Optimal design of ring-shaped alumina catalyst: A way to intensify bioethanol-to-ethylene production in multi-tubular reactor

摘要

The present work is focused on the intensification of catalytic ethanol-to-ethylene dehydration process in multitubular reactor by applying the ring-shaped particles of the optimal geometric sizes instead of conventional granules. A new simulating approach allowed us to select the optimal sizes of rings under wide variation of their height h, inner d and outer diameter D. Reducing the pellets size h x d x D from 6 x 2.3 x 6 to 3 x 4.4 x 6 mm leads to an increase in the effectiveness factor from 0.46 to 0.76, thus enhancing catalyst activity due to less intraparticle diffusion. The impact of various factors on the total enhancement of ethylene productivity over ring-shaped catalysts was examined. The mechanical crushing strength of ring-shaped alumina catalysts and hydraulic resistance of the catalyst bed were tested experimentally. Increase in the effectiveness factor eta plays the major role, while heat and mass transfer parameters contribute less than 8%. Among other aspects, the process intensification (PI) pursues the goals of enhancing the process capacity, or downsizing the reactor. Our study revealed that at a fixed ethanol conversion, PI due to the optimal geometries may be expressed either as 2.1-fold increase in the reactor capacity, or as respective reduction in the tubes quantity. Both options may result in a significant improvement of the process performance. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.