CATALYTIC COAL HYDROGASIFICATION PROCESS - Patent 3847567
Since Methane is required for tri-reforming processes, such as the one explained, as we have documented, by Penn State University; and, the one we recently reported, which has been patented (US4886651; "Process for co-production of higher alcohols, methanol and ammonia") by Air Products and Chemicals, wherein Carbon Dioxide is consumed, recycled, as a co-reactant in the production of liquid hydrocarbons from Methane; and the CO2-recycling technology we just, in our last dispatch, reported as being described by West Virginia University; and the Carbon Dioxide utilization and recycling process patented by Exxon, as US5266175, we wanted to further document that, not only can the Methane needed for CO2 recycling be itself synthesized from Carbon Dioxide, via the Nobel-winning Sabatier, and other, technologies, it can also be generated from processes of Coal gasification.
And, Exxon knows it.
We have earlier reported Exxon's, then Esso's, development of coal gasification technology many decades ago, in the 1960's, and even the 1950's.
Herein, we see that Exxon further refined their early gasification technology, and were awarded a United States Patent for that refinement of their process to manufacture Methane, from Coal.
The excerpt, edited for brevity, with some comment inserted and appended:
CATALYTIC COAL HYDROGASIFICATION PROCESS United States Patent 3847567
Inventors:
Kalina, Theodore (Morris Plains, NJ); Moore, Roger E. (El Paso, TX)
Application Number: 05/391082; Publication Date: 11/12/1974; Filing Date: 08/27/1973
Assignee: Exxon Research and Engineering Company (Linden, NJ)
Claims:
1. A process for the manufacture of methane which comprises:
2. A process as defined by claim 1 wherein carbonaceous solids are reacted with said steam and hydrogen in said hydrogasifier at a temperature in the range between about 1,200 F. and about 1,500 F. and at a pressure in the range between about 100 and about 5,000 psig.
(That is a lot of heat and pressure. This process does require a great deal of energy, and perhaps renewable hydroelectric could be harnessed to the task. There are options.)
8. A process as defined by claim 1 wherein said carbonaceous solids comprise a bituminous or lower rank coal.
9. A process as defined by claim 2 wherein said solids are reacted with said steam and hydrogen in said hydrogasifier at a pressure between about 500 and about 1,000 psig.
11. A process as defined by claim 4 wherein said gas is reacted with said steam in said reforming furnace at a pressure between about 500 and about 1,000 psig
Background and Description:
1. Field of the Invention
This invention relates to the gasification of coal and other carbonaceous materials and is particularly concerned with gasification processes carried out over alkali metal catalysts for the production of methane.
2. Description of the Prior Art
Efforts to develop processes for the conversion of coal and similar carbonaceous materials into high Btu synthetic gases suitable for use as fuels have focused ... on ...hydrogasification: C + 2H2 = CH4 .
Because this reaction is highly exothermic and requires the presence of hydrogen, it has been suggested that it be integrated with endothermic hydrogen-producing reactions such as the steam/carbon gasification reaction, C + H2O = CO + H2, and the methane/steam reforming reaction, CH4 + H2O = CO + 3H2. ... to conserve heat and reduce the amount of hydrogen which must be provided. It has been found that this can be done by reacting the coal or other carbonaceous material with steam and hydrogen in a hydrogasification zone to produce a methane-rich gas, passing at least a portion of this gas stream through a methane reforming zone where it is contacted with steam to reduce part of the methane and form hydrogen, and then recycling hydrogen and carbon monoxide recovered from the steam reformer overhead gas to the hydrogasification zone.
(Note both, that some needed Hydrogen can be generated by using steam to "reduce part of the methane"; and, as in other of our reports, one of the reactions in the process is "highly exothermic", and could provide at least some of the energy needed to drive the entire process.)
Coal char or other carbonaceous solids are circulated between the hydrogasification and reforming zones to provide heat integration. This system results in a substantially thermoneutral process which has numerous advantages over other processes suggested in the past.
(So, as in other citations we've submitted of similar technologies and processes, this process is, in part, exothermic and "substantially thermoneutral", thus reducing needed energy inputs, and costs. We know we are belaboring that point, but it is one that needs driven home, since, aside from environmental issues, cost objections seem the ones most commonly raised in opposition to employment of carbon conversion technologies.)
SUMMARY OF THE INVENTION
This invention provides an improvement over the process referred to above which permits significant savings in operating costs and has other advantages. In accordance with the invention, a high Btu gas suitable for pipeline purposes is produced by reacting finely divided coal or similar carbonaceous material with steam and hydrogen in the presence of an alkali metal catalyst, passing the resultant gas to a catalytic reforming unit where steam and methane react to form hydrogen and carbon monoxide, treating the reformer gas product for the removal of carbon dioxide and other acidic gases, and then separating the treated gas into a hydrogen stream which is recycled to the gasifier, a carbon monoxide stream which is used to fuel the reformer and provide heat for the process, and a product gas stream composed primarily of methane. The hydrogen and reactant steam concentrations in the gasifier are controlled so that the exothermic hydrogasification reactions provide sufficient heat for the endothermic steam reactions, reactant preheat and reactor heat losses. This results in a substantially thermoneutral process which has economic advantages over processes employed in the past.
The hydrogasification reaction is preferably carried out in a fluidized bed containing from about 1 to about 50 percent by weight, based on the carbonaceous feed material, of an alkali metal catalyst such as potassium carbonate, sodium carbonate, or the like. The use of such a catalyst permits operation of the gasifier at temperatures within the range of about 1,200 to about 1,500 F., which in turn favors the production of methane. The net hydrogen required for reaction with the carbonaceous material in the hydrogasification zone is generated by steam reforming the overhead gas, preferably in the presence of an alkali metal or similar methane reduction catalyst ... in a steam reformer furnace. ... The hydrogen is recycled to the hydrogasification zone where it reacts with the carbonaceous material in the methane-forming reaction.
The recovered carbon monoxide is not recycled as in earlier processes and instead is burned with ambient pressure air to fire the steam reformer furnace. This provides essentially all of the heat required in the process and eliminates the necessity for burning ... fuels ... . The methane from the cryogenic unit is of high purity and can be employed as a pipeline gas without further treatment."
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Or, the Methane can be condensed, via further catalysis, as we've documented, directly into liquid fuels; or, perhaps better, reacted with more Carbon Dioxide, in a process similar to Penn State's Tri-Reforming Process, as we've documented, or, more likely, in Exxon's own, patented, US5266175, technology for the "conversion of methane, carbon dioxide and water using microwave radiation" into synthesis gas.
And, as in the title of this US Patent, awarded to Exxon more than 35 years ago, it all - liquid fuel production and Carbon Dioxide recycling - can start with the "hydrogasification" of Coal.