Experimental study and kinetic modeling of methanol conversion to propylene with co-feeding of C4 and C5/C6 hydrocarbon cuts over a ZSM-5 catalyst.

Extensive experimental data were used to develop a comprehensive kinetic model for the methanol to propylene (MTP) process over a ZSM-5 catalyst. Preliminary experiments were performed to determine the reaction conditions that would ensure the absence of external (film) and internal mass transfer resistances. The kinetic experiments were subsequently carried out at 420-500 °C under conditions where mass transfer limitations were absent. A detailed reaction network was proposed for the MTP process based on the experimental product distribution and various reported kinetic models in the literature. According to the first series of experiments (without C4 and C5/C6 recycle streams) conducted at various temperatures, the best yield for propylene production was achieved at 480 °C with a water to methanol ratio of 0.7. Subsequently, kinetic experiments were performed at 480 °C and a water to methanol ratio of 0.7 using feeds with different amounts of C4 and C5/C6 hydrocarbons as recycle streams. Species material balances for the integral tubular reactor along with power-law rate functions and the Arrhenius equation for rate constants were employed in an optimization algorithm to obtain the kinetic parameters. The predictive ability of the model was checked against experimental data, and the kinetic parameters were validated by additional experiments.

A catalyzed method to remove polychlorinated biphenyls from contaminated transformer oil.

The disposal of polychlorinated biphenyls (PCBs) as persistent organic pollutants from the environment has been normally performed by isolation from soil or water because of their biological activity and toxic potential. In the present investigation, catalytic hydrodehalogenation was used to detoxify PCBs-contaminated transformer oil. All reactions were directed on an oil containing 11.09 wt% of PCBs utilizing palladium supported on multi-walled carbon nanotubes (Pd/MWCNTs). The amount of hexa-chlorine homologues reduced considerably from 5.07% to less than 800 ppm utilizing HDC at the atmosphere of argon. Moreover, the amounts of long half-lives and bioaccumulative congener of PCB 153 decreased considerably from 3.2% to less than 200 ppm. Besides, the quantity of some environmental pollutants like PCB 105 as a mono-ortho-substituted congener decreased considerably. The significant effects of reaction time, reaction temperature, and catalyst concentration on the efficiency were confirmed and modeled through Box-Behnken design. The optimal reaction condition with an efficiency of 96.67% was 70°C, with catalyst loading of 8 wt% and reaction time of 3.23 h. Furthermore, the quantity of turnover frequency of Pd/MWCNTs showed that it has more activity than palladium-carbon active supported in the ambient pressure without utilizing hydrogen gas in transformer oil complex. The study of the kinetic model revealed that the required activation energy (of 12.99 kJ/mol) to remove PCBs from transformer oil utilizing the present catalyst was lower than other catalyzed hydrodechlorination methods.