Physicochemical properties and catalytic performance of galloaluminosilicate in aromatization of lower alkanes: a comparative study with Ga/HZSM-5

Remarkably efficient CoGa catalyst with uniformly dispersed and trapped structure for ethanol and higher alcohol synthesis from syngas

“…In the XRD patterns ( Fig. 2A), in addition to the reflections of c-Al 2 O 3 , the ZnAl-LDO phase can be clearly seen in each reduced sample according The H 2 consumption between 500 and 700°C is attributed to the reduction of Co(II) to Co 0 [54] and Ga (III) to Ga 0 [55]. Notably, the temperatures of H 2 consumption for CoZnAl-LDHs/c-Al 2 O 3 or ZnGaAl-LDHs/c-Al 2 O 3 are much higher than those for Co 2+ /ZnAl-LDHs/c-Al 2 O 3 (269°C) or Ga 3+ /ZnAlLDHs/c-Al 2 O 3 (361 and 390°C), indicating that the reduction of Co(II) or Ga(III) confined in the LDH layers is more difficult.…”

A highly efficient Ga/ZSM-5 catalyst prepared by formic acid impregnation and in situ treatment for propane aromatization

“…According to the characterization data, the reductionoxidation cycles processes were shown to adjust the state of Ga species and thereafter enhance their diffusion into the ZSM-5 5 zeolite channels, enhancing the dispersed Ga species (such as Ga + , GaO + and to a lesser extent Ga(OH) 2+ ) on the catalyst in substitution of framework acidic protons. In addition to the reduction-oxidation cycles treatment, other treatment processes have been shown to increase the dispersion of Ga species on 10 Ga/ZSM-5. Fricke et al 25 reported improvements in Ga dispersion as a function of pH during impregnation.…”

“…The binding energy values were corrected for charging effect by referring to the adventitious C1s line at 284.5 eV. 10 27 Al MAS NMR measurements were performed on Bruker AVANCE III 600 MHz equipment. 27 Al MAS NMR spectra were obtained by a single pulse length of Π/6, and Al chemical shifts were referenced to Al(NO 3 ) 3 .…”

“…As observed, comparison between ICP-AES and XPS data for Ga modified HZSM-5 zeolites shows surface of these catalysts are enriched in 5 aluminum according to the smaller Si/Al ratios measured by XPS than the bulk Si/Al ratios determined by ICP-AES. After pretreatment to HZSM-5 (impregnated with the bear gallium nitrate aqueous solution with and without formic acid, respectively), the surface aluminium content of the resulting Ga/dried and H- 10 Ga/dried samples are higher than that of untreated HZSM-5 according to the surface Si/Al ratios, surface Al mol%, Al Td /Al Oh ratios and Al Oh % (Td: four-coordinate framework Al and Oh: octahedral extra framework 27 Al as shown in Fig. S2).…”

New insights into hierarchical metal-containing zeolites; synthesis and kinetic modelling of mesoporous gallium-containing ZSM-5 for propane aromatization

“…To alleviate this, several methods have been proposed for improving the dispersion of Ga. Nowak et al [6] reported that pretreatment of Ga-containing HZSM-5 obtained via ion exchange, under reducing-oxidizing cycles enhances the migration of Ga species into the zeolite structure. Choudhary et al [7] and Al-Yassir et al [8] employed the in situ incorporation method (hydrothermal (one-pot)), for the proper dispersion of Ga species in the structure. It was also shown that steam [9] or chemical vapor deposition method [10] can promote the formation of extra framework Ga species.…”