An Effective Approach to Synthesize High-Performance SSZ-13 Membranes Using the Steam-Assisted Conversion Method for N₂/CH₄ Separation

Abstract

Thin and high-quality SSZ-13 membranes were synthesized by the steam-assisted conversion (SAC) method for the first time. More than 95% gel/solution was saved for membrane growth compared with conventional hydrothermal synthesis. Another advantage for the SAC method was that the competitive crystallization between the bulk solution and support was eliminated. The thickness of SSZ-13 membranes was well controlled from 1.2 to 3.0 μm by the dilution of sucked solution and synthesis time. Three membranes prepared under optimized conditions displayed N 2 permeances of (1.4 ± 0.12) × 10 −7 mol m −2 s −1 Pa −1 (∼418 GPU), N 2 /CH 4 selectivities of 14.8 ± 0.45 and a separation index of 0.19 ± 0.02 mol m −2 s −1 at 298 K, and 0.2 MPa pressure drop for an equimolar N 2 /CH 4 mixture. The membranes synthesis by the SAC method had a good reproducibility. Such separation performances of current SSZ-13 membranes were beyond the upper bound for N 2 /CH 4 separation among the reported membranes. The influences of temperature, pressure drop, and feed flow rate on separation performance of the membranes were investigated. High-pressure N 2 /CH 4 separation was also reported using SSZ-13 membranes at the pressure drop up to 2.5 MPa.

Improved Gas Permeation Properties of 6FDA-TrMPD Mixed-Matrix Membrane with SAPO-34 Crystals Toward CO2 Separation

“…The separation of CO 2 from N 2 and CH 4 is thus of importance. − The conventional CO 2 separation and capture technology mainly includes low-temperature distillation, absorption, adsorption, and membrane separation. , Low-temperature distillation is energy intensive and not economical. Compared with the absorption and adsorption methods, membrane technology has become a competitive CO 2 separation method due to its low investment and operating costs and energy savings as well as being easy to install and environmentally benign. − Polymeric membranes with a low price, good processability, good mechanical properties, and good selectivity are widely used for CO 2 separation applications. , However, the trade-off effect between the permeability and the selectivity leads to a so-called Robeson upper bound, limiting its further improvement within industrial gas separation. , On the contrary, inorganic membranes have high permeability and selectivity but poor workability. ,, Mixed-matrix membranes are have attracted intensive investigation in the field of gas separation because of the combined advantages of polymer membranes and inorganic membranes. , The emerging technology that combines inorganic moieties and polymers is considered to be a promising approach to overcome the alleged Robeson upper bound limit. ,, …”

Prospective of Upfront Nitrogen (N2) Removal in LNG Plants: Technical Communication

“…This indicates that there might be a need to reduce the pressure of the gas and re-compress it again, as is the case in CH 4 -permeable membranes. Yet, PBI mixed-matrix membrane and SSZ-13 zeolite membrane have shown considerable performance over other membranes as they have an order of magnitude higher permselectivities compared to other membranes [55,57,58].…”

“…Zeolite membranes: Inorganic membranes where microporous zeolite crystals are grown as a layer supported by a flat or tubular surface, such as silicoaluminophosphate (SAPO) [54] and SSZ-13 [55] membranes.…”

“…The direction of membrane research for CH 4 /N 2 separation in the literature is similar to that of adsorption: the majority is focused on the design of the membrane and testing its permeance and selectivity without considering real-life scenarios or discussing the product purity and recovery obtained, as can be seen in Table 2 [44,45,[54][55][56][57][58]. All types of membranes formerly described have been tested for CH 4 /N 2 separation.…”

“…It can separate CO 2 and N 2 from methane, making it advantageous as the CO 2 removal step would be eliminated from NG processing. Nevertheless, a general trend was observed where higher pressures reduced the permselectivity of the membranes; thus there were fewer separation efficiencies [45,[55][56][57]. This indicates that there might be a need to reduce the pressure of the gas and re-compress it again, as is the case in CH 4 -permeable membranes.…”