United States Patent: 4218389

 

In our recent report to the West Virginia Coal Association, available as ConocoPhillips CO2 to Methanol | Research & Development | News, we documented "United States Patent Application 20030060355", a process for "Converting Carbon Dioxide to Oxygenates" wherein ConocoPhillps disclosed their catalyst and technology for, as they put it, "converting carbon dioxide to methanol".

Keeping in mind that Methanol is an extraordinarily versatile substance which can serve as the raw material for the further, efficient synthesis of various plastics and Gasoline, we wanted, via the United States Patent we disclose herein, to confirm that Conoco also knows, and have known for a shade more than three decades, how to make such valuable Methanol from Coal.

And, we alert you that, in confirmation of many other similar technologies we have cited for you, the hydrogenation of Coal, to form Methanol, is accomplished via seemingly-obvious reaction with Steam.


One Conoco innovation herein is that they also figured out a way to minimize any formation of pollutant Nitrogen oxides, when less-expensive ambient air, instead of costly purified Oxygen, is utilized, along with Steam, in the initial Coal gasification - thus making, we presume, the entire process more cost-efficient.

Brief comment follows excerpts from:

 

"United States Patent 4,218,389 - Process for Making Methanol

 

Date: August, 1980

 

Inventors: Robert Jackson and Richard Tillman, OK

 

Assignee: Conoco, Inc., OK

 

Abstract: A process for producing methanol from air-blown gasified coal. A feed gas stream obtained by the coal gasification step is combined with a recycle gas stream and fed to a reactor where carbon oxides are converted to methanol. Exit gas from the reactor is scrubbed to remove carbon monoxide, and the carbon monoxide-free exit gas is then chilled to remove all components except hydrogen. The hydrogen is then combined with the carbon monoxide and used as a recycle stream. The process enables use of an air-blown gasified coal stream while maintaining the nitrogen content in the reactor at an acceptably low level.

Claims: A process for producing methanol from solid carbonaceous material comprising: subjecting said carbonaceous material to an air-blown gasification step to produce a feed gas stream comprising nitrogen, hydrogen, carbon monoxide, carbon dioxide and methane; reacting said feed gas stream in a reactor to produce an effluent gas stream containing methanol; condensing methanol from said effluent gas stream and withdrawing condensed methanol therefrom; scrubbing carbon monoxide from said effluent gas stream; 
condensing the higher boiling components from said effluent gas stream after carbon monoxide scrubbing to produce a recycle gas stream which is predominantly hydrogen; combining said predominantly hydrogen recycle gas stream with carbon monoxide previously scrubbed from said effluent gas stream; combining said recycle gas stream including carbon monoxide with said feed gas stream to provide a combined feed gas stream and recycle gas stream including recycle carbon monoxide for introduction to said reactor, said combined feed gas stream and recycle gas stream having a nitrogen content of less than 25 volume percent; and introducing said combined feed gas stream and recycle gas stream into said reactor. 

(A) process ... wherein said feed gas stream is about 50 percent nitrogen by volume (but) wherein the combined feed gas stream and recycle gas stream including recycled carbon monoxide has a nitrogen content of not more than 15 volume percent.

(And) wherein said carbonaceous material is coal.

Field (of Invention): This invention relates ... particularly ... to production of methanol utilizing a feed gas obtained by air-blowing coal. The feed gas contains carbon oxides which are converted to methanol by catalytic hydrogenation. 

Most coal gasification processes utilize an oxygen-blown gasifier. The amount of oxygen required for this process is large, and accordingly a costly air separation plant is necessary. 

Air-blown gasifiers, not requiring an air separation plant, are available, but the gas from air-blown gasifiers has a high (about 50 volume percent) nitrogen content. Reactors for making methanol from gas obtained from coal gasifiers generally do not operate efficiently if the feed gas has a nitrogen content above about 25 volume percent. For this reason, feed gas from air-blown gasifiers has not (previously) been successfully used to produce methanol.

Summary: According to the present invention, methanol is produced using feed gas from an air-blown coal gasifier (which) contains a high amount of nitrogen, and the conversion reaction does not proceed efficiently in the presence of more than about 25 volume percent nitrogen. Removal of nitrogen from the feed gas is not practical, so a low-nitrogen recycle gas stream is utilized to effectively lower the nitrogen ratio in the reactor.

Methanol from the reactor is condensed and recovered, and the methanol-free exit gas from the reactor is then processed to obtain a relatively nitrogen-free recycle gas stream (which is combined with the) feed gas stream from an air-blown gasifier in which coal is reacted with steam ... ."

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Simply, this is just a method for converting Coal into Methanol, via the formation of an hydrogenated synthesis gas, by the reaction of Coal with Steam; and, wherein off-gas is recycled into the "syngas" to reduce both Nitrogen contamination and, by avoiding use of "a costly air separation plant" so that untreated air, instead of purified Oxygen, could be used, some significant capital expense.

Aside from those niceties, herein is just further confirmation that we have known now for several decades that we can make liquid hydrocarbons by starting with, aside from air, only Steam and Coal.


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