Novel fuel

A process for generating energy in a furnace or combustion engine which comprises burning therein the novel alcohol-soluble portion of the product obtained as a result of the mild reaction of a lignin-containing material, such as peat, with aqueous nitric acid. The alcohol-soluble portion of such reaction is also claimed as a novel fuel alone or in combination with an alcohol or a liquid hydrocarbon fuel.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a process for generating energy in a furnace or 
combustion engine which comprises burning in said furnace or said 
combustion engine the novel alcohol-soluble portion of the product 
obtained as a result of the mild reaction of a lignin-containing material 
with nitric acid. This invention additionally relates to said 
alcohol-soluble portion of said product itself as a new fuel and to a 
novel fuel composition containing said alcohol-soluble portion. 
2. Description of the Prior Art 
Lignin-containing materials, such as peat and wood, are available in large 
amounts and are known to have fuel value since they are susceptible to 
combustion. However, since their fuel value is comparatively low, their 
use is generally limited to heating applications and steam generation. It 
would be highly desirable, therefore, to render such lignin-containing 
materials more attractive as fuels, or as components of fuels, and to 
enlarge on their considerable potential as an energy source. 
SUMMARY OF THE INVENTION 
I have discovered that lignin-containing materials can be upgraded as fuels 
and fuel additives and their utilization, therefore, can be greatly 
extended by subjecting the same to a mild reaction with nitric acid and 
recovering as said novel fuel, or fuel additive, the alcohol-soluble 
portion of the nitric acid reaction product so obtained for use in 
generating energy in a furnace or a combustion engine. 
By a "lignin-containing material," I mean to include any material that 
includes in its normal state at least about five weight percent lignin, 
generally at least about ten weight percent lignin. As an example, on a 
water-free basis, the lignin-containing material can contain from about 
five to about 100 weight percent lignin, generally from about 20 to about 
100 weight percent lignin. By lignin I mean a high molecular derivative of 
phenylpropane, wherein the phenyl groups are substituted with one to two 
methoxy groups and the propane side chains with hydroxyl groups. The 
phenyl-propane units are linked with each other from the side chain to the 
nucleus partially by carbon-to-carbon, partially by ether linkages. 
(Reference: Lignin Structures and Reactions, Advances in Chemistry, Series 
#59, American Chemical Society publications #59). Remaining organic 
material associated with the lignin-containing material can be cellulose, 
hemicellulose, bitumen, humic acid, etc. The lignin-containing material in 
its normal state usually contains large amounts of water; for example, 
from about 0 to about 95 weight percent, generally from about 20 to about 
95 weight percent water. Examples of lignin-containing materials that are 
particularly attractive for use herein include peat, wood, biomass, such 
as bagasse and lignin, etc. Peat is the partially decomposed residue of 
dead plants and animal microorganisms associated with about 80-90 weight 
percent of water. 
The novel fuel defined and claimed herein for use in generating energy in a 
furnace or combustion engine is easily obtained by subjecting the 
above-defined lignin-containing material or mixtures of lignin-containing 
materials to a mild reaction with nitric acid and then recovering from the 
nitric acid reaction product the alcohol-soluble portion thereof. Thus, 
nitric acid can be added to the above-defined lignin-containing material, 
while stirring the mixture, until the reaction of the nitric acid with the 
lignin-containing material has continued to the extent desired. During the 
reaction water and nitrogen oxides produced, and any other volatile 
materials that may result from the reaction, are permitted to escape. 
Solid reaction product obtained is then subjected to extraction with an 
aliphatic alcohol or mixtures of aliphatic alcohols having from 1 to 10 
carbon atoms, particularly from 1 to 6 carbon atoms. These include 
methanol, ethanol, normal propanol, isopropanol, butanol, decanol and 
mixtures of the lower alcohols such as those obtained in the industrial 
production of fuel grade methanol and ethanol. If desired, any suitable 
polar solvent, for example, such as defined hereinafter can also be used 
as an extractant. 
The conditions that can be used above in subjecting the lignin-containing 
material to reaction with nitric acid must be mild. The reaction can be 
carried out using an aqueous mixture containing the lignin-containing 
material and aqueous nitric acid. The nitric acid used can have a 
concentration of about 5 to about 100 weight percent nitric acid, 
preferably about 15 to about 70 weight percent nitric acid. The mixture 
can contain about 0 to about 95 weight percent water, preferably about 40 
to about 80 weight percent water. On a weight basis, the lignin-containing 
material (on a dry basis) and the nitric acid (as 100 percent nitric acid) 
can be in the range of about 1:0.1 to about 1:10, preferably about 1:1 to 
about 1:2. The above is mixed while it is maintained in a temperature 
range of about -10.degree. to about 150.degree. C., preferably about 
20.degree. to about 100.degree. C., and a pressure of about 14.5 to about 
1000 pounds per square inch gauge, preferably about 14.5 to about 100 
pounds per square inch gauge, for about 1 minute to about 10 hours, 
preferably about 0.5 to about 2 hours. The resulting reaction product is 
then subjected to extraction with any suitable polar solvent, for example, 
a ketone, such as acetone, methylethylketone, cyclohexanone, etc., an 
alcohol, such as methanol, ethanol, normal propanol, isopropanol, butanol, 
decanol, and mixtures of the lower alcohols such as those obtained in the 
industrial production of fuel grade methanol and ethanol, etc., 
tetrahydrofuran, dioxane, etc., or mixtures thereof. The extraction can be 
carried out at temperatures in the range of about 0.degree. to about 
200.degree. C. and the extraction can be continued until no further 
extract is obtained. Removal of polar solvent from the extract can be 
effected by subjecting the extract to drying or distillation. The solid 
material obtained is the novel alcohol soluble product herein. 
If desired, the procedural steps defined in U.S. Pat. No. 4,052,448, dated 
Oct. 4, 1977, of Schulz, et al, can be used in reacting the 
lignin-containing material with nitric acid, provided the reaction 
parameters defined above are maintained. 
The nitric acid reaction product obtained above, as the novel fuel herein, 
contains both water-soluble and water-insoluble components. The 
water-soluble components will be in the range of about 10 to about 95 
weight percent, generally about 40 to about 70 weight percent. I have 
found that since the lignin-containing materials, as defined herein, 
contain phenyl groups with a large number of aliphatic chains linking the 
same to each other, under the mild reaction conditions defined above, 
cleavage within the molecule is easily effected by oxidation, without 
resultant decarboxylation, and nitration also occurs to varying extents. 
The resultant reaction product so obtained thus has a molecular weight 
substantially lower than the lignin-containing material that was subjected 
to reaction with nitric acid and now additionally carries carboxyl and 
nitro groups. 
The nitric acid reaction product obtained above can be used as such in a 
conventional manner for generating energy in a furnace or a combustion 
engine by burning the same therein. Combustion engines that can be used 
include internal combustion engines, such as a Diesel engine, or a 
turbine, or an external combustion engine, such as a steam engine. 
Alternatively, the product can be used to prepare a novel fuel composition 
for use in a furnace or a combustion engine. In one embodiment, the 
product can be dissolved in an alcohol, such as methanol, ethanol, 
mixtures thereof and mixtures of lower alcohols such as those obtained in 
the industrial production of fuel-grade methanol or ethanol wherein, the 
reaction product can amount to about 3 to about 95 weight percent, 
preferably about 25 to about 75 weight percent, of the final solution, 
with the remainder being the alcohol used. This solution, which will be 
discussed further below, is an excellent Diesel fuel. Alternatively, a 
slurry can be prepared that includes the nitric acid reaction product and 
a hydrocarbon fuel wherein the nitric acid reaction product can amount to 
about 5 to about 95 weight percent, preferably about 30 to about 80 weight 
percent, of the final product. By "hydrocarbon fuel," I mean to include 
liquid hydrocarbons, such as petroleum fractions, oils resulting from coal 
liquefaction or other coal conversion processes, the extract from oil 
shale and tar sands, liquids resulting from the pyrolysis of organic 
matter, etc. Additionally, a slurry can also be prepared that includes the 
nitric acid reaction product and up to 30 percent, preferably 20-25 
percent, of water. 
As pointed out above, the solution of methanol, ethanol, mixtures thereof, 
and mixtures of lower alcohols, such as fuel-grade methanol and fuel-grade 
ethanol with the nitric acid reaction product results in an unexpectedly 
well performing Diesel fuel. In order for a material to be effective when 
incorporated into an alcohol for a diesel fuel, it must produce 
satisfactory ignition promotion, have excellent solubility in the alcohol 
and equally important possess viscosity and lubricity properties close to 
or equivalent to those of conventional petroleum-derived diesel fuel. I 
have found that the nitric acid reaction product defined herein, when 
added to one of the defined alcohols, will result in a Diesel fuel having 
all of the defined desired properties. 
I have found, for example, that the product obtained when peat is subjected 
to a mild reaction with nitric acid, as defined above is infinitely 
soluble in the alcohols defined immediately above. This is believed to 
result from the presence of a large number of aliphatic substituents in 
the peat and carboxyl groups in the resulting reaction product. 
Additionally, liquidity of the solute at injector nozzle temperatures is 
highly desirable, particularly in a "solution-type" Diesel fuel, since 
solvent evaporation, after engine shut-off, can leave behind solid 
residues, especially in the fuel injector, resulting in problems to 
restart the engine. Since the product containing the defined alcohol, for 
example, methanol, and nitric acid reaction product, possesses viscosities 
(for example, 7 centipoise at 25.degree. C.) and lubricity close to those 
of conventional Diesel fuels, it can be injected with standard injection 
systems. High viscosities and lack of sufficient lubricity are 
undesirable, for Diesel fuels having such characteristics can cause wear 
of pump elements, resulting in engine failure. On the other hand, no 
mechanical problems were encountered with the novel fuels herein. That the 
nitric acid reaction product defined herein is a good ignition promoter is 
shown by the fact that the products containing equal amounts by weight of 
methanol and the alcohol-soluble portion of the nitric acid reaction 
products using peat as the lignin-containing charge material have ignition 
delays comparable to good Diesel fuels with a cetane number of 52. 
Essentially smoke-free emissions, reduced nitric oxide production compared 
to conventional Diesel fuels and an increase in power output over methanol 
alone were consistently observed. 
The above results are surprising. When coal or lignite are subject to 
reaction with nitric acid, for example, as in U.S. Pat. No. 4,052,448 to 
Schulz, et al, referred to above, or in U.S. Pat. No. 4,278,443 to 
Beuther, et al, substantially all of the organic reaction product obtained 
is water-insoluble, whereas herein generally at least about 50 weight 
percent is water soluble. The water-soluble product obtained in said 
patents has no ignition properties at all of its own when added to 
methanol, for example, for use in a diesel engine. Not only is the novel 
fuel composition herein characterized by the fact that generally more than 
half of it is water-soluble, but that when added to an alcohol, for 
example, methanol, all of its components including its water-soluble 
portion, are excellent ignition promoters therein. Therefore, the use of 
an extraneous ignition promoter, such as an alkyl nitrate (for example, 
octyl nitrate), is not required. Infinite solubility of the nitric acid 
reaction product of peat in the alcohol, for example, methanol, and 
desired viscosity, lubricity and liquidity properties of the resulting 
solution when used in a Diesel engine, are lacking in the comparable 
product when using the nitric acid reaction product of the Schulz, et al, 
and the Beuther, et al, patents referred to above. 
When the lignin-containing material used herein to make the novel fuel is 
peat and the nitric acid reaction product is subjected to extraction with 
one of the polar solvents defined above, for example, methanol, most of 
the contaminants that were in the original peat remain in the insoluble 
residue and the extract contains only small amounts of polar 
solvent-soluble metal contaminants. These contaminants can be removed from 
the extract by any suitable means, for example, by treating the same with 
an ion-exchange resin, such as "Amberlyst 15" acid ion exchange resin.

DESCRIPTION OF PREFERRED EMBODIMENTS 
A number of reactions was carried out as follows. Aqueous nitric acid was 
added to Finnish high humification peat uniformly over a period of 0.75 
hours while the mixture was agitated. While the resulting mixture was 
stirred, it was maintained at selected temperatures and ambient pressure 
for two hours after the nitric acid addition. At the end of the reaction 
period, residual water was removed from the reaction product by 
evaporation, and the dry reaction product remaining was extracted 
exhaustively with methanol at ambient temperature and ambient pressure. 
The methanol extracts thus obtained were then evaporated for the recovery 
of methanol-soluble reaction product (MSP), which contained both 
water-insoluble components and water-soluble components. The relative 
amounts of water-insoluble components and water-soluble components present 
were determined by extracting the total solids with water. In Table I, the 
reactions were each carried out at 85.degree. C. and the weight ratio of 
nitric acid to peat was varied. The results obtained on analysis of the 
reaction product are tabulated in Table I. 
TABLE I 
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Run No. 1 2 3 4 
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HNO.sub.3 /Peat Weight Ratio 
0.25:1 0.5:1 1:1 2:1 
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Product Analysis 
% Selectivity 
NE* 
% Selectivity 
NE % Selectivity 
NE % Selectivity 
NE 
__________________________________________________________________________ 
Intermediates Plus Ash 
75.0 248 
61.5 256 
28.0 250 
16.3 185 
Water-Insoluble MSP 
14.0 215 
18.0 219 
31.0 149 
28.8 153 
Water-Soluble MSP 
13.0 138 
20.9 138 
35.0 110 
47.0 86 
Total MSP 27.0 38.9 66.0 75.8 
Ratio of Water-Insoluble 
1:1 0.9 0.9 0.6 
MSP to Water-Soluble MSP 
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In Table I, as elsewhere, "NE" designates the neutral equivalent of the 
fraction referred to and "Intermediates Plus Ash" refers to the partially 
reacted residual product and contaminants. Note that nitric acid to peat 
ratios have a pronounced effect on peat conversion and the ratio of 
water-insoluble to water-soluble components produced. In all cases, the 
water-soluble components were present in at least the same amount as the 
water-soluble components but generally much higher. 
In Table II, the comparable effects of nitric acid to peat ratios were 
studied at different temperatures. 
TABLE II 
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Run No. 5 6 7 8 
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HNO.sub.3 /Peat Weight Ratio 
1:1 1:1 2:1 2:1 
Temperature, .degree.C. 
85 50 50 85 
__________________________________________________________________________ 
Product Analysis 
% Selectivity 
NE % Selectivity 
NE % Selectivity 
NE % Selectivity 
NE 
__________________________________________________________________________ 
Intermediates Plus Ash 
28.0 250 
28.4 214 
19.1 216 
16.3 185 
Water-Insoluble MSP 
31.0 149 
32.3 161 
30.0 169 
28.8 153 
Water-Soluble MSP 
35.0 110 
36.1 105 
53.8 94 
47.0 86 
Total MSP 66 68.4 83.8 75.8 
Ratio of Water-Insoluble 
0.9 0.9 0.6 0.6 
MSP to Water-Soluble MSP 
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In Table II, it can be seen that variations in temperature from 50.degree. 
to 85.degree. C. have little effect on the amount of product obtained and 
on product distribution. 
The data in Table III show the effect of temperature on the reaction 
product obtained wherein the nitric acid to peat ratio was maintained at 
1:1. 
TABLE III 
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Run No. 9 10 11 12 13 
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Temperature, .degree.C. 
25 35 50 65 85 
__________________________________________________________________________ 
Product Analysis 
% Selectivity 
NE % Selectivity 
NE % Selectivity 
NE % Selectivity 
NE % Selectivity 
NE 
__________________________________________________________________________ 
Intermediates Plus Ash 
47.4 226 
37.3 213 
28.4 214 
35.0 246 
28.0 250 
Water-Insoluble MSP 
29.7 163 
38.1 149 
32.3 161 
33.0 163 
31.0 149 
Water-Soluble MSP 
30.0 125 
33.0 95 
36.1 105 
36.0 102 
35.0 110 
Total MSP 59.7 77.1 68.4 69.0 66.0 
Ratio of Water-Insoluble 
1 1,2 0.9 0.9 0.9 
MSP to Water-Soluble 
MSP 
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The data in Table III shows that while the temperature is rate determining 
it has hardly any effect on product distribution. 
In Table IV results from peats of different humification, high, medium, and 
low, are tabulated. Humification levels signify age of peat and 
corresponding degrees of decomposition. The nitric acid to peat weight 
ratio was 1:1 and the reaction temperature 50.degree. C. 
TABLE IV 
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Run No. 14 15 16 
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Humification High Medium Low 
__________________________________________________________________________ 
Product Analysis 
% Selectivity 
NE % Selectivity 
NE % Selectivity 
NE 
__________________________________________________________________________ 
Intermediates Plus Ash 
28.4 214 
35.5 189 
26.6 172 
Water-Insoluble MSP 
32.3 161 
21.7 147 
18.8 145 
Water-Soluble MSP 
36.1 105 
34.9 99 
47.2 110 
Total MSP 68.4 56.6 66 
Ratio of Water-Insoluble 
0.9 0.6 0.4 
MSP to Water-Soluble MSP 
__________________________________________________________________________ 
Results with peats of various age differ mainly in product distribution. 
Older, high humification peat will give about equal amounts of 
water-insoluble and water-soluble components. Products from low 
humification peat predominates in the water-soluble components. In all 
cases the reaction product obtained from all peats appear to be similar as 
evidenced by their neutral equivalent and solubility in methanol. Analysis 
of the methanol-soluble product from Run No. 14 is typical. This is shown 
below in Table V. 
TABLE V 
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Weight Percent 
______________________________________ 
Carbon 45.26 
Hydrogen 5.08 
Nitrogen 3.23 
Sulfur 1.84 
Oxygen 43.81 
Ash 0.78 
Hydrogen to Carbon Ratio 
0.11 
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Run No. 17 
In this run Finnish Peat was used. Aqueous nitric acid having a 
concentration of 70 weight percent was used and added to the peat over a 
two-hour period, followed by a two-hour hold period all at 50.degree. C. 
Weight ratio of nitric acid (as 100 percent nitric acid) to peat was 1:1. 
No water was used as diluent. The air-dried peat charge contained a 
mixture of peats of high, medium and low humification with varying 
moisture content. The dried products were slurried at ambient temperature 
with sufficient amounts of methanol to permit their removal from the 
reactor flask. The slurries were filtered and re-extracted with methanol 
to generate methanol-soluble reaction products. Methanol-insoluble filter 
cakes were recycled to the solubilization step alone or along with fresh 
peat. Methanol product solutions were evaporated to adjust their content 
of methanol-soluble reaction product to 50 weight percent. Moisture 
content of the products so obtained varied from four to 12 weight percent, 
with ash around three weight percent. Removal of residual metal 
contaminants was carried out by contacting the methanol solutions with 
"Amberlyst 15" acid ion exchange resin. The product after this treatment 
contained 0.42 weight percent ash. Further removal of ash could still be 
obtained by repeating this procedure. Table VI below sets forth the 
elemental analysis of the original solid nitric acid reaction product. 
TABLE VI 
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Weight Percent 
______________________________________ 
Carbon 49.0 
Hydrogen 4.9 
Nitrogen 3.7 
Sulfur 0.5 
Oxygen 39.6 
Ash 2.4 
Neutral Equivalent 
119 
BTU/Pound 7718 
______________________________________ 
Viscosities of the 50 percent by weight methanol solution are given below 
in Table VII. 
TABLE VII 
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Temperature, .degree.C. 
Centipoise 
______________________________________ 
-9.9 66 
0 36.6 
10.1 21.5 
25.2 13.2 
40 5.3 
BTU/Pound 7266 
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Run No. 18 
A Diesel fuel was prepared containing 50 weight percent of the total 
methanol-soluble product obtained in Run No. 14 and 50 weight percent 
methanol. A series of runs was carried out using one-gallon quantities of 
the Diesel fuel so prepared to power a CLR Diesel test engine, 
manufactured by Lab Equipment Corporation of Mooresville, Ind. In each run 
the engine was started with methanol containing about five weight percent 
of octyl nitrate as ignition promoter and one weight percent of castor oil 
as lubricant. After about 5 minutes of operation in this mode, injection 
of the methanol fuel was discontinued and operation was continued using 
the novel Diesel fuel prepared above. In each case, operation was 
continued over a period of 30 minutes until the fuel was exhausted. In 
each case where the test fuel was used the engine ran smoothly, with a 
power output in excess of the power output using methanol alone. No 
visible emissions of particulates were noted. 
Obviously, many modifications and variations of the invention, as 
hereinabove set forth, can be made without departing from the spirit and 
scope thereof, and therefore only such limitations should be imposed as 
are indicated in the appended claims.