甲醇制烯烃反应过程中SAPO-34分子筛催化剂的积碳行为研究

Study on Carbon Deposition on SAPO-34 Molecular Sieve Catalyst in Transformation of Methanol to Olefins

在固定床积分反应器内考察了甲醇制烯烃反应过程中SAPO-34分子筛催化剂(以下简称催化剂)上积碳的生成规律,实验结果表明,随着反应温度的升高,催化剂积碳量呈指数规律增长,反应初始阶段的积碳生成速率很快,随后趋于平缓;用水作稀释剂,可以有效地减缓催化剂的积碳速率;催化剂床层内呈现明显的积碳分布,床层入口处的积碳量(质量分数)平均为9.56%,而出口处的积碳量仅为3.20%,符合平行失活机理。积碳催化剂的傅里叶变换红外光谱和热重分析结果表明,反应温度不同,积碳的组成也不同,较低反应温度下生成的积碳主要以脂肪烃为主,而在较高的反应温度下,积碳中多环芳烃的比例增大。

Behavior of carbon deposition on SAPO -34 molecular sieve catalyst （abbreviate catalysts） in transformation of methanol to olefins was investigated in a fixed bed integral reactor. Carbon deposition exponentially increased with raising of reaction temperature. Rapid carbon formation was observed in initial phase of reaction, and then rate of carbon deposition was smoothened down. The classical Voorhies model for carbon deposition could be used to illustrate the varying behavior of carbon deposition on catalyst with reaction temperature and time. Some water added in feed could effectively reduce the rate of carbon deposition during a certain period of reaction time. An obvious distribution of carbon deposition was found in the catalyst bed with a carbon mass fraction of 9.56% at the inlet of catalyst bed and 3.20% at the outlet, which mainly corresponded with a deactivation mechanism in parallel reaction. The Fourier - transform infrared spectroscopy and thermo - gravimetric analysis results showed that the carbon depositions were mainly paraffins at lower temperature and polycyclic aromatic hydrocarbon at higher temperature.