Cost-effective and fast synthesis of Sn-β zeolite with less silanol defects for efficient conversion of glucose to methyl lactate

Sn-β with strong Lewis acid sites is considered as the state-of-the-art solid catalyst for converting glucose to alkyl lactate. However, the extensive use of organic template and mineralizing agent and long preparation period in the synthesis of Sn-β brought serious environmental pollution and high synthesis cost. Herein, a cost-effective and fast synthesis strategy using fewer organic template and mineralizing agent, fumed silica as Si source, Mg2+ cation as crystallization promoter and without additional solvent, is proposed to alleviate the aforementioned shortcomings. The results reveal that highly crystalline Mg-Sn-β can be synthesized in 3 days from the gel of 0.005MgO/0.005SnO2/SiO2/0.15TEAOH/0.15NH4F/3.75H2O. Besides accelerating the crystallization, it is found that Mg2+ cation facilitated Sn4+ incorporation into the framework site and lessened the silanol defects of zeolite notably. For conversion of glucose to methyl lactate (MLA), a higher yield of MLA was obtained over 1Mg-Sn-β-3d (54.4%) compared with Sn-β-H-7d (37.2%) and Sn-β-7d (41.3%).