CA1164379A - Liquefaction of carbonous material with vapor phase hydrogen donor solvents - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Disclosed is a method for enhancing the con-version of carbonous materials, such as coal and oil shale. The method comprises converting the carbonous material in the presence of a vapor phase hydrogen donor material containing one or more hydrogen donor solvents wherein each donor material is characterized by: (a) a heterocyclic ring in which the heteroatom is nitrogen, (b) having at least one donatable hydrogen located on the heterocyclic ring, and (c) becoming more unsaturated and/or aromatic upon the loss of the donata-ble hydrogen(s). The conversion is performed at sub-stantially atmospheric pressure, at an effective vapor residence time and at a temperature from about the boil-ing point of the hydrogen donor material to about 550°C.

Description

1 ~ 6~3~9 1 sAcKGRouND OF T~E INVE~NTION

2 The present invention relates to a method for

3 enhancing the conversion of carbonous materials such as

4 coal, oil shale, and peat, to liquids, by use of specific type hydrogen donor materials under critical processing 6 conditions.
7 Coal, once the leading source of energy in 8 the United States, is beginning to play a more important 9 role in the nation's energy future. The primary reason for the ~rowing importance of coal is the rapid depletion 11 of known petroleum and natural gas reserves. These known 12 reserves are being depleted at a rate considerably faster 13 than the rate of discovering new reserves. As the era of 14 petroleum growth draws to a close, the world's energy mix will have to change. Transition energy sources will be 16 needed as a bridge between petroleum and the potentially 17 unlimited energy sources of the future; such sources 18 being, for example, solar power and nuclear fusion.
19 ~wing to their great abundance, coal and oil shale, are perceived as the keystones of such a bridge. Consequent-21 ly, much work is presently in progress to provide eco-22 nomical ways of converting these resources to valuable 23 liquids and gases. Coal liquefaction processes in which 24 coal, with or without a diluent, is subjected to elevated temperatures and pressures to convert solid coal to nor-26 mally liquid hydrocarbonaceous products, are well known.
27 Because the ratio of hydrogen to carbon in 28 coal derived liquids and gases is higher than coal it-29 self, gases, much emphasis has been put on more efficient uses of hydrogen in liquefaction processes. In order to 31 use hydrogen more efficiently, processes have been devel-32 oped wherein a source of hydrogen is an organic compound, 33 usually a solvent, which is capable of donating hydrogen 34 to radicals formed during the decomposition of coal.
~lthough such processes teach the conversion of coal to 36 liquids and gases under various conditions, and with 37 various yields, none are able to achieve relatively high 3 7 ~

1 conversion to liquids under low pressure conditions.
2 SU~RY OF THE INVENTION
_ _ 3 In accordance with the present invention, 4 there is provided a method for enhancing the conversion

5 to liquids of solid carbonous materials selected from the

6 group consisting of coal, oil shale, peat and solid

7 products thereof, to liquids. The method comprises con-

8 verting the carbonous material in the presence of a

9 vapor phase hydrogen donor material containing one or more effective hydrogen donor solvents wherein each effective 11 donor solvent is characterized by: (a) a heterocyclic 12 ring in which the heteroatom is nitrogen, ~b) having at 13 least one donatable hydrogen located on the heterocyclic 14 ring, and (c) becoming more unsaturated and/or aromatic 15 upon the loss of the donatable hydrogen(s). The conver-16 sion is performed at substantially atmospheric pressure, 17 at an effective vapor residence time and at a tempera-18 ture from about the boiling point of the hydrogen donor 19 material to about 550~C.
In one embodiment of the present invention, 21 the carbonous material is subbituminous coal, the hydro-22 gen donor matexial is comprised of 1,2,3,4-tetrahydro-23 quinoline, the pressure is atmospheric pressure, the 24 maximum conversion temperature is about 500C, and the donor vapor residence time is about 1 second.
26 In a preferred embodiment of the present 27 invention the carbonous material is coal or oil shale 28 and the hydrogen donor material is recycled from a prod-29 uct stream resulting from the practice of the present invention.
31 BRIEF DESC~IPTION OF THE DRA~INGS
32 Figure 1 illustrates the effectiveness of 33 short vapor residence times as claimed herein.
34 Figure 2 illustrates total liquid yield on coal versus the donatable hydrogen concentration on the 36 nitrogen ring of the type donor solvents employed herein.

~ ~ 6~ 37'3 . _ . . _ .
2 Compounds claimed herein which are capable of 3 donating hydrogen to carbonous material radicals under 4 the conditions claimed herein are particularly suitable for the conversion of such materials to liquids. It is 6 believed that the chemical mechanism which may partially 7 account for their exceptional conversion ability results 8 from a solvent-coal physical interaction (e.g., acid-9 base coordination, etc.), followed by the subsequent donation of available hydrogen to the reactive carbonous 11 fragments, thereby stabilizing the fragments as they are 12 formed. The hydrogen donor in turn is converted, to a 13 degree, to an aromatic form which may subsequently or 14 concurrently be regenerated.
The art generally teaches that all known 16 hydrogen donor compounds, which generally also serve as 17 solvents for the coal, are suitable for converting coal 18 to liquids and gases. We have surprisingly found that 19 only certain specific types of hydrogen donor compounds 20 or mixtures thereof, when used under the critical reac-21 tion conditions of the present invention, enhance -the 22 conversion of certain carbonous materials to liquids 23 when compared to the conversion of such carbonous materi-24 als without the use of the hydrogen donor materials 25 claimed herein.
26 Effecti~e hydrogen donor compounds suitable 27 for use herein include those compounds which: (a) con-28 tain a heterocyclic ring in which the heteroatom is 29 nitrogen, (b) have at least one donatable hydrogen 30 located on the heterocyclic ring, and (c) have a tendency 31 to become more unsaturated and/or aromatic upon the loss 32 of the donatable hydrogen(s). ~onlimiting examples of 33 such compounds include, 1,2,3,4-tetrahydroquinoline;
34 1,2,3,4-tetrahydroisoquinoline; 1,2,3,4-tetrahydrocarba-zole; 1,2,3,4,5,6-hexahydrocarbazole; acrilan, piperidine, 36 pyrrolidine, indoline and their alkylated derivates and 37 mixtures thereof. Preferred are 1,2,3,4-tetrahydroquino-38 line; 1,2,3,4-tetrahydroisoquinoline and indoline.

~ ~ 6~3~9 1 It wlll be noted that other conventionally 2 used hydrogen donor materials, which do not meet the 3 re~uirements set forth above, are unsuitable for use in 4 the practice of the present invention. Such donor materials include tetralin, phenanthrene, C12 and Cl3 6 acenaphthenes, their hydrogenated analogs and indole.
7 The pressure at which the carbonous material 8 is converted herein is preferab]y about atmospheric g pressure (14.7 psia), although pressures slightly higher or lower may be employed to facilitate mass transfer in 11 the processing scheme.
12 The temperature at which conversion occurs in 13 the presence of the hydrogen donor vapor may range from 14 the initial boiling point of the hydrogen donor material to about 550~C. For example, for THQ, it is preferred 16 that the conversion temperature be about 200C to about 17 500C, more preferably from about 250C to about 500C;
18 most preferred is about 350C to about 500C.
19 The residence time at which the donor vapor is in contact with the solid carbonous material, at con-21 version temperatures must be an effective residence 22 time. By an effective residence time we mean a time 23 long enough so that reaction with the carbonous material 24 takes place, but short enough so that undesirable secondary reactions are minimized. Such undesirable 26 reactions include donor solvent degradation (other than 27 loss of hydrogen) and irreversible combinations of donor 28 molecules with either the converted or unconverted car-29 bonous material. These conditions also minimize unde-sirable secondary reacl:ions of first formed carbonous 31 material derived fragments. That is, the donor material 32 is preferably removed from the reaction zone, and cooled, 33 substantially immediately after donating its hydrogen.
34 This is generally a time from about 0.1 to about 30 seconds, although less than 10 seconds is generally 36 desired. It will be noted that less than 0.1 second 37 may also be feasible when the invention is employed in ~ 3 6~37~

1 specially designed, short residence time reaction 2 vessels.
3 For economic reasons, a donor vapor residence 4 time is chosen, based on the particular hydrogen donor material and the temperature employed, such that a mini-~ mal amount, e.g., no more than about 5 wt.~ of the 7 donor material is lost through degradation, other than 8 by aromatization. The longer the vapor residence time, 9 the greater the degree of donor degradation at any given temperature; therefore, it is preferred that a donor 11 material and process conditions be chosen such that 12 maximum conversion to liquids occursbefore about 5 wt.
13 of donor i5 spent by degradation. For example, Figure 14 1 herein illustrates that at a maximum temperature of 500C, at atmospheric pressure, at a donor to coal 16 weight ratio of 1 to 1, and with 1,2,3,4-tetrahydro-17 quinoline as the donor material, substantially maximum 18 conversion to liquids is achieved within a donor vapor 19 residence time of about seven-tenths of a second. Also illustrated in Figure 1 is a relative plot showing THQ
21 degradation other than by aromatization at 500~C. With 22 the teaching of the present invention as well as general 23 knowledge known in the art, one having ordinary skill in 24 the art can determine a sufficient residence time and optimum reaction conditions by routine experimentation.
26 ~y choosing the proper vapor residence time, 27 substantially maximum conversion of carbonous material 28 to liquids and recovery of the hydrogen donor material 2~ or its aromatic form in relatively high yields for hydrogenation and recycling is achieved. Recovery and 31 hydrogenation of this material can be achieved by appro-32 priate conventional methods suitable for such purposes.
33 Although not wishing to be limited thereby, hydrogena-34 tion can be accomplished with hydrogen in the presence of a suitable hydrogenation catalyst. For example, 36 hydrogenation temperatures can range from about 100C
37 to about 450~C at pressures up to about 2000 psi~. A

~ 3 ~3'~

l variety of hydrogenation catalysts can be employed such 2 as those containing components from Group VIB and Group 3 VIII, of the Periodic Table oE the Elements, e.g., co-4 balt, molybdate or nickel molybdate, on a suitable sup-port, such as alumina, silica, titania, etc. The hy-6 drogenated product can then be fractionated to the 7 desired boiling range and recycled to the reaction zone.
8 It is within the scope of this invention, and 9 even preferred from a commercial point of view, that a portion, if not all of the hydrogen donor material 11 employed herein, be derived from the liquids resulting 12 from the practice of this invention. That is, especial-13 ly in the case of oil shale, liquids derived therefrom 14 are generally rich in cyclic nitrogen-containing com-pounds which can be separated from the product stream 16 and hydrogenated, by conventional techniques, to give a 17 recycle stream rich in the type hydrogen donor material 18 suitable for use herein. The effectiveness of any par-19 ticular recycle stream may be determined by measuring the total donatable hydrogen associated with the hetero-21 cyclic nitrogen ring of those type donor solvents 22 claimed herein. That is, the recycle stream is analyzed 23 by any appropriate analytical technique, such as gas 24 chromatography, to determine its content of specific suitable donor solvents and their concentrations, on a 26 weight percent dry carbonous material basis. After the 27 specific type and concentration of suitable donor sol-28 vents are known, the number of donatable hydrogens on 29 the heterocyclic nitrogen ring of the donor solvent can be easily calculated. The number of donatable hydrogens, 31 as calculated, can then be compared to a model curve for 32 determining the projected liquid yield for that particu-33 lar concentration of donatable hydrogens. The recycle 34 stream can then be upgraded with respect to the donor material depending on the desired liquid yield.
36 Figure 2 herein shows a plot of li~uid yield 37 (weight percent on dry coal basis) versus weight percent ~ ~ ~4379 of donatable hydrogen on heterocyclic nitrogen ring on a dry coal basis, at a maximum temperature of 500C, 1 atmospheric pressure, and helium as a sweep gasO The plot was obtained by use of model hydrogen donor solvents such as 1,2,3,4-tetrahydroquinoline;
1,2,3,4-tetrahydroisoquinoline; 1,2,3,4-tetrahydrocarbazole, and indoline and mixtures thereof at various solvent to coal ratios.
Similar correlation curves can easily be prepared for oil shale and peat by routine experimentation by those having ordinary skill in the art.
The donor solvent/carbonous material ratio, on a weight basis, can preferably range from about 0.1/1 to about 10/1, more preferably from about 0.1/1 to about 4Jl. The optimum ratio of donor material to carbonous material will depend on such things as the particular carbonous material being converted, the processing conditions employed, and the type and the concentration of the particular donor materials comprising the recycle solvent. Of course, the optimum ratio can be determined by routine experimenta-tion by one having ordinary skill in the art.
; Generally, any type of coal, peat, oil shale or products thereof which are normally solid at room temperature may be uti-lized in the practice of the present invention. When coal is utilized, liquid yields from bituminous/ subbituminous and lignite will be particularly enhanced. While not wishing to be limited by theory, the data herein suggest that there is a correlation between liquid yield and reactive organic functionality in the feed stock.
Therefore, when coal is employed in the practice of the invention, lower rank coals are preferred because of their higher content of reactive organic functionality.
It is preferred that the carbonous material have as high a surface area as possible; although, it is not economically justifiable to pulverize the material to a very fine powder.
Consequently, it is desirable to expose as much of the carbonous material surface ~ .

1 ~6~l3~

1 area as possible without losing carbonous material as 2 dust or fines or as the economics of material grinding 3 or process equipment ma~ dictate. Generally, the car-4 bonous material will be ground to a finely divided state and will contain a majority of particles less than 6 about 4 mesh, U.S. sieve size. The carbonous material 7 may be dried by conventional drying techniques, for ~ example, heating to a temperature of abo~lt 100C to 110C.
9 In practicing the present invention, the car-bonous material is fed to a reaction vessel and heated 11 to the re~uired temperatures. The hydrogen donor mate-12 rial is introduced into the reaction vessel when the 13 temperature of the carbonous material is greater than 14 the boiling point of the donor material.
The present invention may be practiced in 16 various types of reaction vessels. ~onlimiting examples 17 of reaction vessels suitable for use herein include, 18 fixed or fluid bed, as well as free fall or entrained 19 solid reactors. The main constraint in any reactor con-figuration is to minimize solvent vapor residence times 21 for any given operating temperature, and can be deter-22 mined routinely by those having ordinary skill in the 23 art.
24 The following examples serve to more fully describe the manner of practicing the above-described 26 invention, as well as to set forth the best modes con-27 templated for carrying out various aspects of the inven-28 tion. It is und~rstood that these examples in no way 29 serve to limit the true scope of this invention, but rather, are presented for illustrative purposes.

. .
32 For each of these comparative examples 15 grams, 33 of subbituminous coal, ground to 10/20 mesh, U.S. sieve 34 size, was charged at room temperature and atmospheric pressure into a continuous gas flow batch fixed-coal 36 bed tubular reactor. Each coal sample was subjected to 37 the following temperature/time cycle -~ ~ 6~3~9 1 I - heat from ambient temperature to 2 250C in 30 minutes;
3 II - hold at 250C for 60 minutes; and 4 III - heat from 250C to 550C in 30 minutes.
Hydrogen, and/or various solvents were used during one 6 or more of the sectlons I, II, and/or III of the temper-7 ature/time cycle. Table I sets forth the reagents, their 8 use and conversion of coal to liquids and gases for each 9 example.

~ ~ 6~37~

o ~
rl ~ N
I
O
O

~1 E~
O ~ I I I . I I
\ E~ ~ o ~1 ' I I I ~r U ~ r~

~q I ~ I ~ I
O E~l o ~ o .IJ H ~ ~ N N
~ NN N ~ ~ \ 1 ~ :c ~c m E~
O~ .~ r~
H ~I N ~I m o ~1 H ~C m o ~ H ~ m C) a a) o ~r ~ rl o ` h ~ ~ rl r~
Q~ 11 11 11 11 q ~

N ~ ~ Ir~ ~ r~ CO C;~ O ~I N ~ ~ Il~

3 ~ ~

1 EX~PLES 1-5 2 The procedure described in Comparative 3 Examples A through G was followed except THQ was intro-4 duced in such a way that conversion of solid coal in liquids and gases was enhanced. Table II illustrates 6 the jadicious use of THQ.

J 1 fi~379 o O ~1 ~ E~
o U~

~ ~`1 1 1 1 ~
o H ~I
H
1~ ~ H ¦ t`~

U~
\ H I E~
o ~ 01 0:

~ 3 ~37~
- ]3 -1 This table when compared with Table I above 2 illustrates the following:
3 (a3 Not all solvents, even some of those 4 generally considered to be effective hydroyen donors under high pressure conditions, will enhance conversion 6 of coal to liquids and gases at the low pressure condi-7 tions claimed herein: i.e., compare Comparative Example 8 D with Example 2:
9 ~b~ The presence of hydrogen donor compound of the type claimed herein is necessary only at elevated 11 temperatures; i.e., compare Comparative Examples C and F
12 with Examples 1-5; and 13 (c) ~ydrogen gas by itself is not effective 14 as the hydrogenating agent for enhancing conversion under the process conditions of the present invention.
16 (Comparative Examples A and B).
17 EXA~lPLE 6 18 The procedure of the Comparative Examples 19 was again followed except THQ and helium were introduced at stage III of the temperature/time cycle. No reagents 21 were introduced during stages A and B. The THQ to coal 22 weight ratio was 1/1 and a conversion of 41 wt.% of 23 coal to liquids and gases resulted. This example illus-24 trates that hydrogen is not even necessary as a sweep gas.
26 EXAMPLES 7-17 AND_CO~P~RATI~E E~A~lPLES H-N
27 In each of the examples set forth in Table 28 III below, except Examples 9, 10 and 12, 15 grams of 29 subbituminous coal of 10/40 mesh, U.S. sieve size, was charged at room temperature and atmospheric pressure 31 into a continuous gas flow batch fixed-coal bed tubular 32 reactor. The reactor was heated to 500C at a rate of 33 about 400C per hour and 15 grams of solvent compound 34 was introduced over the temperature range from 250C to 500C. For Example 9, 45 grams of coal ancl 90 grams of 36 solvent were employed; for Example 10, 45 grams of coal 37 and 45 grams of solvent were employedi and fo Example 3 ~1 ~

-- 1'1 --1 12, 45 grams of coal and 81 grams of solvent were 2 employed. The vapor residence time of any given solvent 3 compound in contact with coal was approximately 1 second 4 and solid residence time at which coal is in contact with solvent vapor was ahout 40 minutes. Table III
6 below sets forth the solvents used as well as the 7 resulting conversion and yield data.

~ ~ ~437g N CO ~ cr~ O CO r~ \ ~ ~ t`J ~
~) ~ ~ ~ ~ U~ ~ N U~ a~ O -H ~ ~ t`'l ~ ~ I` u ~ol U ~ ~ .

~ ~ . 0~
~ ~ ~ ~ o ~ o ,~

3 ~-1 ~o ~ Z
.
a~
~ ~ ~c~ ~r o ~ ~ c~ o co o L~
H ¦ C~ D CO ~ O O ~ ~ 0~

~ 1: ~
1l . ~ U~ C~
h ~ u:: r-l ~1 ~ o c~ CJ~ ~ ~ o Ln ~1 O C~C ~7 ~ 1~ ~ ~ ~ ~I ~ ~r tn u~ u~ u~ r In ~ ~ ~:r 3 . ~-~
V
a) 3 0 3 '~ R
b ~ ~ v `

Lr) ~1 ~ ~1 ~ P~ H H ~ ~ a) E-l O Z :1, ~ H ~ ~ Z
X ~ 3 R, 3 ~ ~ ~ 1` CO a~ o ~1 ~ t~) ~ It~
O O O O O O O

~ ~ ~437~

-.

C~
C) -rl a o ~
_, ~ o O ~1 N
U:~ 3 ~1 ~ Q
h O h ~q o tn H r~) hra :~ ~ h h H o a) h H :~ :5 U O S S :3 h ~ ~15 o ~q ~ ~1 ~ ~ O
o ~ o 4~
O C) o ~ ~ ra _ , ~

h ~ h ` ` I
al ~ ~ ~1 ~ N

H
~ Q

~ :~ 6~379 l The results shown in this Table III illustrate 2 that in order for the solvent to significantly enhance 3 liquid yield, under the claimed reactor conditions, a 4 donor solvent must be employed which is characterized by (a) having a heterocyclic ring in which the hetero-6 atom is nitrogen, (b) having at least one donatable 7 hydroyen located on said heterocyclic ring, and (c) 8 having a tendency to become more unsaturated and/or 9 aromatic by donating its hydrogen. ~his table also illustrates again, that hydrogen is not needed as a ll sweep gas in the practice of this invention for enhanc-12 ing liquid yields.
13 Gaseous product streams resulting from selec-14 ted examples were analyzed and the results are set forth in Table IV below.

x _I o o o ~ o o ~ n o ~, U~
U) X
~r u~ ~ ~ ~ r~l ~ ~ ~r ~
o o o o o o ~ ~ o ~ U
a o X
~ O . 1~ CC! O ~ o : ~: U ~ ~ ~ O O' O O O ~ C~ O
V
o C~O
s X
,~
~ ~ o o o o o o ~ r~ o .

ta o u v v u v u c~ v ~ ~
o :~ . V

3 ~ 9 ~I N ~ t-- O r- l O OO O t r--l 1` O

U~
Ulr--l ~ ~1 ~r ~ r -l r ¦ ~~1 0 0 0 0 r~l 1-') 0 C~

o H ~ ~ ~ ¦ 1~ ~ ~ r~ I~ O r-l 3 ~C o I r--l r--l O C~ O ~1 ~D O
~ ~ C~

o c ~o 1~r--l ~ r--l ri O ~ O
.C r--l O~1 + + l +i+ I + I
+ I ~ 111 cr~ C r.~lC~) + I + I ~D
. X C~ O ~ 1 r~l r--l r--l O O O O ~--1 U) O

S~

OU C~ U ~ ~) U~) ~ U
o r~ 9 1~ CO ~ Or--I ~ t~ ~ Ltl ~ r-1 r l I--I r--~ r--l i :~ 643~

1 The analysis results shown in l'able I~ suggest 2 that the specific type donor solvents as claimed herein, 3 when employed under the claimed process conditions, 4 increase liquid yield at the expense of char and carbon oxide gases. That is, oxygen is most likely being 6 directed to liquid product as opposed to gaseous product 7 and charO
8 EXAMPLES 18 A~D 19 AMD COMPARATIVE EXAMPEES O ~ND P
.._ ~ __ ... _ . .. ...._.. . _ 9 In Example 18, 15 grams of Green River Oil Shale was charged at room temperature and atmospheric 11 pressure into a continuous gas flow batch fixed-bed 12 tubular reactor. In Example 19, 45 grams of Kentucky 13 Devonian Oil Shale was charged, also at room temperature 14 and pressure, into a continuous gas flow batch fixed-bed tubular reactor. The reactors were heated to a tempera-16 ture of about 500C at a rate of about 400C per hour 17 and 25 grams and 42.6 grams of THQ, respectively, were 18 introduced. Identical base runs without THQ were run 19 for comparative purposes. That is, Comparative Example O is the base for Example 18 and Comparative Example P
21 is the base for Example 19. The vapor residence time of 22 solvent in contact with shale was approximately 1 second 23 and solid residence time at which the shale was in con-24 tact with solvent vapor was about 40 minutes. Helium was used as a sweep gas for all examples. The results of 26 liquid and gaseous yield are shown in Table V below.

a) ~U~ ~ ~ o o o O ~

~ O
~ ~1 OD ~1 0 0 0 0 P~
; a.) 0~ ~ Ln ~ a~ O
E t~ u) ~ ~ . . co o ~q ~ ~l o ~ o o ~

o ~a o ~ ~ ~ r~
a ~ o ~ ~I ~ m ~ ~r ~ ~
~i ~p~

~ ~I co ~ o o o ~ ~ ~
o o O ~ OD ~ o D\~

D h o C~ o 0~ t~ O

~ 7 ~ 3 '~

1 These examples illustrate that the present 2 invention is suitable for enhancing liquid yields from 3 oil shale.

Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for enhancing the conversion of car bonous materials to liquids wherein the carbonous material is selected from the group consisting of coal, oil shale, peat and solid products thereof, the method which com-prises converting the carbonous material:
(a) in the presence of a hydrogen donor mate-rial, in the vapor phase, said donor material characterized by (aa) a heterocyclic ring in which the heteroatom is nitrogen, (ab) having at least one donatable hydrogen located on the heterocyclic ring, and (ac) becoming more aromatic upon the loss of the donated hydrogen(s); and (b) at a temperature from the boiling point of the hydrogen donor material to about 550°C; and (c) at substantially atmospheric pressure; and (d) at an effective vapor residence time.

2. The method of claim 1 wherein the tempera-ature is about 350°C to about 500°C.

3. The method of claim 1 wherein the hydrogen donor material is selected from the group consisting of 1,2,3,4-tetrahydroquinoline; 1,2,3,4-tetrahydroisoquinoline;
piperidine, pyrrolidine, indoline and their alkylated derivates or mixtures thereof.

4. The method of claim 1 wherein the hydrogen donor material is selected from the group consisting of 1,2,3,4-tetrahydroquinoline; 1,2,3,4-tetrahydroisoquinoline;
indoline and mixtures thereof.

5. The method of claim 1 wherein at least some of the hydrogen donor material is recycled hydrogen donor material obtained from a product stream resulting from the method herein claimed.

6. The method of claim 1 wherein the vapor residence time is from about 0.1 to about 30 seconds.

7. The method of claim 1 wherein the vapor residence time is from about 0.5 to about 10 seconds.

8. The method of claim 1 wherein the carbonous material is oil shale, the vapor residence time is about 005 to about 10 seconds, and the temperature is from about 350°C to about 500°C.

9. The method of claim 1 wherein the donor solvent/carbonous material ratio ranges from about 0.1/1 to about 10/1.