Microwave Synthesis And Characterization Of MCM-41Molecular Sieve Containing Hetero Atom And Aluminosphate Units And Alkylation Of Benzene

A series of MCM-41molecular sieves containing aluminosphate units are synthesized by microwave hydrothermal crystallization process, and the effect of crystallization temperature on the synthesis of the molecule sieve is investigated and discussed. MCM-41molecular sieves containing hetero atom and aluminosphate units are synthesized under appropriate condition above, and characterized by XRD、BET、 NH3-TPD、TG/DTA、TEM、NMR. Consequently, the catalysis activities of MCM-41molecular sieves containing hetero atom and aluminosphate units to alkylation of benzene with1-dodecene are evaluated over a continuous fixed-bed microreactor. The conclusion are as follows:(1) MCM-41molecular sieves containing hetero atoms (such as Mg, Zr, B) and aluminosphate units are firstly synthesized successfully by microwave radiation. XRD testing shows that the synthesized samples possess micropores and regularly hexagonal pore arrangement, and a lower regularly hexagonal pore arrangement is obtained when the content of herero atoms reduces. The appropriate condition are90℃for crystallization temperature and90minute for crystallization time.(2) NH3-TPD testing show that hetero atoms could help enhance the acid quantities over MCM-41molecular sieves containing aluminosphate units greatly. The acid quantities increase, and then decrease as the content of hetero atom increases, and optimal when n(Me)/n(Al)=0.05. Alkylation reaction over catalyst show that MCM-41molecular sieves containing hetero atom and aluminosphate units are superior to MCM-41molecular sieves containing aluminosphate units.(3) BET testing show that there are micropore of0.58nm and mesopore of2nm in MCM-41molecular sieves containing hetero atom and aluminosphate units, and the hetero atom could reduce the pore size to1.9nm.(4) TEM testing show that there are micropores and regularly hexagonal pore arrangement in MCM-41molecular sieves containing hetero atom and aluminosphate units as XRD and BET do.(5) The alkylation reaction of benzene with1-dodecene over MCM-41molecular sieves containing Mg and aluminosphate units demonstrates that the appropriate operating condition are160℃for reaction temperature,3MPa for reaction pressure. The selectivity of dodecyl benzene over MCM-41molecular sieve containing hetero atom and aluminosphate units is best when n(Mg)/n(Al)=n(B)/n(Al)=n(Zr)/n(Al)=0.05, however, the stability activity of the molecular sieve need to be improved farther.