Narrow Results

A Monte Carlo Simulation study of the monomer dimer (CO–NO) heterogeneous catalytic reaction on body-centered cubic structure (BCC) is presented. The effect of Eley–Rideal (ER), diffusion of nitrogen and carbon monoxide on the phase diagram is investigated. The steady reactive state is observed while using Langmuir–Hinsehelwood (LH) mechanism. Whenever the ER mechanism is included in our simulation, the production of CO₂ starts as soon as y_CO departs from zero, which is consistent with the experimental results. The ER mechanism does not affect the production of N₂. The effect of diffusion of CO and N are found very little on the steady state reactive region where the concentration of CO is very high.

In order to reduce the carbon emissions of fuel vehicles, hydrogen has received extensive attention as a new clean energy. In this paper, a packed-bed microreactor for hydrogen production from methanol steam is designed for use in hydrogen fuel cells. By considering the heating gas velocity in the heating tubes, the inlet temperature of the microreactor, the size and number of heating tubes, inlet pressure, pellet porosity and thermal conductivity, parameters such as methanol conversion rates and hydrogen concentration were evaluated. First, the rate at which the gas is heated has a great influence on the reaction results. Choosing a larger heating gas velocity leads to an increase in the temperature inside the microreactor, thereby increasing the CH₃OH conversion, resulting in a higher H₂ concentration at the outlet. Changing the inlet temperature of the microreactor affects the reaction speed, but has little effect on the H₂ concentration at the outlet. By studying the radius and number of heating tubes, we selected three different sets of data to compare the conversion rate of reactants and the concentration of products, and finally determined the optimal parameters as R = 4 mm and N = 8. Second, the inlet pressure has little effect on the H₂ concentration at the outlet, but has a significant effect on the reaction speed. Particle porosity has no effect on the reaction results. Finally, the larger the thermal conductivity, the higher the temperature in the microreactor, which is more conducive to the reaction.

Hydrogen has received widespread attention as a new clean energy in order to reduce the carbon emissions of fuel vehicles. This paper studies a tubular microreactor based on methanol steam reforming. Methanol and steam are mixed in proportion and the chemical reaction takes place in a porous catalytic bed. For heating purposes, hot gas from the burner penetrates the reactor bed through heating tubes. Energy is supplied through the heating tubes to drive the endothermic reaction system. The microreactor is enclosed in an insulated jacket. In this paper, parameters such as methanol conversion and hydrogen concentration are evaluated by considering microreactor materials, heating gas temperature and flow direction, heating tube distribution, pressure drop and reaction channel length. First of all, choosing a microreactor material with a smaller thermal conductivity can avoid excessive heat loss, and improve heat transfer performance. Increasing the heating gas temperature leads to an increase in the temperature of the reaction zone, thereby increasing the CH₃OH conversion rate and H₂ mass fraction. Changing the flow direction of the heating gas affects the reaction rate, but has little effect on the reaction result. Through the research on the distribution of the heating tubes, the results show that the hydrogen production rate is higher when the contact area between the heating tubes and the reaction zone is larger. Secondly, through the comparison of the data under different pressure drops, the best parameter $P=50$pa is obtained, and the CH₃OH conversion rate is 80.6% at this time. Finally, increasing the length of the reaction channel can make the reaction more complete. For example, when the reaction channel length $L=0.39$m, the CH₃OH conversion rate is as high as 83.7%.

In this paper, the monophasic catalytic reaction in the microreactor is studied. Several factors that may affect the catalytic reaction are discussed, including the pressure drop, the size of catalyst particles, and the channel structure. Finally, some important conclusions can be reached. The change of pressure drop has an effect on the reaction. For example, the C₃H₆ conversion rate is 62.88% when the pressure drop is 8atm, and the C₃H₆ conversion rate is 61.78% when the pressure drop is 11atm. The effect of the change particle radius is not obvious on the reaction. Enhancing the mixing of substances before entering the reaction domain is helpful to the catalytic reaction. There are different substances concentration in catalyst particles at different positions in microreactors. But from the surface to the inside of catalyst particles, the substances concentration has a clear change rule.

In this paper, a model of simultaneous mass and heat transfer within a porous catalyst in a flat particle is considered. A new modification of the shooting reproducing kernel Hilbert space (SRKHS) method is proposed, which is also capable of handling the system of nonlinear boundary value problems by employing Newtons method. The proposed method is a well-performance technique in both predicting and calculating multiple solutions of the nonlinear boundary value problems. Applying the SRKHS method shows that the mentioned model might admit multiple stationary solutions (unique, dual or triple solutions) depending on the values of the parameters of the model. Furthermore, the convergence of the method is proved and some numerical tests reveal the high efficiency of this new version of SRKHS method.

One-pot synthetic approach to produce trifluoroacetamide has been developed using an electrochemical method with the B${}_{12}$ complex as a catalyst under mild conditions, in open air at room temperature. Thirty examples of trifluoroacetamide were synthesized from 1,1,1-trichloro-2,2,2-trifluoroethane (CFC-113a) in moderate to good yields. This user-friendly strategy is compatible with a broad range of trifluoroacetamide syntheses.