Cycling and Regeneration of Adsorbed Natural Gas in Microporous Materials

Abstract

Adsorbed natural gas (ANG) technology is an energy-efficient method for storing natural gas at room temperature and low pressure. The search for high-storage-performance natural gas sorbents for gaseous fuels is currently pursued by numerous research groups worldwide. While research in this field is mainly devoted to optimizing the gravimetric and volumetric storage capacity of methane, this work investigates the long-term effect of large alkanes on natural gas storage. This article investigates the evolution of storage capacity and gas composition during adsorption/desorption cycles at room temperature (charge/discharge of an ANG tank) and at various elevated temperatures (regeneration of tank) on a commercial, high-surface-area activated carbon (Maxsorb MSC-30, Kansai Coke and Chemical Co. Ltd.). Cycling and regeneration study of sorbent for hundreds of cycles has been investigated. The evolution of storage capacity is measured after successive cycling using a custom-built Sievert apparatus. For natural gas, gravimetric excess adsorption drops to 33% in the first 100 cycles and continues to decrease slowly until it reaches 25% by the 1000th cycle. Volumetric storage capacity shows a deterioration of 50% after 100 cycles and remains approximately constant after that. The contaminant gas composition is measured as a function of successive cycling using gas chromatography. Finally, efficient regeneration techniques have been tested to allow a continuous operation for thousands of cycles.

Implementing Metal-Organic Frameworks for Natural Gas Storage

“…Regeneration is one option to regain performance after cycling in microporous materials [104]. In the case of a commercial, high-surface-area activated carbon (Maxsorb MSC-30, Kansai Coke and Chemical Co. Ltd.), a similar phenomenon as seen in MOFs was found with a 50% deterioration of volumetric storage capacity after 100 cycles.…”

“…Future work should seek to address information needed in this area of research. An important experiment that is missing from published experiments on the application of MOFs for ANG is the Regeneration is one option to regain performance after cycling in microporous materials [104]. In the case of a commercial, high-surface-area activated carbon (Maxsorb MSC-30, Kansai Coke and Chemical Co. Ltd.), a similar phenomenon as seen in MOFs was found with a 50% deterioration of volumetric storage capacity after 100 cycles.…”

Adsorbed Natural Gas Storage for Onboard Applications

“…Nonmethane hydrocarbon gases exhibit irreversible adsorption to adsorbents such as ACs and HKUST‐1. [ 37,65,159,160 ] Using an adsorbent prepared from petroleum coke, Li and Chen reported that the adsorption capacity of the components of NG is in the order: C 3 H 8 , H 2 S (0.980), CO 2 (0.691), C 2 H 6 (0.160), CH 4 (0.136), N 2 (0.096) g g −1 at 3.5 MPa and 298 K. [ 161 ] Under these conditions, the methane adsorption capacity was 145.2 v/v, while the delivery capacity was 105.7 v/v with poor reversibility over 10 adsorption–desorption cycles. [ 161 ] In a more recent study, using Maxsorb MSC‐30 (AC) in both CH 4 and NG, the gravimetric excess adsorption decreased to 33% after 100 cycles and gradually decreased to 25% by the 1000th cycle.…”

“…[ 161 ] In a more recent study, using Maxsorb MSC‐30 (AC) in both CH 4 and NG, the gravimetric excess adsorption decreased to 33% after 100 cycles and gradually decreased to 25% by the 1000th cycle. [ 160 ] Similarly, the volumetric storage capacity decreased to 50% by the 100th cycle before remaining unchanged. [ 160 ] Therefore, a preadsorption system (e.g., guard beds of tailored filters) at the inlet of the ANG tank may be required for the selective permeation of methane, driving up the cost and complexity of the ANG system.…”

“…[ 160 ] Similarly, the volumetric storage capacity decreased to 50% by the 100th cycle before remaining unchanged. [ 160 ] Therefore, a preadsorption system (e.g., guard beds of tailored filters) at the inlet of the ANG tank may be required for the selective permeation of methane, driving up the cost and complexity of the ANG system. [ 22,65,83,161 ] Regeneration is another option to mitigate the adverse impact of impurity accumulation and regain the uptake performance of the ANG system.…”