The Dutch scientists who worked for Houston's Shell Oil Company were, in their formal Summary of the United States Patent we enclose herein, quite succinct about what their invention was, and is, all about.
It is, as they state: "a process for preparing liquid hydrocarbons from coal".
But, it is "a process for preparing liquid hydrocarbons from coal" with a slight twist; and, perhaps, with some unstated, though valuable, potentials.
Note, that, in the course of their Disclosure, these Shell scientists reveal that their Coal-to-Gasoline process generates one significant by-product: Isobutane.
Shell proposes that, after the bulk of their Coal-derived synthesis gas has been converted into Gasoline, via their indirect Coal liquefaction process, the by-product Isobutane can, as well, "by alkylation", be converted into Gasoline.
But, there might be more intriguing options for it, as we point out, following excerpts from the link to:
"United States Patent 4,218,388 - Preparing Hydrocarbons from Gasification of Coal
Date: August, 1980
Inventors: Lambert Schaper, et. al., The Netherlands
Assignee: Shell Oil Company, Houston
Abstract: Synthesis gas is converted into gasoline by contacting the gas with a crystalline aluminosilicate zeolite catalyst, the process being characterized by conversion of by-product isobutane into gasoline by alkylation.
Claims: A process for preparing liquid hydrocarbons from coal, comprising: converting coal into a mixture of carbon monoxide and hydrogen by gasification ...; converting the mixture of carbon monoxide and hydrogen into an aromatic hydrocarbon mixture in the presence of a catalyst which contains a crystalline aluminosilicate zeolite (as specified); separating from the aromatic hydrocarbon mixture an isobutane-containing gaseous fraction and an aromatic liquid fraction boiling in the gasoline range; converting the isobutane-containing gaseous fraction by alkylation into a product from which a fraction boiling in the gasoline range is separated; and mixing the two fractions boiling in the gasoline range.
Background: It is known that carbon-containing materials, such as coal, can be converted into mixtures of carbon monoxide and hydrogen by gasification. It is further known that mixtures of carbon monoxide and hydrogen can be converted into mixtures of hydrocarbons by contacting the gas mixtures with suitable catalysts. .
Investigation has shown that gasoline having a high octane number can be prepared from coal by combining (those) processes.
In the first step of the process according to the invention, a mixture of carbon monoxide and hydrogen is prepared by gasification of coal at a temperature between 1050 and 2000 C. As a result of the use of this high temperature, the synthesis gas prepared contains very little methane, if any at all. In comparison with a process in which in the first step a lower temperature is used, for instance between 800 and 1000 C., the process according to the invention gives a higher yield of CO and H2 per ton of coal and a higher gasoline yield per ton of coal.
Because of the use of a gasification temperature between 1050 and 2000 C. the product contains very small amounts of non-gaseous by-products such as tar, phenols and condensable hydrocarbons, if any at all. The absence of these products also leads to a higher yield of CO and H2, and therefore to a higher gasoline yield than when a lower temperature is used in the gasification step. In addition, no provisions have to be made to remove tar, phenols and condensable hydrocarbons from the synthesis gas, which will promote the economy of the gasoline preparation.
The starting materials in the process according to the invention may, for instance, be: lignite, bituminous coal, subbituminous coal, anthracite and coke.
Summary: The present invention, therefore, relates to a process for preparing liquid hydrocarbons from coal, in which: the coal is converted into a mixture of carbon monoxide and hydrogen by gasification at a temperature between 1050 and 2000 C; the mixture of carbon monoxide and hydrogen is converted into an aromatic hydrocarbon mixture using a catalyst which contains a crystalline aluminosilicate zeolite ... ; from the aromatic hydrocarbon mixture an isobutane-containing gaseous fraction and an aromatic liquid fraction boiling in the gasoline range are separated; the isobutane-containing gaseous fraction is converted by alkylation into a product from which a fraction boiling in the gasoline range is separated, and, the two fractions boiling in the gasoline range ... are mixed."
----------------------
All of that is wonderful, of course; or, would be wonderful - - if anyone in US Coal Country actually knew about it.
But, there might be other, even more productive, options for the "isobutane-containing gaseous fraction", that arises, we must emphasize, from a Coal conversion process that involves a rather complete initial gasification of the Coal, with very little co-production of unwanted "tar" and "phenols" that would otherwise require additional processing to be made useable..
Rather than being "alkylated", and converted thereby, like the bulk of the "aromatic hydrocarbon mixture" produced by that catalytic condensation of the "carbon monoxide and hydrogen" generated from Coal, into another liquid "boiling in the gasoline range", we submit, that, instead, such by-product "isobutane" can be utilized for the productive recycling of Carbon Dioxide.
As seen in:
http://www.anl.gov/PCS/
we can react the Isobutane obtained as a by-product from the process, above, of "USP 4,218,388 - Preparing Hydrocarbons from Gasification of Coal"; with Carbon Dioxide, reclaimed from whatever source, and thereby synthesize "isobutylene".
We know that "isobutylene" might, at first, elicit a "so what?"; and, by way of easy answer, we refer you to:
Isobutylene - Wikipedia, the free encyclopedia; wherein we are instructed that "Isobutylene (can be) reacted with methanol and ethanol in the manufacture of the gasoline."
And, as seen, for just two, out of now many possible, examples, in:
California Recycles CO2 to Methanol | Research & Development; concerning the "recycling of carbon dioxide from natural and industrial sources ... to methanol"; and:
LeHigh University Converts Coal to Ethanol for USDOE | Research & Development; which reports on "a novel catalytic process for the conversion of coal-derived synthesis gas into ... ethanol";
we can make those Alcohols - - which we need, in order to convert a product, "isobutylene" - which is made from a by-product, "isobutane", of a process that converts Coal into Gasoline, by reacting that by-product isobutane with Carbon Dioxide - into even more Gasoline - - from either Coal or Carbon Dioxide.
Although we've tried to summarize all of that as succinctly as we can, we know that it's confusing.
In non-specific sum, it is documented herein, via all our sources in combination, that: both Coal and Carbon Dioxide can, together, and pretty-darned thoroughly, be converted completely into Gasoline.