Diesel fuel containing manganese tricarbonyl and oxygenated compounds

The amount of soot and invisible particulates emitted with the exhaust of engines run on diesel fuel is reduced by incorporating therein an additive consisting of a mixture of an oxygenated compound and an alkyl cyclopentadienyl manganese tricarbonyl. Also disclosed is a method of operating a diesel engine using the fuel of the invention.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to means and a process for reducing exhaust 
emissions of diesel fuels. More particularly, the invention is concerned 
with reducing the amount of invisible particulates in diesel engines 
exhaust emissions. The invention also relates to a method for operating a 
diesel engine in such a manner that there is produced a minimum of harmful 
obnoxious exhaust smoke by that engine. 
Diesel fuels used in diesel engines give off in the exhaust of the engine 
particulates which recent tests indicate to be harmful pollutants. These 
particulates include not only those that exist as visible smoke when the 
diesel engine is overloaded or when the engine is worn or dirty, but also 
those that are invisible and emerge from partly loaded clean diesel 
engines. The Federal Environmental Protection Agency recently determined 
that diesel-powered automobiles emit unacceptably high levels of air 
pollution and must be reduced to ward off a possible health hazard. 
Tests of 10 foreign and domestic cars showed many of the vehicles emitted 
particulate matter in amounts exceeding the agency's proposed standard for 
diesel-powered autos. 
The proposed standards would allow six-tenths of a gram per mile for 1981 
model cars, to be reduced to two-tenths of a gram per mile by the 1983 
model year. 
2. Description of the Prior Art 
The prior art to which this invention relates is aware of U.S. Pat. Nos. 
2,916,454; 3,410,670; 3,413,102; 3,539,312 and 3,499,742. These patents 
show smoke suppressants are commonly employed in or added to diesel fuel 
oils particularly when the diesel engine are to be operated in areas of 
high population density. In general, the most common smoke suppressants 
employed are the organic compounds of barium, particularly the barium 
carbonate overbased barium sulfonates, which are effective for 
substantially reducing the amount of smoke exhaust from a diesel engine. 
There are serious questions concerning the use of barium compounds as 
smoke suppressants, however. It is well known that some barium compounds 
are toxic to ingestion by human beings at high dosages. Calcium compounds, 
particularly calcium carbonate overbased calcium sulfonate, have been 
proposed to replace the barium carbonate overbased barium compounds in 
diesel fuels. However, the calcium carbonate overbased calcium sulfonates 
have not enjoyed any appreciable degree of use because of a number of 
serious disadvantages connected with their use. The last mentioned patent 
discloses a smoke inhibited diesel fuel composition comprising a 
hydrocarbon distillate fuel containing smoke suppressing amounts of a 
calcium alkyl-phenolate or sulfurized calcium alkylphenolate overbased 
with calcium 2-methoxyethoxide alone or with calcium 
hydroxide-2-methoxyethoxide. None of these patents is concerned with 
reducing the amount of both visible and invisible particulates emitted by 
diesel engines. 
OBJECTS AND SUMMARY OF THE INVENTION 
The main object of this invention is to provide diesel fuel compositions 
which emit, during use, reduced amounts of particulate combustion 
products. 
Other objects and advantages of the invention will be apparent from the 
following description and the accompanying claims. 
The present invention provides a hydrocarbon base diesel fuel composition 
containing a minor, particulate-reducing amount of an additive consisting 
of an oxygenated compound and an alkyl cyclopentadienyl manganese 
tricarbonyl. The method of the invention comprises supplying to and 
burning the fuel in a diesel engine. 
In accordance with this invention there is blended with the diesel fuel 
from 0.01 to 1.5 weight percent of the oxygenated compound and 0.1 to 1.0 
weight percent of the organometallic compound. 
Whenever the expression "diesel fuel" is employed in the following 
description and claims, it is to be understood that it designates that 
hydrocarbon fraction which distills after kerosine. Its property 
requirements are those given on page 11-37 of the "Petroleum Processing 
Handbook", 1967 Edition. Generally, the diesel fuel will comprise a 
mixture of hydrocarbons boiling in the range of 350.degree. to 700.degree. 
F. 
DISCLOSURE OF THE INVENTION 
In accordance with the invention, the diesel fuel is modified by mixing 
therewith an oxygenated compound and an alkyl (preferably methyl) 
cyclopentadienyl manganese tricarbonyl (MMT). Suitable oxygenated 
compounds include aldehydes and ketones having from 3 to 16 carbon atoms 
such as propionaldehyde, acetone, cyclic ethers, butyl heptyl ketone and 
normal alcohols having from 3 to 16 carbon atoms in the chain and ethers 
containing from 2 to 10 carbon atoms such as tetrahydrofuran. In general 
enough of these compounds or mixtures thereof should be added to the 
diesel fuel to provide from 0.01 to 1.5 weight percent of oxygen in the 
combined form.

The following examples are set forth as representative and illustrative of 
the present invention. 
EXAMPLE I 
A diesel fuel containing tetrahydrofuran and MMT when burnt in a diesel 
engine gives reduced particulates compared to the neat diesel fuel. 
EXAMPLE II 
The procedure of Example I is repeated using acetone and MMT to give 
substantially similar results. 
EXAMPLE III 
The procedure of Example I is repeated using n-undecanol and MMT to give 
substantially similar results. 
EXAMPLE IV 
The procedure of Example I is repeated using propionaldehyde and MMT to 
give substantially similar results. 
The effectiveness of the fuel and of the method of the invention are 
determined by burning untreated fuel and treated fuel in automotive diesel 
engines and running the exhaust into a dilution tube equipped with a 
Millipore filter which was weighed before and after combustion. Tests are 
run at 25 miles per hour road load, 40 mph road load, and 55 mph grade. 
The effect on particulate production of advanced, standard and retarded 
injection timing for each of the additives at each of the loads is noted.