Hydrogenation Research Of Phenol In High-temperature Water With Phosphotungstic Acid Modified Palladium Catalyst

With the development of society, energy becomes completely important, and fossil fuel is dominant in energy consumption. But there is damaging to environment with the using of fossil fuel. With the impact of fossil fuels on the environment, there is an increasing interesting on questing for suitable, environmentally friendly alternative processes to produce fuels.The obstacle in biomass energy is high oxygen content and low ratio of H/C, which is just because the presence of aromatic compounds and its difficulty in hydrogenation. Hydrogenation of phenol was investigated in a high-temperature water (HTW) system according the farmer study. The characterization of the catalyst used in the system was investigated by BET surface area, XRD, XPS, TEM and STEM-EDS testing methods. The results indicated that phosphotungstic acid (PTA) modified Pd/Ce-A10x catalyst, i.e., Pd/W-Ce-AlOx, could not only increase the values of binding energy of the major elements and thus enhance its ability in attracting electrons, but also enhance the phenol degradation and selectivity in HTW when comparing with non-PTA modified catalysts.The Pd/W-Ce-AlOx catalyst also showed a high activity for the phenol hydrogenation and high selectivity at a moderate temperature (180℃) in HTW system, because cyclohexanone is the major products (more than 95%) from the reaction. However, at the temperatures greater than 260℃, the changes of transport properties would increase the dissociation of cyclohexanone from the acidic sites, which resulted in the future reactions with hydrogen to form cyclohexanol rather than cyclohexane.Based on the observation, a kinetic model of detail pathways to give the insight views was proposed.