DEVELOPMENT OF A CATALYST/SORBENT FOR METHANE REFORMING
This work has led to the initial development of a very promising material that has the potential to greatly simplify hydrocarbon reforming for the production of hydrogen and to improve the overall efficiency and economics of the process. This material, which was derived from an advanced calcium-based sorbent, was composed of core-in-shell pellets such that each pellet consisted of a CaO core and an alumina-based shell. By incorporating a nickel catalyst in the shell, a combined catalyst and sorbent was prepared to facilitate the reaction of hydrocarbons with steam. It was shown that this material not only catalyzes the reactions of methane and propane with steam, it also absorbs CO{sub 2} simultaneously, and thereby separates the principal reaction products, H{sub 2} and CO{sub 2}. Furthermore, the absorption of CO{sub 2} permits the water gas shift reaction to proceed much further towards completion at temperatures where otherwise it would be limited severely by thermodynamic equilibrium. Therefore, an additional water gas shift reaction step would not be required to achieve low concentrations of CO. In a laboratory test of methane reforming at 600 C and 1 atm it was possible to produce a gaseous product containing 96 mole% H{sub 2} (dry basis) while also achieving a H{sub 2} yield of 95%. Methane reforming under these conditions without CO{sub 2} absorption provided a H{sub 2} concentration of 75 mole% and yield of 82%. Similar results were achieved in a test of propane reforming at 560 C and 1 atm which produced a product containing 96 mole% H{sub 2} while CO{sub 2} was being absorbed but which contained only 69 mole% H{sub 2} while CO{sub 2} was not being absorbed. These results were achieved with an improved catalyst support that was developed by replacing a portion of the {alpha}-alumina in the original shell material with {gamma}-alumina having a much greater surface area. This replacement had the unfortunate consequence of reducing the overall compressive strength of the core-in-shell pellets. Therefore, a preliminary study of the factors that control the surface area and compressive strength of the shell material was conducted. The important factors were identified as the relative concentrations and particle size distributions of the {alpha}-alumina, {gamma}-alumina, and limestone particles plus the calcination temperature and time used for sintering the shell material. An optimization of these factors in the future could lead to the development of a material that has both the necessary mechanical strength and catalytic activity.
- Research Organization:
- Iowa State University Of Science & Technology
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG26-02NT41549
- OSTI ID:
- 893288
- Country of Publication:
- United States
- Language:
- English
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