Hydrogen coal-based

Newer coal-based methods of acetylene manufacture under development include the AVCO process, based on the reaction of coal in a hydrogen plasma. Finely divided coal is passed through a hydrogen plasma arc generating temperature gradients of up to 15,000 K. About 67% of the coal is consumed, yielding char and acetylene in concentrations up to 16%. An energy requirement of 9.5 kW h/kg acetylene has been reported (33). 

In very broad terms, hydrogenation activity in terms of hydrogen utilization increases as coal rank decreases. Thus, in the absence of any other information, one can expect WVGS 13423 to be the more reactive of the two Obviously, generalities about hydrogenation behavior should not be extended to other coals based solely on a limited data set. Nevertheless, important differences between the pitches derived from WVGS 13421 and WVGS 13423 are apparent. 

Figure 2. Effects of hydrogenation on CTE of coal-based graphites...

Autoclave Results - Solvent Activity Test. The initial microautoclave work was done with tetralin and methylnaphtha-lene, using Indiana V bituminous coal (Table I). Base line data is shown in Figure 4. All three tests, Kinetic, SRT, and Equilibrium, show an increase in coal conversion with an increase in the concentration of tetralin. The Equilibrium Test shows the highest coal conversion of approximately 86 wt% of the MAF coal (based on the solubility in the tetrahydrofuran) at the 50% tetralin concentration. The Kinetic Test shows lower coal conversion. The hydrogen transferred to the coal from the tetralin in the Equilibrium Test at the 50 wt% tetralin feed concentration is approximately 0.5 wt% of the MAF coal. In the Kinetic Test 50 wt% tetralin feed concentration results in a much smaller transfer at the short reaction time of 10 minutes. 

The Vision 21 program is focused on new concepts for coal-based energy production where modular plants could be configured to produce a variety of fuels and chemicals depending on market needs with virtually no environmental impact outside the plant s footprint. Membranes would be used to separate oxygen from air for the gasification process and to separate hydrogen and carbon dioxide from coal gas. 

This advanced coal-based, near-zero emission plant is planned to produce electricity that is only 10% more costly than current coal-generated electricity while providing hydrogen that can compete with gasoline. The cost of hydrogen delivery is not included in this goal. 

Under the assumption that CCS will be widely applied from 2025 on, a remarkable reduction of C02 emissions could be achieved in the transport sector by hydrogen fuel-cell vehicles over the next few decades, even if hydrogen was produced mainly on the basis of fossil fuels. In the case of a predominantly coal-based production mix without CCS, C02 emissions from hydrogen production will exceed those saved through its use in the transport sector. If around 50% of total hydrogen production was to depend on CCS from coal gasification, the total C02 volumes to be stored in... 

Given the low cost and abundance of coal, we find that coal-based hydrogen with CCS is the cheapest central production technology in many parts of the USA. 

Figure 15.14. Optimal infrastructure configuration at different market penetration levels for a coal-based hydrogen supply system with carbon capture and sequestration in Ohio, USA (Johnson et al., 2006).

Hydrogen corridors based on hard coal or natural gas are not suitable. It is better to transport these feedstocks directly instead of hydrogen, because of their much higher energy content and consequently lower transport cost and because the infrastructure for it is already in place. 

Jhe distribution of hydrogen types in coals continues to be a subject of considerable interest in coal structure studies. Published data indicate that the fraction of aromatic hydrogens usually increases with increasing rank, but the absolute values depend on the specific analytical method used (7). Hydrogen type analysis of a single coal based on the application of NMR spectroscopy to the soluble fraction from depolymerization with phenol-BFa has been reported by us (3). The conversion of coal to soluble fragments in substantial yields under very mild conditions permits a reliable determination of the hydrogen types by NMR analysis, and these results can be extrapolated to the parent coal with considerable confidence. 

Based on experience obtained by hydrogenating coal during World War II, the Noguchi Institute of Japan began to study lignin liquefaction. By 1952 they had discovered a superior catalyst which converted a substantial portion of the lignin into relatively few monophenols and substantially suppressed additional hydrogenation of the phenols. This catalyst was improved some years later and, based on these two catalysts,... 

Four model compounds, n-undecane, tetralin, cis/trans decalin and mesitylene, and a natural gas condensate from the North Sea were also cracked. Analyses and the reference code key of the coal-based feedstocks and the gas condensate are given in Table 1. Paraffin, naphthene, and aromatic-type analyses were calculated from gas chromatographic analyses of the partially hydrogenated anthracene oil and gas condensate whereas, mass spectrometric analysis was performed on the two coal extract hydrogenates and their further hydrogenated products. 

It is also likely that as the cost of solar-hydrogen drops, the costs of fossil and nuclear energy will rise. Robert Stavins of Harvard University estimates that if a 100/ton charge is placed on C02 emissions, that would increase the cost of coal-based electricity by 400% and natural gas-based electricity by 100%, making the cost of solar-, wind, and geothermal-based electricity more than competitive. Table 1.62 lists the effect of a 50/ton carbon emission charge on the unit costs of electricity from a variety of power plants. 

Hydrogen is present in fossil fuels and water in sufficient quantities that it can be produced on a large scale by three different methods 1) Petrochemical Processes, 2) Coal-based Chemical Processes and 3) Electrochemical Processes (Electrolysis). In Table 5.7, the percentage of hydrogen production is broken down by type of manufacturing process for the years between 1974 and 198846. A similar distribution for 2002 is shown in Table 5.8162. 

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