1. Project Introduction
The Phoenix proprietary hydrogen generation project is a system for light driven production of pure hydrogen gas from an ordinary water feedstock. The system comprises a combination of mixed-metal complexes, catalysts, and electron donors, including a selection of light absorbing units.
2. General System Description
To date, the Phoenix system for light-driven production of hydrogen from a water feedstock has employed mixed-metal supramolecular complexes containing rhodium cores, aromatic bridging ligands and a variety of light absorbing units to construct a system producing hydrogen gas photochemically from the water feedstock. The mixed-metal complex absorbs light throughout the UV and visible region of the spectrum, converting it to the reactive “metal to ligand charge transfer” and “metal to metal charge transfer” states.
3. Project Status and Summary
The supramolecular complexes employed to date contain rhodium cores, aromatic bridging ligands and a variety of light absorbing units, which focus initially on ruthenium and osmium. Systems with this supramolecular architecture have been shown previously in the Phoenix project to be capable of light-initiated electron collection. The subject description of the issued U.S. patent basically covers the more general system of hydrogen gas production by photoelectrochemical means.
4. Major Project Accomplishments to Date
The research and development work, in progress for upwards of 15 years, is well beyond the proof of concept stage. The work has shown that there are a variety of supramolecular complexes applicable as photocatalysts for solar light-generated hydrogen gas production of pristine purity. An array of catalysts that have varying light absorbing qualities, to allow for a broader coverage of the solar spectrum have been developed. Alternative electron donors, of which there are a wide variety, will allow for the most economical production of hydrogen employing this technology.
It is critically important to understand that the Phoenix photochemical process has been reviewed in comprehensive detail, through several complex “office actions,” by the senior U.S. patent examiner involved who has determined that there is no “prior art” that conflicts with the proprietary “foundation” technology that drives the solar light-powered generation of hydrogen gas from an ordinary water feedstock — following decades, if not centuries, of experimental water-splitting efforts.
5. Major Project Goals
Optimization of the Phoenix hydrogen generation system will require experiments involving varying combinations of catalysts, of electron donors, the advanced study of the reactive intermediaries and the variation, in general, of the reaction conditions. More detailed studies will be undertaken of the “excited” states in the process which determine the driving force for oxidation of the electron donors which result in the multi-electron reduced complex. To date, the optimum viable electron donors are aromatic amines, ascorbic acid, sulphides, ethanol and other biomass sources.
6. Hydrogen Generation System Scale-up and Optimization
The proposed work for the project continuation will focus on the leverage of the successful results to date which target specific goals for the project development which would include the following, in more general terms:
• Preparation of an increased number of supramolecular photocatalysts which have been partially proven to function for solar light-driven hydrogen production.
• The scale-up of the developed hydrogen production system, using rhodium-centered supramolecular photocatalysts — scaling up from proven microliter hydrogen production to millilitre volumes, and beyond.
• The improvement of the hydrogen sensors to allow for simpler and longer term photolysis in the scaled-up system.
• In depth evaluation of the range of electron donors that are most technically and economically feasible in the Phoenix photocatalytic system with respect to — high turnover of the system — functioning at the widest pH ranges — and with the possibility of providing commercial end products after their depletion.
The program development personnel will also maintain the records required to support IP protection efforts for what is deemed as unique and innovative new technology.
The optimization goal will include direct support of the parallel engineering efforts required to develop the system to quasi-commercial pilot plant feasibility, financing and construction.
7. Preliminary Production Engineering Design Study
Parallel with the system scale-up and optimization of the primary chemistry of the process will be the engineering studies and planning leading to commercial hydrogen generation. The project engineering will include the collection, concentration and delivery of the solar light to the hydrogen production vessel which will also contain the combination of catalysts and electron donors required to generate the hydrogen gas.
It is presently contemplated that the physical components and equipment of the hydrogen gas production system will largely be available off-the-shelf — including the suggestion of side-emitting fibre optic cable to maximize the distribution of introduced light energy to the hydrogen production component mix.
Another essential requirement to be determined during the engineering phase would involve the physical separation of the produced hydrogen and oxygen gas produced during the process. The successful conclusion of this engineering phase of the project will fairly definitively establish that the system is approaching pilot plant feasibility.
Among the several obvious and potentially commercial, applications for the produced hydrogen gas would include its introduction into a conventional utility boiler to eventually generate commercial power — or to employ the generated hydrogen for conventional fuel cell technology — or for the transmission and delivery of the generated hydrogen gas through the existing natural gas infrastructure — or for its compression and marketing in conventional compressed gas canisters for established industrial hydrogen gas markets (including the presently few service stations now operating for appropriately retro-fitted automobile, truck and bus vehicles).
24 November 2008