Note that the flow volumes refer to those before splitting into the 10 channels. The effluent from each reaction tube was sampled into QMS for 2.0 s for evaluation, followed by the evacuation of the sampling line for 12 s. This corresponds to 140 s per lap of sampling from 10 channels and about 20 mass spectra were recorded during each sampling. In this study, the products were dominantly comprised of BD, AcH, ethylene, butene, and unreacted EtOH. The EtOH conversion, and the yield and selectivity for the individual products were derived based on: