A series of novel palladium catalysts supported on carbon nanofibers of various nanostructures have been prepared, characterized, and tested in gas-phase synthesis of dimethyl oxalate. Significant improvements in both activity and selectivity have been achieved over well-defined carbon nanofiber supported palladium catalysts. Carbon nanofiber produced on 20% NiFe/Al2O3 (CNF-05) supported palladium catalyst possesses the highest activity, which can be ascribed to the high surface area of the support, relatively weak metal-support interaction, and smaller metal particles. The low metal-support interaction might improve the redox properties of the catalyst, and thus the activity. The functionalization of CNF-05 in air is found to dramatically increase the conversion of methyl nitrite compared to the functionalization in HNO3.

Electrosynthesis of glyoxylic acidby electroreduction of oxalic acidhas long been well known. However, attempts to commercialize the process have encountered problems due to rapid deactivation of the cathode. The cathode activity can be continuously restored by adding small amounts of chemical activators to the catholyte. In this paper the structural e5ect of chemical activator on electrode reaction is studied. The results show that (1) It is the cation of the chemical activator, but not the anion that a5ects the current e6ciency and the reaction selectivity. (2) The more symmetrical the cation, or the shorter the longest alkyl chain, the higher the current e6ciency and the reaction selectivity become. (3) Mechanism of the activation is discussed. Adsorption of the cations of the activator on the cathode surface protects the electrode. (4) Quantitative characterization of the activator molecule is given using some topological indices, with which the activation ability can be predicted, and screening of the proper activator is made possible.

A model coupled the chemical kinetics with heat transfer was applied for simulation of the dynamic behavior of the gas-solid fixed-bed reactors used in chemical heat pumps (CHP). The kinetic parameters and the thermal parameters were identified, respectively. Good agreement was found between the simulation and the experimental data. Moreover, the sensitivity of the global advancements and the radial temperature profiles to the thermal parameters was analyzed. The thermal capacity of the reactive medium has little influence on the global advancement, while the effective thermal conductivity of the medium has an apparent effect on the global advancement. The influence of the effective thermal conductivity on the global advancement is significant until its value is larger than 15Wm−1 K−1. The contact heat transfer coefficient between reactive salt and reactor wall has less influence on the global advancements and the radial temperature profiles when its value is higher than 800Wm−2 K−1. This model can be used for optimal design of CHPs, optimization of the operation conditions, and determination of the influence of various parameters on the reactor performances, including the kinetic and thermal parameters, the operational parameters (imposed pressure and temperature), and the configuration parameters of the medium or reactor (geometry and dimensions).

Hydrogenation of benzene to cyclohexane was conducted in an adiabatic fixed-bed reactor under a phase transitional condition. In which process, a mixture of benzene and cyclohexane was fed into the reactor at the bottom under the liquid condition, however, the liquid phase disappeared and turned into gas phase at the reactor outlet through vaporization. It follows from this novel idea that the problems associated with reaction heat removal and low catalyst e6ciency of the liquid-filled catalyst could be solved simultaneously with emptying of the liquid from the catalyst. However, the benzene concentration in the mixture should not exceed 14% if simple phase transition is employed, since the reaction heat is seven times the liquid vaporization heat. To optimize this primitive operation, a side stream quenching operation was proposed and attempted experimentally, and it was found that the side stream quenching with double injection points could be an acceptable operating strategy.

A control vector parameterization approach using the Karhunen-Loeve (K-L) expansion for optimal control is presented. Optimal control proples at different initial conditions are represented bya truncated K-L expansion and the optimal control is thus transformed into a parametric optimization with the K-L coefficient (s) as the optimization variable (s). Closed-loop optimal control therefore becomes feasible because the number of optimization variables is minimized. The presented approach is demonstrated on a batch electrochemical reactor in which reduction of oxalic acid glyoxalic acid is carried out under conditions with known or unknown disturbance, or electrode deactivation. The closed-loop control with the K-L expansion outperforms the open-loop optimal control with very little computational e!ort.