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The effect of Si/Al ratio of ZSM-12 zeolite on its morphology, acidity and crystal size for the catalytic performance in the HTO process
RSC Advances ( IF 3.9 ) Pub Date : 2024-02-12 , DOI: 10.1039/d3ra08792a Samira Soltani 1 , Akbar Zamaniyan 2 , Jafar Towfighi Darian 1 , Saeed Soltanali 2
RSC Advances ( IF 3.9 ) Pub Date : 2024-02-12 , DOI: 10.1039/d3ra08792a Samira Soltani 1 , Akbar Zamaniyan 2 , Jafar Towfighi Darian 1 , Saeed Soltanali 2
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In this research, ZSM-12 zeolite with six Si/Al ratios (20 to 320) was synthesized by a hydrothermal method and systematically investigated. The physicochemical properties of the synthesized nano zeolites were evaluated and compared by XRD, FE-SEM,ICP-AES, NH3-TPD, BET, FT-IR, and TGA analyses. The results show that when the Si/Al ratio increases, the amount of microcrystals increases with the dominant competitive phase of cristobalite by decreasing the MTW phase. The catalytic assessment of synthesized zeolites in the (n-hexane to olefins) HTO process in a fixed bed reactor under atmospheric pressure and WHSV equal to 4 h−1 at 550 °C was evaluated and various parameters such as selectivity towards light olefins, P/E ratio, production of light alkanes, and aromatic compounds (BTX) were investigated. The result of the n-hexane to olefins process indicated that the presence of cristobalite as an impurity phase strongly affects the activity of the catalysts. The Z80 zeolite, with a Si/Al ratio of 80, corresponds to the pure form of ZSM-12 and exhibits the highest light olefin yield at 52.5%. This zeolite demonstrates superior propylene selectivity (P/E = 1.75) owing to its well-suited pore structure, wide channels, and optimal acidity derived from the MTW zeolite. On the other hand, zeolite Z320 has a lower light olefin yield (19.4%) and a lower P/E (1.1) ratio. In addition, according to the results of the TGA analysis, the content of coke on the Z80 catalyst after the catalytic reaction is much less than other catalysts after the catalytic reactor test.
中文翻译：
ZSM-12沸石Si/Al比对其形貌、酸度和晶体尺寸对HTO催化性能的影响
本研究通过水热法合成了六种Si/Al比（20至320）的ZSM-12沸石并进行了系统研究。通过XRD、FE-SEM、ICP-AES、NH 3 -TPD、BET、FT-IR和TGA分析对合成的纳米沸石的物理化学性质进行了评价和比较。结果表明，当Si/Al比增加时，通过减少MTW相，微晶数量增加，并且方石英占主导地位的竞争相增加。在固定床反应器中，在大气压和 550 °C WHSV 等于 4 h -1的条件下，对（正己烷制烯烃）HTO 工艺中合成沸石的催化评估进行了评估，并评估了各种参数，例如对轻质烯烃的选择性、P对/E比、轻质烷烃和芳香族化合物（BTX）的产生进行了研究。正己烷制烯烃过程的结果表明，方英石作为杂质相的存在强烈影响催化剂的活性。 Z80沸石的Si/Al比为80，相当于ZSM-12的纯形式，并且表现出最高的轻质烯烃产率，为52.5%。由于其源自 MTW 沸石的合适的孔结构、宽通道和最佳酸度，该沸石表现出优异的丙烯选择性 (P/E = 1.75)。另一方面，Z320沸石具有较低的轻质烯烃产率（19.4％）和较低的P/E（1.1）比。另外，根据TGA分析结果，经过催化反应器测试后，Z80催化剂上催化反应后的焦炭含量远低于其他催化剂。
更新日期：2024-02-12
中文翻译：
ZSM-12沸石Si/Al比对其形貌、酸度和晶体尺寸对HTO催化性能的影响
本研究通过水热法合成了六种Si/Al比（20至320）的ZSM-12沸石并进行了系统研究。通过XRD、FE-SEM、ICP-AES、NH 3 -TPD、BET、FT-IR和TGA分析对合成的纳米沸石的物理化学性质进行了评价和比较。结果表明，当Si/Al比增加时，通过减少MTW相，微晶数量增加，并且方石英占主导地位的竞争相增加。在固定床反应器中，在大气压和 550 °C WHSV 等于 4 h -1的条件下，对（正己烷制烯烃）HTO 工艺中合成沸石的催化评估进行了评估，并评估了各种参数，例如对轻质烯烃的选择性、P对/E比、轻质烷烃和芳香族化合物（BTX）的产生进行了研究。正己烷制烯烃过程的结果表明，方英石作为杂质相的存在强烈影响催化剂的活性。 Z80沸石的Si/Al比为80，相当于ZSM-12的纯形式，并且表现出最高的轻质烯烃产率，为52.5%。由于其源自 MTW 沸石的合适的孔结构、宽通道和最佳酸度，该沸石表现出优异的丙烯选择性 (P/E = 1.75)。另一方面，Z320沸石具有较低的轻质烯烃产率（19.4％）和较低的P/E（1.1）比。另外，根据TGA分析结果，经过催化反应器测试后，Z80催化剂上催化反应后的焦炭含量远低于其他催化剂。
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