Superficial Velocity Effects on HZ-PAN and AgZ-PAN for Kr/Xe Capture

Abstract

Nearly all previous testing of HZ-PAN and AgZ-PAN was conducted at the same flow rate in order to maintain consistency among tests. This testing was sufficient for sorbent capacity determinations, but did not ensure that sorbents were capable of functioning under a range of flow regimes. For this reason, a series of tests were conducted on both HZ-PAN and AgZ-PAN at superficial velocities between 20 and 700 cm/min. For HZ-PAN, Kr capacity increased from 60 mmol/kg to 110 mmol/kg as superficial velocity increased from 21 to 679 cm/min. Results for AgZ-PAN were similar, with Xe capacity ranging from 72 to 124 mmol/kg over the same range of superficial velocities. These results are promising for scaling up to process flows, demonstrating flexibility to operate in a broad range of superficial velocities while maintaining sorbent capacity. While preparing for superficial velocity testing it was also discovered that AgZ-PAN Xe capacity, previously observed to diminish over time, could be recovered with increased desorption temperature. Further, a substantial Xe capacity increase was observed. Previous room temperature capacities in the range of 22-25 mmol Xe/kg AgZ-PAN were increased to over 60 mmol Xe/kg AgZ-PAN. While this finding has not yet been fully explored to optimize activation and desorption temperatures, it is encouraging.

Cycle Testing of AgZ-PAN and HZ-PAN

“…As may be seen in Figures 1 and 2, sorbent performance remained essentially unchanged over the entire series of thermal cycles. Initial performance of this sorbent prior to cycle testing was based on the average results from previous tests under the same or similar flow conditions (Welty, Greenhalgh, & Garn, 2016), reported in Table 1 at 17 cycles which is the number of cycles the sorbent was subjected to prior to this series of thermal cycles.…”

Milestone Report - Data Requirements and Test System Needs for Development of an Integrated Off-Gas Treatment System

“…Similar measurements are lacking for the MOF materials. Testing of PAN materials has shown little velocity effect up to 6.4 m/min, but higher velocities have not been tested (Welty et al 2016).…”