billnotgatez,I think you're absolutely correct.After taking an open-minded look at all kinds of catalysis(including some exotic,far-out methods like ultrasound and/or microwave assisted catalysts),the direct dimmerization of ethanol into butanol with water molecule dehydration removal at room temperature in one simple,beautiful and glorious step just does not seem very amenable to chemistry as we know it.The rules are simply working against us.
Although the beautiful idea is so irresistably tempting you hate to give-up.It's almost like trying 20 billion times to invent a perpetual motion contraption that defies conservation of energy.
Some type of genetically modified yeast or bacteria(which they are currently working on through a butyric acid pathway)is about the best that can be achieved at present time.Mother Nature and living cells already have several billion years worth of more chemical experience in this regard than us humans do.