Skip to comments.Clean Diesel from Coal
Posted on 04/19/2006 5:56:25 AM PDT by aculeus
As the cost of oil soars and worries over the U.S. dependence on foreign petroleum escalate, coal is becoming an increasingly attractive alternative as a feedstock to make a range of fuels. Now chemists have invented a new catalytic process that could increase the yield of a clean form of diesel made from coal.
The method, described in the current issue of the journal Science, uses a pair of catalysts to improve the yield of diesel fuel from Fischer-Tropsch (F-T) synthesis, a nearly century-old chemical technique for reacting carbon monoxide and hydrogen to make hydrocarbons. The mixture of gases is produced by heating coal. Although Germany used the process during World War II to convert coal to fuel for its military vehicles, F-T synthesis has generally been too expensive to compete with oil.
Part of the problem with the F-T process is that it produces a mixture of hydrocarbons -- many of which are not useful as fuel. But in the recent research, Alan Goldman, professor of chemistry and chemical biology at Rutgers University, and Maurice Brookhart, professor of chemistry at the University of North Carolina at Chapel Hill, use catalysts to convert these undesirable hydrocarbons into diesel. The catalysts work by rearranging the carbon atoms, transforming six-carbon atom hydrocarbons, for example, into two- and ten-carbon atom hydrocarbons. The ten-carbon version can power diesel engines. The first catalyst removes hydrogen atoms, which allows the second catalyst to rearrange the carbon atoms. Then the first catalyst restores the hydrogen, to form fuel.
Diesel fuel produced in this way has several potential advantages. Ordinary diesel contains molecules, called aromatics, that, when combusted, produce particulates, Goldman says. But the diesel formed by the new catalysts does not include aromatics, so it burns much cleaner, overcoming one of the major objections to diesel fuel. This could lead to more vehicles using diesel engines, which are about 30 percent more efficient than gasoline engines.
But the biggest advantage may be that the United States has huge amounts of coal: "We have as much energy in coal as the rest of the world has in oil. That's enough to last us the next hundred years or so," Goldman says. Thus, a more efficient, and so less expensive method of converting coal to diesel could significantly cut U.S. dependence on foreign oil, and do so for a long time.
"When I saw this I thought it was really a terrific contribution that could be very important," says Richard Schrock, professor of chemistry at MIT, who won the Nobel Prize in Chemistry in 2005, with two other scientists, for discovering the type of catalyst used in the second step. Combining two catalysts this way "is pretty rare," he says. "You can't just throw any two things together and expect to get the results you anticipated."
According to Robert Grubbs, professor of chemistry at Caltech, who shared the Nobel prize with Schrock, "The key is finding catalyst systems that are compatible, and will operate at the temperatures where you can do both processes together."
At this time, the new catalytic method is still a proof-of-concept, and not ready for commercial use. For example, the second catalyst tends to break down. But Schrock says this problem should be solvable: "It's theoretically possible that this could become practical. I e-mailed Alan Goldman and said, 'Look, we've got a lot of catalysts, and I can think of some things that might be thermally more stable.' So I'm going to send him some catalysts, and he's going to try them out."
It also might be possible to make catalysts that use products from the first reaction to regenerate themselves. "Then the catalyst wouldn't die, and you could in fact keep the reaction going," says Schrock.
Hello? We're currently using high sulfur diesel fuel, not the clean diesel that can be obtained from coal or crude. That's changing this year, and by October we will be using ultra low sulfur diesel nationwide (<15 ppm sulfur).
This will allow for particulate traps and catalytic converters on diesels.
Besides that, the nastiest pollutants are the ones you can't smell.
Perhaps we need a diesel ping list. Heck, there's a ping list for everything else, no matter how obscure. :-)
Might be a good idea - dhuffman and I both own VW TDIs, so I am aware of his interest in the subject.
I wish there were more diesels available in the US. Damned hippies ruing everything. :-)
> having sat behind a diesel bus, there is nothing clean about diesel
Well, the diesel fuels and motors used in typical trucks and buses are generally pretty nasty, especially when operating at non-optimal RPM, i.e. accellerating.
However, a diesel engine burning dimethyl ether - which can be synthesized from coal - at optimal RPM - such as in a properly designed hybrid, produces much less pollution than almost any gasoline engine.
They're coming. At least from Daimler-Chrysler. I think others will jump on board in the next few years. As you know, ULSD was the hold-up, and we're getting it this year.
D-C can't build worth a damn, either, unfortunately.
If Ford, GM (ok, maybe not GM), Toyota or Honda could put diesels in smaller vehicles, I would buy from them and not VW, which has serious kwality control issues (yeah, VW put the "kw" in "quality").
OPEC. If it didn't exist, you would have a free market in oil, but OPEC is a solid reason for consuming countries to either act collectively (think how well it works with the UN) or to take unilateral action to protect their own industries for a foreign monopoly.
I would support the tax penalty concept on the grounds that it provides long term stability for alternative fuels, when OPEC decides to wipe out Western investments in alternative fuels (and what good is a monopoly if you don't attack the competition).
It would not raise energy costs on the consumer, unless oil were to drop substantially. Nor would it hurt domestic oil production.
All you are doing is protecting your domestic market from a large and active foreign monopoly.
I don't know about that. The new OM642 engine looks pretty good, and I've read that it may show up in some Chrysler vehicles.