http://wvuscholar.wvu.edu:8881//exlibris/dtl/d3_1/apache_media/22699.pdf
We have many times made reference to West Virginia University's "West Virginia Process" for the direct liquefaction of Coal.
In that technical process, WVU employs, we have been led to believe, as do others in similar technologies we have documented for you, a Hydrogen-donor solvent most commonly referred to as "Tetralin".
The more proper, technical name is "Tetrahydronaphthalene", and, it is synthesized by hydrogenating the primary Coal oil, Naphthalene.
Herein, we wanted, especially in light of pending reports concerning developments, in Saudi Arabia and elsewhere, to affirm and further illustrate the detail and depth of understanding, as regards the preparation and utility of Tetralin, that exists at WVU.
We do so by presenting another, in addition to one or two we've previously sent along, Master's Thesis submitted to WVU's College of Engineering and Mineral Resources.
Brief comment follows excerpts from the enclosed link to:
"Hydrogenation of Naphthalene and Coal Tar Distillate over Ni/Mo/Al2O3 Catalyst
Abhijit Bhagavatula; Thesis submitted to the College of Engineering and Mineral Resources at West Virginia University in partial fulfillment of the requirements for the degree of Master of Science in Chemical Engineering.
John W. Zondlo, Ph.D., Chair; Elliot B. Kennel, M.S; Alfred H. Stiller, Ph.D; Department of Chemical Engineering; Morgantown, West Virginia. 2009.
Abstract: The hydrogenation of naphthalene and coal-tar distillates has been carried out in a Trickle Bed Reactor, in which the liquid is allowed to flow through the catalyst bed in the presence of hydrogen. The purpose of these experiments is to reduce the residence time of the distillates in the reactor, taking advantage of the geometry of the trickle bed system. A model compound naphthalene dissolved in a solvent, n-hexadecane, was used to replicate the hydrogenation of coal tar distillates.
The operating conditions employed for the hydrogenation of naphthalene (were varied, and the results monitored, and a) unique peak for naphthalene was observed ... (as was) the peak for the hydrogenated product, tetralin (1,2,3,4 Tetrahydronaphthalene).
(Specified) coal tar distillate was also hydrogenated in the trickle bed reactor. A method to extract the solvent, n-Hexadecane, from the feed and product was devised in order to perform elemental analysis on the samples. A 25 % increase in the percentage of hydrogen was observed from feed to product indicating that the trickle bed reactor can be used to hydrogenate coal-derived solvents. It was also noted that the sulfur content of the hydrogenated product was reduced by about 85 % and the nitrogen content reduced by
about 41 % from that of the feed.
(Note the above reductions in potential pollutants.)
It is a well known fact that the importance of coal as a major source of fuel has been increasing over the past few decades. West Virginia produces about 15% of the total coal mined annually in the United States. The booming price of crude oil along with a major decline in the domestic crude stocks, has accentuated the importance of alternate sources of fuel and chemical feedstocks.
Therefore, the production of liquid fuel from solid coal is a major area of research.
The process of converting solid coal to liquid is called liquefaction. Coal is liquefied by reacting with hydrogen. ... Therefore, the process of producing liquid fuels from solid coal necessitates increasing the ratio of hydrogen to carbon. This can be done either by removing carbon or by adding hydrogen.
A particular characteristic of hydrogenation or hydroprocessing is that heavy feeds containing high percentage of nitrogen and sulfur can be treated easily thereby increasing the hydrogen-to-carbon ratio
of the feed and thus the fuel value of the resulting oil.
Pyrolysis, direct liquefaction, indirect liquefaction are different types of coal liquefaction processes. Pyrolysis is nothing but heating pulverized coal in an inert atmosphere at high temperature to produce coke, liquids and tars.
The hydrogenation of coal can be done either directly or indirectly.
Direct liquefaction, the direct reaction between coal and hydrogen, involves the conversion of coal to refinable crude hydrocarbons, from which liquid fuels such as gasoline, diesel, kerosene, etc., can be produced.
By contrast, indirect liquefaction, an example of which is the Fischer-Tropsch process, produces synthesis gas (a mixture of carbon monoxide and hydrogen) by gasification of coal and then converts the synthesis gas to liquid fuels.
Coal derivatives are mostly aromatic compounds, while petroleum and gas derivatives are primarily aliphatic compounds. Advances in materials science over the years provide a definite advantage for the coal-derived compounds over petroleum and gas derivatives because aromatic compounds are the key building blocks
for many new high-performance materials such as general engineering plastics, high temperature heat resistant plastics, aromatic resins, liquid crystalline polymers, etc.
Feedstocks for carbon products from coal which are used in the industry are generally by-products of the metallurgical coke industry. During the production of metallurgical coke, coal tar is formed as a by-product by capturing the volatiles and condensing them. ... Carbon feedstocks such as naphthalene, tar acids, tar bases, coal tar pitch, etc. can then be obtained from the distillation of the coal tar produced during the manufacture of metallurgical coke.
Coal-derived liquids have been produced at West Virginia University (WVU) by hydrogenating coal and combining it with a solvent extraction process. For example, coal was hydrogenated ... using (tetralin) as the solvent in a continuously stirred tank reactor.
Tetralin, a specialty chemical, was used as a hydrogen donor for this process. However, tetralin, a hydrogen donor, is converted to naphthalene in the course of the process and cannot be reused without external separation and rehydrogenation.
Though very effective as the hydrogen donor solvent, tetralin is very expensive. To be economically competitive, it is necessary to recover and recycle all the tetralin used in the process ... .
(Thus) coal tar distillates were used as a substitute for tetralin as the liquefaction solvent. Coal tar distillates are by-products of the metallurgical coke industry and are comparatively available at a lower cost thus improving the raw materials cost and the economic viability of the process. It has been observed that these low-cost solvents dissolved approximately 90% of bituminous coal on a dry, ash-free basis which is comparable to the effectiveness of tetralin.
(We can, in other words, convert 90% of Coal's Carbon content into pre-hydrocarbon liquids.)
Carbon feedstocks such as naphthalene ... can then be obtained from the distillation of the coal tar produced during the manufacture of metallurgical coke.
An alternative to decrease the residence time of (the Coal liquefaction) reaction and to make the process continuous is to use a trickle bed reactor ... . A trickle bed reactor is nothing but a fixed bed reactor whose diameter is very small compared to its length.
The purpose of the present research is to attempt a reduction of the residence time of the distillates in the reactor, taking advantage of the geometry of the trickle-bed system.
In direct liquefaction processes, the organic structure of coal is broken down to produce distillable liquids through the addition of heat and hydrogen.
Many commercial processes for the direct liquefaction of coal have been developed over the years. Most of
these processes involve the dissolution of coal in a solvent at high temperature and pressure ... while treating the coal slurry with hydrogen and a catalyst.
Some of the major commercial direct coal liquefaction processes ... discussed in this section (are, the) Exxon Donor Solvent Process, ... the H-Coal Process, ... the Shenua Direct Liquefaction Plant, (and) the Solvent Refined Coal Process.
Some of the past research work done at WVU involved the hydrogenation of coal in the presence of tetralin which is a very effective, but expensive, hydrogen donor. During this reaction, tetralin is converted to naphthalene. Due to this, rehydrogenation has to be done so that tetralin can be recycled. Thus, gaseous hydrogen plays an important role in producing these coal-derived materials. Later, much research related to
hydrotreatment of coal was done using coal-derived solvents in place of tetralin. Hydrogenated coal tar distillate was used as the source of the H-donor solvent.
Coal Tar Distillates are derived from metallurgical coke oven tar, which is produced during the high temperature coking of bituminous coal. The distillates ... are high molecular weight aromatic hydrocarbons (middle and heavy distillates), one of the main constituents of which is naphthalene. Hydrogenated
naphthalene-like molecules are used as proton transfer agents in some liquefaction procedures.
Naphthalene is one of the major aromatic substances present in coal tar distillate. (And, much) research has been done in the area of reaction kinetics based on the hydrogenation of naphthalene to tetralin in a trickle bed reactor. ... Naphthalene when hydrogenated at high pressure and high temperature in the presence of a hydrotreating catalyst forms 1,2,3,4 tetrahydronaphthalene (Tetralin).
From the results of (our work and analyses) it can be clearly seen that ... the trickle bed reactor can indeed be used for hydrogenating coal derived solvents. (Further, the) nitrogen percentage decreases by about 41 % while the sulfur percentage decreases by about 85 % from feed to product.
Conclusions: A trickle bed reactor has been designed, constructed and operated successfully for hydrogenating naphthalene and Kopper’s coal tar distillate.
Kopper’s Coal Tar distillate was successfully hydrogenated in the trickle bed reactor.
Thus, it is verified that using the trickle bed reactor can be an effective method for hydrotreating coal tar distillates. Also, a decrease in percentage of other elements like nitrogen and sulfur (as noted above) was observed. (And) some denitrification and desulfurization reactions are also occurring in the trickle bed
reactor."
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Our excerpts, though perhaps over-long, do not, cannot, do justice to the technical depth of Bhagavatula's work. The entire thesis itself is so compendious that we elected not to attempt transmission of it as an attached file in this dispatch.
The detail can be somewhat overwhelming. And, in fact, we discovered, perhaps misread, some points that seemed to us contradictory, or worthy of much fuller explanation.
One, for instance, is that Tetralin can be expensive to use, but the expense can be reduced through recycling. Or, other Coal-derived liquids can used as hydrogenating Coal solvents in it's stead.
However, there are, quite obviously, some fully-functioning and highly-informed folk at WVU who could better explain to us all how we can, as above, convert "90%", as above, or more, of Coal's Carbon content into "liquid fuels ... (and) high-performance materials such as general engineering plastics".