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Researchers Develop New Process for Direct Conversion of Cellulose into Furanics

Researchers at the University of California, Davis have developed a new method for the direct conversion of cellulose into furanics, which can become the basis for new biofuels. The simple, low-cost process delivers furanic compounds in yields not yet achieved, according to Mark Mascal and Edward B. Nikitin in an early view paper published online 1 August in the journal Angewandte Chemie.

Currently, biofuel producers primarily use starch, which is broken down to form sugars that are then fermented to give ethanol. Cellulose, however, is the most common form of photosynthetically fixed carbon. Exploiting that resource for fuels via a fermentation pathway—e.g., cellulosic ethanol—is difficult because the degradation of cellulose into its individual sugar components, which could then be fermented, is a slow and expensive process.

Another problem is that the carbon economy of glucose fermentation is poor. For every 10 g of ethanol produced, you also release 9.6 g CO2.

—Mark Mascal

Researchers are thus looking for effective approaches to biomass conversion which avoid fermentation altogether and exploit all of the available carbon present. One of the promising areas of effort in this area is the production and use of furanics—high-energy, furan-based organic liquids. Work at the University of Wisconsin led by Professor James Dumesic (earlier post) showed that fructose could be efficiently converted, via 5-hydroxymethyfurfural (HMF). Researchers at the Pacific Northwest National Laboratory (PNNL) led by Z. Conrad Zhang (earlier post) have converted glucose directly and with high yield to HMF.

Mascal and Nikitin developed a process for the conversion of cellulose directly—i.e., without relying on glucose or fructose—into furanic products in isolated yields of greater than 80% by conversion mainly into 5-(chloromethyl)furfural (CMF), a hydrophobic molecule.

The process entailed adding microcrystalline cellulose to a stirred solution of lithium chloride (5 wt%) in concentrated hydrochloric acid to give a homogeneous mixture, which was introduced into a reaction chamber containing 1,2-dichloroethane. The solvent was heated to reflux and the aqueous slurry was kept at 65°C with continuous mechanical stirring and extracted for 18 h. At this point, a further solution of LiCl in concentrated hydrochloric acid was added to the reaction chamber and extraction continued for another 12 h. The combined organic extracts were distilled to recover the solvent.

The process yielded 71% CMF; 8% 2-(2-hydroxyacetyl)furan; 5% HMF; and 1% levulinic acid. Total, isolated yield of these four simple organics was thus 85%. Applied to glucose, the process delivered the same organics in yields of 71%, 7%, 8% and 3%, respectively. Applied to sucrose, it yielded 76%, 6%, 4% and 5% respectively.

While CMF itself is not a biofuel candidate, it can be combined with ethanol to give ethoxymethylfufural (EMF). CMF can also be catalytically hydrogenated to yield 5-methylfurfural (HMF). Both of these compounds are suitable as fuels. EMF has previously been investigated and found to be of interest in mixtures with diesel by Avantium Technologies, a spin-off of Shell. (Earlier post.)

While future reports will address further optimization, scaleup, and applications of the method to raw biomass, these preliminary results suggest that this simple, efficient approach to cellulose deconstruction has the potential, at the very least, to complement fermentation as a means to produce biomass-derived automotive fuels, and to establish furanics both as a renewable energy source and industrial chemical feedstock of the future.

—Mascal and Nikitin (2008)

Resources

  • Mark Mascal and Edward B. Nikitin (2008) Direct, High-Yield Conversion of Cellulose into Biofuel. Angew. Chem. Int. Ed. 2008, 47, 1 – 4 doi: 10.1002/anie.200801594

Comments

Henric

@What's the big advantage of BtL? That you can sell it through a pump with an oil-company logo on it?

Yes, Engineer, exactly! The fact that you can "charge" your car from a pump for 500 miles of driving in about a minute is a huge advantage for a person living in a city. You know what city lifestile means, don't you? You don't have a minute of free time. Even charging a battery from a plug each night will be annoying for most. Not to mention firing up a gasogene each morning! People are laisy; consumers in the city are going to demand liquid fuels and pay a lot for them. That is why LPG and nat gas are used so little even though they are cheaper per megajoule. Thus I think that nothing yet beats liquids in ease of operation. And people are going to pay for less annoyance in their dayly lives, trust me!
The Biomass-electricity-BEV route you mentioned is an option. But it is questionable if it is more efficient because you are going to use a heat engine i.e. turbine for conversion. Same abot 30% efficient step. Then count off transmission losses in the grid. The biomass thermal plant is not going to be substantially less expensive than a BtL plant.
Gasogene is a good thing though. I plan to use it for the tractors and other heavy machinery that is used in collection and chipping of wood, forget about horse - that was a joke!
I by the way am a chemist and I find this type of fuel chemistry pretty impressive and exciting. I have looked into this problem pretty deeply and I have come to conclusion that a 50 % conversion to liquids based on thermal energy (Lower heating value) is possible in fairly non-complicated systems that can work on small (100 bbl/day) scale.
But let's see, maybe I change my mind!

Engineer-Poet
The fact that you can "charge" your car from a pump for 500 miles of driving in about a minute is a huge advantage for a person living in a city.
You must not buy much liquid fuel.  It takes me at least 10 minutes to get my car filled up, not including the time required to find a station and make as many as 2 trips to the cashier to pre-pay and get change.

Plugging in would be a dream by comparison.  Pull into the garage, yank the charging cord down from the reel on the ceiling, plug the car in, done:  perhaps 10 seconds.  This would reduce my trips for liquid fuel to roughly 1/4 of what they are now, as well as cut the cost by 3/4.  All for about 70 seconds a week!  Figuring my fuel cost at $20/week (conservative) and $15/week savings, plus a couple of fumbles to make 90 seconds a week, my time would be compensated at $600/hour.

Even charging a battery from a plug each night will be annoying for most. Not to mention firing up a gasogene each morning!
Who'd fire up a gasogene each morning?  That would only be for long-distance trips, and if your cost per gallon-equivalent was $2 or less, wouldn't it be attractive?

More to the point, the oil-company-branded liquid is the only useful energy stream from that route, while the process of making charcoal for a gasogene can yield both energy and chemicals.  You could heat your house while making charcoal, then run your car on the charcoal.  No energy needs to go to waste.  If buying that Shell-branded biofuel means your house is cold and dark... I know which option I'd choose.

Henric

Cmon, Engineer, try to find a station that's on your way! ;)
No doubt electricity is going to play an increasingly important role in personal transportation. Todays HEVs and PHEVs where the electrical part increases the overall effectiveness show this trend.
But this comes with a high price, and until cheaper electricity storage units are developed ICE drivetrain is going to win. This is somewhere in the future.
Now liquid fuels will still be needed, because of ease of operation and distribution. They might not be the most efficient way, but people not always do things in most efficient ways.

Engineer-Poet

Quoth Henric:

until cheaper electricity storage units are developed ICE drivetrain is going to win.
ICE is already a loser at $3.00/gallon prices, at least for short ranges.  Technologies as primitive as lead-acid with carbon-foam backing (Firefly Energy) are cheaper than petroleum for a significant distance per trip.  Tomorrow's PHEV will do 60 all-electric miles, but it doesn't mean that today's batteries can't do 20 miles at less cost than gasoline.
Now liquid fuels will still be needed, because of ease of operation and distribution.
We already distribute electricity to 99% or so of all dwellings in the USA, and the ease of operation is such that we can trust children to plug things in.  I think you've got it backwards, and only the combined forces of inertia and propaganda are keeping the system from going hard over to the situation which prevailed at the turn of the 20th century.  Electricity ruled then, and will rule again.  Soon.

Henric

Engineer, what do you think about the efficiency of having to drive around with a 250-kg or heavier battery (about 1/4 of the total vehicle mass)? What effect is this going to have on acceleration and breaking?

Engineer-Poet

Why are you asking me?  Go look at the reports on the RAV-4 EV, EV1, Tesla and the like.  I recall the performance of the EV1 reported as being rather sprightly.

Henric

No, I understand that they are going to be sprightly.
What I mean is - don't you think that having to constantly accelerate 250+ kg battery will seriously reduce the overall efficiency of such vehicle? Because it is acceleration to the cruising speed where a significant portion of the energy is expended i.e. giving the vehicle its kinetic energy which is directly proportional to its mass.

Engineer-Poet

What I think matters not at all, because the facts are in, and all you'd have to do is go look at them (energy consumption of various EV's in watt-hours/mile).

Henric

You are right, the facts are in. I just looked at the facts for Tesla Roadster. 100,000$ upfront cost, a battery that weights 450 kg. Where do the 100,000$ come from? Is this the battery? It is made of mass-produced Li-ion cells that all of the laptops use. OK, the efficiency. It uses 13 kWh/100 km. My old VW Passat gets 8 L/100 km in the city which translates to 14 kWh/100 km (8.9 kWh per liter (gasoline energy density) times 8 liters times 0.2(the efficiency)).
Essentially the same.
Now, let's assume that I have only biomass at my disposal and I want to make those 13-14 kWh.
I could make them in a biomass fired thermal power plant with 35 % efficiency. For that I would need 13/0.35=37 kW hrs of biomass thermal energy.
Or, I could make BtL gas/diesel at about 50 % efficiency, using for that 13/0.5=26 kWh of biomass thermal energy.
In my calculations, BtL is about 1.4 times more efficient. Disagree?

Engineer-Poet
100,000$ upfront cost, a battery that weights 450 kg. Where do the 100,000$ come from? Is this the battery?
You must not look at too many low-volume, hand-built vehicles.  They're expensive because of all the custom labor which cannot be reduced through automation.
My old VW Passat gets 8 L/100 km in the city which translates to 14 kWh/100 km (8.9 kWh per liter (gasoline energy density) times 8 liters times 0.2(the efficiency)). Essentially the same.
No, it's not.  You don't get to multiply by 0.2; you're consuming all of that 71 kWh/100 km, not just the part that goes to the wheels.
Now, let's assume that I have only biomass at my disposal and I want to make those 13-14 kWh.
BTL:  140-200 kWh biomass input per 100 km, give or take. Thermal to electricity via steam cycle @ 35%:  37 kWH biomass input. Biomass co-fired CAES @ 75% fuel-to-electric:  19.8 kWh biomass input.

The thermal to electric yields 4 to 6 times as much mileage per unit as BTL, and CAES yields 7-10 times as much.

In my calculations, BtL is about 1.4 times more efficient. Disagree?
You cannot possibly be including the ICE losses in the calculations for electric drivetrains and be the slightest bit honest.  It's time to go away, troll.

Henric

Ok, man, sorry, I did it wrong, I admit that, I got that right after I posted. Ok, let's do it over again.
So, for an electrical car:
13 kWh/100 km - 13/0.3=43 kWh thermal; 30 % steam-cycle efficiency is maximum with biomass. It is 30 % in coal-fired plants; because biomass generally has low combustion temperatures, for biomass it will be even less. Here I am not counting transmission/charging-discharging loses. In reality it will be more like 13/0.2 or 65 kWh thermal input. Tesla gave 20 kWh/100 km plug-to-wheel after prototype tests as referenced in wikipedia. So in reality the thermal input can be as much as 20/0.2 or 100 kWh. 20 % biomass-to-plug is a realistic assumption knowing that the combustion of solid biomass will give low flame temperatures which translates to low steam temperatures/pressures. 75 % efficiency is not realistic, trust me! This is not a realistic technology. So let's stop at 100 kWh biomass thermal.
No, for gasoline car I need to make 8 l of gasoline or 71 kWh. Assuming 50 % biomass-to-liquids it translates to 142 kWh thermal input. If you are interested I can tell you where I got those 50 %. Actually, the maximum theoretical efficiency for biomass-to-hydrocarbons via gasification-FT is 83 % if the biomass input is used to supply the heat for the endothermic gasification reaction i.e. no outer heat sources used.
So if we compare these two realistic technologies, 100 kWh and the need to install half a ton Li-ion battery in each car (which costs a lot even though it is made of mass-produced Li-ion cells),
or 150 kWh and no change in the infrastructure at all; there is not even a need to upgrade the BtL product, it can be added to liquid fuel made from fossil oil.
1.5 is not big enough increase as to warrant the expensive batteries.
Same goes for electricity made from coal. At 2 kWh/kilogram, one would need 10 kg coal/100 km for an electric car, or about 10 L oil/100 km for a gasoline car. The same in the terms of CO2 emissions.

Henric

More to the point, biomass to electricity via steam cycle is highly inefficient, this is like old-fashioned steam engine. The accepted strategy to use for making electricity from biomass is downdraft gasification - gas engine/genset. The cooling water of the ICE gas engine is used for district heating. As the ICE has much higher efficiency this is way better, about 30 % biomass to electricity because the biomass to gas by downdraft is about 85 % efficient.
BtL has definite advantages under certain conditions, like when there are no other energy carriers. The technology is fairly simple, the plant can be built using relatively cheap materials like low-alloy steel and fireclay refractories.
It is interesting to note that fermenting of glucose to ethanol has a thermal conversion efficiency of about 95 %. It would be very tempting to find ways to hydrolyze and ferment cellulose because of improved efficiency. Unfortunately, I am confident it cannot be done cheaply because cellulose has a crystalline structure that is like rock, unsusceptible to any treatment. Further, it is coated in lignin polymer. Thermochemical is the only way to efficiently deal with lignocellulosic biomass.

If there ever appears a reasonably good electricity storage unit, I am definitely going to consider electricity. But it is not going to be batteries because the best battery that we can get is based on Lithium (this is purely by looking at the periodic table, H batteries would be better, but H battery is the fuel cell, and it is bad as you know). And as you perfectly know, the energy density is unacceptably low.
If ever a room-temperature superconductor gets discovered, then a superconducting coil storage unit could be perfect.
But right now, it appears that we do not have it.
For example: The Roadster batteries weight 450 kg, and has a capacity of 53 kWh (wikipedia). By comparison, the same energy from gasoline is (53 kWh/0.2)/8.9 = 30 liters! That's about 22 kg!

Henric

As far as lowering the price by mass production, only the large car manufacturers are going to ever be able to do that. It appears that they are not taking this direction, i.e. purely electrical vehicle. There must be reasons behind this. What exactly are they I do not know, but they must be related to the commercial viability of that. Trust me, if it was profitable to make electrical vehicles, they would do that. They would do everything for money. Remember that when nuclear was popular in the 50-ties they even proposed prototypes of nuclear cars.

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