Enhanced Syngas Conversion to Light Aromatics over ZSM-5@boron-modified Silicalite-1 Zeolites Integrated with ZnCrOx

Detailed information on catalyst characterization; TEM images of the fresh and spent ZnCr oxide, element mapping of the fresh ZnCr oxide; Zn 2p and Cr 2p XPS spectra of the fresh and spent ZnCr oxide; The pore size distribution curves of Z5, Z5@S-1, Z5@B0.005S-1, Z5@B0.01S-1, and Z5@B0.02S-1; Deconvolution of the 27Al NMR spectra at 56 ppm; 11B magic-angle spinning NMR spectra of Z5@B0.02S-1; Kinetic studies for CO hydrogenation over ZnCr/Z5@S-1 and ZnCr/Z5@B0.02S-1 catalysts; Dependence of the CO conversion on the b-axis thickness of Z5@S-1 and Z5@BxS-1 zeolites; The TG analysis of ZnCr/Z5, ZnCr/Z5@S-1, ZnCr/Z5@B0.005S-1, ZnCr/Z5@B0.01S-1, and ZnCr/Z5@B0.02S-1; Propylene-desorption DRIFTS spectra over Z5@S-1 and Z5@B0.02S-1 at different desorption times (a), the percentage of the remaining propylene as a function of time according to the intensity of the DRIFTS signal at 2953 cm-1 (b); Catalytic performance of ZnCr/Z5@B0.02S-1 at different temperature; The intensity of the reaction intermediates varies with respect to temperature and time; The catalytic performance of CO hydrogenation in this study and reported work; The acid density of zeolites; Catalytic performance and aromatics distributions of CO hydrogenation over bifunctional catalysts (DOCX).X-ray diffraction (XRD) analyzer (Rigaku Ultima IV) was used to record the XRD patterns of the samples. The ratio of Si/Al was determined by X-ray fluorescence (XRF) using a Rigaku ZSX Primus II instrument.Emission scanning electron microscopy (SEM) (ZEISS SUPRRATM55 SAPPHIRE) and transmission electron microscopy (TEM) (JEOL JEM-F200) were used for morphological observation. The samples were dispersed in ethanol following ultra-sonication and then dropped on a carbon-coated copper grid for measurement. The crystal size, particularly the b-axis thickness, is determined through a statistical analysis of the SEM images. For each sample, the average b-axis length was manually measured for at least 50 well-defined crystals from representative images.N2 adsorption-desorption was carried out on the specific surface area and pore size analyzer (BSD-600M). The sample was firstly degassed at 300 °C in a vacuum for 10 h and then moved to the analysis station for adsorption-desorption at −196 °C. The specific surface area was determined based on the Brunauer-Emmett-Teller (BET) method and the pore volume and pore diameter were calculated based on the Barrett-Joyner-Halenda (BJH) model.X-ray photoelectron spectroscopy (XPS) was collected on a Thermo Scientific K-Alpha with Al Kα at 150 W (hν = 1486.6 eV) under 5 × 10–7 Pa, calibrated internally by the carbon deposit C1s (Eb = 284.8 eV).27Al MAS NMR experiments were tested on Bruker AVANCE III 600 spectrometers with a MAS probe at a spinning rate of 10 kHz at 130.32 MHz. 1.0 M Al(NO3)3 solution was referenced to the chemical shift of 27Al.NH3 temperature-programmed desorption (NH3-TPD) experiments were recorded with a thermal conductivity detector (TCD). Typically, 100 mg sample was pretreated in an Ar flow (30 mL·min–1) at 400 °C for 1 h. After cooling to 100 °C, the sample was saturated with ammonia flow for 0.5 h, and then the Ar flow was introduced as the sweep gas. Finally, NH3-TPD was presented in the temperature range from 100 to 500 °C at a rate of 10 °C/minThe H2-D2 exchange experiments were carried out on the Micromeritics Autochem 2920 connected to MS. Firstly, 100 mg of sample was loaded into a quartz tube and processed in a 30 mL·min–1 Ar atmosphere at 350 °C with the rate of 5 °C·min–1 for 1 h. After the temperature was lowered to 50 °C, the sample was cut to a H2/D2 mixture at a flow rate of 30 mL·min–1, and the test was initiated after the baseline was stable. During the test, the temperature was increased to 500 °C at 5 °C·min–1.CO temperature-programmed desorption (CO-TPD) was performed on a Micromeritics Autochem 2920 instrument. The 100 mg catalyst was pretreated in an Ar flow (30 mL·min–1) at 350 °C for 1 h and then cooled to 50 °C. Then, after adsorbing CO for 30 min, physically adsorbed CO2 on the catalyst surface was purged with an Ar flow of 30 mL min−1. After baseline stabilization, the catalyst was heated from 50 to 750 °C at a rate of 10 °C min−1.Pyridine absorbed infrared (Py-IR) spectroscopy was recorded on a Thermo Scientific (Nicolet 380) spectrometer instrument equipped with an MCT detector. The sample was placed in a thermostated cell with CaF2 windows and evacuated to 10–2 Pa at 450 °C for 2 h. Then, pyridine vapor was introduced and saturated the sample for 1 h. The Py-IR desorption spectrum was recorded at 150 and 350 °C.In situ Diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) experiments were tested on a Nicolet 6700 instrument equipped with an MCT detector. In situ absorbance spectra were obtained by collecting 32 scans at 8 cm–1 resolution. Before DRIFTS analyses, the catalysts undergone the same pretreatment in Ar atmosphere at 350 °C for 1 h, which was then cooled down to the target temperatures under Ar and the corresponding background spectra were collected for subsequent DRIFTS analyses. Then, the sample was exposed to a reaction gas (H2/CO = 1, 10 mL min–1). Subsequently, the spectra were recorded at set intervals.