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Promotion effect of Mg on a post-synthesized Sn-Beta zeolite for the conversion of glucose to methyl lactate
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2019/12/19 , DOI: 10.1039/c9cy02376c Xiaomei Yang 1, 2, 3, 4 , Bin Lv 1, 2, 3, 4 , Tianliang Lu 2, 3, 4, 5 , Yunlai Su 1, 2, 3, 4 , Lipeng Zhou 1, 2, 3, 4
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2019/12/19 , DOI: 10.1039/c9cy02376c Xiaomei Yang 1, 2, 3, 4 , Bin Lv 1, 2, 3, 4 , Tianliang Lu 2, 3, 4, 5 , Yunlai Su 1, 2, 3, 4 , Lipeng Zhou 1, 2, 3, 4
Affiliation
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Mg-Sn-Beta zeolites with different Mg/Sn molar ratios were prepared from the parent deAl-Beta by a coimpregnation method. The samples were characterized by powder X-ray diffraction (XRD), N2 physisorption, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy of the –OH region and probe molecule (pyridine, CD3CN and CHCl3) adsorption. The results indicate that Mg2+ and Sn4+ can react with silanol nests and incorporate into the framework of Beta zeolite. Moreover, it is relatively facile to incorporate Sn4+ into the framework. The framework metal sites generate Lewis (L) acid sites; however, the L acid strength of the framework Mg2+ is weaker than that of framework Sn4+. A small amount of Mg2+ interacts with isolated silanols to form extraframework species. Therefore, the introduction of Mg2+ results in a significant reduction in silanol defects and an increase in L acidity/basicity of Mg-Sn-Beta. Mg-Sn-Beta with Mg/Sn molar ratio of 1 has the least silanol defects. In the conversion of glucose to methyl lactate (MLA), Mg-Beta is less active than Sn-Beta due to its weaker L acidity. The TOF value for MLA formation increased in the order of Sn-Beta < 0.25Mg-Sn-Beta ≈ 4Mg-Sn-Beta < 1Mg-Sn-Beta, which is closely related to the amount of silanol defects in the catalysts. A kinetic study indicates that the apparent activation energy of the retro-aldol of fructose to MLA, which is the rate-determining step of glucose conversion to MLA, decreases over Mg-Sn-Beta compared to that over Sn-Beta and thus, the formation of MLA was promoted.
中文翻译：
镁对后合成Sn-Beta沸石的促进作用，可将葡萄糖转化为乳酸甲酯
通过共浸渍法由母体deAl-Beta制备了具有不同Mg / Sn摩尔比的Mg-Sn-Beta沸石。通过粉末X射线衍射（XRD），N 2物理吸附，紫外可见漫反射光谱（UV-vis DRS），X射线光电子能谱（XPS），傅里叶变换红外（FT-IR）光谱对样品进行表征。 -OH区和探针分子（吡啶，CD 3 CN和CHCl 3）的吸附。结果表明，Mg 2+和Sn 4+可以与硅烷醇巢反应，并掺入Beta沸石的骨架中。而且，掺入Sn 4+相对容易进入框架。骨架金属位点产生路易斯（L）酸位点；但是，骨架Mg 2+的L酸强度比骨架Sn 4+的L酸强度弱。少量的Mg 2+与分离的硅烷醇相互作用形成框架外物质。因此，引入Mg 2+导致硅烷醇缺陷的显着减少以及Mg-Sn-β的L酸度/碱度的提高。Mg / Sn摩尔比为1的Mg-Sn-β具有最小的硅烷醇缺陷。在葡萄糖向乳酸甲酯（MLA）的转化中，Mg-Beta的活性弱于Sn-Beta，因为它的L酸度较弱。MLA形成的TOF值按Sn-Beta <0.25Mg-Sn-Beta≈4Mg-Sn-Beta <1Mg-Sn-Beta的顺序增加，这与催化剂中硅烷醇缺陷的数量密切相关。动力学研究表明，果糖后向醛醇向MLA的表观活化能（是决定葡萄糖向MLA转化的速率的步骤）在Mg-Sn-Beta上比在Sn-Beta上降低，因此，促进了MLA的形成。
更新日期：2020-02-13
中文翻译：
镁对后合成Sn-Beta沸石的促进作用，可将葡萄糖转化为乳酸甲酯
通过共浸渍法由母体deAl-Beta制备了具有不同Mg / Sn摩尔比的Mg-Sn-Beta沸石。通过粉末X射线衍射（XRD），N 2物理吸附，紫外可见漫反射光谱（UV-vis DRS），X射线光电子能谱（XPS），傅里叶变换红外（FT-IR）光谱对样品进行表征。 -OH区和探针分子（吡啶，CD 3 CN和CHCl 3）的吸附。结果表明，Mg 2+和Sn 4+可以与硅烷醇巢反应，并掺入Beta沸石的骨架中。而且，掺入Sn 4+相对容易进入框架。骨架金属位点产生路易斯（L）酸位点；但是，骨架Mg 2+的L酸强度比骨架Sn 4+的L酸强度弱。少量的Mg 2+与分离的硅烷醇相互作用形成框架外物质。因此，引入Mg 2+导致硅烷醇缺陷的显着减少以及Mg-Sn-β的L酸度/碱度的提高。Mg / Sn摩尔比为1的Mg-Sn-β具有最小的硅烷醇缺陷。在葡萄糖向乳酸甲酯（MLA）的转化中，Mg-Beta的活性弱于Sn-Beta，因为它的L酸度较弱。MLA形成的TOF值按Sn-Beta <0.25Mg-Sn-Beta≈4Mg-Sn-Beta <1Mg-Sn-Beta的顺序增加，这与催化剂中硅烷醇缺陷的数量密切相关。动力学研究表明，果糖后向醛醇向MLA的表观活化能（是决定葡萄糖向MLA转化的速率的步骤）在Mg-Sn-Beta上比在Sn-Beta上降低，因此，促进了MLA的形成。
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