Kurt S. Rothenberger

Nature of the electron paramagnetic resonance intensity in iodine treated coals

Abstract Three British coals and their iodine treated counterparts were examined in order to investigate the increase in electron paramagnetic resonance (e.p.r.) signal intensity that occurs upon iodine uptake. The iodine is not removed by vacuum. Scanning electron microscopy (SEM) results show that the iodine exists in a highly dispersed form. Correlation of elemental analysis and e.p.r. spin density measurements indicates two to ten new spins added per 100 added I 2 molecules. A study of e.p.r. intensity as a function of temperature reveals nearly identical trends for untreated and iodine treated coals. High frequency e.p.r. resolves additional signal at lower fields in the iodine treated samples. Such observations contradict the notion of donor-acceptor complex formation between iodine and aromatic constituents of the coal. Although there is considerable evidence of iodine participation in the formation of this additional signal, it would appear to be of a non-bonding nature.

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.