Flash Autothermal Reforming of Liquid Bio-Feedstocks to Produce Hydrogen
02 November 2006
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| Schematic of reactor. Click to enlarge. |
University of Minnesota researchers have developed a process that flash evaporates nonvolatile liquid bio-feedstocks such as soy oil or glucose-water solutions by catalytic partial oxidation to produce hydrogen in high yields with a total reactor time of less than 50 milliseconds.
The new process works 10 to 100 times faster than current technology, with no input of fossil fuels (except for the use of methane at reactor startup and shutdown) and in reactors at least 10 times smaller than current models. The work, which will be published in the 3 Nov 2006 issue of Science, could significantly improve the efficiency of fuel production from renewable energy sources.
It’s a way to take cheap, worthless biomass and turn it into useful fuels and chemicals. Potentially, the biomass could be used cooking oil or even products from cow manure, yard clippings, cornstalks or trees.
—Prof. Lanny Schmidt, U of M
The liquid feedstocks are sprayed as fine droplets from an automotive fuel injector through a tube onto a ceramic disk made of a rhodium and cerium catalyst material. At reactor startup, CH4 (methane) and air are passed over the catalyst at 350° C and reacted to form synthesis gas (H2 and CO), releasing high levels of heat.
Once the catalyst surface reaches temperatures of 1,000° C or higher, the injectors spray a liquid fuel-air mix directly onto the hot surface. With the appropriate mix, the bio-feedstocks reform autothermally in air without the addition of more methane.
The catalytic reactions of these products generate approximately 1 megawatt of heat per square meter, which maintains the catalyst surface above 800°C at high drop impact rates. At these temperatures, heavy fuels can be catalytically transformed directly into hydrogen, carbon monoxide, and other small molecules in very short contact times without the formation of carbon.
Pyrolysis, coupled with the catalytic oxidation of the liquids upon impact with the hot rhodium-cerium catalyst surface, avoids the formation of deactivating carbon layers on the catalyst.
Because the catalytic disk is porous, the syngas passes through it and is collected downstream in the tube.
In trials using soy oil as a feedstock, the process converted about 70% of the hydrogen in the oil to hydrogen gas. Schmidt and his university colleagues—graduate students James Salge, Brady Dreyer and Paul Dauenhauer—have produced a pound of synthesis gas in a day using their small-scale reactor.
The research work was supported by the Department of Energy and the University of Minnesota Initiative for Renewable Energy and the Environment.
Resources:
“Renewable Hydrogen from Nonvolatile Fuels by Reactive Flash Volatilization”; J. R. Salge, B. J. Dreyer, P. J. Dauenhauer, L. D. Schmidt; Science 3 November 2006: Vol. 314. no. 5800, pp. 801 - 804 DOI: 10.1126/science.1131244
No need for air plant?
Posted by: allen_Z | 02 November 2006 at 03:53 PM
Syngas-fuel/chemical plants often have a O2 generator onsite, if not nearby. This might remove the need for one, which may improve yields per unit BTU raw feedstock. One question I have is what since it takes in N2, does it emit NOX?
Posted by: allen_Z | 02 November 2006 at 04:02 PM
A syngas full of H2 would be far too reducing to have NOx.
Posted by: Engineer-Poet | 02 November 2006 at 07:39 PM
This is fine IF you're using manure as a feedstock.
What's the point of turning soy oil into H2 + CO ??
Posted by: Dursun | 02 November 2006 at 08:50 PM
To make fuels and other chemicals. It could also be for making H2 for various purposes (nitro fertilizer, petroleum upgrade, etc), and CO for power generation.
Posted by: allen_Z | 03 November 2006 at 05:32 AM
Allen -
significant amounts of NOx are only formed at the much higher temperatures (>>1600 deg C) observed in e.g. ICEs.
The point of this compact reformer is to work around the problem of storing hydrogen on board a fuel cell vehicle. Instead, you'd fill up with a liquid fuel and produce the hydrogen as needed. Since only 70% of the hydrogen in the fuel is converted into the hydrogen gas the fuel cell needs, the other 30% is presumably lost as H20. The poor thermodynamic efficiency of this reformation completely negates any energetic advantage the fuel cell might have over just burning the biofuel in an ICE.
The process might still make sense in stationary applications iff it can be modified to use low-grade feedstocks such as agricultural wastes. The resulting syngas can then be used for industrial processes incl. electricity generation using e.g. a SOFC (which would be too heavy for any vehicle other than a ship or perhaps a locomotive).
Posted by: Rafael Seidl | 03 November 2006 at 06:21 AM
You could put the CO and H2 into an SOFC and get electricity at 60% efficiency, using plant oils or other fuels. This has some real applicatioin as a reformer.
Posted by: SJC | 03 November 2006 at 06:28 AM
SJC -
0.7 * 0.6 = 0.42, so burning the plant oil in a diesel that drives a generator is thermodynamically equivalent to the proposed reformer + SOFC combo, but the up-front investment is much lower. Emissions, noise and vibration are other important aspects, which is why it might still make sense to spend more for certain niche applications.
Posted by: Rafael Seidl | 03 November 2006 at 07:51 AM
It seems like a good reformer with potential. What people do with it is their business.
Posted by: SJC | 03 November 2006 at 08:12 AM
Rafael,
The reformer produces heat, which can be used. The SOFC also can be fitted to recover heat for various purposes.
Posted by: allen_Z | 03 November 2006 at 12:38 PM
How is CO used to generate power? Wouldn't this be far better in stationary applications or places where both methane and waste biomass were plentiful and easy to collect-- producing electricity for EVs?
Shouldn't we be aiming to simplify the application of renewable energy to motor vehicles by universalising EVs and diversifiying sources of renewable electricity production?
Fran
Posted by: Fran | 09 November 2006 at 03:50 PM
This can be used in lots of applications. It makes synthesis gas, which can be used to synthesize SNG, mthanol...the list goes on.
As far as diversity of electric power, I do not see a lot of diversity in the near future. That was one factor that was given for degregulation, which has not happen. If we could get 10% renewable nationwide in the next 10 years, that would be doing well. As far as EVs are concerned, when I see the battery that costs little, is small, light, has great capacity and a long life, then maybe we are getting closer.
Posted by: SJC | 10 November 2006 at 12:54 PM
Has anyone thought of using the earth to compress hydrogen? More precisely, what stops a company from running two cables down into the ocean 10,000 feet and supplying the cable with wind powered elecrtricity, thereby producing hydrogen from the ocean at a pressure of 4454 psi. The hydrogen would be collected at depth and piped, at a collection pressure of 4454 psi, up to a surface collection station and further into existing high pressure gas distribution infrastructures.
Posted by: JB | 07 March 2007 at 10:12 AM
There are developments in DME in China today:
DME is an LPG-like synthetic fuel can be produced through gasification of Biomass. The synthetic gas is then catalyzed to produce DME. A gas under normal pressure and temperature, DME can be compressed into a liquid and used as an alternative to diesel. Its low emissions make it relatively environmentally friendly. In fact, Shandong University completed Pilot plant in Jinan and will be sharing their experience at upcoming North Asia DME / Methanol conference in Beijing, 27-28 June 2007, St Regis Hotel. The conference covers key areas which include:
DME productivity can be much higher especially if
country energy policies makes an effort comparable to
that invested in increasing supply.
By:
National Development Reform Commission NDRC
Ministry of Energy for Mongolia
Production of DME/ Methanol through biomass
gasification could potentially be commercialized
By:
Shandong University completed Pilot plant in Jinan and
will be sharing their experience.
Advances in conversion technologies are readily
available and offer exciting potential of DME as a
chemical feedstock
By: Kogas, Lurgi and Haldor Topsoe
Available project finance supports the investments
that DME/ Methanol can play a large energy supply role
By: International Finance Corporation
For more information: www.iceorganiser.com
Posted by: Cheryl Ho | 22 May 2007 at 11:36 PM
What are you talking about fran
Posted by: Bandit | 17 July 2007 at 02:05 PM