Staged catalysts for millisecond contact time reactions

Hydrogen has received increased interest over the last few years as an attractive alternative to dwindling fossil fuel resources. A cheap and abundantly available supply of hydrogen is required for the viability of the fuel cell as a highly efficient and clean energy conversion system. Production of synthesis gas or syngas, a mixture of carbon monoxide and hydrogen, is the route for the production of hydrogen starting with natural gas. The research described in this thesis focuses on the use of staged catalysts to examine methane conversion to syngas and subsequent production of hydrogen at millisecond contact times.; By employing a partial oxidation catalyst as the first stage and a reforming catalyst in the second stage 95% conversion of methane can be obtained when the temperature of the second stage is increased to 1050°C. Addition of 20% steam (based on the dry gas feed flow rate) leads to essentially complete conversion when the second stage temperature is ∼1000°C due to the availability of more steam to facilitate reforming in the second stage.; The production of a hydrogen rich syngas mixture from methane involves production of syngas followed by the water gas shift of the CO produced to generate a hydrogen-rich stream. The effect of steam addition both to a single partial oxidation stage as well as to two stages where the second stage has a shift catalyst are examined. By adding 400% steam, based on the dry gas inlet flow rate of 2 slpm to the first stage, a H₂/CO ratio greater than 10 can be achieved by employing Rh in the first stage and either Rh or Ni as the second stage.; An elementary step surface reaction mechanism is developed for the partial oxidation of methane on Rh. This mechanism is now used to perform two dimensional simulations of the partial oxidation experiments by coupling the surface mechanism with the computational fluid dynamics package FLUENT. A two-zone model for partial oxidation is proposed—with direct oxidation responsible for methane conversion in the first zone followed by a reforming zone.