Alcohol fuels for internal combustion engines. Onboard catalytic treatment of fuels and emissions

摘要

In the first part of this dissertation, a catalytic method is presented for upgrading methanol prior to combustion. Methanol is decomposed to hydrogen and carbon monoxide and combusted in the engine. Neat methanol is used as baseline fuel to ensure fast response of the system and also to obtain high maximum power output. At low loads the fuel will consist mainly of decomposed methanol. When increasing the torque liquid methanol is added, ending with pure methanol at maximum torque. The relative efficiency gain compared with neat methanol operation is 15-20% in the torque interval 10-60 Nm. Since octane rating of methanol is higher than for gasoline the efficiency gain for this system compared with gasoline operation will be even higher. Detected NO(sub x) emissions were very low. The second part of this study includes an investigation of a method for cold starting a neat methanol vehicle with the constraint of not using any auxiliary fuel additives or starting agents. A cold start reactor was constructed based on partial decomposition of methanol. An engine was started at -30 degrees C with this device. The work presented in the third section of this thesis is the first part of a project aiming at the development of tailor-made oxidation catalysts for diesel engines fueled by alcohol fuels, ethanol or methanol. The main interest in this study was focused on low temperature oxidation of alcohols or aldehydes. Catalytic oxidation of ethanol and acetaldehyde in the presence of carbon monoxide and nitric oxide was studied using precious metal catalysts applied on monolithic cordierite substrates. Four different supports were studied. The results indicate that the choice of support affects the product distribution in ethanol oxidation.