Rapid Cycling Thermal Swing Adsorption Apparatus: Commissioning and Data Analyses for Water Adsorption of Zeolites 4A and 13X Over 2000 Cycles

Abstract

Evaluation of adsorbent integrity over thousands of cycles is necessary to establish the service time and sustainability of adsorbents employed in industrial dehydration. Herein, an adsorption apparatus for rapidly cycling multiple adsorbents through a thermal swing adsorption process is introduced with results for 2000 cycles. This apparatus has eight sample cells arranged in parallel, which are embedded in an aluminum block for rapid heating and cooling. At the outlet of each cell, the water content and temperatures are measured using capacitance relative humidity sensors, which incorporate resistance thermometers. The analysis of the breakthrough curves generated for each adsorbent gives inference into the change in water uptake capacity over continuous cycling. To handle the large sets of data generated by this instrument, an automated analysis program was implemented. To demonstrate the functionality of the instrument, zeolites 4A and 13X were cycled in a thermal swing process over 2000 cycles and the change in the uptake capacity was monitored by the analysis of the breakthrough plots for each cycle. Furthermore, the results of the breakthrough analyses were verified with the thermogravimetric analysis of the adsorbents. From these experiments, zeolites 4A and 13X were observed to lose 7 ± 3 and 19 ± 7% of the adsorption capacity, respectively.

The role of carbon dioxide and water in the degradation of zeolite 4A, zeolite 13X and silica gels

“…1 The schematic of the instrument used during the rapid cycling experiments adapted from the our previous literature. 21 from Air Liquide and used as received. 2.2 nm pore size silica gel (High purity, Davisil Grade 12, 28-200 mesh) and 3.0 nm pore size silica gel (High purity, Davisil Grade 923, 100-200 mesh) were purchased from Sigma Aldrich and used as received.…”

“…1 The schematic of the instrument used during the rapid cycling experiments adapted from the our previous literature. 21 Paper NJC…”

“…The detailed methods for the analysis of the rapid cycling data have been presented in our previous work. 21 Two methods were used to track the water uptake for the breakthrough experiments. The first method was to track the change in breakthrough time, t b , for each sample as a fraction of the average breakthrough time for the first 30 cycles, t b / t b,0 .…”

“…To test the materials for their stability in the long-term TSA process, a rapid cycling TSA instrument was used, this instrument was introduced in our previous work 21 (Fig. 1).…”

“…As described in our previous work, a Nafion water saturator was used to introduce water into the adsorbing gas feed. 21 The water content of the gas feeds also are present in Table 1.…”