Ethane → Ethane propane n-butane

The negative value recorded for % ethane conversion in Table 7 for Performance Test 7 indicates that the amount of ethane made as a byproduct of propane and/or butane conversion exceeded the amount of ethane converted in this test. Nevertheless, it can be seen from Table 7 that the one stage method produced 49.57 wt % total aromatics from the given ethane/propane/n-butane feedstock, while the two stage method produced 55.50 wt % total aromatics based on a 100 wt % total feed to stage 1 followed by stage 2 which is fed with the ethane from stage 1. In a true two stage operation, it is likely that the feed to stage 2 would include all non-aromatics from the outlet of stage 1 except the fuel gas (methane and hydrogen). These non-aromatics would include not only unconverted ethane but also ethylene, propylene, propane, etc. which would likely increase the total aromatics yield to slightly more than 56 wt % based on a 100 wt % total feed to stage 1.