Abstract

In this paper, the effect of variation of crystallization temperatures and times on the synthesis of SAPO-34 catalysts for conversion of methanol to light olefins has been investigated. These are two of the very effective parameters in the synthesis of SAPO-34 which affect phase purity, crystallinity, acidic properties, and finally the performance of catalysts. For this purpose, 9 samples have been synthesized by varying of temperature and time of crystallization in the range of 170–210°C, 12–36 h, respectively and the molar ratio of 1Al₂O₃ : 1P₂O₅ : 0.4 SiO₂: 0.5 TEAOH : 1.5 MOR : 70 H₂O and characterized by XRD, SEM, FTIR, BET, and NH₃–TPD techniques. Finally, performance of catalysts was investigated in the process of conversion of methanol to light olefins in a fixed-bed reactor 410°C. The results show that crystallinity, phase purity, size, and distribution of particles, surface area, and acidic properties have great effects on performance and selectivity of ethylene and propylene and these properties themselves severely depend on Crystallization temperature and time. The results of characterized of catalysts show that high characterized temperature, reduces the phase purity and increases size in particles. The catalysts that have been synthesized at 190°C and 24 h have the highest crystallinity, suitable size, and distribution of particles, high surface area, and suitable acidic sites, so it has the highest selectivity of light olefins at MTO process.

中文翻译：

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结晶温度和时间对合成轻质烯烃SAPO-34催化剂影响的研究

摘要

本文研究了结晶温度和时间的变化对合成SAPO-34催化剂的影响，该催化剂用于将甲醇转化为轻质烯烃。这是SAPO-34合成中两个非常有效的参数，它们会影响相纯度，结晶度，酸性和催化剂的性能。为此目的，通过在170–210°C，12–36 h范围内分别改变温度和结晶时间以及1Al ₂ O ₃：1P ₂ O ₅：0.4 SiO的摩尔比，合成了9个样品₂：0.5 TEAOH：1.5 MOR：70 H ₂ O并通过XRD，SEM，FTIR，BET和NH ₃表征–TPD技术。最后，在410℃的固定床反应器中，在甲醇转化为轻质烯烃的过程中研究了催化剂的性能。结果表明，结晶度，相纯度，颗粒尺寸和分布，表面积和酸性对乙烯和丙烯的性能和选择性有很大影响，而这些性质本身严重取决于结晶温度和时间。催化剂的表征结果表明，较高的表征温度，降低了相纯度并增加了颗粒尺寸。在190°C和24 h合成的催化剂具有最高的结晶度，合适的尺寸和颗粒分布，高的表面积以及合适的酸性部位，因此在MTO工艺中对轻烯烃的选择性最高。