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In this paper, nine samples of SAPO-34 Nanocatalysts were synthesized, at three temperatures (170, 190, 210 °C) and three times (12, 24, and 36 h) using the hydrothermal treatment and experimental design approach. All samples were characterized by XRD, SEM, FTIR, BET, and NH 3 -TPD techniques, to evaluate the morphology, crystal size, and surface acidity. The catalytic performance of SAPO-34 zeolites for methanol to light olefins (MTO) was investigated in a fixed-bed reactor at 410 ◦ C. According to catalytic results, all prepared catalysts showed similar trends, but olefin selectivity and lifetime were greatly different. Catalysts synthesized at 170 °C and 24 h because of their high crystallinity, the small size of crystals and high surface area showed relatively high ethylene and propylene selectivity of 48.71% and 32.6%, respectively. Sample with low crystallinity, synthesized at 210 °C, and 36 h because of the existing high value of the SAPO-5 and amorphous phase, deactivate rapidly. Comparing with the other sample, the sample synthesized at 170 °C and 12 h because of high crystallinity, mild acidity, and small crystal size possesses a longer lifetime. Graphic Abstract Hierarchical nine samples of SAPO-34 Nano catalysts were synthesized, at three temperatures (170, 190, 210 °C) and three times (12, 24 and 36 h.) using hydrothermal treatment and experimental design approach. Comparing with the other sample, the sample synthesized at 170 °C and 12 h. because of high crystallinity, mild acidity and small crystal size, possesses a longer lifetime.

A population balance-based model was developed to describe the crystallization kinetics of the SAPO-34 zeotype through the hydrothermal method at three distinct temperatures of 180, 200, and 220 °C. The synthesized SAPO-34 catalysts were characterized by XRD, FESEM, BET, and DLS analysis. The model was constructed based on XRD patterns and incorporated established kinetic expressions for homogeneous nucleation and diffusion-controlled crystal growth. The developed model was also employed in a well-mixed batch system to predict the crystal size distribution. To solve the model equations, the Grey Wolf Optimization technique, as a powerful tool for optimizing complex systems, was applied. Then, the experimental data and the model’s predictions from zeolite synthesis were compared. Specifically, the nucleation rate, growth rate, crystallization profiles, and mean size of the resulting product crystals of SAPO-34 were evaluated for the first time. Remarkably, a notable agreement between the model and the experimental outcomes, particularly concerning the mean crystal size, was demonstrated. This connection between theory and experiment underlined the effectiveness of the population balance-based model in describing the complex crystallization process of the SAPO-34 zeotype across the range of temperatures. Indeed, this investigation demonstrated valuable insights into the hydrothermal synthesis of SAPO-34, showing the value of population balance modeling in predicting and optimizing crystallization processes. In addition, such findings indicated a great deal of promise for enhancing the precision and control of zeolite crystallization, a key element in several industrial applications, such as catalysis, ion exchange, and adsorption.

This study explores the methanol-to-olefins (MTO) performance of three SAPO-34 catalysts: SP (conventional), SPG1 (green, synthesized with okra mucilage as a hard template), and SPG (green, synthesized using a dual-template method with brewed coffee and okra mucilage). The dual-template strategy in SPG promotes the formation of a hierarchical micro-mesoporous structure, resulting in enhanced catalytic behavior. Structural and physicochemical characterizations (XRD, FT-IR, FESEM, EDS, N 2 adsorption–desorption, and NH 3 -TPD) confirm that SPG possesses smaller crystallites, higher mesoporosity, and moderated acidity compared to SP and SPG1. These features contribute to superior total olefin selectivity (89.8% at 240 min), higher ethylene selectivity (53.8%), lower propylene-to-ethylene (P/E) ratio, and improved catalyst stability. Furthermore, SPG exhibits reduced coke formation and better mass transport properties due to its tailored porosity. The utilization of renewable bio-templates not only enhances performance but also aligns with sustainable catalyst design. Overall, the SPG catalyst demonstrates significant potential for efficient and eco-friendly MTO processes.

In this work, we explored the hydrothermal synthesize and crystallization process of SAPO‐34 zeolites from two‐dimensional layered silicate magadiite by using tetraethylammonium hydroxide (TEAOH) as a templating agent. Comprehensive characterization was conducted by XRD, SEM, FTIR, Raman, and BET. Time‐resolved PXRD analysis revealed that SAPO‐34 zeolite exhibited a steep growth curve when the crystallization time was 30 h, and the crystallinity reached 98.65 % at 48 h. Specifically, the disruption of the magadiite layer exposed charged silanol groups on the surface, fostering an affinity for AlO4 and PO4 species, thereby initiating the nucleation process. Under the guidance of TEAOH, these nucleation sites transformed into SAPO‐34 nuclei, gradually advancing towards crystallization. FTIR and Raman analyses affirmed the presence of 6Rs, followed by D6R and 4Rs SBUs, along with the characteristic CHA structure. Combined with 29Si NMR established that disaggregated silicate minerals served as zeolite synthesis “seeds”, enhancing nucleation sites and overall crystallization efficiency. The disturbance of the magadiite layer exposed surface silanol groups, which in turn attracted AlO4 and PO4 species, leading to their incorporation into the 6Rs and D6R units and initiating the nucleation process. These sites then evolved into SAPO‐34 nuclei, facilitating subsequent crystal growth.

Cu/SAPO-34 synthesized via a one-pot method with relatively low silicon content and copper loading at around 2 wt.% facilitated continuous oxidation of methane to methanol with a methanol space time yield of 504 μmolCH3OH/gcat/h. Remarkably, the methanol yield exceeded 1800 mmolCH3OH/molCu/h at 623 K. Typically, the presence of trace oxygen in the system was the key to maintaining the high selectivity to methanol. Characterization results from a series of techniques, including XRD, SEM, TEM, H2-TPR, NH3-TPD, UV-vis, and FTIR, indicated that Cu2+ existed in the position where it moves from hexagonal rings to elliptical cages as the active center.

In this study, nano-sheet SAPO-34 molecular sieves were synthesized using an aminothermal method. Triethylamine (TEA) was used as the major solvent and template, along with varying amounts of tetraethylammonium hydroxide (TEAOH). Physicochemical properties of the synthesized catalysts were characterized by techniques of XRD, SEM, BET, XRF, and NH 3 -TPD. As the amount of TEAOH increases, the composition of the product changes from a mixture of SAPO-5 and SAPO-34 to pure nano-sheet SAPO-34 molecular sieves. A TEAOH increment causes a reduction in crystallinity and particle size, as well as an increase in acid sites. Additionally, there is a non-linear relationship between the silicon content in molecular sieves and the amount of TEAOH added in the system. In the conversion of methanol to olefins using various SAPO-34 catalysts, the nano-sheet samples with the highest crystallinity and moderate acidity exhibited the longest lifetime and higher selectivity to C 2 =  + C 3 = olefins. Graphical Abstract

Submicron-sized low-silica SAPO-34 zeolite crystals with the hierarchical hollow structure are synthesized using a micron-sized SPAO-34 seed activation method hydrothermal synthesis in a low silica gel that contains triethylamine and polyethylene glycol. The resulting catalysts were characterized by XRD analysis, SEM, TEM, BET surface area analysis, etc.; The ~ 600–800 nm SAPO-34 crystals show superior MTO reaction performance of 10 h catalytic lifetime and enhanced olefins (C2H4 + C3H6) selectivity of 91.0%.

The methanol-to-olefins (MTO) process is a promising method for producing light olefins, which are essential intermediates in petrochemical processes. SAPO-34, a crucial catalyst for the MTO process, often suffers from compromised quality when synthesized using low-cost precursors. This study presents a novel and efficient gel preparation method to enhance the performance of amine-templated SAPO-34. Comprehensive characterization through XRD, SEM, EDX, XRF, N 2 physisorption, and FTIR analyses provided insights into the catalyst structure and composition. The results exhibit promoting nucleation, crystal growth, and silica incorporation while suppressing impurities. Notably, increased silica incorporation led to the formation of crystal cracks, significantly boosting the specific surface area. The optimized SAPO-34 catalyst exhibited improved catalytic performance, characterized by a short induction period and a sustained high light olefin selectivity of 84% for over 6 h, showcasing the potential of this approach for producing cost-effective, high-performance MTO catalysts.Kindly check and confirm the corresponding author of the article and the first/last name of the authors are correctly identifiedYes. The corresponding author of the article and the first/last name of all authors are correct.

The preparation circumstances and effects of the kaolin-modified SAPO-34 molecular sieves were studied in order to support the industrial application of the cutting-edge technology for producing light olefins from syngas catalyzed by bifunctional catalyst. Additionally, their apparent morphology, crystal structure, structural features, and acid strength were tested. The results demonstrated that kaolin-based molecular sieves are thinly layered and have an acid strength and pore structure that are more conducive to reactions. The effect of the mass ratio of the oxide to the molecular sieve, the hydrogen to carbon ratio of the feed gas, and other reaction conditions on the catalytic activity of the bifunctional catalyst was investigated using modified molecular sieves. Under the reaction conditions of the oxide to molecular sieve mass ratio of 2:1, feed gas composition of n(H 2 )/n(CO) = 2, 400 °C, and 3 MPa, a CO conversion of 50.11% with a low CO 2 selectivity of 17.01% and a light olefins yield of 24.18% could be achieved. Graphical Abstract

Direct synthesis of light olefins from syngas (STO) using bifunctional catalyst composed of oxide and zeolite has attracted extensive attention in both academia and industry. In this study, we present a facile post-treatment approach to obtain hierarchical SAPO-34 by treating the crystallized product in mother liquor at low temperature. The physical and chemical properties of the resulting molecular sieves were characterized by XRD, SEM, TEM, N2 adsorption–desorption, XRF and NH3-TPD. The obtained hierarchical SAPO-34 were mixed with ZnCrAlOx oxide to prepare the bifunctional catalyst, and the catalytic performance for direct conversion of syngas to light olefins was examined. Compared with the bifunctional catalyst obtained from the SAPO-34 molecular sieves without post-treatment, the bifunctional catalyst with hierarchical SAPO-34 obtained by mother liquor post-treatment showed enhanced performance with higher selectivity of light olefins. Importantly, the bifunctional catalyst with hierarchical SAPO-34 has a good catalytic stability with no obvious deactivation over 100 h of testing. The enhanced catalytic performance of the bifunctional catalyst with hierarchical SAPO-34 could be attributed to the hierarchical structure of SAPO-34 that can increase the rate of mass transfer to avoid further hydrogenation and conversion of olefin products on the catalyst, thus could improve the selectivity of C2–C4 olefins.