甲烷氧化菌素介导合成催化葡萄糖氧化负载型纳米金催化剂

发布时间：2018-05-13 09:29

本文选题：甲烷氧化菌素 + 生物还原　；参考：《哈尔滨商业大学》2015年硕士论文

【摘要】：本文主要采用初湿含浸法利用甲烷氧化菌素(Methanobactin, Mb)绿色合成负载型纳米金催化剂并将其应用于催化葡萄糖氧化的研究。 Mb是由甲烷氧化菌分泌到细胞外捕获和运输Cu(II)的小分子荧光肽,其同时也具有螯合Au(HI)并将其还原成Au(0)的能力。实验第一部分对从Methylosinus trichosporium3011发酵液中提取的Mb介导一步还原合成纳米金颗粒(Gold nanoparticles, AuNPs)进行了研究。考察了不同Mb浓度、反应温度和反应时间对合成AuNPs的影响。通过紫外-可见光谱、荧光光谱、透射电镜、X-射线光电子能谱和红外光谱对合成的AuNPs进行了表征。利用紫外-可见光谱分析表面等离子共振(Surface plasmon resonance, SPR)特征吸收峰可以证明AuNPs的形成,其最佳合成条件为：Mb:HAuCl4=10:1(mol/mol),反应温度为70℃,反应时间为30min。荧光光谱分析Mb具有三个主要的特征发射峰,在加入HAuCl4时发生了荧光猝灭现象。利用透射电镜分析了AuNPs的粒径和形态,其粒径为19.3±5.5nm,主要呈圆球形。X-射线光电子能谱证明Mb将Au(Ⅲ)还原成Au(0)。通过红外光谱分析表明,在AuNPs表面键合有Mb分子,增强了其稳定性。在pH1.5时,葡萄糖酸钠能够形成内酯,并能与羟胺-三氯化铁络合形成异羟肟酸-Fe3+络合物。利用这一性质,实验第二部分建立了羟胺-三氯化铁法测定催化反应液中葡萄糖酸钠的含量。络合物在500nm处具有最大吸收峰。因此,在500nm处建立了葡萄糖酸钠浓度为1～9mmol/L的标准曲线,其线性方程为y=113.0833x+0.1162,R2=0.9999,具有良好的线性线性关系。通过回收率试验发现,其平均回收率为99.79%。因此可以用于测定Au/γ-Al2O3催化剂催化葡萄糖氧化反应液中葡萄糖酸钠的含量。在实验第三部分,利用初湿含浸法由Mb介导原位还原制备了Au/γ-Al2O3催化剂。并用于催化葡萄糖氧化的研究。考察了Au负载量、焙烧温度以及焙烧时间对催化剂催化葡萄糖氧化比活性的影响。研究发现,Au负载量达到1wt%时,通过该方法制备的催化剂表面的AuNPs仍具有较小的粒径(4nm)。同时,通过焙烧处理部分脱除AuNPs表面键合的Mb分子可以提高催化剂的比活性。通过实验发现,催化剂制备的最佳条件为Au负载量为1wt%,450℃焙烧处理2h,其比活性为1760.56±15.95mmol·min-1·g-1.通过X-射线光电子能谱研究发现,催化剂前驱体的Au仍保持氧化状态(+3价),经Mb还原后催化剂表面Au呈零价,并且焙烧处理对Au的还原状态无影响。通过XRD分析,证明了催化剂表面AuNPs的晶体性质。催化剂重复利用8次后,其仍具有良好的比活性,说明催化剂具有良好的催化稳定性。本实验首次利用利用初湿含浸法由Mb介导原位还原制备了Au/γ-Al2O3催化剂用于催化葡萄糖氧化的研究。实验最后一部分讨论了Au/γ-Al2O3催化剂以H202作为氧化剂催化葡萄糖氧化的动力学过程。实验制备了1wt%Au/γ-Al2O3催化剂,AuNPs粒径为3.48±0.881nm,在排除传质阻力的影响后,确定了葡萄糖、H202、催化剂、葡萄糖酸钠的反应级数(0.4696、0.3729、0.4088、-0.9794),建立了幂指数速率模型。通过阿伦尼乌斯曲线确定了该催化剂的活化能为6.114kJ/mol。此外,通过已有数据建立了Langmuir-Hinshelwood动力学模型,最终发现预测值与实验值有较好的拟合性。本文通过初湿含浸法利用Mb介导原位还原制备了Au/γ-Al2O3催化剂,并成功用于液相催化葡萄糖氧化研究,催化剂具有较高的比活性和稳定性。同时,本文催化剂的“绿色”制备具有良好的应用前景。
[Abstract]:In this paper, a supported gold nanoparticle catalyst was synthesized by the green synthesis of Methanobactin (Mb) in the initial wet leaching process and applied to the study of the catalytic glucose oxidation.
Mb is a small molecular fluorescent peptide secreted by methane oxidizing bacteria to capture and transport Cu (II) outside the cell, and it also has the ability to chelate Au (HI) and reduce it to Au (0). The first part of the experiment was carried out by the Mb mediated one step synthesis of gold nanoparticles (Gold nanoparticles, AuNPs) from the Methylosinus trichosporium3011 fermentation broth. The effects of different Mb concentration, reaction temperature and reaction time on the synthesis of AuNPs were investigated. The synthesized AuNPs was characterized by UV visible spectrum, fluorescence spectrum, transmission electron microscope, X- ray photoelectron spectroscopy and infrared spectroscopy. The characteristics of the surface ion resonance (Surface plasmon resonance, SPR) were analyzed by UV visible spectroscopy. The peak collection can prove the formation of AuNPs. The optimum synthesis conditions are: Mb:HAuCl4=10:1 (mol/mol), the reaction temperature is 70 C, the reaction time is 30min. fluorescence spectrum analysis, Mb has three main characteristic emission peaks, and the fluorescence quenching occurs when HAuCl4 is added. The particle size and morphology of AuNPs are analyzed by transmission electron microscopy, the particle size is 19.3 + 5. .5nm, mainly circular spherical.X- ray photoelectron spectroscopy, proved that Mb reduced Au (III) to Au (0). The IR spectrum analysis showed that the bonding of Mb molecules on the surface of AuNPs enhanced its stability.
At pH1.5, sodium gluconate can form lactone and can form a hydroxamic acid -Fe3+ complex with hydroxylamine trichloride. Using this property, the second part of the experiment established the content of sodium gluconate in the catalytic reaction liquid by hydroxylamine trichloride method. The complex has the maximum absorption peak at 500nm. Therefore, it has been established at 500nm. The concentration of sodium gluconate is 1 ~ 9mmol/L standard curve, its linear equation is y=113.0833x+0.1162, R2=0.9999, and has a good linear linear relationship. The recovery rate test shows that the average recovery rate is 99.79%., so it can be used to determine the content of sodium gluconate in the catalytic glucose oxidation reaction of Au/ gamma -Al2O3 catalyst.
In the third part of the experiment, the Au/ gamma -Al2O3 catalyst was prepared by Mb mediated in situ reduction by the initial wetting method and used to catalyze the oxidation of glucose. The effect of Au load, calcination temperature and calcination time on the catalytic activity of the catalyst on the catalyst glucose oxidation was investigated. It was found that the method was prepared by this method when the load of Au was 1wt%. The AuNPs on the surface of the catalyst still has a smaller particle size (4nm). At the same time, the specific activity of the catalyst can be enhanced by the removal of the Mb molecule with the surface bonding of the AuNPs surface by roasting. The best condition for the preparation of the catalyst is that the Au load is 1wt% and the 2H is calcined at 450 C, and its specific activity is 1760.56 + 15.95mmol. Min-1. G-1.. The X- ray photoelectron spectroscopy study found that the Au of the precursor of the catalyst still maintained the oxidation state (+3 valence), and the catalyst surface Au was zero after Mb reduction, and the calcination treatment had no effect on the reduction state of the Au. The crystal properties of the AuNPs on the surface of the catalyst were proved by XRD analysis. After 8 times the reuse of the catalyst, the catalyst still had a good specific activity. It shows that the catalyst has good catalytic stability. In this experiment, Au/ gamma -Al2O3 catalyst was used to catalyze the oxidation of glucose by Mb in situ reduction.
The last part of the experiment discussed the kinetic process of Au/ gamma -Al2O3 catalyst using H202 as an oxidizing agent to catalyze the oxidation of glucose. The 1wt%Au/ gamma -Al2O3 catalyst was prepared by experiment. The particle size of AuNPs was 3.48 + 0.881nm. After removing the influence of mass transfer resistance, the reaction progression of glucose, H202, catalyst and sodium gluconate was determined (0.4696,0.3729,0.4088). -0.9794), the power exponent rate model was established. The activation energy of the catalyst was determined to be 6.114kJ/mol. by the Arrhenius curve. The Langmuir-Hinshelwood kinetic model was established through the existing data. Finally, the predicted value was better than the experimental value.
In this paper, Au/ gamma -Al2O3 catalyst was prepared by Mb mediated in situ reduction by initial wet leaching. The catalyst has been successfully used in the study of liquid phase catalytic glucose oxidation. The catalyst has high specific activity and stability. At the same time, the "green" preparation of the catalyst has a good application prospect.

【学位授予单位】：哈尔滨商业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TB383.1

【参考文献】