. Total hydrogen consumption in the presence of 3.3 g of coal is higher for unsupported than supported catalysts. An important role of the catalyst in the first stage of coal liquefaction is to provide hydrogen (H2) to cap thermally produced free-radicals, aid conversions, and prevent retrogressive reactions. Unsupported catalysts, that provide higher H2 consumptions than supported catalysts are suited for first-stage coal liquefaction.