Michal Mazur, 1 Paul S. Wheatley,2 Marta Navarro,2 Wieslaw J.Roth, 1 Miroslav Položij,3 Pavla
Eliášová,1 Petr Nachtigall,3 Jiří Čejka1 and Russell E. Morris2
1J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic
2EaStCHEM School of Chemistry, University of St Andrews, St Andrews KY16 9ST, UK
3Department of Physical and Macromolecular Chemistry, Faculty of Sciences, Charles
University in Prague, Hlavova 8, 128 43 Prague 2, Czech Republic
Supporting information
Table of Contents
1. Synthesis 2
1.1 Synthesis of zeolite UTL and the layered precursor IPC-‐1P 2 1.2 Synthesis of IPC-‐9 2 1.3 Synthesis of IPC-‐10 2 2. Characterization 3
2.1 X-‐ray Diffraction 3 2.2 Adsorption isotherms 3 2.3 Structure determination of IPC-‐9 3 2.4 Structure determination of IPC-‐10 5
3. Computational Investigation 7 3.1 Models and Methods 7 3.2 Interaction of choline cation with negatively charged IPC-‐1P surface 8 3.3 Interaction of IPC-‐1P layers 9 4. The structure of IPC-‐10 13 5. Assessing the Feasibility of IPC-‐9 and IPC-‐10 15
6. Incorporation of Al into IPC-‐9 and IPC-‐10 17
1. Synthesis 1.1 Synthesis of zeolite UTL and the layered precursor IPC-‐1P A reaction mixture with following ratio was used to prepare parent UTL zeolite: 1.0SiO2: 0.5GeO2: 0.2ROH/Br: 37.5H2O, where ROH is the SDA, (6R,10S)-‐6,10-‐dimethyl-‐5-‐azoniaspiro[4,5]decane hydroxide. Al-‐containing UTL zeolite was prepared using aluminum hydroxide as a source of Al. The ratio used in the reaction mixture was: 0.782SiO2: 0.4GeO2: 0.018AlO1.5: 0.5ROH/Br: 30H2O,. In the standard procedure SDA in bromide form (46.70 g) was dissolved in the distilled water (250 g) and stirred with resin (Bio-‐Rad AG 1-‐X8, 80 g) for 4 h to exchange it to hydroxide form. After separation of resin, the crystalline germanium oxide (19.38 g) and silicon dioxide (Cab-‐O-‐sil® M5, 22.25 g) was introduced, and the mixture was homogenized for 30 min at room temperature. The resulting fluid gel was charged into Teflon-‐lined autoclave and heated at 175 oC for 7 days under agitation (25 rpm). The solid product was recovered by filtration, washed with distilled water, and dried at 60 oC. To remove the SDA, the as-‐synthesized zeolite was calcined in a stream of air at 550 oC for 8 h with a temperature ramp of 1 oC/min. Calcined UTL was hydrolyzed in 0.1 M HCl with w/w ratio of 1/200 at 95 oC under reflux, for 16 h. The solid product (IPC-‐1P) was isolated by filtration and centrifugation, washed with water, centrifuged again, and dried in air. 1.2 Synthesis of IPC-‐9 zeolite IPC-‐9P precursor was prepared by intercalation of choline hydroxide to IPC-‐1P layered zeolite. It was performed in two ways: by direct intercalation and by de-‐swelling method. Direct intercalation was performed using 50% water solution of choline hydroxide. The choline hydroxide was prepared by ion-‐exchange of choline chloride 50% water solution using Ambersep® 900 resin (100 g of resin per 100 g of solution). Then, 1 g of zeolite precursor IPC-‐1P was mixed with 30 g of choline hydroxide solution and stirred for 4 h at room temperature. Solid IPC-‐9P was centrifuged, washed with water, centrifuged again, and dried in oven at 60 oC. De-‐swelling method involves exchange of intercalate in between layers. First step of the preparation is swelling of IPC-‐1P with CTMA-‐OH 25% solution with w/w ratio of 1/30 for 16 h at room temperature. Solid product was centrifuged, washed with water and dried. Next step is choline-‐assisted de-‐swelling of swollen layered precursor (IPC-‐1PSW). A 0.62 g of IPC-‐1PSW was introduced into choline chloride (16 g) solution in absolute ethanol (40 g). The mixture was stirred for 10 h at room temperature, zeolitic powder was separate by centrifugation, decanted, washed once with absolute ethanol (~15 ml) and centrifuged again, then decanted and dried in oven at 60 oC. Repeating of the de-‐swelling ensures more complete exchange. IPC-‐9P was calcined at 550 oC for 8 h with temperature ramp of 2 o/min. The obtained material was designated as IPC-‐9. To get the IPC-‐9 zeolite with aluminum content the Al-‐UTL was used as the parent material and the same procedure followed. 1.3 Synthesis of IPC-‐10 zeolite
A 0.1 g of IPC-‐9P was introduced to 25 ml Teflon-‐lined autoclave. Then, 0.05 g of diethoxydimethylsilane and 10 ml of 1M HNO3 was added. Autoclave was kept in the oven without agitation for 16 h at 175 oC. Product was filtered, washed with water (100 ml) and dried in oven at 60 oC. Final step was calcination at 550 oC for 8 h with temperature ramp of 2 o/min. Obtained product was designated as IPC-‐10. The IPC-‐10 samples containing aluminum had been prepared using Al-‐UTL as parent material and additionally 0.1 g of Al(NO3)3·∙9H2O was added to the autoclave in the synthesis step.
2. Characterization
2.1 X-‐ray Diffraction The crystallinity of samples was determined by powder X-‐ray diffraction on a Bruker AXS D8 Advance Diffractometer with a Vantec-‐1 detector in the Bragg-‐Brentano geometry using CuKα radiation. All samples were ground to mitigate the effects of preferential orientation of individual crystals. 2.2 Transmission Electron Microscopy High resolution transmission electron microscopy (HRTEM) was carried out on a Jeol JEM-‐2011 electron microscope operating at an accelerating voltage of 200 kV. The HRTEM images were recorded using a 9 Gatan 794 CCD camera. The camera length, sample position and magnification were calibrated using standard gold film methods.
2.3 FT-‐IR spectroscopy
Concentration of the Lewis (cL) and Brønsted (cB) acid sites was determined after adsorption of d3-‐acetonitrile (ACN) by FT-‐IR spectroscopy using a Nicolet Protégé 460 Magna with a transmission MTC/A detector. The zeolites were pressed into self-‐supporting wafers with a density of 8.0 – 12 mg·∙cm–2 and activated in situ at T = 450 °C and p = 5·∙10–5 Torr for 4 h. D3-‐acetonitrile adsorption was carried out at room temperature for 20 min at a partial pressure of 3.5 Torr, followed by desorption for 20 min at the same temperature. Before adsorption d3-‐acetonitrile was degassed by freezing-‐pump-‐thaw cycles. Spectra were recorded with a resolution of 4 cm–1 by collecting 128 scans for a single spectrum at room temperature, and then recalculated using a wafer density of 10 mg·∙cm–2. For a quantitative characterization of acid sites, the following bands and absorption coefficients were used: d3-‐acetonitrile Brønsted band at 2296 cm-‐1 , ε = 2.05 cm·∙μmol-‐1, d3-‐acetonitrile strong and weak Lewis bands at 2323 and 2310 cm-‐1 respectively , ε = 3.60 cm·∙μmol-‐1 [(See B. Gil, S.I. Zones, S.J. Hwang, M. Bejblová, J. Čejka, Phys. Chem. C, 112 (2008) 2997 for further information).
2.4 Structure determination of IPC-‐9
The structure of IPC-‐9 was identified by comparing the experimental X-‐ray diffraction pattern with that predicted from computational studies REF 16. The unit cell for the material was confirmed by a whole pattern Le Bail type refinement against the diffraction data and the atomic positions confirmed by a Rietveld refinement. The final refinement details are as follows and the final structure is contained in the attached crystallographic information file. The final refinement included soft constraints on the Si-‐O, Si-‐Si and O-‐O distances to ensure chemically sensible results. Details of the refinement can be found in Table S1
Table S1 Crystallographic data from the Rietveld refinement of IPC-‐9
A 18.6695(20) B 13.8984(15) C 12.1020(30) Β 102.409(34) Space Group C 2/m Geometric Restraints Si-‐O 1.61(2) O-‐O 2.62(3) Si-‐Si 3.07(4) RF2 0.0296 wRp 0.0315 Rp 0.0260
Figure S1. Observed (+), calculated (red line) and difference (blue line) for the Rietveld refinement of IPC-‐9 against X-‐ray diffraction data. Calculated reflection positions are shown as pink tick marks and the fitted background is shown as a green line.
Figure S2 Transmission electron microscopy image of IPC-‐9, showing fringes due to the layered arrangement in the structure. The inset shows the Fast Fourier Transform of the image, with sharp spots consistent with the ordered nature of IPC-‐9.
Figure S3 High resolution image of IPC-‐9 viewed parallel to the 10-‐ring channels. The image clearly shows the 10-‐ring and 6-‐ring arrangements. As a guide, the structural model is overlaid onto a portion of the image.
2.5 Structure determination of IPC-‐10
The structure of IPC-‐10 was identified by comparing the experimental X-‐ray diffraction pattern with that predicted from computational studies (REF 17). The unit cell for the material was confirmed by a whole pattern Le Bail type refinement against the diffraction data and the fit to the diffraction pattern is shown in Figure S3. As discussed in the main text, the structure of IPC-‐10 is likely to be disordered as there are two ways in which the layers can be linked by a single four ring. Transmission electron microscopy confirms that this is likely to be the case (Figure S4). The disordered nature of the sample prevents a high quality Rietveld refinement of the structure.
Figure S5 Transmission electron microscopy image of IPC-‐10, showing fringes due to the layered arrangement in the structure. The inset shows the Fast Fourier Transform of the image, with significantly diffuse spots consistent with the disordered nature of IPC-‐10. Further details are given in section 4.
3 . Computational investigation
3.1 Models and Methods
All IPC-‐10 and IPC-‐1P structure investigations were performed within a periodic model with relaxed lattice parameters; in the case of IPC-‐1P the model consists of interacting layers that were treated as an infinite stack. Unit cell (UC) details for particular systems are given below. Calculations on the choline cation interaction with single IPC-‐1P layer were performed with a fixed UC shape and volume using the monoclinic UC of UTL separated by vacuum in the a crystallographic direction (a = 30 Å). Calculations with IPC-‐1P layer terminated by S4R and separated by vacuum in the a crystallographic direction were performed with a fixed UC shape and volume and parameters a = 35.000 Å, b = 13.931, c = 12.072 Å, α = 89.99, β = 81.47 and γ = 58.29 Å).
All force field calculations were performed using the program GULP1, 2. Optimizations of the IPC-‐10 zeolite structure were done using a SLC potential3 included in GULP libraries. To study the IPC-‐1P and SDA interaction a modified ClayFF force-‐field introduced by Bushuev and Sastre4 was used (adding parameters for quarternary N following the procedure of Bushuev and Sastre).
DFT calculations were performed with the VASP program suite5, 6, 7, 8 using the projector augmented wave approximation9 and vdW-‐DF2 non-‐local functional10, 11 for all calculations on layered materials and the PBE exchange-‐correlation functional12 was employed for calculations on 3D zeolites (IPC-‐10). A standard PAW approximation13 for Si, O, C N and H with ENMAX values of 245, 400, 400, 400 and 250 eV, respectively, was used together with the plane wave basis set with 800 eV kinetic energy cutoff for calculations with relaxed lattice parameters and 400 eV cutoff for calculations with a constrained unit cell. Brillouin-‐zone sampling was restricted to the Γ point.
3.2 Interaction of choline cation with negatively charged IPC-‐1P surface
To mimic experimental conditions for IPC-‐1P layers intercalated with choline (relatively high pH) choline was assumed to be in the form of cation while the IPC-‐1P surface was partially charged to maintain electroneutrality14. Preferential interaction sites of choline cations with the IPC-‐1P surface were investigated first using a periodic model containing one layer of IPC in UC and vacuum (20 Å) along the a vector. Some of the surface silanols were deprotonated resulting in negatively charged silanolate groups in the UC which were charge-‐compensated by an appropriate number of choline cations. The interaction energy of choline with IPC-‐1P surface was defined as
Adsorption of water was not taken into account. Considering just one choline cation in UC, choline cation preferentially interacts with IPC-‐1P layer at the pocket formed between two surface silanol quadruplets in the former (in parent UTL) 12R channel (Figure S6a). Such structure allows for optimal electrostatic interaction of choline OH-‐group located between surface silanolate and silanol groups and optimal dispersion interaction between choline and the surface. In the case of two choline cations in UC the cations are located in the pockets between silanol quadruplets in former 12R and 14R channels (Figure S6b). Interaction energies calculated at the vdW-‐DF2 level for the first and the second choline molecules were 168 and 201 kJ mol-‐1 (note that the ionicity of the system increases with the increasing number of choline cations). A strong preference of choline cation for interaction side in between two silanol quadruplets is apparent from Table S3 that reports relative energies of choline(+)/IPC-‐1P(-‐) complex for single choline cation.
Table S3. Relative energies of choline cation interacting with IPC-‐1P surface choline position Erela
12R/14R intersection (along 14R channel) 30.4 a In kJ mol-‐1.
Reliability of a force-‐field was also tested using vdW-‐DF2 results as the reference; however, a qualitative disagreement was observed. Therefore, all the calculations on layer interactions described below were carried out at the vdW-‐DF2 level of theory.
Figure S6 IPC-‐1P single-‐layer interacting with one (a) and two (b) choline cations in the energetically most preferable positions: a) choline cation in 12R “cup”, b) choline cations in
12R and 14R “cups”
3.3 Interaction of IPC-‐1P layers
Structures of interacting IPC-‐1P layers (without any SDA molecules in the inter-‐layer space) was recently investigated by Grajciar et al.15 using a two-‐layer periodic model. Their main results can be summarized as follows: (i) the interaction between layers was driven by the formation of a maximal number of inter-‐layer hydrogen bonds (H-‐bonds); (ii) inter-‐layer arrangements forming H-‐bonds networks connecting neighbouring layers with or without inter-‐layer shift (with respect to connectivity of original UTL zeolite) could be formed; (iii) the arrangement without inter-‐layer shift was energetically favourable; (iv) the vdW-‐DF2 exchange-‐correlation functional was found to provide reliable results.
The periodic model of an infinite stack of IPC-‐1P layers was employed herein for the investigation of layer interaction without and with SDA in interlayer space. Four different types of interlayer arrangements were found and they can be classified based on the shift along b and c vectors with respect to parent UTL zeolite (Table S4). Layer arrangements are denoted with respect to channel system of corresponding zeolite to be formed upon direct condensation of layers in such arrangement. Structures of these zeolites including channel system description were reported recently16, 17. Positive and negative inter-‐layer shifts along b and c vectors led to inequivalent structures; only energetically more favourable arrangements of each type are reported in Table S4 and these structures are also shown in Figure S6, including choline cation positions. Structural parameters of interacting IPC-‐1P layers are reported in Table S5 upon transformation to a UC consisting of two ICP-‐1P layers. All structures reported in Table S5 are provided as cif files and the most favourable arrangements for 0, 2, and 4 choline cations are also depicted as moving objects in separate gif files.
IPC-‐1P-‐10R/8R -‐D4R(C2/m) no no 0.0 103.0 164.7 IPC-‐1P-‐10R/7R -‐D4R(P1) no yes 24.8 21.5 0.0 IPC-‐1P-‐8R/8R -‐D4R(Pm) yes no 8.7 0.0 82.5 IPC-‐1P-‐8R/7R -‐D4R(Pm’) yes yes 58.3 a Notation for hypothetical zeolites derived from UTL as described in Ref. 17. b In kJ mol-‐1.
In agreement with previous investigations15 the IPC-‐1P-‐10R/8R arrangement was found energetically the most favourable when no SDA cations were present in the inter-‐layer space. This arrangement corresponds to interlayer connectivity found for IPC-‐4 (PCR) and IPC-‐2 (OKO) zeolites reported previously18 and it is in agreement with experimental findings. The interaction is driven by the formation of maximum number of inter-‐layer hydrogen bonds (six) between silanol quadruplets on adjacent surfaces. The situation was completely different when just one of surface silanols in the quadruplet was deprotonated (corresponding to higher pH) and corresponding number of choline cations (two per UC) was placed into the inter-‐layer region. Each surface silanol quadruplet bears the charge -‐1 (Si4(OH)3O-‐) and due to the electrostatic interaction it is energetically favourable to shift adjacent layers in at least one (b or c) direction (Table S4). The favourable arrangement is the one shifted along b crystallographic direction (Figure S6c). All choline cations were found to be located in the pocket in former 12R channel (Figure S7). Note that the unshifted arrangement is energetically the least favourable one and that even the structure of inter-‐layer arrangement shifted in both b and c directions was found in the case of two choline cations per UC (and not in other investigated cases). In case of four choline cations in the inter-‐layer region (requires deprotonation of two out of four silanols in the quadruplet, Si4(OH)2(O-‐)2) half of the choline cations stays located in 12R pockets while the other cations are located in the 14R pockets (Figure S7b). However, energetically the most favourable shift is now along the c vector (Figure S7) leading to the IPC-‐1P-‐10R/7R arrangement corresponding to UTL-‐D4R(P1) zeolite.
Table S5 Lattice parameters of IPC-‐1P layers with different interlayer arrangements and 0, 2 or 4 choline cations in models optimized at the vdW-‐DF2 level of theory.
Figure S7 IPC-‐1P containing 0, 2 or 4 choline cations in UC, columns denote projection along c and b crystallographic directions. a) IPC-‐1P-‐10R/8R, b) IPC-‐1P-‐10R/7R, c) IPC-‐1P-‐8R/8R, d) IPC-‐1P-‐8R/7R
Structures of hypothetical zeolites that can be obtained by ADOR process from UTL parent zeolite were reported recently17. Based on a good agreement between proposed structure of UTL-‐D4R(P1) zeolite and newly synthesised IPC-‐9 it is reasonable to assume that also IPC-‐10 zeolite should correspond to the UTL-‐S4R(Pm) zeolite shifted along the c crystallographic direction. However, significantly worth agreement between theoretical and experimental powder XRD led us to further investigate possible structures of corresponding UTL-‐S4R zeolites. Since the original work by Trachta et al.17 has assumed that all subsequent layers are connected in the same way we have lifted this constraint and calculated possible new zeolite structures. In the UTL-‐S4R(Pm) zeolite the S4R rings between IPC-‐1P layers forms 5R and 6R with upper and lower IPC-‐1P layer (view along b vector, Figure S7), respectively. Thus formed 9R channels along b are stacked on top of each other. However, without a need for additional lateral shift of adjacent layers the S4R can be alternatively formed as depicted in the lower part of Figure S8, with 9R channels along b somewhat shifted in adjacent layers. The structure of such zeolite was optimized following the protocol used for other –S4R zeolites in Ref. 17. Resulting structure of P-‐1 symmetry (provided as a cif file) was denoted UTL-‐S4R(P-‐1) and it was found 2 kJ mol-‐1 (SiO2)-‐1 energetically below UTL-‐S4R(Pm), still about 6 kJ mol-‐1 (SiO2)-‐1 above the most stable zeolite of UTL-‐S4R family with OKO topology (unshifted layers). Relative energies obtained with the SLC force-‐field were in very good agreement with DFT ones.
Relative energies of UTL-‐S4R(Pm) and UTL-‐S4R(P-‐1) were further analysed using a one-‐layer IPC-‐1P+S4R model (Figure S8). While each layer in UTL-‐S4R(Pm) zeolite is the same (it contains one S4R connected via 5R and one via 6R, denoted 5/6) there are two regularly alternating layers in UTL-‐S4R(P-‐1) denoted 5/5 and 6/6. As it is apparent from Figure S8 it is energetically slightly more favourable to form 5/5 layers.
Figure S8 Comparison of UTL-‐S4R(Pm) and UTL-‐S4R(P-‐1), columns denote projection along c and b crystallographic directions and a schematic representation of both structures.
Figure S9 Structures and relative energies of IPC-‐1P layers terminated by S4R from both sides with different S4R types.
Note that the orientation of the layers is geometrically suitable for reassembly to form fully connected zeolite materials – i.e. there are no silanols groups in the material. This is shown diagrammatically in Figure S10
Figure S10 The orientation of the layers is such that each silanols group in the intermediate structures can be paired up with another silanol group so that condensation between the two groups is essentially complete leaving no uncondensed silanols in the final structure. The figure shows views in two directions (parallel to the 10-‐ring channels in IPC-‐9, a and c) and parallel to the 7-‐ring directions (b and d)
5. Assessing the Feasibility of IPC-‐9 and IPC-‐10
As described in the main text of the manuscript there have been several attempts to rationalise the feasibility of zeolites as synthesis targets. The first target is the feasibility factor, ϑ, which should be as near to zero as possible. This is essentially a measure of how close the framework energy of the material, calculated using SLC force field3 as described above, lies to the energy-‐density correlation. For IPC-‐9 this value of ϑ is 1.7 and for IPC-‐10 it is larger still at 4.9.
The Local Interatomic Distance (LID) criteria were developed to describe the local distortions from idealized tetrahedron that are possible in feasible zeolites. All of these five criteria, described below, are met by all previously known zeolite materials. Table S6 and S7 list the calculated framework energies and densities (calculated using both DFT and SLC force field) together with the values of ϑ and whether the LID values are obeyed or not.
Table S6. The values of framework energies and framework densities (calculated using both DFT and SLC force field) for zeolites IPC-‐9 and IPC-‐10. Also listed is the ϑ, the feasibility factor and the LID criteria (1 = pass, 0 = fail). For comparison the values for zeolites with the OKO and PCR topologies are also listed.
a in kJ mol-‐1, b in 10-‐3 Å-‐3
Table S7. Average T-‐O, O-‐O and T-‐T distances (<DTO>, <DOO> and <DTT> respectively.
This criterion suggests that the average tetrahedron should be very close to an idealized tetrahedron, by saying that the values of <DTO> and <DOO> should fit the correlation described by the equation <DOO> = 1.6284 x <DTO> -‐ 0.0071. ε<OO> is a measure of the distance away from this correlation and for all previously known zeolites this value was less that 0.0009. For both IPC-‐9 and IPC-‐10 this criterion is not met. This indicates that the average tetrahedron in both these structures is the furthest away from the ideal of any zeolites so far prepared.
LID criterion 2. ε<TT> should be less than 0.0046
This criterion is similar to criterion 1 except that it is the correlation between <DTO> and <DTT> that is tested, with the regression equation for the correlation being <DTT> = -‐4.8929 x <DTO> + 10.9128. Once again all previously known zeolites give values that lie extremely close to this line, giving rise to the criterion that ε<TT> should be less than 0.0046. Both IPC-‐9 and IPC-‐10 obey this criterion. This says that the T-‐T distances and T-‐O-‐T angles are within normal parameters for a zeolite.
σTO, σOO, σTT are the standard deviation values for the averages <DTO>, <DOO> and <DTT> respectively. The third LID criterion states that these standard deviations should be within tight limits, meaning that local distortions of the structures are kept to a minimum. IPC-‐9 actually passes this criterion but IPC-‐10 fails the test on σOO, indicating that, as for LID criterion 1, it is the tetrahedral angles in this material that show a larger distortion than would be expected.
LID criterion 4. RTO < 0.0634, ROO < 0.2746, RTT < 0.3332 Å
LID criterion number 4 deals with the ranges of values that the T-‐O, O-‐O and T-‐T distances can adopt, indicating that all distances should lie within the ranges indicated. Neither IPC-‐9 nor IPC-‐10 passes this test.
LID criterion 5. For conventional zeolites only, 1.5967 < DTO < 1.6076 Å
The final criterion is for so-‐called conventional zeolites only. These are zeolites, like IPC-‐9 and IPC-‐10, whose chemical composition is based on silica, aluminosilicate and aluminophosphate (as opposed to other compositions that are deemed unconventional). Both IPC-‐9 and IPC-‐10 meet this requirement.
6. Cif files for the structures plus moving Gif files
Structures of interaction IPC-‐1P layers with and without choline cations reported in Tables S4 and S5 of this Supporting Information are provided in the cif format. All these structures were obtained at the DFT level and they can be found in "cif/IPC-‐1P-‐SDA" subfolder of attached zip file. In addition, the most stable structures of interacting IPC-‐1P layer with 0, 2, and 4 choline cations in UC are also provided as a moving gif objects (they can be found in "cif/GIF movie" subfolder of attached zip file).
The structure of UTL-‐S4R(P-‐1) zeolite obtained at the DFT and FF levels are provided in form of cif files in "cif/UTL-‐S4R" subfolder. The corresponding predicted structures of IPC-‐9 (zeolite UTL-‐S4R(Pm)) were reported recently in Ref. 17.
The most common way in which activity is incorporated into zeolites is the substitution of Al for Si, which produces acid sites in the material. As we have published previously18, the ADOR process can be slightly modified to include Al in the parent zeolite (as described in section 1 above). The same approach can be used for the synthesis of Al-‐IPC-‐9 and Al-‐IPC-‐10. The retention of Al in the materials throughout the assembly-‐disassembly-‐organisation and reassembly processes can be followed using 27Al NMR, which shows that even though in the original parent zeolite there is both octahedral and tetrahedral aluminium, after the disassembly process only the tetrahedral Al remains (Figure S11). The Al-‐containing materials can then be characterised using infra-‐red spectroscopy, using acetonitrile as a probe molecule to assess the nature of acid sites in the material.
Figure S11 Characterisation of Al-‐containing zeolites. (a) 27Al MAS NMR of the parent Al-‐UTL material (red spectrum (i)), IPC-‐1P (green spectrum (ii) and IPC-‐9 (black spectrum (iii)). Note that the spectra here are not quantitative but there is some evidence of a small amount of dealumination, especially during the disassembly (degermanation) stage completed at higher temperatures. Note that the parent zeolite contained some extraframework aluminium that is not present after the hydrolysis process. (b) and (c) IR studies on Al-‐IPC-‐9
using d3-‐acetonitile as a probe molecule shows clear evidence of acid sites present in the material, with Bronsted acid sites at 2296 cm-‐1 (marked B in panel (c)) together with strong and weak Lewis acid sites (marked L).
A preliminary catalytic experiment (the tetrahydropyranylation of alcohols) was performed in the liquid phase under atmospheric pressure at room temperature (25 °C) in a multi-‐experiment workstation Star-‐Fish (Radleys Discovery Technologies). Before use, the catalyst (100 mg) was activated at 450 °C for 90 min at a rate of 10 °C/min. Methanol (9 mmol), mesitylene (0.05 g; internal standard), hexane (10 ml, solvent) and the catalyst (100 mg) were added to a two-‐necked vessel equipped with a thermometer. DHP (15 mmol) was then added to the vessel. Samples of the reaction mixture were taken periodically and analyzed by using Agilent 6850 GC equipped a polar DB-‐WAX column (length 20 m, diameter 0.180 mm, and film thickness 0.3 μm) and flame ionization detector. The reaction products were identified by using Thermo Finnigan Focus DSQ II Single Quadrupole GC/MS. Al-‐IPC-‐9 showed some clear activity for the reaction although conversion was relatively low at ~20% after 300 minutes reaction time.
References:
1. Gale JD. GULP: A computer program for the symmetry-‐adapted simulation of solids. Journal of the Chemical Society, Faraday Transactions 1997, 93(4): 629-‐637.
2. Gale JD, Rohl AL. The general utility lattice program (GULP). Molecular Simulation 2003, 29(5): 291-‐341.
3. Sanders M, Leslie M, Catlow C. Interatomic potentials for SiO2. J Chem Soc, Chem Commun 1984(19): 1271-‐1273.
4. Bushuev YG, Sastre G. Atomistic Simulation of Water Intrusion–Extrusion in ITQ-‐4 (IFR) and ZSM-‐22 (TON): The Role of Silanol Defects. The Journal of Physical Chemistry C 2011, 115(44): 21942-‐21953.
5. Kresse G. Efficient iterative schemes for ab initio total-‐energy calculations using a plane-‐wave basis set. Physical Review B 1996, 54: 11169-‐11186.
6. Kresse G, Furthmüller J. Efficiency of ab-‐initio total energy calculations for metals and semiconductors using a plane-‐wave basis set. Computational Materials Science 1996, 6: 15-‐50.
7. Kresse G, Hafner J. Ab initio molecular-‐dynamics simulation of the liquid-‐metal–amorphous-‐semiconductor transition in germanium. Physical Review B 1994, 49: 14251-‐14269.
8. Kresse G, Hafner J. Ab initio molecular dynamics for liquid metals. Physical Review B 1993, 47: 558-‐561.
10. Lee K, Murray ÉD, Kong L, Lundqvist BI, Langreth DC. Higher-‐accuracy van der Waals density functional. Physical Review B 2010, 82: 81101-‐81104.
11. Klimeš J, Bowler DR, Michaelides A. Van der Waals density functionals applied to solids. Physical Review B 2011, 83: 195131-‐195142.
12. Perdew JP, Burke K, Ernzerhof M. Generalized Gradient Approximation Made Simple. Physical Review Letters 1996, 77: 3865-‐3868.
13. Kresse G, Joubert D. From ultrasoft pseudopotentials to the projector augmented-‐wave method. Physical Review B 1999, 59: 1758-‐1775.
14. Rimola A, Costa D, Sodupe M, Lambert J-‐F, Ugliengo P. Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments. Chemical Reviews 2013, 113(6): 4216-‐4313.
15. Grajciar L, Bludský O, Roth WJ, Nachtigall P. Theoretical investigation of layered zeolite frameworks: Interaction between IPC-‐1P layers derived from zeolite UTL. Catalysis Today 2013, 204: 15-‐21.
16. Trachta M, Bludský O, Čejka J, Morris RE, Nachtigall P. From Double-‐Four-‐Ring Germanosilicates to New Zeolites: In Silico Investigation. ChemPhysChem 2014, 15(14): 2972-‐2976.
17. Trachta M, Nachtigall P, Bludský O. The ADOR synthesis of new zeolites: In silico investigation. Catalysis Today 2014, 243(0): 32-‐38.
18. Roth WJ, Nachtigall P, Morris RE, Wheatley PS, Seymour VR, Ashbrook SE, et al. A family of zeolites with controlled pore size prepared using a top-‐down method. Nature chemistry 2013, 5: 628-‐633.
