Dutch Researchers Developing Catalytic System for Producing Hydrogen from Gas-Fired Power Stations
29 April 2009
| Cartoon of the proposed combined hydrogen and conventional power plant (top). Combined methane combustion, coking and generation of H2 and coke combustion (bottom). More H2 can form via the water–gas shift reaction if CO is present. Credit: RSC. Click to enlarge. |
Researchers at the University of Amsterdam in the Netherlands are developing ceria-based catalysts as candidates for integrating methane combustion and hydrogen generation in power plants. The proposed process combines methane combustion, coking, simultaneous generation of hydrogen and coke combustion.
The process can be applied in existing gas-fired power plants, using methane from both fossil and renewable sources. In a paper published in the RSC journal Green Chemistry, the team led by Dr. Gadi Rothenberg showed that good results can be obtained from ceria-based catalysts with platinum, ruthenium, and importantly, nickel, with its lower cost.
| Methane conversion and hydrogen yield at 550 °C. Click to enlarge. |
In an evaluation of 21 different catalysts at 400 °C, 450 °C, 500 °C and 550 °C, they found that a Pt-based catalyst delivered the highest hydrogen yield of 32%, with six other catalysts ranging from 27-31%. One nickel-based catalyst achieved a yield of 31%; another a yield of 28%.
The data show several highly active catalysts (with up to 97% methane conversion), that also display high hydrogen yields (~30%). The best catalysts contain either Pt, Ru or, importantly, Ni as active metal. Interestingly, most of the good catalysts consist of ceria and one of the active metals, without an extra dopant.
Indeed, the second metal can have three effects: Firstly, it can lower activity and hydrogen yield...Secondly, it can inhibit the hydrogen generation but not the combustion. Thirdly, it can inhibit both hydrogen generation and combustion. All of the inactive catalysts contain chromium, and the inhibition occurs for both the impregnated and mixed oxide samples (calcined at 500 °C and 700 °C, respectively). This shows that there is a strong interaction between the active metal and the poisoning chromium.
—Beckers et al. (2009)
Platinum and nickel catalysts show the smallest variation in activity across the tested temperature ranges. All the catalysts that produce hydrogen do so only at full O2 conversion—i.e., when no oxygen is left for combustion.
The catalyst can be regenerated in situ by temporarily closing the CH4 feed, making all the oxygen available for the combustion of the coke. This in situ regeneration, the researchers noted, allows a continuous generation of heat.
Resources
Jurriaan Beckers, Cyril Gaudillère, David Farrusseng and Gadi Rothenberg (2009) Marrying gas power and hydrogen energy: A catalytic system for combining methane conversion and hydrogen generation. Green Chem., doi: 10.1039/b900516a
I envision power plants becoming more like fuel plants. They create the heat which can be used for many things. We talk of Combined Heat and Power (CHP) for home use, so why not for power plants?
There are lots of power plants with waste heat and then when we think of bio refineries we wonder where the heat will come from for the process. Thinking outside the box may provide some of those answers.
Posted by: SJC | 29 April 2009 at 11:03 AM
Fuel is one place to start, how much fuel we use is equally important. Climate change can be improved even by our using less water. I saw a really great video earlier that might help get some people living more water efficient lives. Check out them out at
http://www.tomorrowsworldcompetition.com/
Students wrote and directed those, can you believe it? They're really working hard to raise awareness and get the public involved. It's a cause worth fighting for!
Posted by: Mark | 29 April 2009 at 11:30 AM
Hydrogen is needed for oil refining and to make ammonia, but we will learn that hydrogen powered cars and even stationary fuel cells are too expensive in terms of both money and CO2 release. Battery electric cars are also too expensive but are far less so than automobile fuel cells. TH!NK's battery lease program is a good approach, but hybrids are a necessary method.
Large diesel engines can get the same overall efficiency as most fuel cell systems. Small diesel engines can be made very efficient and are then far less costly for the life of a vehicle. A 100 percent efficient car that cost a million dollars, is obviously not worth the money.
The nuclear reactor that gets CO2 and adds Hydrogen to make methanol, ethanol or Butanol is the eventual solution to the automotive fuel issue. The fuel will be used in hybrid cars. ZEBRA batteries are sufficient for many hybrid cars and lead or lithium or even a combination can be used in others.
Even if inefficient electrolysis is used, methanol fuel made from CO2 and hydrogen is cheaper than $3.00 a gallon gasoline. The US should put an immediate tax of $40 a barrel on imported oil from restricted producers. The pice of gasoline has crept up 70 cents recently because of the production restrictions imposed to raise the price. Where is the peak oil that the US government was using as an excuse for not imposing restrictions on speculation in the non free market of oil production. The US govenment itself is limiting the free market by opposing oil drilling, oilshale production and Coal to liquids. If the US wishes to impose limits on production for any excuse then they must also eliminate speculation. ..HG..
Posted by: Henry Gibson | 02 May 2009 at 06:15 AM
In continuation, natural gas is a proven fuel for vehicles and also can be made into more convenient liquid fuels.
Nuclear power plants can be buried deep under most large cities to provide steam heating. Chernobyl has proved that even the explosion of a dangerous reactor on the surface will not kill any residents of nearby towns, and the extreemly unlikely explosion of a much safer reactor under three hundred feet of earth and rock would not be noticed.
To provide additional automotive fuel, no methane would be used to heat buildings in a city, and people could pretend that they are using geothermal heat. Small amounts of electricity could also be made with geothermal methods. The steam would be hot enough to operate heat powered air conditioning systems and eliminate even more electrical demand.
Geothermal heat is assumed to come from the decay of thorium and uranium deep in the earth. Fission reactors get four times the energy out of Uranium or Thorium than does decay. Replacing carbon fuel combustion for heating with nuclear heat is the quickest and cheapest way of reducing CO2 release. Statistically considered it is also the safest. Many dam failures have caused more deaths than Chernobyl.
Electricity and hydrocarbons for hybrid cars; Nuclear reactors for electricity and heat. Nuclear reactors provide heat at such a cheap price it can even be used eventually to remove CO2 from the air to make it into liquid fuel. ..HG..
Posted by: Henry Gibson | 02 May 2009 at 06:43 AM
"The US should put an immediate tax of $40 a barrel on imported oil from restricted producers."
I would favor a 10% imported oil fee. A $50 barrel of oil would be taxed $5. This could amount to over $20 billion per year, considering how much we import. You can repair a lot of roads and bridges with that money as well as promote renewable fuels.
Posted by: SJC | 03 May 2009 at 03:02 PM