Altering C₂H₄/C₃H₆ yield in methanol to light olefins over HZSM-5, SAPO-34 and SAPO-34/HZSM-5 nanostructured catalysts: influence of Si/Al ratio and composite formation

Abstract

HZSM-5 zeolites with various Si/Al ratios were synthesized by hydrothermal method and the sample with optimum Si/Al ratio combined with SAPO-34. In MTO reaction, SAPO-34/HZSM-5 composite shows high activity and selectivity toward light olefins.

Beneficial Use of Ultrasound in Rapid-Synthesis of SAPO34/ZSM-5 Nanocomposite and Its Catalytic Performances on MTO Reaction

“…Figure represents the FTIR spectra of as-prepared samples. The results confirm the formation of aluminosilicate MFI structure and the silicoaluminophosphate CHA framework . Based on FTIR spectra, the band around 3450 cm –1 belongs to the structural O–H that Si­(OH)­Al attached to the hydroxyl group. , Meanwhile, at the U-SAPO-34 and composite of U–S/Z ( m ), there is a high peak intensity of the hydroxyl group.…”

“…For this purpose the structure directing agent, initial components, and synthesis conditions are changed. − However, in order to compensate the deficiencies of each of the aforementioned cases, the other approach was the combination of these two zeolitic structures. It was shown that zeolite composite with binary structure has none of the disadvantages of its components while it exhibits special catalytic properties due to different functionalities and pore structures of each individual component and leads to a synergistic behavior in most cases. ,− In this regard, the nanocomposites based on ZSM-5 and SAPO-34 have been synthesized through a hydrothermal method and studied in propane dehydrogenation process (ZSM-5/SAPO-34 and SAPO-34/ZSM-5), benzene oxidation (Pd/ZSM-5/MCM-48), ethanol conversion to propylene (HZSM-5/SAPO-34), , methanol to aromatics, and methanol conversion to olefins (ZSM-5/SAPO-34). ,,, However, the major deficiency of the conventional hydrothermal method in the crystallization of zeolites is difficulty in the control of the nucleation process. It is to say, lack of proper mixing in the hydrothermal method usually causes an unstable supersaturation which in turn leads to uncontrollable nucleation .…”

Mixed Matrix Membranes Incorporated with Aminosilane-Functionalized SAPO-34 for Upgrading CO2/CH4 Separation Performances

“…In the spectrum of SAPO-34, the band around 3450 cm −1 was related to structural O−H for a Si(OH)Al bridging hydroxyl group. 24 The stretching vibration at 1632 cm −1 could be attributed to physically adsorbed water molecules. 25 A broad band around 1100 cm −1 was ascribed to the asymmetric stretching vibration of O−P− O groups, while the band stretching at 710 cm −1 implied the symmetric stretching of O−P−O groups.…”

“…FTIR spectra of pristine and APDS-modified SAPO-34 crystals are shown in Figure b. In the spectrum of SAPO-34, the band around 3450 cm –1 was related to structural O–H for a Si­(OH)Al bridging hydroxyl group . The stretching vibration at 1632 cm –1 could be attributed to physically adsorbed water molecules .…”

Incorporation of mono and bimetallic MnNi into SAPO‐34 framework used in conversion of methanol to ethylene and propylene: Alteration of acidic properties and catalytic performance

“…This molecular sieve has the flexibility of altering the ratio between the two olefins by varying the operating conditions . In general, the main problem with these catalysts in industrial processes is their short life due to the coke formation . Thus, a number of efforts have been performed to improve the lifetime and the selectivity of light olefins through modification of SAPO‐34 catalyst .…”