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Aged CoO/Mo08/Si0.JA1203 catalyst pellets, used in a pilot plant for the single-stage liquefaction and hydrodesulfurization of coal, were analyzed with an electron microprobe and scanning electron microscope. The results demonstrate the occurrence of catalyst aging processes which could lead to bed plugging and pore mouth blocking. Department of Chemical EngineeringUniversity of Delaware Newark, Delaware 1971 1 SCOPETo meet the need for new sources of clean fuels, procalytic hydrodesulfurization of the derived liquids. In some of these processes, the liquefaction and catalytic hydrodesulfurization take place in a single reactor. CONCLUSIONS AND SIGNIFICANCEPellets of the hydroprocessing catalyst used in the Synthoil process (sulfided CoO/Mo03/Si02/A1203) accumulated inorganic and organic contaminants both on the exterior surface and in the pore mouths. The inorganic (carbon free) deposit found in the upstream end of the fixed-bed reactor has been identified as primarily ferrous sulfide, Fe14S15. This material covered 50 to 7@% of the catalyst's peripheral surface and penetrated into the catalyst pores to a depth of about 100 pm. The total aceumulated deposit caused a reduction in catalyst surface area and pore volume. The inorganic deposit found in the downstream end of the reactor was mainly aluminum and silicon and covered 10 to 20% of the catalyst's peripheral surface. Titanium penetrated about 150 pm into the pores. All of these deposits caused a 40% loss of pore volume. These results imply that deposition in coal hydroprocessing reactors could lead to bed plugging and pore mouth blocking.Conversion of coal to clean liquid fuels can be accomplished by processes being developed for liquefaction ( a reductive depolymerization of the organic coal matrix) followed by catalytic hydroprocessing of the derived liquid, which removes sulfur and increases the H/C ratio.The liquefaction and hydroprocessing steps typically have been carried out in separate stages, with interstage removal of the mineral matter of the coal. Alternatively, in processes such as Synthoil (Yavorsky, 1973), both liquefaction and hydroprocessing are carried out in a single reactor. The fixed-bed reactor of the Synthoil process is fed with a slurry of coal in coal derived liquid which flows concurrently with hydrogen through a preheater, reaching a temperature of about 720°K at a pressure of 1 . 4~1 0~ N/m2. The organic coal matrix is largely liquefied in the preheater, and the resultant gas-liquid-solid mixture flows through a packed-bed reactor containing particles of CoO/Mo03/SiOz/A1203 hydrodesulfurization catalyst. Highly turbulent flow is used with the intention of preventing plugging of the catalyst bed by deposition of inorganic material, coke, and unconverted coal.Correspondence concerning this paper should be addressed to J. J. Stanulonie.The research described here was undertaken to evaluate catalyst aging in reactors used for coal liquefaction and hydroprocessing. The aging problem is unidentified in the literature, but data from a S...

A strategy for fault detection and diagnosis in a closed-loop nonlinear system is described. An extended Kalman filter (EKF) is applied inside the control loop. The EKF recovers information from noisy measurement signals, providing estimates of state variables and unknown parameters of the process. The state estimates produced by the EKF are the inputs to the controller. Since the noise in the measurements is reduced significantly, the control quality is much better than that achieved with application of exponential filters. The estimates of unknown process parameters, where the deviations from normal values are considered faults, are the basis to make alarm decisions. The EKF successfully tracks and distinguishes faults occurring simultaneously. The influences of correlated noises, a special issue of estimation in closed-loop systems, model errors, and number of measurements have been studied. The proposed strategy is applied to a 30-stage binary distillation column with a partial condenser and a reboiler. The simulation results are presented to show the effectiveness of the approach.