Japan Uses Zinc to Liquefy Coal

 
 
Two links are enclosed in this dispatch, one above and one below, with excerpts from each. They describe studies undertaken by Japanese researchers on an alternative process to obtain the necessary Hydrogen, for coal hydrogenation and direct liquefaction into petroleum-like materials, from plain water.
 
Other coal liquefaction processes, most notably WVU's "West Virginia Process", employ Hydrogen donor solvents to convert high-carbon coal into liquid hydrocarbons; others use syngas recycled back into the coal feed; or, they propose breaking water up into Hydrogen and Oxygen via electrolysis. Some researchers suggest using biomass as a Hydrogen source.
 
Appropriately-prepared Zinc, according to these Japanese researchers, will accomplish the necessary fission of Hydrogen and Oxygen from water, as well, without the need for large amounts of electricity, though some heat is required, thus making Hydrogen available to liquefy the coal. And, Zinc can, it seems, be used for that purpose as a part of the "batch", or process stream. 
 
As follows:  
 
"Coal liquefaction by in-situ hydrogen generation.: 1. Zinc-water-coal reaction 

Fanor Mondragon, Hironori Itoh and Koji Ouchi

Faculty of Engineering, Hokkaido University, Sapporo 060, Japan

Abstract

Liquefaction of coal was carried out in a zinc—water—solvent system to give a product with high concentration of pyridine and benzene solubles. In this system the metal reacts with water to produce the corresponding metal oxide and hydrogen. This hydrogen was used for in-situ hydrogenation of coal. The effects of reaction time, temperature, type of solvent, the quantity of metal used and the rank of coal were investigated. The solvent has a very marked effect on the conversion of coal to benzene-soluble materials, especially at short reaction times. A maximum benzene conversion of 96% for Taiheiyo coal was obtained when it was treated at 445 °C for 1 h using wash oil as solvent. With regard to the influence of coal rank it was found that low rank coals were more reactive than high rank coals. The amount of preasphaltene is only slightly influenced by coal rank but depends on the temperature and the type of solvent used.

 
Coal liquefaction by in-situ hydrogen generation.: 2. Zinc-water model compound reactions  

Fanor Mondragon and Koji Ouchi

Faculty of Engineering, Hokkaido University, Sapporo 060, Japan 

Abstract

Model compound studies were carried out to elucidate the reaction mechanisms taking place during the liquefaction of coal with the hydrogen produced from the reaction of zinc and water. In compounds of the type Ph-(CH2)n-Ph the splitting of the aliphatic bridge was easier with higher n values. Ether type compounds such as diphenylether were unreactive although the C-O bond in dibenzylether was easily cleaved. Condensed ring aromatic compounds gave low conversion with hydrogenation being facilitated by an increase in ring number. Phenolic compounds such as phenol did not react well, but the reactivity increased with increase in aromatic ring size. The cleavage of the aliphatic bridge was accelerated by the OH group, for example, in the case of 4-hydroxydiphenylmethane bond scission was about 15 times higher than that of diphenylmethane. Heterocyclic compounds were unreactive."

Make special note that, in the first Abstract, these researchers report achieving a 96 percent conversion rate of the coal they used in their development work into, essentially, petrochemicals soluble in an organic solvent, when zinc was included in the coal/water starting "mix".

We should note that Zinc is oxidized in these reactions and would, at some point, need to be "refreshed", or, in technical terms "reduced", by removing the oxygen and then recycling the zinc back into the coal liquefaction process.

Refining and recycling the zinc oxide is not difficult.

Without direct reference, we relate that, in Israel, some work has been done on developing Hydrogen-fueled automobiles. Rather, though, than attempting to fuel cars directly with Hydrogen, and then having them zip about the highways like 70 mile-per-hour mini-Hindenburg's, the Israeli's are developing prototypes that would fill up with water, and then convert the water, over on-board Zinc, into Hydrogen and Oxygen, as needed. The spent Zinc Oxide would be exchanged for fresh Zinc, and then "renewed" at a central refinery where the Zinc Oxide would be reduced, via solar energy, back into pure Zinc and Oxygen.

Note that such a concept would be unlikely to work that well in the US. Driving range would almost certainly be a problem, as hydrogen just doesn't have the energy density of liquid hydrocarbons. Even with a full tank of water, these Israeli concepts would be unlikely to have more range than a battery-powered electric vehicle, which might be fine for a physically very small country, like Israel.

But, the same recycling concept could work for coal-to-oil conversion refineries using Zinc to fission water for Hydrogen, even though we don't have that many sunny deserts handy to provide us with abundant solar power. Spent Zinc Oxide could be refreshed, perhaps, in coal furnaces, or in crucibles heated by coal-generated electricity; or, by environmentally-correct hydroelectric power. 

In any case, this is yet another demonstrated channel for the conversion of our abundant coal into needed liquid fuel, and of effecting that conversion using widely-availabe, non-exotic, recyclable materials.