Kinetics of the Fischer-Tropsch synthesis on silica-supported cobalt-cerium catalyst

Eco-Friendly Piper cubeba Official Extract Corrosion Inhibition of C-Steel in 1 M Sulfamic Acid

This work offers a high-performing, environmentally friendly corrosion inhibitor for carbon steel in 1 M sulfamic acid (H2NSO3H). Potentiodynamic polarization and electrochemical impedance spectroscopy were used to evaluate the anticorrosion properties of Pipper cubeba official extract (P.cubebaOE) for carbon steel in 1 M H2NSO3H at 25 to 45 °C. At a temperature of 45 °C, the P.cubebaOE reached a maximum corrosion inhibition efficiency of 96%. P.cubebaOE was also subjected to Fourier transform infrared spectroscopy in order to ascertain its primary chemical composition. Additionally, the behavior of P.cubebaOE in terms of corrosion inhibition on carbon steel was examined at the microscopic level using scanning electron microscopy. The findings demonstrate that P.cubebaOE's adsorption type on carbon steel conforms to the Langmuir adsorption isotherm model. Based on the adsorption isotherm model, the free energy was estimated to be approximately -20.0 kJ/mol, suggesting that P.cubebaOE is physically adsorbing on the surface of carbon steel. The results of the density functional theory and molecular dynamics simulations show that P.cubebaOE exhibits excellent inhibition performance on carbon steel in H2NSO3H solution and are consistent with the electrochemical experimental results. This work offers significant information on the development of environmentally friendly corrosion inhibitors for carbon steel.

Determination of Kinetic Parameters of Fischer–Tropsch Synthesis in the Presence of a Granular Cobalt Catalyst

Some kinetic parameters of Fischer–Tropsch synthesis (FTS) were determined in the presence of a granular cobalt/zeolite catalyst. Usually, kinetic studies of granular catalysts are considered to be complicated by external and internal diffusion. We managed to obtain a catalyst with a special structure of the active surface, where sites active in FTS are isolated from each other due to the environment of inactive spinel CoAl2O4 and inter-site transport is provided by an extensive intragranular graphitic network serving simultaneously as a heat-conductive medium. As a result, FTS proceeded in the kinetic region. It was found that the reaction kinetics obey the Arrhenius law; whereas, the activation energy is different in different temperature ranges, i.e., 118.2 kJ/mol in the range of 180–210 °C, and 173.6 kJ/mol in the range of 232–243 °C. This behavior is determined by the presence of zeolite, which becomes active in the secondary transformations of FTS products at temperatures beyond 210 °C.

Kinetics and Selectivity Study of Fischer–Tropsch Synthesis to C5+ Hydrocarbons: A Review

Fischer–Tropsch synthesis (FTS) is considered as one of the non-oil-based alternatives for liquid fuel production. This gas-to-liquid (GTL) technology converts syngas to a wide range of hydrocarbons using metal (Fe and Co) unsupported and supported catalysts. Effective design of the catalyst plays a significant role in enhancing syngas conversion, selectivity towards C5+ hydrocarbons, and decreasing selectivity towards methane. This work presents a review on catalyst design and the most employed support materials in FTS to synthesize heavier hydrocarbons. Furthermore, in this report, the recent achievements on mechanisms of this reaction will be discussed. Catalyst deactivation is one of the most important challenges during FTS, which will be covered in this work. The selectivity of FTS can be tuned by operational conditions, nature of the catalyst, support, and reactor configuration. The effects of all these parameters will be analyzed within this report. Moreover, zeolites can be employed as a support material of an FTS-based catalyst to direct synthesis of liquid fuels, and the specific character of zeolites will be elaborated further. Furthermore, this paper also includes a review of some of the most employed characterization techniques for Fe- and Co-based FTS catalysts. Kinetic study plays an important role in optimization and simulation of this industrial process. In this review, the recent developed reaction rate models are critically discussed.

Kinetics of Fischer–Tropsch Synthesis in a 3-D Printed Stainless Steel Microreactor Using Different Mesoporous Silica Supported Co-Ru Catalysts

Fischer–Tropsch (FT) synthesis was carried out in a 3D printed stainless steel (SS) microchannel microreactor using bimetallic Co-Ru catalysts on three different mesoporous silica supports. CoRu-MCM-41, CoRu-SBA-15, and CoRu-KIT-6 were synthesized using a one-pot hydrothermal method and characterized by Brunner–Emmett–Teller (BET), temperature programmed reduction (TPR), SEM-EDX, TEM, and X-ray photoelectron spectroscopy (XPS) techniques. The mesoporous catalysts show the long-range ordered structure as supported by BET and low-angle XRD studies. The TPR profiles of metal oxides with H2 varied significantly depending on the support. These catalysts were coated inside the microchannels using polyvinyl alcohol and kinetic performance was evaluated at three different temperatures, in the low-temperature FT regime (210–270 °C), at different Weight Hourly Space Velocity (WHSV) in the range of 3.15–25.2 kgcat.h/kmol using a syngas ratio of H2/CO = 2. The mesoporous supports have a significant effect on the FT kinetics and stability of the catalyst. The kinetic models (FT-3, FT-6), based on the Langmuir–Hinshelwood mechanism, were found to be statistically and physically relevant for FT synthesis using CoRu-MCM-41 and CoRu-KIT-6. The kinetic model equation (FT-2), derived using Eley–Rideal mechanism, is found to be relevant for CoRu-SBA-15 in the SS microchannel microreactor. CoRu-KIT-6 was found to be 2.5 times more active than Co-Ru-MCM-41 and slightly more active than CoRu-SBA-15, based on activation energy calculations. CoRu-KIT-6 was ~3 and ~1.5 times more stable than CoRu-SBA-15 and CoRu-MCM-41, respectively, based on CO conversion in the deactivation studies.

Kinetic Study Based on the Carbide Mechanism of a Co-Pt/γ-Al2O3 Fischer–Tropsch Catalyst Tested in a Laboratory-Scale Tubular Reactor

A Co-Pt/γ-Al2O3 catalyst was manufactured and tested for Fischer–Tropsch applications. Catalyst kinetic experiments were performed using a tubular fixed-bed reactor system. The operative conditions were varied between 478 and 503 K, 15 and 30 bar, H2/CO molar ratio 1.06 and 2.11 at a carbon monoxide conversion level of about 10%. Several kinetic models were derived, and a carbide mechanism model was chosen, taking into account an increasing value of termination energy for α-olefins with increasing carbon numbers. In order to assess catalyst suitability for the determination of reaction kinetics and comparability to similar Fischer–Tropsch Synthesis (FTS) applications, the catalyst was characterized with gas sorption analysis, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) techniques. The kinetic model developed is capable of describing the intrinsic behavior of the catalyst correctly. It accounts for the main deviations from the typical Anderson-Schulz-Flory distribution for Fischer–Tropsch products, with calculated activation energies and adsorption enthalpies in line with values available from the literature. The model suitably predicts the formation rates of methane and ethylene, as well as of the other α-olefins. Furthermore, it properly estimates high molecular weight n-paraffin formation up to carbon number C80.

Enhancing the thermophysical properties and tribological behaviour of engine oils using nano-lubricant additives

This paper presents the enhancement of the thermophysical properties of engine oil using nano-lubricant additives and a characterization of tribological behaviour in terms of sliding contact interfaces in automotive engines.