Dr. Linsheng Wang
National Institute for Materials Science, Japan
Title: Efficient and selective synthesis of phenol by direct oxidation of benzene with molecular oxygen in sub-nano spaces and development of sub-nanotech for 3E production of phenol
Abstract:
Phenol is an important intermediate for the manufacture of fine chemicals and engineering plastics utilized in many commodities, which is produced mainly by the three steps so-called cumene process via the decomposition step of cumene hydroperoxide intermediate with sulfuric acid to an equimolar acetone production besides phenol in a liquid phase. Compared to the cumene process, direct phenol synthesis from benzene in a one-step gas-phase reaction is highly desirable for industry, and various oxidants have been examined for the direct benzene-to-phenol synthesis. The development of new gas-phase heterogeneous catalytic systems is of great significance from the viewpoints of both fundamental research and industrial applications. In the present presentation, Pt, Ir, Ni based clusters are fabricated in the sub-nano pores of ZSM-5 and beta zeolites as the novel efficient catalysts for the selective benzene-to-phenol process. It has been found that the selective oxidation catalysis of zeolite β-supported Ir , Pt and Ni catalysts for the gas-phase phenol synthesis of benzene with O2 under coexisting NH3, whereas in their bicomponent systems (benzene+O2 or NH3+O2) benzene and NH3 were deeply oxidized with O2 to CO2 and N2, respectively. However, in the three component reactions, benzene was oxidized to phenol selectively (up to 93.1% selec.), where the switchover of the reaction pathways from the combustion to the selective oxidation occurred and the combustion of both benzene and NH3 was remarkably suppressed. The active structure of fabricated nano-catalysts and the reaction mechanism for the novel benzene-to-phenol process were identified by characterization with XAFS, STEM/EDS, XRD, XRF, XPS, DFT, etc. The novel alternating process involving benzene-O2-NH3 and benzene-H2O processes was also developed for the selective phenol synthesis from benzene with O2, in which the phenol selectivity was maximized and the ammonia consumption was minimized. In the novel alternating benzene-to-phenol process, about 99% phenol selectivity with negligible ammonia consumption have been achieved. Based on the above laboratory experimental results, a novel 3E (ecologic, economic and environmentally-friendly) industry process for phenol production from benzene with air can be expected in the near future.
Biography:
Dr. Linsheng Wang and his coworkers have found and developed efficient nanostructured catalysts for converting methane or methane with CO/CO2 to aromatics and hydrogen since the early 1990s; Since 2000s he and his coworkers have found and developed the efficient and selective catalysts for phenol synthesis from benzene with O2 in one step. He has also developed nanoscale reaction engineering for efficient and selective synthesis of phenol from benzene with molecular oxygen and for efficient and selective synthesis of various nitriles such as acetonitrile, acrylonitrile and aromatic nitriles from ethane propane and aromatics. He has developed an efficient and lower cost novel synthesis method for production of transition metal or alloy nanowires as novel catalyst materials. He and his coworkers have found developed Ni-Re-based super-alloy nano-catalysts for steam/dry reforming of methane or other hydrocarbons and for hydrogenation of benzene/toluene to produce cyclohexane/MCH.