The present study investigates the oxidative dehydrogenation of propane-butane (C3–C4) fraction over mono (Cr or Mo) and bi-metal (Cr-Mo) loaded SiO2 catalysts. The catalysts were prepared by sequential impregnation method at 500oC calcination temperature. Experiments were performed by feeding C3–C4 fraction, oxygen, nitrogen, and steam into a continuous flow quartz reactor at an atmospheric pressure (P = 1 atm.), reaction temperatures between 500 – 650oC, gas hourly space velocity (GHSV) within 100 – 400 h-1, and at reaction time (tr) = 2h. Appropriate water vapor addition to the feed sinificantly minimizes oxidation into coke deposits on the catalyst surface, and also prevents further olefin conversion into undesirable product. The physicochemical properties were evaluated by BET, XRD, IR, and EPR characterization techniques. The major oxidation products are ethylene, propylene, isobutylene, butylene. This paper reports that the total yield of olefins (Ʃ C2-C4) = 66.0 % was achieved at 83.5 % conversion level of C3–C4 at 630oC. The results indicate that the addition of Mo to catalysts of Cr/SiO2 modifies its catalytic activity for the ODH reaction. Mono-metallic catalysts (Cr/SiO2 and Mo/SiO2) were prepared for comparison purposes.
Inhaltsverzeichnis (Table of Contents)
- 1. Introduction
- 2. Experimental
- 2.1 Materials and Methods
- 2.2 Catalysts Preparation
- 2.3 Catalysts Treatment
- 2.4 Catalysts Test
- 2.5 Oxidative De-hydrogenation of C3-C4
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
The objective of this study was to investigate the oxidative dehydrogenation of a propane-butane (C3-C4) fraction over mono- and bi-metallic catalysts supported on SiO2, aiming to optimize olefin production. The research explored the effects of different catalyst compositions (Cr, Mo, and Cr-Mo) on catalytic activity, selectivity, and the overall yield of olefins.
- Oxidative dehydrogenation of C3-C4 fraction for olefin production.
- Catalyst design and synthesis using Cr, Mo, and Cr-Mo on SiO2.
- Impact of catalyst composition on catalytic activity and selectivity.
- Optimization of reaction parameters (temperature, GHSV) for maximizing olefin yield.
- Mitigation of coke formation and catalyst deactivation.
Zusammenfassung der Kapitel (Chapter Summaries)
1. Introduction: This chapter introduces the importance of olefins in industrial organic chemistry and discusses traditional methods for their production, such as steam cracking and fluid catalytic cracking. It highlights the drawbacks of these methods, including thermodynamic limitations, coke formation, and high energy consumption. The chapter then introduces oxidative dehydrogenation (ODH) as a potentially more attractive alternative, emphasizing its potential to overcome the limitations of traditional methods. However, it also acknowledges the challenges associated with ODH, primarily concerning selectivity control and the risk of over-oxidation leading to the formation of undesirable carbon oxides. The chapter lays the groundwork for the study by outlining the need for effective catalytic systems to address these challenges and improve the efficiency and cost-effectiveness of olefin production.
2. Experimental: This chapter details the experimental procedures employed in the study. It describes the materials used, including the source and purity of chemicals like tetraethyl orthosilicate (TEOS), ethanol, and the propane-butane fraction. The preparation of the catalysts, involving wet impregnation and calcination, is explained in detail, along with the specific procedures for preparing mono-metallic (Cr/SiO2 and Mo/SiO2) and bi-metallic (Cr-Mo/SiO2) catalysts. The chapter also outlines the catalyst treatment methods (calcination and reduction) and the experimental setup used for the oxidative dehydrogenation tests, including the continuous flow quartz fixed-bed reactor, the reactant flow rates, and the analysis techniques used for gas product samples. Specific details are provided on the decoking process and the purpose of nitrogen purging to ensure safety and reproducibility. The chapter concludes by describing the experimental design for evaluating the performance of different catalysts.
Frequently Asked Questions: Oxidative Dehydrogenation of C3-C4 Fraction
What is the main objective of this study?
This study investigated the oxidative dehydrogenation (ODH) of a propane-butane (C3-C4) fraction over mono- and bi-metallic catalysts supported on SiO2 to optimize olefin production. The research focused on the effects of different catalyst compositions (Cr, Mo, and Cr-Mo) on catalytic activity, selectivity, and overall olefin yield.
What are the key themes explored in this research?
Key themes include: oxidative dehydrogenation of C3-C4 for olefin production; catalyst design and synthesis using Cr, Mo, and Cr-Mo on SiO2; the impact of catalyst composition on catalytic activity and selectivity; optimization of reaction parameters (temperature, GHSV) for maximizing olefin yield; and mitigation of coke formation and catalyst deactivation.
What are the traditional methods for olefin production, and what are their drawbacks?
Traditional methods like steam cracking and fluid catalytic cracking are discussed. Their drawbacks include thermodynamic limitations, coke formation, and high energy consumption. Oxidative dehydrogenation (ODH) is presented as a potentially more attractive alternative due to its potential to overcome these limitations.
What are the challenges associated with oxidative dehydrogenation (ODH)?
The challenges associated with ODH include selectivity control and the risk of over-oxidation, leading to the formation of undesirable carbon oxides. Effective catalytic systems are needed to address these challenges and improve the efficiency and cost-effectiveness of olefin production.
What materials and methods were used in the experimental section?
The experimental section details the materials used (tetraethyl orthosilicate (TEOS), ethanol, propane-butane fraction), catalyst preparation (wet impregnation and calcination) for mono-metallic (Cr/SiO2 and Mo/SiO2) and bi-metallic (Cr-Mo/SiO2) catalysts, catalyst treatment methods (calcination and reduction), the experimental setup (continuous flow quartz fixed-bed reactor), reactant flow rates, and gas product analysis techniques. The decoking process and nitrogen purging are also described.
What is the structure of the report?
The report includes an introduction, an experimental section detailing materials, methods, and catalyst preparation, and chapter summaries providing a detailed overview of the findings. A table of contents is provided for easy navigation.
What are the key words associated with this study?
Key words would include: Oxidative Dehydrogenation, Olefins, Propane, Butane, Catalyst, Chromium, Molybdenum, SiO2, Catalytic Activity, Selectivity, Yield, Coke Formation, Reaction Optimization.
- Quote paper
- Ayodeji Ijagbuji (Author), I. I. Zakharov (Author), T. C. Philips (Author), M. G. Loriya (Author), M. B. Saltzberg (Author), A. B. Tselishtev (Author), R. J. Taylor (Author), B.V. Shevchenko (Author), K. M. Jackson (Author), D. B. Woods (Author), J. K. Johnson (Author), 2015, Production of olefins via oxidative de-hydrogenation of C3‒C4 fraction by O2 over (Cr‒Mo)SiO2, Munich, GRIN Verlag, https://www.grin.com/document/292808
