Integrated chemistry for carbon monoxide-free hydrogen synthesis at short contact-times.

摘要

The generation of high-throughput, CO-free H2 from hydrocarbons in a portable reactor for fuel cell applications requires a series of staged reactions occurring at very short contact-times. CH 4, abundantly available in the form of natural gas, is ideally suited for H2 production because of its simple chemical structure and high hydrogen to carbon ratio. This thesis presents an in-depth study of the catalyst supports, active catalytic material and reactor conditions involved in H2 production from CH4 using three reactions-partial oxidation (POX), water-gas shift (WGS) and preferential oxidation (PROX). Autothermal operation, low thermal mass and relative stability of the noble metal catalysts for different feed conditions are the main advantages of short contact-time reactor system over conventional reactors and offer scalability options for different applications.; Our analyses of the three reactions for CO-free H2 production from CH4 show that noble metals catalysts with high metal loadings can be used for small portable applications where robustness is essential and catalyst cost is not a primary concern. Further study is required to optimize the amount of catalyst and examine the effect of promoters in increasing the rate of the concerned reactions. Modification of the existing elementary-step mechanisms for Rh and Pt, and development of similar mechanisms for other metals will provide a better understanding of various reaction subsets that occur at different temperatures. This will aid in not only commercializing this technology but help gain better insights into reaction subsets for other more complex fuels like ethanol and biodiesel, which are renewable. The use of short contact-time reactors for these renewable fuels will pave the way for zero carbon emission-based H2 economy for sustainable development.