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CO Enrichment from Low-Concentration Syngas by a Layered-Bed VPSA Process

Zhou, Yan, Shen, Yuanhui, Fu, Qiang, Zhang, Donghui
Industrial & engineering chemistry process design and development 2017 v.56 no.23 pp. 6741-6754
adsorbents, adsorption, carbon dioxide, carbon monoxide, copper, hydrogen, mathematical models, methane, nitrogen, prediction, process design, sorption isotherms, synthesis gas, temperature
A layered-bed vacuum pressure swing adsorption (VPSA) process with a hybrid packing of Cu(I)AC and Cu(I)Y adsorbents was developed to recover CO from a low-concentration syngas mixture (2.4%CH₄–32.3%CO–1.0%CO₂–46.0%H₂–18.3%N₂). Prior to performing a sequential separation VPSA process design, the statical adsorption equilibrium isotherms of pure CH₄, CO, CO₂, H₂, and N₂ on two dissimilar improved copper-supported adsorbents of Cu(I)AC and Cu(I)Y were first determined under four different temperature values (293.15, 303.15, 313.15, and 323.15 K) with pressures up to 500 kPa. The experimental adsorption equilibrium data of the pure component were then proved to be well fitted by a Langmuir isotherm model. Further, multicomponent breakthrough curves were separately measured by experiments and simulations with a fixed-bed adsorption mathematical model to obtain a successful prediction for multicomponent adsorption dynamics and equilibrium. On the basis of these, a pilot-scale multibed VPSA simulation work with continuous feeding was performed to study the effects of operation conditions on the process separation performances so as to achieve optimization of process manipulation parameters. In the optimized layered-bed VPSA process design, results indicated that a high CO product purity of 99.05% with a recovery of 91.65% as well as an adsorbent productivity of 5.122 mol·kg–¹·h–¹ could be obtained under a relatively economic energy costing of 0.166 kW·h·Nm³– CO.