The Preparation And Oxidizing Reaction Of Functional Hydrotalcite-like Compounds

Hydrotalcite-like compounds ?HTLcs? are a kind of solid base, which are also called layered double hydroxides ?LDHs?, whose formula are [M2+1-xM3+x?OH?2]x+?An-?x/n·mH2O. M2+ and M3+ are different cations, An- are different anions. Feitknecht have made LDHs for the first time. LDHs have a wide range of application as catalyst.The alkaline-earth metals Ba and Ca, alkali metal K, transition metals Co and Cu replace part of Mg to make the LDHs of Mg₃Al₁?Ba₁Mg₂Al₁?Ca1Mg2Al1?K1Mg2Al1?Co3Al1? Mg3Cu1Al1 and Co3Cu1Al1. The XRD shows that all of them have a good pattern and the N2 adsorption-desorption implies that they are IV adsorption-desorption isotherm. Using TG-DTA to detect the thermal decomposition, we find that the LDHs have two endothermic peaks, the first stage is the decomposition of interlayer water and phasical adsorption of water, the second stage is the decomposition of CO32-.Using CO₂-TPD detect the basicity and amounts of Mg₃Al₁?Ba₁Mg₂Al₁?Ca1Mg2Al1? K1Mg2Al1, we find that the amounts of LDHs is consistent with the cationic alkalinity. We also used the titration to detect basicity and amounts of the LDHs?LDO and Spinels. The results of the titration of the LDHs are consistent with the CO₂-TPD.p-hydrox benzaldehyde ?PHB? is an important fine chemical intermediates, looking for a right PHB preparation method has a great significance. In this paper we use the LDHs of Mg₃Al₁?Co3Al1?Mg3Cu1Al1 and Co3Cu1Al1 as catalyst to oxide p-cresol to make PHB, we find that Co is esstntial in this reaction, and Cu can improve the selectivity of PHB, the Co3Cu1Al1 has the best resulut. Using Co3Cu1Al1 as catalyst and contral the temperature at 70 ?, with the flow of oxygen 20 mL/min keeping the reaction for 12 hours, the yield of PHB can attain 72.08%.