Effect of H-ZSM-5 zeolite content on the intrinsic kinetics of the methanol dehydration to dimethyl ether over H-ZSM-5/Al2O3 molded catalyst

A series of H-ZSM-5/Al2O3 molded catalysts with various zeolite/alumina ratios has been prepared and their catalytic activity in the methanol dehydration to dimethyl ether has been studied. Based on Langmuir-Hinshelwood...

Gastight Rotating Cylinder Electrode: Towards Decoupling Mass Transport and Intrinsic Kinetics in Electrocatalysis

Decoupling and understanding the various mass, charge and heat transport phenomena involved in the electrocatalytic transformation of small molecules (i.e. CO2, CO, H2, N2, NH3, O2, CH4) is challenging but it can be readily achieved using dimensionless quantities (i.e. Reynolds, Sherwood, Schmidt, Damköhler, Nusselt, Prandtl, and Peclet Numbers) to simplify the characterization of systems with multiple interacting physical phenomena. Herein we report the development of a gastight rotating cylinder electrode cell with well-defined mass transport characteristics that can be applied to experimentally decouple mass transfer effects from intrinsic kinetics in electrocatalytic systems. The gastight rotating cylinder electrode cell enables the dimensionless analysis of electrocatalytic systems and should enable the rigorous research and development of electrocatalytic technologies.

Six Flux Model for the Central Lamp Reactor Applied to an External Four-Lamp Reactor

One of the difficulties of establishing the intrinsic kinetics of photocatalytic oxidation processes is due to the complex mathematical formula used to determine the rate of photon absorption. To solve this problem, some models have been proposed and checked, such as the Six Flux Model (SFM) confirmed in central lamp photoreactors. External lamp photoreactors are also one of the most used configurations to study the photocatalytic oxidation of contaminants in water, and complex mathematical solutions have been reported to solve the rate of photon absorption. In this work, SFM Equations already reported for the central lamp photoreactor have been adapted to determine the rate of photon absorption in an external four-lamp photoreactor. The results obtained show slight differences from those of the Monte Carlo method. Additionally, once the rate of photon absorption was validated, the intrinsic rate constant and scavenging factor of the photocatalytic oxidation of some contaminant compounds from results already published have been determined.

Kinetics and mechanism of catalytic oxidation of sodium ethyl mercaptide with microfluidics

Catalytic oxidation desulfurization of gasoline is a key process for the utilization of petroleum hydrocarbons. However, the inherent mechanism still remains unclear and the kinetic investigation is usually performed in processes with limited mass transfer rates. Herein, the kinetics and mechanism of catalytic oxidation of sodium ethyl mercaptide were investigated with microfluidics. On the basis of eliminating mass transfer resistance, the effects of temperature, pressure, residence time, and gas-liquid flow ratio on the oxidation were assessed. According to the results of UV-vis spectra and binding constant, it was confirmed that the catalytic center was in the form of dimer. A heterogeneous reaction kinetic model was proposed as such. The kinetic parameters close to intrinsic kinetics and corresponding kinetic rate expression were obtained.