Highly permeable tubular silicalite-1 membranes for CO2 capture

Muhammad Tawalbeh; F Handan Tezel; M Al-Ismaily; Boguslaw Kruczek

doi:10.1016/j.scitotenv.2019.04.290

Highly permeable tubular silicalite-1 membranes for CO₂ capture

Sci Total Environ. 2019 Aug 1:676:305-320. doi: 10.1016/j.scitotenv.2019.04.290. Epub 2019 Apr 24.

Authors

Muhammad Tawalbeh¹, F Handan Tezel², M Al-Ismaily², Boguslaw Kruczek²

Affiliations

¹ Department of Sustainable and Renewable Energy Engineering, University of Sharjah, P.O.Box: 27272, Sharjah, United Arab Emirates. Electronic address: mtawalbeh@sharjah.ac.ae.
² Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur Street, Ottawa, ON K1N 6N5, Canada.

PMID: 31048162
DOI: 10.1016/j.scitotenv.2019.04.290

Abstract

Membranes represent one of the most promising alternatives for CO₂ separation and capture. Zeolites membranes, in particular, that can withstand high temperatures and pressures, offer energy efficient way to capture CO₂ compared to conventional separation techniques such as amine absorption. In this work, silicalite-1/ceramic composite membranes were prepared on the inner surface of zirconium oxide and/or titanium oxide tubular supports by a pore plugging hydrothermal synthesis. Five types of supports with different pore sizes ranging from 0.14 to 1.4 μm, were studied. The synthesized membranes were characterized by scanning electron microscope (SEM), electron diffraction spectrometer (EDS), x-ray diffraction (XRD), and gas permeation with pure and mixed gas feeds. All membranes showed high concentrations of Si within the active layer of the support, suggesting successful pore-plugging of the membranes. The greater the pore size of the active layer of the support, the greater was the concentration of Si observed. In addition, large coffin-shape crystals, which are characteristics of silicalite-1, were also observed on top of each membrane. The analysis of XRD micrographs revealed that the crystals were mostly oriented with either the a- or b-axes perpendicular to the membrane surface, which is desirable from the point of view of minimizing the resistance to gas transport through the zeolite membrane. Except for the membranes synthesized using the supports with 0.14 μm pores, all membranes were very selective with CO₂/N₂ permselectivities up to 30 at low-pressure differentials. At the same time, the membranes were very permeable with CO₂ permeance in the order of 10^-6 mol m^-2 Pa^-1 s^-1. Assuming the thickness of the selective layer to be equivalent to the thickness of the active layer of the support, all membranes fell above the revised Robeson upper-bound line for CO₂/N₂ separation.

Keywords: CO(2) capture; CO(2)/N(2) separation; Pore plugging synthesis; Silicalite-1 membranes; Titania/zirconia supports.