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Synthesis and Product Recovery

The materials reported here were obtained hydrothermally by combining sources of the metal framework species with distilled water and the desired template (and co-base where appropriated), to form a homogeneous gel. All the reagents were used as supplied without further purification (Table 3.2). The organic templates were purchased from either Aldrich or Avocado.

Table 3.2Inorganic reagents used in this work.

Reagent Purity (%) Supplier

Magnesium(II) acetate tetrahydrate Zinc(II) acetate dehydrate

Manganese(II) acetate tetrahydrate Cobalt(II) acetate tetrahydrate

99 98.5 98 98 Fluka BDH Avocado Aldrich

Aluminium hydroxide hydrate - Aldrich

Aqueous orthophosphoric acid 85 Prolabo

Silica, fumed

Silica, colloidal LUDOX HS-30

97 -

Fluka Aldrich

Copper(II) acetate 98 Hopkin and Williams Ltd

HF 48 Aldrich

Silver(I) oxide 97 Acros

In a typical synthesis, aluminium hydroxide was dissolved in a solution of orthophosphoric acid in water. Next, the metal acetate or the silica source was added followed by the template. Then, the co-base was introduced drop-wise until a pH of 7 was achieved. The gel was stirred until it became homogenous. Then it was loaded into a Teflon-lined stainless steel autoclave and heated under autogenous pressure in static conditions at 190 ºC for two or seven days for MAPO and SAPO gels respectively (Table 3.3). The variations in gel compositions, aging, reaction temperatures, heating times and stirring conditions were investigated and are clearly marked in the text in the appropriate sections.

Table 3.3Typical ratios in gel, x denotes the addition drop-wise of co-base up to pH 7.6

Gel Typical Ratios Time (days)

Temp. (ºC)

AlPO Al : P : 40H2O : 0.2HF : 0.108template : x co-base 2 190 MAPO 0.2Mg : 0.8Al : P : 40H2O : 0.108template : x co-base 2 190 SAPO Al : 0.8P : 0.2Si : 40H2O : 0.108template : x co-base 7 190

In syntheses where metal complexes of the macrocycle were used, the complex was pre- prepared by adding the ligand to an aqueous solution of the metal acetate and this solution was then introduced to the gel.

After hydrothermal treatment, the autoclave was removed from the oven and allowed to cool. A sample of the reaction product was examined under the optical microscope to observe the crystallinity of the product. Crystalline products were separated from the resulting mixtures by filtration, washed with distilled water and dried in air. In cases where a mixture of phases was obtained, the sample was suspended in water and sonicated to separate the products by density.

Calcination

Calcination was used to remove the organic species occluded within the pores in the as- prepared materials. Selected samples were calcined overnight in a tube furnace at the desired temperature, typically 550 ºC (achieved via a heating ramp of 1.5 ºC/min) under dry flowing oxygen and kept at that temperature for 12 hours before allowing the sample to cool down.

Characterisation

Phase identification of the products was performed by powder X-ray diffraction using a Stoe STADIP diffractometer operating in transmission mode with Cu Kα1 X-rays. Diffraction patterns were collected over the range 5-50º 2θ for 1.5 hours, and indexed using the Stoe software suite.7For structural analysis on calcined samples, XRD was measured in 0.7 mm quartz glass capillaries sealed after dehydration at 200 ºC under vacuum; data are recorded over the range 5-80º 2θ for 12 hours and structures were refined via the Rietveld method using the GSAS program suite.8Single crystal X-ray diffraction (SXRD) was applied for suitable samples: as-prepared, calcined and Cs+ exchanged SAPO STA-7, as-prepared MgAPO and SAPO STA-14 and as-prepared novel layer phase (Chapter 3, 4 and 5 respectively). The structures were solved by direct methods and refined using the program SHELXTL9from data collected by Prof. A. M. Z.

Slawin at St Andrews University on Rigaku diffractometers using either Mo Kαor Cu Kα X-rays.

MAS NMR spectra were collected at the EPSRC solid-state NMR Facility in Durham University by Dr David Apperley on samples summarised in Table 3.4. 27Al and 31P experiments were performed on a Varian UNITY VNMRS 400 spectrometer, using a 4 mm probe and for 29Si and13C a Unity Inova 300 spectrometer, using a 7.5 mm probe. Table 3.5 summarises the experimental conditions. MAS NMR spectra on samples4and

5 calcined were collected by Dr Philip Wormald at the University of St Andrews on a Varian UNIT plus 500 spectrometer, using a 7.5 mm probe. The 0 ppm in the spectra was defined as the shift for 1M aqueous AlCl3, 85% H3PO4 and tetramethylsilane (TMS), for 27

Al,31P and29Si respectively.

Inorganic chemical analysis was performed by EDX on a JEOL JSM-5600 SEM with an Oxford INCA Energy 200 analyser, and the organic component (CHN) was measured on a Carlo Erba EA 1110 CHNS analyser. TGA was performed under flowing oxygen at 5 ºC/min on a TA Instruments SDT 2960 thermogravimetric analyser from room temperature to 700 ºC. N2 adsorption was performed at 77 K on dehydrated samples using an automated HIDEN gravimetric porosimeter. Elemental analysis and N2 adsorption were performed by Mrs Sylvia Williamson at St Andrews.

Modelling and energy minimisation were calculated using the software MS MODELLING 4.0 of Accelerys ®10and the force field Universal.11

Table 3.4STA-7 samples used for MAS NMR experiments ordered according to their appearance in the text.

Samples Composition in Gel

1 2 3 MgAPO Mg/P 0.50 0.20 0.10

Table 3.5Experimental parameters for27Al,31P,29Si and13C MAS NMR spectra on samples summarised in Table 3.4 (DP = Direct Polarisation, CP =Cross Polarisation, DD = Direct Detected, ID = Indirect Detected). Sample Freq (MHz) Acq time (ms) Relaxation delay (s) Polaris Contact time (ms) Pulse time (μs) Spin rate (kHz) 27 Al 1 104.199 10.0 0.2 DP - 1.0 14 4 104.198 20.0 0.2 DP - 1.0 14 27 Al 1 104.199 5.1 0.2 DD (F2) ID (F1) 3.4 and 1.2 14 4 104.198 2.5 0.1 DD (F2) ID (F1) 3.3 and 1.4 14 31 P 1, 2 161.878 10.0 300.0 DP - 3.4 10 3 161.878 20.0 300.0 DP - 3.4 10 4 161.878 15.0 10.0 CP 3.00 - 10 29 Si 4 59.557 30.0 120.0 DP - 90º 5 5 59.557 30.0 1.0 CP 1.00 - 5 6 59.557 20.0 120.0 DP - 90º 5 4 calc. 99.360 15.7 300.0 DP - 2.5 5 5 calc. 99.360 15.7 300.0 DP - 3.0 5 6 calc. 59.557 50.0 120.0 DP - 90º 5 13 C 4 75.398 30.0 1.0 CP 1.00 - 5