STUDIES ON ETHANOL CONVERSION FOR CLEAN FUELS

摘要

Due to increasing energy demands and environmental problems, the development of clean and renewable energy becomes more and more urgent. Ethanol produced by fermenting biomass is potentially a cleaner starting material to generate clean fuels and chemicals. Currently, there are two main thermochemical processes to convert ethanol, including steam reforming to produce H2 and dry reforming to produce syngas and liquid fuels. The steam reforming provides the highest yield of hydrogen with the H2/CO2 molar ratio of 3, while the dry reforming introduces both renewable energy (bio-ethanol) and CO2 recycling into the chemical production chain, leading to carbon- negative syngas and liquid fuel generation. In fact, in spite of reforming routes, ethanol decomposition is one of the key steps. A number of studies have revealed that ethanol conversion largely depend on catalysts and reaction conditions. Thus, selecting and modifying catalysts becomes a crucial issue in the entire thermochemical process. Although some experimental efforts have been made to develop catalysts by modifying surface composition and crystallographic structure, 3-10 lack of understanding of the detailed reaction mechanism hinders further improvement of a catalyst for the reactions. Some basic issues like the adsorption behavior of key chemical species, the energy profile of the ethanol decomposition, the water effect on reaction pathways, as well as kinetic models for the reactions need to be further studied. In this work we investigated ethanol reforming processes on Rh surface by theoretical simulations and experimental techniques in order to uncover the reaction mechanism.