Recovery of hydrocarbons from mixtures containing C3H6, C3H8 and N2 using NaX membranes

Mixed matrix membranes for hydrocarbons separation and recovery: a critical review

The separation and purification of light hydrocarbons are significant challenges in the petrochemical and chemical industries. Because of the growing demand for light hydrocarbons and the environmental and economic issues of traditional separation technologies, much effort has been devoted to developing highly efficient separation techniques. Accordingly, polymeric membranes have gained increasing attention because of their low costs and energy requirements compared with other technologies; however, their industrial exploitation is often hampered because of the trade-off between selectivity and permeability. In this regard, high-performance mixed matrix membranes (MMMs) are prepared by embedding various organic and/or inorganic fillers into polymeric materials. MMMs exhibit the advantageous and disadvantageous properties of both polymer and filler materials. In this review, the influence of filler on polymer chain packing and membrane sieving properties are discussed. Furthermore, the influential parameters affecting MMMs affinity toward hydrocarbons separation are addressed. Selection criteria for a suitable combination of polymer and filler are discussed. Moreover, the challenges arising from polymer/filler interactions are analyzed to allow for the successful implementation of this promising class of membranes.

Fabrication of Diatomite/Silicalite-1 Composites and Their Property for VOCs Adsorption

Adsorption technology is an effective method to remove volatile organic compounds (VOCs). In this work, we prepared hierarchical porous materials using modified diatomite (Dt) as a support and nano-sized silicalite-1 (S-1) seeds as inorganic fillers, which were applied to adsorb volatile organic compounds (VOCs). The characterization of the composites indicated that S-1 was successfully coated onto the surface of modified Dt, and the best surface area of the composites was 398.8 m²/g, nearly 40 times as large as Dt. The adsorption capacities of Dt/S-1 composites for three probe VOCs (ethyl acetate, acetone, and toluene) were rather superior to Dt, and the composites had preferential adsorption selectivity for ethyl acetate. Effects of seeded zeolite contents and hydrothermal conditions for the adsorption capacity of composites were discussed in this paper. The composite seeded with 5 wt% S-1 zeolite, which was subsequently synthesized by hydrothermal reaction at 100 °C for four days, showed the maximum adsorption capacity (1.31 mmol/g for ethyl acetate). The pseudo second-order model provided a perfect fit to adsorption kinetics, while the Langmuir model agreed the best with the adsorption isotherms. In addition, the composites had selective adsorption to ethyl acetate among these three probes VOCs. The regeneration experiments were also carried out, and the adsorption efficiency of the adsorbents was still up to 67% after five adsorption⁻desorption cycles. The hierarchical porous Dt/S-1 composites have an excellent VOC adsorption performance, satisfactory selectivity, and recycling ability.