Copper-containing LDHs、LDO Catalytic Reaction Of Benzene To Phenol

Phenol is a key intermediate and is broadly applied in chemistry, agriculture, medicine and so on. China needs much phenol as raw material and must increasingly import it every year because the production of phenol is less than that of consumption. Although Cumene process by which phenol was synthesized traditionally dominates in phenol production and the proportion by the process is about92%of all phenol production at home and abroad, it showed more and more shortcomings including high energy consumption, easy equipment corrosion, low efficiency in atomic economy and yield of phenol, impure products and serious pollution. According to needs for phenol production which demand low cost, simple process, mild conditions and high selectivity to phenol, a benign process for phenol synthesis by direct oxidation of benzene was investigated in the paper. The mixture of LDHS and sequent calcinated complex oxidant LDO showed special structure and performance, and was selected as catalyst for oxidation of benzene to form phenol. Experimentally derived the following conclusions:(1)Analysis on the binary copper-containing LDHs and LDO showed that:At the appropriate pH value, all binary copper LDHs made in the experiment get single compound crystal and have layer structure, which is the peculiar structure of hydrotalcite. The laminate structure of the LDHs is destroyed as the calcinations temperature exceeds300℃, then CuO appeared. There wasn’t metal oxides appeared when the temperature exceeds400℃. This showed that crystal structure of the LDO is uniform. This paper take binary copper LDHs and LDO as the catalyst, which is used to catalyze benzene to make phenol. The catalytic activity ranking in order are: CuAl-LDHs>CuFe-LDHs>CuCr-LDH; CuAl-LDO>CuFe-LDO>CuCr-LDO.(2) Analysis on the ternary copper-containing LDHs and LDO showed that:A series of ternary copper-containing LDHs is made at the appropriate pH value, and their M2+/M3+=3/1、Cu2+/(Ni2+、Co2+、Zn2+)value is different. The ternary copper-containing LDO is roasted at different temperature by the LDHs with the value of Cu2+/(Ni2+、Co2+、Zn2+)=3/1. Characterization shows that:the ternary copper-cont-aining LDHs with a rule structure can be made at the value of Cu2+/(Ni2+、Co2+、Zn2+) is5/1～1. In the XRD spectra of LDO, the feature diffraction peak of CuO appear and enhanced as the temperature rises. There aren’t feature diffraction peak of other metal oxide appear, so we can consider that other metal oxide distribute in the CuO lattice at the form of amorphous state. This paper take LDHs with the Cu2+/(Ni2+Co2+、Zn2+)value is3/1and LDO made at the temperature of400℃as catalyst, which is used to catalyze benzene to make phenol. The catalytic activity ranking in order are: CuNiAl-LDHs> CuCoAl-LDHs> CuZnAl-LDHs; CuNiAl-LDO> CuCoAl-LDO> CuZnAl-LDO.(3) A series of layers anion made in experiment are as follows:Cr2O72-、V2O76-、 C2O42-and CuNiAl-LDHs with M2+/M3+=3/1、Cu2+/Ni2+=3/1. Characterization shows that:They all have layer structure as LDHs. And the distance between the layer increase. At the reaction of using benzene to make phenol, compared with the CuNiAl-LDHs with the layers anion is CO32-, the catalytic activity of CuNiAl-LDHs ranking in order are:Cr2O72-> CO32-> V2O76-> C2O42-(4) CuNiAl-LDO is made by CuNiAl-LDHs, which is take CO32-,M2+/M3+=3/1and Cu2+/Ni2+=3/1as layers anion. This paper take CuNiAl-LDO as catalyst and changing the single factor to reach the best reaction condition of using benzene to make phenol:the best reaction temperature is65℃,the best reaction time is6h, The best solvent consumption is15mL, the best catalyst dosage is10mg and the C6H6/H2O2=3/1.In conclusion, both Contain copper LDHs and LDO have catalytic activity in the reaction of using benzene to make phenol. And the catalytic activity of LDO is higher than LDHs. The catalytic activity of LDHs and LDO is related with quantity of acid center, acid of layers anion, oxidizing and species of intercalated anion.