## 2 Materials and Methods
### Characterization Techniques  
The X-ray diffraction (XRD) patterns of the samples were measured in a Cubix'Pro diffractometer from Panalytical, using CuK radiation (\(\lambda_{1}\) = 1.5406 A) at 45 kV and 40 mA in the 2\(\theta\) range from 4 to 40\({}^{\circ}\). The chemical composition of the samples was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES) for analyzing Si and P in a Varian 715-ES device after dissolution of the solids in a mixture of acids (HNO\({}_{3}\)/HF/HCl), and by elementary analysis (EA) for the quantification of C, H, and N in a EuroEA3000 instrument from Eurovector. The thermogravimetric analyses (TGA) were measured in a Netzsch STA449 F3 Jupiter apparatus up to 800 \({}^{\circ}\)C at a heating ramp rate of 10 \({}^{\circ}\)C/min in air flow. The morphology and size of the crystals were evaluated by field emission scanning electron microscopy (FESEM) in a Zeiss Ultra-55 microscope equipped with an energy dispersive X-ray analyser (EDX). The P content was measured by EDX on multiple points of several MFI crystals. No significant differences in the P content were found, indicating the homogeneity of P distribution across the MFI crystals.  
MAS NMR experiments were done by using a Bruker Avance III HD 400 MHz spectrometer. \({}^{1}\)H/\({}^{13}\)C CP MAS NMR was recorded with a 4.0 mm probe spinning the sample at 10 kHz, using a \({}^{1}\)H \(\pi\)/2 pulse length of 2.5 \(\upmu\)s with SPINAL \({}^{1}\)H decoupling, 2 ms as contact time, and 3 s as recycle delay. \({}^{1}\)H MAS NMR spectra were carried out on a 3.2 mm probe at 20 kHz spinning speed, \(\pi\)/2 pulse length of 2.5 \(\upmu\)s, and 15 s as recycle delay. 2D DQ-SQ \({}^{1}\)H MAS NMR experiments were done using the 2.5 mm probe spinning at 25 kHz, using a BABA-type pulse sequence with 2 rotor periods recoupling and a radiofrequency field of 100 kHz, rotor synchronized time evolution of 40 \(\upmu\)s, and 3 s as a recycle delay. \({}^{31}\)P MAS NMR spectra were registered by using a 3.2 mm probe spinning at 20 kHz using a \(\pi\)/2 pulse length of 3.7 \(\upmu\)s with SPINAL proton decoupling and recycle delay of 20 s. \({}^{19}\)F MAS NMR experiments were acquired with a 3.2 mm probe spinning the sample at 20 kHz, using a \(\pi\)/2 pulse length of 4 \(\upmu\)s and 60 s recycle delay for quantitative analysis, done by integration of the signals, using an external reference with a known amount of fluorine. \({}^{29}\)Si MAS NMR spectra were recorded by using a 7.0 mm probe with 3.5 \(\upmu\)s pulse length corresponding to a 60\({}^{\circ}\) flip angle, SPINAL proton decoupling, and 180 s as recycle delay. NMR spectra were referenced to TMS, CFCl\({}_{3}\), adamantine, phosphoric acid, and water for \({}^{29}\)Si, \({}^{19}\)F, \({}^{13}\)C, \({}^{31}\)P, and \({}^{1}\)H, respectively. The \({}^{1}\)H-\({}^{31}\)P 2D HETCOR spectra were obtained using the 2.5 mm rotor spinning the sample at 25 kHz. The contact time was set to 3 ms and the recycle delay to 4 s. \({}^{1}\)H CW decoupling (\(\
u_{\text{RF}}\sim\) 50 kHz) was applied during acquisition.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **OSDA 1** & **Crystallization Time 2 (Days)** \\ \hline TPA-MFI & 1.00 TPA/0.00 TPP & 12 \\ TPX-MFI\({}_{\text{25}}\) & 0.25 TPP/0.75 TPA & 7 \\ TPX-MFI\({}_{\text{45}}\) & 0.50 TPP/0.50 TPA & 10 \\ TPP-MFI & 0.00 TPA/1.00 TPP & 7 \\ \hline \hline \end{tabular} 1  
Molar ratios. 2 All the syntheses carried out at 175 \({}^{\circ}\)C.  
\end{table}
Table 1: Detailed synthesis conditions of the silicalite-1 samples prepared using TPA, TPP, and mixtures of them as OSDAs.