SAPO-11分子筛的合成

SYNTHESIS OF SAPO-11 ZEOLITES

以二正丙胺(DPA)为模板剂、利用水热法合成SAPO 11分子筛,系统考察了硅源、硅含量、模板剂用量以及晶化条件(晶化温度、时间以及pH值)对SAPO 11分子筛合成的作用。研究结果表明:硅源是决定SAPO 11分子筛合成及结构的关键组分之一,其释放出活性硅物种的速率要与磷酸铝分子筛的前驱体生成的速度相一致;酸性硅溶胶是合成SAPO 11的合适硅源;在SiO2/Al2O3=0～0 7,DPA/P2O5=0 8～1 8,pH=5 8～7 8条件下,可合成纯SAPO 11分子筛。此外,SAPO 11分子筛的合成,还存在明显的诱导期以及晶型的转化过程。在合成条件下,晶化时间4h时,SAPO 11开始晶化,至24h,SAPO 11分子筛可晶化完全。继续延长晶化时间,SAPO 11分子筛与SAPO 31分子筛之间发生转晶现象。

SAPO-11 zeolites were hydrothermally synthesized with n-dipropylamine(DPA) as template The effects of nature of silica sources, ratios of raw materials and crystallization parameters such as crystallization temperature,time and pH value, on SAPO-11 crystallization were systematically discussed Of interest is that the nature of silicon feed was justified to be one of key factors for synthesis of SAPO-11 zeolites The selective tests of Si resources proved that acidic silica gel is a suitable feed, which could provide active silica intermediates just accompanying by slow formation of SAPO-11 precursor It was shown that highly crystalline SAPO-11 zeolites could be produced with material ratios of SiO 2/Al 2O 3=0～0 7,DPA/P 2O 5=0 8～1 8 and under contiguously neutral media environment (pH=5 8～7 8) In addition, it was found that SAPO-11 zeolite appeared after 4?h and completely crystallized after 24?h, following by transformation between SAPO-11 and 31 with time on