Sulfur in fuels is a major environmental problem, contributing to air pollution and acid rain when burned. To address this, scientists are constantly looking for better ways to remove sulfur from fossil fuels. One promising approach is to use specially designed materials called mesoporous catalysts. These catalysts are like tiny sponges with lots of holes that help them trap and convert sulfur compounds into harmless substances. This new research focuses on improving the efficiency of these catalysts, making the process cleaner and more efficient than ever before.
Researchers have developed innovative mesoporous catalysts that significantly enhance the hydrodesulfurization (HDS) of thiophene, a sulfur-containing compound found in crude oil. The team, led by Professor Antonio Araujo together with Professor Marcio Araujo, Dr. Jilliano Silva, and Professor Valter Fernandes Jr. from the Federal University of Rio Grande do Norte; Dr. Ana Coutinho from the Federal University of Fluminense; Professor Joana Barros from the Federal University of Campina Grande; Dr. Marcelo Souza from the Federal University of Sergipe; and Regina Delgado from the Federal Rural University of the Semiarid, published their findings in the journal Catalysts.
Hydrodesulfurization is a crucial process in modern refineries, which aims to reduce the sulfur content in fossil fuels to meet stringent environmental regulations. The research focused on the development of catalysts containing cobalt and molybdenum supported on mesoporous materials, specifically SBA-15 and AlSBA-15. These materials are known for their high specific surface area and large pore diameter, which enhance the dispersion of active metals and improve access to sulfur compounds during the HDS process.
Professor Araujo and his team synthesized the catalysts using a hydrothermal method, followed by coimpregnation with cobalt nitrate and ammonium heptamolybdate. The resulting CoMo/SBA-15 and CoMo/AlSBA-15 catalysts were characterized by various techniques, including X-ray diffraction (XRD), thermogravimetric analysis (TG/TGA), and scanning electron microscopy (SEM). XRD analysis confirmed the presence of MoO3Co3Oh4and CoMoO4 oxides, which are active in HDS reactions.
In laboratory tests, these catalysts demonstrated impressive activity for the hydrodesulfurization of thiophene in an n-heptane stream, yielding mainly cis- and trans-2-butene, 1-butene, n-butane, and minor amounts of isobutane. Notably, the presence of undesirable byproducts such as 1,3-butadiene and tetrahydrothiophene was not detected. The researchers proposed a reaction mechanism involving desulfurization, hydrogenation, dehydrogenation, and isomerization steps to explain the observed product distribution.
The significant findings of the study highlight the advantages of using mesoporous materials as supports for HDS catalysts. “The high specific surface area and pore structure of SBA-15 and AlSBA-15 are critical to maximizing metal dispersion and improving the efficiency of hydrodesulfurization processes,” said Professor Araujo. These catalysts showed potential for producing ultra-low sulfur fuels, which are essential for reducing SOx emissions and meeting environmental standards.
The researchers highlight the need for further research into the modification of mesoporous supports and optimization of metal loading to improve the performance of HDS catalysts. They also suggest exploring the use of other mesoporous materials and mixed metal oxides to further improve desulfurization efficiency and selectivity.
This study represents a promising step towards more efficient and environmentally friendly hydrodesulfurization processes, which will contribute to cleaner fuel production and reduced air pollution. Professor Araujo and his colleagues are optimistic about the future applications of their findings, with the aim of revolutionizing the fuel industry with greener and more efficient desulfurization technologies.
Journal reference
Coutinho, ACSLS; Barros, JMF; Araujo, MDS; Silva, JB; Souza, MJB; Delgado, RCOB; Fernandes Jr., VJ; Araujo, AS Hydrodesulfurization of thiophene in n-heptane stream using mesoporous catalysts CoMo/SBA-15 and CoMo/AlSBA-15. Catalysts 2024, 14, 198. DOI: https://doi.org/10.3390/catal14030198
About the authors
Institute of Chemistry, Federal University of Rio Grande do Norte, Brazil
Antonio S. Araujo He received his PhD in Inorganic Chemistry from the University of Sao Paulo (Brazil). He was a visiting scientist and postdoctoral fellow at Kent State University. As a postdoctoral researcher at KSU, he was involved in the synthesis, characterization and acidic properties of zeolites and mesoporous silica-based materials. His research interest is pyrolysis, kinetics and thermal analysis of catalytic degradation of heavy oil, petroleum residues and plastic waste, using zeolites and micro-mesoporous hybrid materials as catalysts, with a focus on fuel production and the environment. Prof. Araujo is a full professor at the Institute of Chemistry and a researcher at the National Council for Scientific and Technological Development of Brazil (Brazil) and was cited in the book “Who is Who in Thermal Analysis and Calorimetry” and in “Verified Synthesis of Zeolitic Materials” edited by IZA. He is also an ad hoc consultant for the ACS – Petroleum Research Fund. Professor Araujo has published more than 200 peer-reviewed articles with over 4000 citations, six patents, with an H-index of 34 and more than 20 invited lectures at conferences.
Institute of Chemistry, Federal University of Rio Grande do Norte, Brazil
Valter J. Fernandes He holds a PhD in Analytical Chemistry from the University of São Paulo, a Postdoc in Environmental Chemistry from INPE, and is a Full Professor at the Institute of Chemistry at UFRN. He is Coordinator of the Fuels and Lubricants Laboratory at UFRN – executor of the Fuels Research and Quality Program of the National Petroleum Agency in the state of RN. He is Pro-Rector of Research at UFRN from 05/2011 to 08/2016. He has been a researcher at CNPq since 1993. He is a Scientific Consultant for FINEP, FAPESP, NSF-National Science Foundation and CNPq, among others. He is Coordinator of the North/Northeast Network of Fuel Laboratories, a permanent professor at the Graduate Programs in Chemistry and Materials Science and Engineering at UFRN, with 37 completed master’s and doctoral degrees. Author of 155 articles in indexed scientific journals (H index = 25), and 4 patents for industrial application with a patent letter granted by the INPI. His main lines of research are: Application of nanostructured materials for tertiary recycling of polymers. Development of analytical methods for fuels, biofuels and petroleum. Evaluation and characterization of additives for fuels and biofuels.
Photographs from Araujo's laboratory
The Fuels and Lubricants Laboratory (LCL) and the Catalysis and Petrochemistry Laboratory are linked to the Graduate Program in Chemistry of the Institute of Chemistry of the Federal University of Rio Grande do Norte (IQ/UFRN). These laboratories work directly in the areas of petroleum and petrochemistry, aiming at the physical-chemical characterization of petroleum and derivatives, with the objective of improving the quality of automotive fuels, in addition to developing analytical methodologies for the processing of petroleum and industrial waste.
LCL coordinates one of the most important programs in Brazil in the fuel area, which is the Fuel Quality Monitoring Program (PMQC), which is regulated by the National Agency of Petroleum, Natural Gas and Biofuels (ANP). In this program, LCL collects samples of automotive fuels in the states of RN and PB and certifies their quality, providing an important service to society.
The LCP conducts research into the development of micro and mesoporous catalysts for application in petroleum and petrochemical industry processes, with the aim of improving the quality of automotive fuels. Research topics include the removal of sulfur contaminants from fuels, the use of catalytic methods for the processing of oil industry waste (atmospheric waste, oily sludge and vacuum gas oil) and the co-processing of polymers, with the aim of their chemical recycling to obtain liquid fuels, using thermal and catalytic pyrolysis methods. The studies are carried out with thermal analysis equipment and a pyrolyzer coupled to chromatography and mass spectrometry.
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