核壳结构Pt@ZSM-5@S-1分子筛用于甲苯甲醇烷基化制对二甲苯的研究

Core-shell Pt@ZSM-5@S-1 molecular sieve for alkylation of toluene and methanol to make p-xylene

以四丙基氢氧化铵为模板剂、正硅酸乙酯为硅源、硫酸铝为铝源,采用原位的方法直接合成出Pt@ZSM-5分子筛,通过外延生长法在Pt@ZSM-5表面生长Silicalite-1壳层,制备具有核壳结构且表面富硅的含Pt分子筛催化剂。通过XRD、SEM、TEM、N2吸附-脱附、ICP-AES、TG等表征手段对催化剂进行表征,并考察不同壳层厚度的Pt@ZSM-5@S-1分子筛在甲苯甲醇烷基化反应中的性能。结果表明,随着壳层厚度的增加,甲苯转化率逐渐降低,对二甲苯的选择性不断提高。

Taking tetrapropylammonium hydroxide as a template,tetraethyl orthosilicate as silicon source,and aluminum sulfate as aluminum source,Pt@ZSM-5 molecular sieve is directly synthesized by in-situ synthesis method.Silicaite-1 shell grows on the surface of Pt@ZSM-5 via epitaxial growth method,and a Pt molecular sieve catalyst with core-shell structure and silicon-rich surface is gained.The catalyst is characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),N2 adsorption-desorption,inductively coupled plasma(ICP-AES),and thermogravimetry(TG).The catalytic performance of Pt@ZSM-5@S-1 molecular sieves with different shell layers thickness is evaluated in the alkylation of toluene and methanol.The results show that as the thickness of the shell increases,the conversion of toluene gradually decreases and the selectivity of para-xylene increases.