Enhanced Performance of Carbon Molecular Sieve Membranes Incorporating Zeolite Nanocrystals for Air Separation

Effective adsorption of zeolite/carbon composite molecular sieve synthesized from spent bleaching earth

Spent bleaching earth (SBE) as an industrious solid rubbish seriously causes the environmental pollution problem. The resourceful utilization of SBE has become increasingly important. In this work, silicon and carbon ingredients derived from SBE were coincidently employed to synthesize a 4A zeolite/carbon composite molecular sieve (4A/CMS). Therein, the graphite carbon components in the form of porous lamellar scattering among the interlayer, surface, and periphery of 4A zeolite promote the rate of mass transfer for the lipophilic gas, which can effectively improve the adsorption property for the volatile organic compounds. The obtained 4A/CMS has large specific surface area, hierarchical pore structure, satisfactory adsorption capacity, and regeneration performance, and its equilibrium adsorption capacity of p-xylene can achieve 209.57 mg·g^-1. The pseudo-first-order rate equation is appropriate for the adsorption kinetics. In the end, the formation mechanism of 4A/CMS was illuminated in detail. □ Spent bleaching earth (SBE) as an industrious solid rubbish were utilized resourcefully. Silicon and carbon ingredients from SBE were coincidently employed to synthesize 4A/CMS. Graphitic carbon with hierarchical pore promoted the rate of mass transfer of organic gas. 4A/CMS exhibited excellent adsorption capacity and regeneration performance of p-xylene.

Recent Advances in Mixed-Matrix Membranes for Light Hydrocarbon (C1–C3) Separation

Light hydrocarbons, obtained through the petroleum refining process, are used in numerous applications. The separation of the various light hydrocarbons is challenging and expensive due to their similar melting and boiling points. Alternative methods have been investigated to supplement cryogenic distillation, which is energy intensive. Membrane technology, on the other hand, can be an attractive alternative in light hydrocarbon separation as a phase change that is known to be energy-intensive is not required during the separation. In this regard, this study focuses on recent advances in mixed-matrix membranes (MMMs) for light hydrocarbon (C1–C3) separation based on gas permeability and selectivity. Moreover, the future research and development direction of MMMs in light hydrocarbon separation is discussed, considering the low intrinsic gas permeability of polymeric membranes.

Emerging Materials for Mixed-Matrix Membranes

This Special Issue, entitled "Emerging Materials for Mixed-Matrix Membranes" was introduced to cover the recent progress in the development of materials for mixed-matrix membranes (MMMs) with potential application in fields such as sea water desalination, gas separation, pharmaceutical separation, wastewater treatment and the removal of pathogenic (viruses and bacteria) microorganisms as well as solvents and resource recovery [...].

Recent Progress in Mixed-Matrix Membranes for Hydrogen Separation

Membrane separation is a compelling technology for hydrogen separation. Among the different types of membranes used to date, the mixed-matrix membranes (MMMs) are one of the most widely used approaches for enhancing separation performances and surpassing the Robeson upper bound limits for polymeric membranes. In this review, we focus on the recent progress in MMMs for hydrogen separation. The discussion first starts with a background introduction of the current hydrogen generation technologies, followed by a comparison between the membrane technology and other hydrogen purification technologies. Thereafter, state-of-the-art MMMs, comprising emerging filler materials that include zeolites, metal-organic frameworks, covalent organic frameworks, and graphene-based materials, are highlighted. The binary filler strategy, which uses two filler materials to create synergistic enhancements in MMMs, is also described. A critical evaluation on the performances of the MMMs is then considered in context, before we conclude with our perspectives on how MMMs for hydrogen separation can advance moving forward.