Hydrogen in coal

Jewell, D.M., Ruberto, R.G., Seshadri, K.S., "Transferable Hydrogen in Coal Liquids An Integrated Approach", presented at the 26th Annual Conference on Mass Spectrometry and Allied Topics", A.S.M.S., St. Louis, M0., May 28, 1978. 

Since inorganic carbonates and nitrogen oxides contribute to the carbon value in coal as it is normally determined, consideration of this issue is necessary. Hydrogen values also are usually high, due to the inclusion of the various forms of moisture that are present in coal. All of these factors limit the reliability of carbon and hydrogen data for predicting the amount of combustible carbon and hydrogen in coal. 

The Role of Aliphatic or Hydroaromatic Hydrogen in Coal Con-version... 

Coal gas is the product of slow distillation of coal with exclusion of air. Blast-furnace gas results from the combustion of coal in a restricted supply of air its ideal composition would be, by weight, CO, 34.4 N, 65.6. Water gas is made by the action of steam on incandescent coal, and should consist ideally of H and CO only the process is necessarily intermittent. Producer gas is a combination of blast-furnace gas and water gas, the supply of steam being so limited as to permit of a continuous process. In all of the manufactured gases, the hydrocarbons (CH4, CeHe, C2H4) come from the coal either directly or as the result of a breakdown of other hydrocarbons. The hydrogen in coal gas and blast-furnace gas has a similar origin. The CO and CO2 in coal gas are due to a partial (and objectionable) combustion of the carbon in the coal. 

Chemically, coal is a complex and highly variable substance. The carbon and hydrogen in coal may be represented approximately as 0.8 atoms of hydrogen per atom of carbon in bituminous coal. Its gasification reaction may be represented by the (unbalanced) reaction equation ... 

Nuclear magnetic resonance spectroscopy has also been used to derive structural parameters for the distribution of aliphatic hydrogen in coal and its extraction products. A ratio of four methylene groups per methyl group was noted also, the methyl group content was higher in the soluble material and varied with the solvent power of the solvent. 

Swansiger, J.T., Best, H.T., Danner, D.A., Youngless, T.L. (1982) Determination of transferable hydrogen in coal liquids by mass spectrometry. Analytical Chemistry, 54, 2576-2582. 

In a natural gas fueled PAFC, water is condensed out of the fuel stream going to the fuel cell to increase the partial pressure of hydrogen. In coal gasification MCFC, water often is added to the fuel stream prior to the fuel cell to prevent soot formation. The addition of excess steam not only prevents soot formation, but also causes a voltage drop of approximately 2 mV per each percentage point increase in steam content (10). The use of zinc ferrite hot gas cleanup can aggravate the soot formation problem because of the catalytic effect of the sorbent on carbon formation, and requires even higher moisture levels (11). 

---