Development of high activity, coal derived, promoted catalytic systems for nox reduction at low temperatures

摘要

This project is directed at an investigation of catalytic NO(sub x) reduction mechanisms on coal-derived, activated carbon supports at low temperatures. Promoted carbon systems offer some potentially significant advantages for heterogeneous NO(sub x) reduction. These include: low cost; high activity at low temperatures, which minimizes carbon loss; oxygen resistance; and a support material which can be engineered with respect to porosity, transport and catalyst dispersion characteristics. During the reporting period, the following has been accomplished: (1) A MS-TGA (mass spectrometric-thermogravimetric analysis) apparatus, which is one of the primary instruments that will be used in these studies, has been refurbished and modified to meet the requirements of this project. A NO(sub x) chemiluminescence analyzer (ThermoElectron, Model 10) has been added to the instrument to monitor NO(sub x) concentrations in the feed and product streams. Computer control and data acquisition system has been updated and modified to accommodate the requirements of the specific types of experiments planned. The diffusion pumps used to maintain vacuum for the mass spectrometer system have been replaced with turbomolecular pumps (Varian 300 HT). (2) A packed bed reactor/gas flow system has been assembled for performing reactivity studies. This system employs a Kin-Tek gas calibration/mixing system for varying NO and CO concentrations in the feed gas to the packed bed, a NO(sub x) chemiluminescence analyzer (ThermoElectron, Model 10), and a quadrupole mass spectrometer (Dycor). This system is required for steady-state reactivity studies, as well as mechanistic studies on the effects of NO and CO in the gas phase on intermediate oxygen surface complex populations on the carbon substrates. (3) Work has continued on the application of contrast matching, small angle neutron scattering to the characterization and development of char porosity. Contrast matching with perdeuterated toluene has been used to discriminate between inaccessible and inaccessible porosity in Pittsburgh No.8 coal char and PRC. This technique is being investigated from the point of view of porosity characterization of the carbon support materials for NO(sub x) reduction systems.