Preparation Of Hydrotalcite-like Compounds Containing Copper And Catalytic Synthesis Of Downstream Products Of Furfural

Anionic pillared interlayer compound has a layered structure with exchangeable anions .The typical representatives are hydrotalcite-like anionic clays, It contain: hydrotalcite (abbreviated as HT), hydrotalcite like compound, (abbreviated HTLcs). Because of their main ingredients are generally constituted by two metal hydroxide, is also called the double-metal hydroxide (Layered Double Hydroxide, abbreviated as LDH), their intercalated chemical product was known as the pillared LDH. Hydrotalcite, hydrotalcite-like compounds and pillared LDH referred as LDHs or HTLcs.layered hydrotalcite-like material is positively charged main layers and interlayer anions through non-covalent interactions assembled compound, its structure is similar to brucite Mg (OH) 2, the MgO6 octahedral shared edges form a cell layer. Due to its special structure, the double-layered compounds with acid-base functionality, memory effect, exchangeable interlayer anions and a series of special performance, is a kind of broad application prospects of the layer of columnar compounds in adsorption, ion exchange, synthetic materials, household chemicals, catalysts, superconductors, and environmental protection has great potential, has become the focus of domestic and foreign research. In this paper, dyadic CuAl-HTLcs, CuFe-HTLcs and CuCr-HTLcs were systematically synthesized by low over-saturation intermittent coprecipitation method and constant pH value coprecipitation method, and their material capability were characterized by X-ray diffraction (XRD),FT-IR,Thermogravimetric-differential thermal analysis (TG-DTA). All show that they has the character of HTLcs.CuFe-HTLcs was investigated in synthesis of the furfural 1,2-propanediol acetal. Meanwhile , the effects of component of catalyst, the ratio of stuff, the amount of catalyst and the reaction time on the conversion of furfural were discussed. The experimental results showed that CuFe-HTLcs has a high catalytic activity and selectivity to synthesize furfural 1,2-propanediol acetal. Under the reaction conditions of CuFe-HTLcs with n(Cu)︰n(Fe)=3(molar ratio) as the Catalyst,n(1,2-propanediol)︰n(furfural)=1.5(molar ratio), the amount of catalyst = 2.60%(relative to the mass of furfural), cyclohexane as water entrainer, the reaction temperature ranged from 95℃to 100℃and the reaction time for 5h, the conversion of furfural reached 81.7% and the selectivity to furfural 1,2-propanediol acetal almost reached 100%. At the same time, there exist a comparison of catalytic activity of the three catalyst for furfural 1,2 - propanediol acetal synthesis.The results show that the CuFe-HTLcs has more excellent catalytic effect than CuAl-HTLcs and CuCr-HTLcs in this reaction. CuAl-HTLcs were applied in synthesis of 2-furaldehyde diethyl acetal. The effects of catalyst composition, reactant composition, the amount of catalyst and reaction time were investigated. The experimental results show that CuAl-HTLcs had a high catalytic activity and selectivity to synthesize 2-furaldehyde diethylacetal. Under the reaction conditions of CuAl-HTLcs with n(Cu):n(Al)=0.5, n(enthanol):n(furaldehyde)=40:3,the amount of catalyst = 0.1g,reaction temperature = 70℃and reaction time = 90min, the conversion of furaldehyde reached 54.43% and the selectivity to 2-furaldehyde diethyl acetal reached almost 100%. The three catalyst has little difference between this reaction, and CuAl-HTLcs in the conversion and selectivity are better than the other two.To conclude: hydrotalcite-like compounds containing copper for condensation reactions of furfural has higher activity and the catalytic activity and product selectivity is closely related to Lewis acid sites and crystal structure of the catalyst.The catalytic mechanism of the two reaction is tentatively proposed according to the results of experiment.