Hydrogen and chemicals from fossil and renewable fuels by autothermal reforming.

摘要

Catalytic partial oxidation of hydrocarbons at short contact times is important because valuable products can be made in small autothermal chemical reactors. In particular, the partial oxidation of hydrocarbons to produce syngas (H2+CO) and olefins over rhodium-coated monoliths at millisecond contact times is an efficient route to obtain hydrogen for fuel cells and feed streams for manufacturing other chemicals. There is tremendous interest in the onboard conversion of logistic fuels such as gasoline and diesel to hydrogen for transportation and military applications because these fuels have an existing distribution infrastructure. Further, in automotive applications with internal combustion engines, onboard conversion of a part of the gasoline or diesel into H2 results in improved engine efficiency and reduced exhaust emissions.; The first chapter presents a review of the different supply options for hydrogen and reforming technologies such as steam reforming and partial oxidation and makes the case for producing hydrogen and chemicals from diesel and biodiesel by partial oxidation. Chapter 2 discusses experimental apparatus and operating procedures for these partial oxidation systems. In chapter 3, the catalytic partial oxidation of n-hexadecane, a surrogate diesel fuel, is examined in more detail. In this chapter, we systematically examine the variations of performance with catalyst and wash coat loadings and correlate these results with catalyst characterization using electron microscopy. We also compare multimetallic catalysts and the roles of additives on performance.; While the catalytic partial oxidation of n-hexadecane offers an approximation in the understanding of the complicated reforming process, certain chemical aspects of the logistic fuel are absent. Chapter 4 examines the catalytic partial oxidation of model hydrocarbon mixtures over Rh-coated monoliths in an effort to determine the appropriate operating conditions for achieving maximum syngas and olefin yields from logistic fuels. We find that the overall reactivity of these fuel mixtures is not simply an average over the reactivities of constituent molecules. In chapter 5, the catalytic partial oxidation of biodiesel over Rh-Ce catalyst in an autothermal reactor is examined and the results are compared to the corresponding reactions of n-hexadecane. The last chapter summarizes this research and discusses potential areas of future work.