Deactivated methanol to olefin catalyst for preparation of SAPO-34 molecular sieve by directing agent method and its application
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,N2 adsorption/desorption,NH3-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.
国家科技期刊平台
NSTL
万方数据
