United States Patent: 5741440

 

We have many times documented the operation, by Eastman Chemical Company, of a commercial plant in Kingsport, Tennessee, wherein Methanol is indirectly synthesized, via gasification, from Coal.

And, we have reported on their published plans to establish a similar, perhaps larger, facility in Texas.

Herein, we see that some of Eastman's Texas Coal scientists have improved the process for gasifying Coal, into a Methanol synthesis gas, so that better - and, importantly, variable - ratios of reactive Carbon Monoxide and Hydrogen, suited for efficient condensation into Methanol, and a range of liquid hydrocarbons, are formed.

And, Eastman effects that improvement by adding variable amounts of Carbon Dioxide to the mix of gasses with which Coal is reacted in the process of gasification.

Such development shouldn't be too surprising to anyone who has followed our posts thus far.

As we have previously documented, and as we will, in future reports, document further, it has been known since the early part of the last century that reactive, and industrially-useful, Carbon Monoxide can be made by the simple expedient of passing Carbon Dioxide over red hot Coal.

Herein, we see that Eastman uses that concept to develop a more efficient, and environmentally-beneficial, process to generate Methanol synthesis gas, wherein both Coal and Carbon Dioxide are employed as raw materials.

Methane, as well, can be included in that mix; a fact with implications that we elaborate following excerpts from the above link to:

 

"United States Patent 5,741,440 - Production of Hydrogen and Carbon Monoxide

 

Date: April, 1998

 

Inventors: James Cooper and Eugene Ingram, Texas

 

Assignee: Eastman Chemical Company, Tennessee

 

Abstract: A method for the preparation of a mixture of hydrogen and carbon monoxide is disclosed. The invention method entails contacting carbon dioxide, hydrogen, and at least one hydrocarbon in the presence of a catalyst containing an active metal.

Claims: A process for the preparation of a mixture of hydrogen and carbon monoxide comprising contacting a feed mixture of carbon dioxide, hydrogen, at least one hydrocarbon and, optionally, water with a catalyst.

(And) wherein the hydrocarbon is selected from the group consisting of ... coal tars (and) coal (and/or) wherein said hydrocarbon is methane.

(And) wherein said catalyst is in the form of a supported catalyst in a fixed bed that has the active metal on a stable support (and) wherein said metal is platinum (or) nickel (and) wherein said support is selected from the group consisting of alumina and magnesium oxide.

(And) wherein said contacting produces hydrogen and carbon monoxide at a mole ratio of hydrogen to carbon monoxide from 0.5:1 to 10:1.

Background and Summary: The catalytic reforming of methane and other light hydrocarbons with steam to produce mixtures of hydrogen and carbon monoxide are well established commercial processes.

It would be very desirable to be able to produce hydrogen and carbon monoxide in a wider molar ratio range, particularly without the adverse effects of coking and wasted hydrocarbon feed. Additionally, it would be very desirable to be able to increase the concentration of synthesis gas per unit volume without the production of carbon, which results in the coking of the reactor and catalyst.

The applicants have unexpectedly discovered a process for the production of hydrogen and carbon monoxide by contacting a feed mixture of carbon dioxide, hydrogen and at least one hydrocarbon that dramatically increases the quantity of synthesis gas prepared when compared to conventional steam reforming of methane and carbon dioxide.

The molar ratio of hydrogen to carbon monoxide produced in the present process can vary dramatically (and a) portion or all of the water in the steam reforming process can unexpectedly be replaced with hydrogen without the formation of carbon resulting in a carbon free operation at higher concentration of synthesis gas per unit volume.

The carbon dioxide to methane ratio in the feed ... can be from 0.01:1 to 100:1 ... .

The carbon dioxide to hydrogen ratio or carbon dioxide to hydrogen plus water ratio in the feed can be within the ... preferred range being from 0.2:1 to 5:1.

Within the scope and ranges of the present invention the composition of the feed gas can vary widely depending on the desired product composition. The replacement of steam with hydrogen significantly increases the quantity of carbon monoxide and synthesis gas produced compared to an equivalent, molar ratio, feed gas containing only steam, hydrocarbon and carbon dioxide. The substitution of hydrogen for steam in the process feed gas does not require a change in the quantity of hydrocarbon or carbon dioxide contained in the feed gas."

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In point of fact, some Carbon Dioxide is generated by downstream components of the process.

The full Disclosure suggests that such CO2 can be recycled back into the mix of raw materials, and indicates that additional CO2, from other sources, can be added.

The amount of Carbon Dioxide added, which can, as in our excerpts, be varied widely, depends, it seems, upon the desired ratio of Carbon Monoxide to Hydrogen in the resulting synthesis gas, which is, thus, presumably, adjusted according to the desired end product, i.e., Methanol, or other.

And, Eastman indicates that replacing a certain amount of the Steam with elemental Hydrogen can help to reduce Carbon deposition on catalyst surfaces.

Well-established processes, as we've documented, exist for the generation of Hydrogen, but the relative costs of Hydrogen addition versus catalyst cleaning when only Steam is employed are not assessed by Eastman.

Note, too, that Methane can be a component of the initial gasification feed; and, keep in mind that Methane can be synthesized, via the Sabatier process now being further developed by NASA, all as we have documented, from Carbon Dioxide.

In sum, Eastman herein defines a process for the production of a hydrocarbon synthesis gas, the final composition of which can be adjusted, depending on the desired end-outcome hydrocarbon product, by varying the amounts of Carbon Dioxide, Water, Hydrogen, and/or Methane, that are, in the first place, reacted with hot Coal.


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