The Study On Metal Salt Phosphate And Hydrotalcite Supported Pt-Bi Catalyst For Glycerol Oxidation In Base-free Conditions

In recent years, biodiesel arouse wide concern for various countries in theworld because of it have environmental and renewable feature, but theproductive process of biodiesel produces a large number of by-product glycerolin the industry. The increase of glycerol production made glycerol to be surpluschemical. Further processing of surplus glycerol to high-value fine chemicalswill not only improve useful value of glycerol but also decline the cost ofbiodiesel production and extend the industrial chain. Catalytic glycerol oxidationwas one of further processing way of glycerol, this way lead to produce a seriesof fine chemicals. The oxidation of glycerol was a complicated parallel andsequential reaction, selective catalytic glycerol oxidation was important becauseof the lower selectivity of production.In this work, we used H2O2as oxidant and two kinds of metal saltphosphate materials containing transition metal Co-VSB-1, Cu-α-ZrP andsupported Pt-Bi catalyst for glycerol oxidation reaction, investigated the effectof reaction condition on reaction activity and selectivity, main research contents and conclusions as follow:1. The metal salt phosphate materials Co-VSB-1and Cu-α-ZrP weresynthesized by hydrothermal method, and they were used to glycerol oxidationreaction as catalyst, investigated the effect of reaction temperature,H2O2/glycerol molar ratio, reaction time, catalyst amount on reaction resultsystematically.i) The catalytic activity site of Co-VSB-1and Cu-α-ZrP were divalentcobalt and copper respectively; main oxidation products of glycerol wereglyceric acid, glycolic acid, formic acid and a little of gas phase COX.ii) Glycerol conversion increased with reaction temperature, reactinon time,H2O2/glycerol molar ratio increasing, but the selectivity of glyceric acid declined.The optimizing reaction condition of glyceric acid was: reaction temperature70℃, reaction time6h, H2O2/glycerol molar ratio3/1, catalyst amount0.3g,the selectivity of glyceric acid reached on52.3%with11.7%glycerolconversion.iii) Compared with Co-VSB-1, the selectivtiy of glyceric acid increasedwhen Cu-α-ZrP as catalyst, The optimizing reaction condition of glyceric acidwas: reaction temperature70℃, reaction time4h, H2O2/glycerol molar ratio2/1, catalyst amount0.2g, the selectivity of glyceric acid reached on78.7%with8.1%glycerol conversion.2. We also synthesized Mg-Al hydrotalcite supported Pt-Bi material byimpregnation method, the structure of the material was characterized by XRD, TEM, N2isotherm curve. Investigated the effect of metal ratio, support nature,prepared method, reaction temperature, reaction time on catalytic activitysystematically, the experimental result show:i) Promoter bimuth is helpful to the selectivity of secondary hydroxy groupoxidation of glycerol; hydrotalcite inhibits the cracking of C-C of product toimprove the selectivity of dihydroxyacetone compared with active carbon andcarbon black support; the catalyst prepared by NaBH4reduced method washigher activity than H2reduced method.ii) Higher reaction temperature lead to decline catalytic activity easily; theconversion of glycerol increased with reaction time increasing, but theselectivity trend of main oxidation production dihydroxyacetone was waveform.In optimal condition, reaction temperature70℃, reaction time6h, catalystamount0.5g, oxygen speed150mL/min, the selectivity of dihydroxyacetonereach on80.6%with25.1%glycerol conversion when5%Pt-7%Bi/LDHs ascatalyst.