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Synthesis and Optimization of Conditions for Protecting the SAPO-34 Catalyst in the Methanol to Light Olefins (MTO) Process

Ghasemi, Amir Hossein | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58728 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghotbi, Sirous; Hamidzadeh, Marziyeh
  7. Abstract:
  8. In this study, with the aim of developing a cost-effective SAPO-34 catalyst based on kaolin and evaluating the effect of synthesis conditions on its performance in the methanol-to-light-olefins (MTO) process, a hydrothermal synthesis route was designed and implemented. Three key factors—gel aging time, calcination temperature for converting kaolin to metakaolin, and the percentage of seed added to the gel—were selected as influential variables. SAPO-34 was synthesized using kaolin as the precursor, with morpholine and tetraethylammonium hydroxide employed as structure-directing agents. The resulting samples were characterized in terms of structural properties and catalytic performance to elucidate the relationship between synthesis conditions and performance indicators (conversion and selectivity). To obtain reliable and reproducible results, experiments were conducted in a systematic and comparable manner using the Design of Experiments (DOE) approach, enabling the individual effects of each factor and the direction of their variations—along with their interactions—to be consistently identified. The data were then analyzed using Minitab software to determine the system response patterns and the more suitable operating conditions within the studied range. The results showed that increasing the calcination temperature beyond an optimal range led to a decrease in selectivity, associated with structural rearrangement and a reduction in surface active sites. In contrast, increasing the SAPO-34 seed content within the range of 1–3% enhanced nucleation and effective contact area, resulting in improved selectivity toward light olefins. Additionally, increasing the aging time within the range of 1–3 hours was accompanied by a decline in selectivity, which may be related to incomplete crystal formation in this interval. Analysis of model residuals and control indices also indicated statistical consistency of the results, supporting their applicability for more informed selection of synthesis conditions and for reducing trial-and-error in development. These findings provide practical guidance for tuning the synthesis parameters of kaolin-based SAPO-34
  9. Keywords:
  10. Kaolin ; Silica Alomina Phosphates 34 (SAPO-34)Catalyst ; Methanol Conversion to Olefin (MTO)Process ; Methanol to Light Olefins (MTO) Conversion ; Hydrothermal Synthesis

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