USC chemists develop catalyst for reusable, air-stabile ammonia borane dehydrogenation; potential for on-board hydrogen storage
01 September 2011
|
|
| The new ruthenium-based catalyst supports air-stabile ammonia borane dehydrogenation. Conley et al. Click to enlarge. |
A team of University of Southern California (USC) scientists has developed an efficient ruthenium-based catalyst for the dehydrogenation of ammonia borane (AB). The new catalyst liberates more than 2 equiv of H2 and up to 4.6 system wt % H2 from concentrated AB suspensions under air. Importantly, the catalyst is robust, delivering several cycles of dehydrogenation without loss of catalytic activity, even with exposure to air and water.
The new catalyst, reported in the Journal of the American Chemical Society, could enable a hydrogen storage system sufficiently lightweight and efficient to have potential mobile hydrogen storage applications. The USC Stevens Institute is in the process of patenting the technology.
AB is of interest as a hydrogen storage medium for transportation because of its high hydrogen density (19.6 wt %); its ability to release H2 under mild conditions (both thermal and catalytic), and its desirable physical properties.
Though catalytic hydrolysis is well-known and very efficient for H2 production from AB, anhydrous dehydrogenation can enable a more efficient fuel cycle. This is because hydrolysis reactions form stoichiometric quantities of ammonia, a hydrogen fuel cell poison, and strong B-O bonds, which preclude an efficient regeneration scheme.
Several heterogeneous and homogeneous transition-metal catalysts are active for AB dehydrogenation, but these are limited by protic and oxidative decomposition in air, low extent of H2 release (≤2 equiv), uncontrolled rate of H2 release, or production of unwanted products such as ammonia (NH3) or borazine (N3B3H6), which are poisonous to fuel cells. Additionally, many are not viable because the catalyst loading is high or the catalyst is not reusable.
We report here a system that is long-lived [turnover number (TON) > 5000], functions under air, and dehydrogenates AB to give >2 equiv of H2. These characteristics make it a leading candidate for use in a commercial H2 storage system.
—Conley et al.
The catalyst, described in an earlier JACS paper (Conley and Williams, 2010) is a boron-pendant ruthenium-based oxidation catalyst.
The team continues to work to uncover the detailed roles of the boron and ruthenium centers in AB dehydrogenation and the application of dual-site catalysis to more general hydride manipulation reactions.
The research was funded by the Hydrocarbon Research Foundation and the National Science Foundation.
Resources
Brian L. Conley, Denver Guess, and Travis J. Williams (2011) A Robust, Air-Stable, Reusable Ruthenium Catalyst for Dehydrogenation of Ammonia Borane. J. Am. Chem. Soc., doi: 10.1021/ja2058154
Brian L. Conley and Travis J. Williams (2010) Thermochemistry and Molecular Structure of a Remarkable Agostic Interaction in a Heterobifunctional Ruthenium−Boron Complex. J. Am. Chem. Soc., 132 (6), pp 1764–1765 doi: 10.1021/ja909858a
Im interrested to buy, why not ??
The most frustrating thing there is is when you want to buy something but there isn't nothing good to buy. Ask that to bill gates or warren buffet, they are full of money and they cannot buy all they want because there is a lack of things to buy so they end-up giving money to charity or invest that on the stock market in old stocks and it end-up as inflation..
It's the same situation for me but on a way smaller scale. So put that hydrogen storage gadjet for sale for cash near where i live along a car hydrogen conversion kit and i will go shopping it if the price and quality are right. My car is a chrysler neon and it's still good enouph to convert to almost free non-polluting hydrogen gas.
Posted by: A D | 02 September 2011 at 02:43 PM
Go for it A D.
I can tell you are someone who can actually do it.
And no posting 'til you're done.
Not a word.
Posted by: ToppaTom | 02 September 2011 at 09:48 PM
The lowest green-house-gas-producing, lowest air-contamination-producing, lowest cost and infinitely abundant working energy source on the face of the earth is nuclear fission of thorium or uranium. For most automobile journeys, a cheap small lead-acid battery powered vehicle will work that can be charged from the mains. TATA could make such a vehicle. TH!NK and TESLA are suitable vehicles as is perhaps the VOLT for people with a lot of money.
For longer excursions, high efficiency diesel engined, Artemis hydraulic hybrid technology use less of the earths resources than any hydrogen technology except if the hydrogen is produced from water with nuclear heat.
Someone could invent a way of extracting hydrogen from diesel fuel that stores carbon for recycling instead of burning it, or it could store liquid CO2 to be recycled where diesel is bought for low pollution long distance travel.
Liquid ammonia can also be used as a very low air-pollution fuel with the highest hydrogen energy density by volume and weight.
Hydrogen made at Nuclear reactors can be combined with nitrogen to make a liquid fuel for long distance zero emission travel, and electric cars with ammonia fueled range extenders that are rarely used may make a very compact, low operational cost solution to most travel needs.
It is now possible to build a cheap locomotive that burns any fuel including coal that theoretically does not release any CO2 or SO2 or mercury vapour. The CO2 and SO2 are saved for recycling.
Solar energy requires many square miles of expensive collection devices including wind turbines.
In countries with natural gas distribution, the most cost effective way of reducing countrywide CO2 release is to spend all monies going to wind or solar or biofuels for cogeneration equipment instead. Even every individual home connected to gas mains can employ cogeneration equipment as well as all other buildings, and most such installations will pay for themselves in a few years without any subsidies, but standards must be used as they are for efficient refrigerators etc. to force the expenditures of capital by builders and buyers. Loans the size of solar, wind and biofuel subsidies can be made available for cogeneration equipment, and the fuel prices can be those given to large electric generation companies for the fuel used in the cogeneration equipment as no additional facilities or activities will be needed to be supplied by the gas mains companies. Heat use and heat storage equipment for both heating and cooling is well understood as are suitable batteries. ..HG..
Posted by: Henry Gibson | 03 September 2011 at 08:48 PM