失活甲醇制烯烃催化剂用于导向剂法制备SAPO-34分子筛及其应用

Deactivated methanol to olefin catalyst for preparation of SAPO-34 molecular sieve by directing agent method and its application

以失活甲醇制烯烃(MTO)催化剂为部分铝源、磷源和全部硅源,以三乙胺为模板剂,在低温(160℃)条件下制备了导向剂,并采用导向剂法绿色合成了S-SAPO-34分子筛,以及不加入导向剂直接合成了C-SAPO-34分子筛。采用XRD、SEM、N_(2)吸/脱附、NH_(3)-TPD、固体MAS-NMR以及TGA等方法对合成的两种分子筛的晶体结构、形貌、孔隙结构、酸性特征、配位状态以及热稳定性等进行了表征。结果表明,通过导向剂法可以在有机模板剂的用量缩减2/3的条件下合成出高结晶度SAPO-34分子筛。在固定床反应器上对S-SAPO-34和C-SAPO-34分子筛进行了催化MTO反应性能评价,反应条件为温度460℃、常压、甲醇质量空速6.0h^(-1)以及原料为纯甲醇。结果表明,相较于C-SAPO-34,S-SAPO-34分子筛的结晶性能更好,相对结晶度达136%,且晶体形貌更加完整。在MTO反应中,S-SAPO-34和C-SAPO-34分子筛均能满足甲醇转化,双烯(乙烯+丙烯)选择性最高分别为82.1%和82.3%。该方法可为低模板剂用量条件下SAPO-34分子筛的绿色合成提供新的思路。

Using deactivated methanol to olefin(MTO)catalyst as a partial aluminum and phosphorus source and entire silicon source,and triethylamine as a template,a directing agent was prepared at low temperature(160℃).S-SAPO-34 molecular sieve was then green synthesized by directing agent method,and C-SAPO-34 molecular sieve was synthesized without directing agents.The crystal structures,morphologies,pore structures,acidic characteristics,coordination states and thermal stabilities of the two molecular sieves were analyzed by XRD,SEM,N_(2) adsorption/desorption,NH_(3)-TPD,solid-state MAS-NMR and TGA.The results indicate that SAPO-34 molecular sieve with high crystallinity can be synthesized by directing agent method under the condition of reducing the amount of organic template agent by 2/3.The catalytic performance evaluation of S-SAPO-34 and C-SAPO-34 molecular sieves for MTO reaction was carried out on a fixed bed reactor under the reaction conditions of temperature 460℃,atmospheric pressure,methanol mass space velocity 6.0 h^(-1) and pure methanol as the raw material.The results show that compared to C-SAPO-34,the crystallization performance of S-SAPO-34 molecular sieve is much better,with a relative crystallinity of 136%,and the crystal morphology is more complete.In MTO reaction,S-SAPO-34 and C-SAPO-34 molecular sieves can ensure methanol conversion,and the highest selectivities of diene(ethylene+propylene)are 82.1%and 82.3%,respectively.This method can provide a new idea for the green synthesis of SAPO-34 molecular sieve under low dosage template conditions.