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

Mohammad Mohammad,Aravamudhan Aravamudhan,Bepari Bepari,Kuila Kuila

doi:10.3390/catal9100872

Mohammad Mohammad, Aravamudhan Aravamudhan + Show 2 more

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https://doi.org/10.3390/catal9100872

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Abstract

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.

Highlights

Fischer–Tropsch (FT) synthesis was discovered by Franz Fischer and Hans Tropsch in the 1920s in Germany [1], it has gained immense attention in last few years due to depletion of non-renewable energy sources
In order to improve the efficiency of FT synthesis significantly, detailed kinetic rate expressions were derived which is very similar to our work reported in literature for both fixed bed reactor as well as microreactor using iron or cobalt-based catalyst [80,81,90,91]
Three different types of mesoporous silica supported Co-Ru based catalysts were synthesized using the one-pot hydrothermal method and performance for FT was evaluated. These catalysts resulted in high surface area with hexagonal ordered mesoporous structure as supported by BET, low angle X-Ray Diffraction (XRD) and Transmission Electron Microscopic (TEM) studies

Summary

Introduction

Fischer–Tropsch (FT) synthesis was discovered by Franz Fischer and Hans Tropsch in the 1920s in Germany [1], it has gained immense attention in last few years due to depletion of non-renewable energy sources. The microreactor platform, which contains microstructured units called microreactors, uses a large number of small, parallel channels with different channel designs This technology provides an alternative platform for controlling highly exothermic reactions like FT synthesis with enhanced mass and heat transfer. It has gained much attention in process intensification of FT synthesis [5,6] as isothermal operating conditions are well maintained in a microreactor with good control over process parameters which favors quick screening of catalyst for different chemical reactions. This has been demonstrated commercially and in R&D by Velocys and Micrometrics Corporations [11,12,13,14]

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