Preparation Of Nano-gold Catalysts And Their Application To Oxidation Of Glucose

Sodium gluconate is an important intermediate of chemical, food, medicine and light Indus- tries. The production methods are mainly bio-fermentation method, electrochemical method and heterogeneous catalytic oxidation method. Compared with the first two method, Heterogeneous catalytic oxidation method received more attention due to its economics,environmental protec- tion and convenient to manufacture in large quantities.But traditional heavy metals (Bi or Pb) modified Pd/C catalyst has some drawbacks on catalytic efficiency and biological toxicity.So it is very important to prepare a kind of new catalyst with high activity, not poisonous or low-toxic for manufacture gluconic acid sodium salton a large scale and high quality.More attention is now paid to new kind of mesoporous material and nano-gold catalysts due to their unique catalytic properties in recent years. The result shows that many catalytic oxidation reactions with oxygen participation in , high dispered nano-gold shown good activity. Considering reaction systems are similar.This paper is focused on the wor as follows:different mesoporous material as carrier,prepared series of supported catalysts,catalyst activity and characterization result shows that the species and structures of carrier and the dispersation of Au has some effect on conversation.,discussed the types and features of carries ,the distribution and particle size effects catalystic oxidation Some contribution and progress made are as follows:.1. Prepare mesoporous materials SBA-15 and catalysts Au/SBA-15. Firstly, we synthesized mesoporous silica molecular sieves (SBA-15). Mesoporous silica molecular sieves SBA-15 was synthesized in the presence of amphiphilic block copolymer (P123) as template and TEOS as silicon source. The results of XRD,SEM,TEM proved that synthesized SBA-15 had a fixed shape, orderly 2D-hexagonal structure, a narrow pore size distribution. XRD of the catalysts appeared the characteristic diffraction peaks of the metals, the particle size was estimated using Scherrer formula. TEM observed the distribution of Au in SBA-15. The result showed that there was a good dispersion and Au particle size was small. Using about 0.3g catalyst 2% Au/SBA-15, the conversion of glucose to sodium gluconate conversation more than 98%2. Prepare mesoporous materialsγ-Al₂O₃ and catalysts Au/γ-Al₂O₃, mesoporous alumina were synthesized using glucose as soft templates, boehmite sol as the precursor. By means of SEM and XRD, the results indicated that the alumina did exist mesoporous structure and it also showed characteristic diffraction peaks ofγ-Al₂O₃. Its pore size was mainly 5.45nm nearby, with the narrow distribution, high surface area (417.1m2/g) and pore volume (0.568cc/g). Au/γ-Al₂O₃ were prepared by DP method. The influence of the preparation conditions such as the loading of gold, the type of precipitating agent, the gold ion concentration and reductant on the acticity of the catalysts in the liquid oxidation of glucose to Sodium gluconate have been investigated. The result shows as follows: KBH4 as reductant, C6H5O7Na3·2H2O as protective agent, (NH4)2CO3 as precipitating agent. Using about 0.1g catalyst prepared at such condition, the conversion of glucose to sodium gluconate amount more than 98%.3. Prepare mesoporous materials Al-SBA-15 and catalysts Au/Al-SBA-15: Al(NO3)3·9H2O as Al source, Mesoporous Al-SBA-15 was successfully synthesized by modified SBA-15 by Al. Both SBA-15 and Al-SBA-15 with different Si/Al ratios were characterized by power XRD and SEM shows as follows: The hexagonal meso-structure of parent siliceous SBA-15 was maintained very well in Al-SBA-15. 2% Au/Al-SBA-15 were prepared by DP method. Using about 0.3g catalyst prepared at such condition, the conversion of glucose to sodium gluconate amount more than 95%.