Supporting Information

Transcription

1 Supporting Information Oriented Zeolitic Imidazolate Framework-8 Membrane with Sharp H 2 / C 3 H 8 Molecular Sieve Separation Helge Bux a, *, Armin Feldhoff a, *, Janosch Cravillon b, Michael Wiebcke b, Yan-Shuo Li c, and Jürgen Caro a, a)institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstr. 3A, D Hannover, Germany b) Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstr. 9, D Hannover, Germany c) Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhong-Shan Road 457, Dalian , China

2 Series A (shown in Table 1) Series B Single, exceptionally highly oriented membrane Time / h CPO 200/110 CPO 200/211 CPO 200/110 CPO 200/211 CPO 200/110 CPO 200/ Table S1 Reproducibility of the oriented growth process in the time dependent studies. The table compares the time dependent evolution of the CPO-indices of Table 1 (Series A) with an experimental repetition (Series B) as well as another exceptionally highly oriented membrane prepared after the same route in 2 h of secondary growth. The table shows that the oriented growth is generally reproducible. However, due to the insufficient number of reference experiments, no founded statement can be given to the sample-to-sample variance.

3 Figure S1 Permeation measurements following the Wicke-Kallenbach technique. The membrane is mounted in the permeation cell and tightly sealed by O-rings (e.g. Viton FKM 50). The top side of the membrane (feed side) is constantly swept with a sample gas or a sample gas mixture. The flow rate can be precisely controlled by mass flow controllers (MFC) 1 and 2 and is kept at a much higher rate than the sample gas flow rate through the membrane. This ensures that the feed side mixture composition is constant. The pressure can be adjusted by the back pressure valve (BPV) and digital manometer (DM) A. The lower membrane side (permeate or sweep side) is continuously swept by N 2. The flow rate is controlled by MFC 3 and kept at 100 ml/min. The pressure below the membrane is 1 atm and can be checked by DM B. The sweep not only carries the permeate below the membrane to the GC, but also reduce the partial pressure of the permeate gas or gases near zero. Without sweep (or evacuation) at the permeate side, the minimum (partial) pressure of the permeate gas below the membrane would be atmospheric pressure. By online gas chromatography (GC), the composition of the sweep gas in volume percent is analyzed. Since the flow rate of the sample gases through the membrane (up to ~ 2 ml/min) is much lower than the sweep gas flow rate (100 ml/min), the total flow rate is assumed to be the equal to the sweep flow rate. Of course, for higher flow rate through the membrane, the total flow rate has to be measured by bubble counter. The minimum range of detection of the GC is highly dependent on the sample gas. Since GC is operated with He, the thermal conductivity detector (TCD) shows only a low hydrogen sensitivity. However, since hydrogen is usually found in high percentages in the sweep gas (1-2%), the sensitivity is sufficient. For light gases as N 2, CO 2, O 2 and short hydrocarbons, the TCD sensor shows a high sensitivity, which makes it possible to detect them reliable in traces of > 0.01 %.

4 Figure S2 Cross-section of the membrane in SEM, colored by EDXS (red: zinc, ZIF-8 layer, green: aluminum, alumina support). Aluminum signals (green spots) in the region of the ZIF-8 layer and vice versa zinc signals (red spots) in the region of the alumina support are redirected to texture effects of the non-polished sample.

5 Intensity / a.u. powder pattern reference experiment Θ / Figure S3 XRD pattern of the reference experiment (black), in which a PEI coated alumina support was treated solvothermal under the same synthesis conditions as for the membrane, and the corresponding powder (red).

6 Equation S1 Definition of the crystallographic preferred orientation (CPO) index. I hkl and I h k l denotes the integrated intensities of a pair of characteristic reflection from the oriented layer. The ratio of both intensities is compared with the ratio of the same pair from the powder pattern of the corresponding precipitate, which is assumed to has a randomly orientation of the crystals.

7 Figure S4 Diffusion theory on basis of Fick s first law. The driving force of permeation through the ZIF-8 layer is the concentration gradient Δc/Δx. The concentration in the boundary regions of the layer (c Feed and c Perm ) is determined by the adsorption at the chosen pressure (p Feed and p Perm ) and can be determined by the sorption isotherm. In Wicke-Kallenbach measurements, c perm is usually assumed to be equal zero (ideal conditions). However, under real conditions, c at the permeate side of the layer might be at an unknown level above zero (c perm ). Hence, depending on the steepness of the sorption isotherm, Δ c might noticeably derivate from Δc. This finally means, that the driving force und real conditions (and hence the flux J) through the membrane is lower than under ideal conditions.