Researchers at Khalifa University’s Center for Catalysis and Separations (CeCaS) have been granted two patents for their work on the effect of magnetic fields on separating mixtures and detecting gases.��

Gas separation is a process used across myriad disciplines and industries, with use cases ranging from purifying natural gas and removing carbon dioxide to producing oxygen for medical use and nitrogen for chemical feedstocks. There are various ways of separating gases in a mixture, including absorption, distillation, and membrane separation.��

The research was initiated in collaboration with the Abu Dhabi National Oil Company (ADNOC) and continues under the umbrella of the CaCaS center of KU in collaboration with the Demokritos National Research Center in Greece.��

“Sorption and desorption are typically controlled by swings in temperature or pressure, or both in combination,” Dr. Karanikolos said. “In our technology, a magnetic field swing is introduced. By switching the magnetic field on and off, gas is absorbed and desorbed without externally changing temperature or pressure, which is a great novelty in this area.”

Examples of application of gas separation are the removal of carbon dioxide from steam methane reforming gas mixtures and as the final step in the large-scale commercial production of hydrogen, which is important for the production of ammonia. Air separation is carried out to produce pure oxygen, while oil refineries and gas processing plants apply separation technologies in hydrocarbon fractionation and in the removal of hydrogen sulfide, a toxic byproduct of certain refinery processes.��

However, gas separation processes typically require generating high temperatures for heat-assisted absorbent regeneration, pumping liquid absorbents between absorption towers and regeneration towers, processing and handling of byproducts, repairing absorbent leakage problems, and replenishing the lost absorbent. In addition to being energy intensive, these processes contribute significantly to the operational cost of a gas separation process, according to Dr. Karanikolos. Gas separation processes with lower energy requirements and lower operational costs would be a substantial advancement in this area.��

“Conventional gas separation processes have high energy requirements,” Dr. Karanikolos said. “Magnetic swing absorption can be far less energy consuming, particularly if the magnetic field used in these cycles is generated by permanent magnetic assemblies. In order to turn the field on or off, these permanent magnets can either be mechanically added to or removed from the absorption cell, or simply switched on and off if they have a permanent magnet switch.”

In this method, a gas mixture is introduced to a magnetic field – responsive liquid and a magnetic field is applied. One of the gases is absorbed into the liquid, effectively separating the gas mixture. Once the non-absorbed gas is purged from the system, the magnetic field is removed or switched off, and the absorbed gas releases.��

Dr. Karanikolos was also awarded a patent for his work on a smart gas sensor to detect impurities and analyze gas mixtures. His technology provides an easy way of measuring gas sorption selectivity: the ratio of adsorbed amounts of two gases being simultaneously adsorbed to the same sample, and can also operate as a gas sensor under certain conditions.��

“Gravimetric microbalance is commonly used to measure the amount of adsorbed gas on sorbent materials,” Dr. Karanikolos said. “Our invention offers a low-cost gas sensing and measuring device, using a modified gravimetric microbalance, in which the hanging sample holder is located in a space where a magnetic field can be turned on and off. This allows us to measure the ratio of adsorbed gases that are simultaneously adsorbed to the same sorbent surface so we can calculate the real adsorbent selectivity.”

This new device and sensor is low-cost and rapid, replacing conventional chromatographic techniques for fast and easy continuous monitoring of gas concentration. It offers a single-step solution to gas analysis and can also measure magnetic susceptibility of the gases in a mixture.

Jade Sterling
Science Writer
1 June 2022

The post Research on Use of Magnetic Fields for Gas Separation and Gas Mixture Analysis Yields Two Patents appeared first on Khalifa University.

International research team including Khalifa University paves way towards the design of new simple and efficient photocatalysts made from covalent organic frameworks (COFs) to reduce captured CO2 into useful products

As the world continues to pump carbon into the atmosphere, it is increasingly important to not only reduce emissions but also find ways to capture and use carbon dioxide. Carbon capture and storage technologies are noble approaches, but don’t tend to make much money. Instead, attention turns to economically viable and valuable approaches to turn carbon dioxide into something useful.

Dr. Dinesh Shetty, Assistant Professor of Chemistry, and Dr. Abdul Khayum Mohammed, Postdoctoral Researcher, collaborated with an international team to develop a new photocatalyst to efficiently and sustainably transform carbon dioxide into useful products. The research team comprised members from New York University Abu Dhabi, American University of Beirut, Instituto de Ciencia de Materiales de Madrid, Spain, University of Strasbourg, France, and University of Nova Gorica, Slovenia. The team’s results were published in

“Excessive anthropogenic emissions of carbon dioxide into the atmosphere have led to global warming,” Dr. Shetty explained. “At the same time, CO2 is a nontoxic, inexpensive, abundant, and renewable source of carbon. Converting it into high value-added products would be a viable and economic use of the carbon dioxide around us.”

Numerous processes already exist to transform CO2 emissions into various chemicals valuable for industry, and among these processes, photocatalytic reduction of CO2 has been noted as particularly promising. There’s little wonder why: this is photosynthesis. Green plants convert carbon dioxide and water into carbohydrates, performing this reaction under ambient conditions using just sunlight, which is an inexhaustible and environmentally-friendly energy source. Even better, photocatalytic CO2 reduction doesn’t create any secondary pollution.

“Carbon dioxide can be reduced into many forms, with carbon monoxide and formate the most common reduction products,” Dr. Shetty said. “Formate is preferred as it is the simplest oxygenated species produced, and an intermediate in the formation of methanol and other higher-order hydrocarbons, which can be used in plastics, paints, organic solvents, and fuel cells.”

Photocatalytic reduction of CO2 is not new—many semiconductor and molecular-based systems have been studied. However, their limited conversion efficiency, low binding affinity for CO2, unfavorable active-site architecture, and rapid charge recombination limit their overall performance. Covalent organic frameworks (COFs), such as that developed by the research team, have the potential to address many of these issues.

COFs are a class of materials that form two- or three-dimensional structures through reactions between their organic components, resulting in strong, covalent bonds that create porous, crystalline materials. They are uniquely tunable, with well-defined structures and good chemical stability and plenty of pores for adsorption applications.

Capturing the CO2 is the first step. A sorbent material is needed to selectively grab the carbon dioxide and allow it to collect in the pores in the material. And COFs for CO2 reduction already exist, but the majority produce carbon monoxide as their product, which is the less desirable of the two common products. Those that do produce formate often involve expensive noble metals or even enzymes.

The research team synthesized a novel COF using two different building units known as porphyrins and isoindigo to ensure the captured carbon dioxide reduces into formate, not carbon monoxide. Their PI-COF has a square layered structure and an improved affinity for carbon dioxide adsorption. Even without expensive rare materials or special catalysts, the research team’s PI-COF reduced carbon dioxide into formate with yields comparable to more complex systems.

“Our system performs similarly to others but requires much less power, making it a much more environmentally-friendly system,” Dr. Shetty said. “We expect this to pave the way towards more sustainable yet equally efficient photocatalytic systems for CO2 reduction.” Currently, Dr. Shetty’s team at KU is working on economically viable COF-based photoconducting materials for CO2 conversion.

Dr. Shetty is also a member of the Center for Catalysis and Separation (CeCaS), one of the research centers at KU.

Jade Sterling
Science Writer
4 February 2022

The post A Unique Photocatalyst Could Turn the CO2 in the Atmosphere into Useful and Valuable Products appeared first on Khalifa University.

Dr. Kyriaki Polychronopoulou, Professor of Mechanical Engineering and Director of the Center for Catalysis and Separations (CeCaS) at Khalifa University, and her research group have recently authored a paper on dry reforming of methane that was published in the prestigious journal , with an impact factor of 19.5 (Elsevier, Q1).

The KU research group was led by Dr. Polychronopoulou ��and included Aseel Hussien, PhD Student, Dr. Aasif Dabbawala, Postdoctoral Fellow and co-advisors Dr. Maryam Khaleel, Assistant Professor of Chemical Engineering, and Dr. Dalaver Anjum, Assistant Professor of Physics. This work was the result of a fruitful collaboration with the University of Cyprus team led by Prof. A.M. Efstathiou.��

The paper, titled ��ݮ��Ƶ the different effects of the presence of dopants such as La³⁺ and Sm³⁺ heteroatoms in the performance of a Ni catalytic system towards the dry reforming of methane (DRM) reaction.

Emphasis is given on the carbon deposition and their removal reaction paths in the dry reforming of methane (DRM) at mid-high temperature (750��°C) utilizing transient kinetic and isotopic experiments.

Coke deposition is the most critical challenge for DRM reaction and the bottleneck for its industrialization.

The role of lattice oxygen is highlighted, especially when it comes to the deposited carbon oxidation by lattice oxygen of support and that by oxygen derived from CO2 dissociation under DRM reaction conditions; both rates were quantified.

Ni nanoparticles (23-nm) supported on La³⁺-doped catalyst exhibited at least 3 times higher initial rates of cleaning the surface through carbon oxidation to CO by lattice oxygen, and ~ 13 times lower rates of carbon accumulation than Ni (18-nm) supported on Sm³⁺-doped catalyst.

The concentration and mobility of labile surface oxygen at the Ni-support interface region seems to correlate with carbon accumulation.

Another important finding was the in situ formation of Ni-Cu nano-alloy as Cu from the support was found to diffuse under reaction conditions to the metal-support interface and being alloyed with Ni. This was found to be partly responsible for lowering carbon deposition and increasing carbon oxidation rates to CO.

The post Dry reforming of methane research published in Applied Catalysis B: Environmental appeared first on Khalifa University.

Dr. Kyriaki Polychronopoulou, Professor of Mechanical Engineering and Director of the Center for Catalysis and Separations (CeCaS) at Khalifa University, and her research group successfully participated in the Materials Research Society (MRS) Fall 2021 Meeting in Boston, Massachusetts, USA, which was held from 29 November till 2 December 2021.

The MRS conference is an international platform for materials research that brings together researchers from fields of chemistry, biology, physics, and engineering. Among the eminent keynote speakers at the conference was Sir Fraser Stoddart, 2016 Nobel Prize in Chemistry.

The work of two KU PhD students from CeCAS was presented in the conference. ��Ayesha Alkhoori presented her research on developing catalysts for CO₂ conversion to fuels. Her talk was titled “Development of Composite Dual Functional Catalysts and Mechanistic Insights for CO₂ Methanation Reaction.” This research investigated Ni-based catalysts with composite supports which were thoroughly studied in terms of their physicochemical properties as well as the reaction mechanistic pathways. The latter is focused on understanding the reaction mechanism of CO₂ hydrogenation using Operando SSITKA-DRIFTS technique. Understanding the governing mechanism is a key to the rational design of highly efficient catalysts.

Aseel Hussien delivered a presentation on her work titled “Elucidating the role of dopants in the carbon paths of dry reforming of methane over Ni catalysts using transient kinetics and isotopic techniques.” Her fundamental work elucidates the carbon formation pathways under realistic reaction conditions. In particular, emphasis is given to decouple the contribution of CO₂ and CH₄ decomposition on the surface of the catalyst and the relative contribution of each reaction towards coke deposition on the catalyst surface. Coke deposition is one of the main challenges of the dry reforming of methane reaction and the bottleneck of its industrialization. ��

The post CeCAS Researchers share CO2 Conversion and Dry Reforming of Methane at MRS Fall 2021 appeared first on Khalifa University.

Agreement Paves Way for Advancing Innovation in the Abu Dhabi Oil and Gas Sector ��

Khalifa University of Science and Technology and the Abu Dhabi National Oil Company (ADNOC) announced they have signed a research and development framework agreement for undertaking a joint research and development program that will advance innovation in the oil and gas sector in the areas of strategic importance to ADNOC.��

The agreement was signed by Dr. Arif Sultan Al Hammadi, Executive Vice-President, Khalifa University, and Abdulmunim Saif Al Kindy, Executive Director, People, Technology & Corporate Support Directorate, ADNOC, on the sidelines of the Abu Dhabi International Petroleum Exhibition and Conference (ADIPEC) 2021 that was held from 15-18 November at the Abu Dhabi National Exhibition Center (ADNEC).��

According to the agreement, a research and development board will be established with particular focus on upstream, downstream and digital solutions for the oil and gas industry and will have members from both partners. Khalifa University’s members are Dr. Steve Griffiths, Senior Vice-President, Research and Development; Dr. Saeed Alhassan, Senior Director, Petroleum Institute; and Dr. Ernesto Damiani, Senior Director, Robotics and Intelligent Systems Institute.��

Khalifa University’s Petroleum Institute is home to the Center of Catalysis and Separation (CeCaS) and the Research and Innovation Center on CO2 and H2 (RICH Center). The two research centers, along with other research undertaken at the Petroleum Institute and elsewhere at Khalifa University, contribute to technology innovations in areas such as hydrogen, carbon capture, catalysis and enhanced oil recovery. Khalifa University’s Robotics and Intelligent Systems Institute provides a broad spectrum of intelligent systems capabilities that can be tailored to the needs of the oil and gas sector.

Clarence Michael
English Editor Specialist
9 December 2021

The post Khalifa University and ADNOC Sign R&D Framework Agreement to Undertake Research and Development Program appeared first on Khalifa University.

Understanding the role of the surfaces and internal structure of the nanocrystal will help researchers develop more effective and efficient catalysts for many important catalytic processes.��

A catalyst is a substance that can be added to a reaction to increase the reaction rate without being consumed in the process. They typically speed up the reaction by reducing the energy needed to activate the reaction or by changing the mechanism by which the reaction occurs. Catalysis is one of the pillars of the chemical industry, so developing effective and efficient catalysts for a wide range of uses is crucial.

Prof. Kyriaki Polychronopoulou, Professor of Mechanical Engineering and Director of the Khalifa University Center of Catalysis and Separation (CeCaS), used an advanced form of imaging to analyze the structure and electronic properties of an engineered nanoparticle that is considered one of the emerging candidates for use in catalysis.

With Dr. Yasser Al Wahedi, Assistant Professor, Dr. Vijay Wadi, Research Scientist, Xinnan Lu, and Marios Katsiotis, all from Khalifa University, the findings were published in. The Khalifa University team collaborated with researchers from Stockholm University in Sweden, the Greek National Center for Scientific Research, and the Korean Electron Microscopy Research Center.

This research was also selected by the editors at Nature Communications to be featured in an Editors’ Highlights webpage of recent research called ‘Materials science and chemistry.’ The Editors’ Highlights pages showcase the 50 best papers recently published in a particular area of science.

“Nanocrystalline materials have been a hot research topic thanks to their use in many important applications from catalysis, to energy conversion and storage, and drug delivery,” Prof. Polychronopoulou said.

This is particularly useful in catalysis, as scaling down the particle size increases the number of sites available for the reactions to take place, but also modifies the material’s electronic properties. Additionally, catalytic reactivity and selectivity can be enhanced by modifying the arrangement of the surface atoms.

The crystals in these materials must be grown through chemical reactions to create the desired structures, with the atoms, molecules and ions assembling into a crystal structure one after another on the growth surface. Once created, these materials are approximately half crystal and half interface, ready for use in many applications. For Prof. Polychronopoulou, that use is catalysis.����

.

However, the stability of Ni2P nanocrystals depends on their experimental synthesis conditions, and this dependence is not well understood. Prof. Polychronopoulou’s research found that when there is excess phosphorous during the synthesis, the nanoparticles come out with hexagonal rod-like shapes.

The underlying symmetry of the resulting crystals can be seen in the facets that appear on the surface. Facets are flat surfaces on geometric shapes: think of gemstones, which commonly have facets cut into them to improve their appearance by allowing them to reflect light. In grown crystals, the facets are a consequence of the material and the surface energy, as well as the general conditions under which the crystal formed.

An inherent challenge in using any material for catalysis is how to access the catalytic sites generally confined inside the structure. In producing Ni2P crystals, Prof. Polychronopoulou’s research combined chemistry with calculations to define the reaction parameters to grow the ideal crystal with the predicted facets and electronic structure.

“It is extremely difficult to manufacture nanostructured materials,” Prof. Polychronopoulou said. “Using advanced calculations, we predicted the structure of the crystals and experimentally verified the crystal facets and structure using nanocrystallography.”

Nanocrystallography is a technique used to analyze the diffraction patterns of a crystal targeted by a beam of electrons. After studying the nickel phosphide nanocrystals that Prof. Polychronopoulou grew using nanocrystallography, her team found that the nanocrystals comprised a variety of surfaces, with three primary facets exposed.

The team then used another advanced technique, known as solid-state nuclear magnetic resonance imaging, to probe the nanocrystal further and determine the distinct surface facets, while also experimentally proving that their calculations and predictions were correct.

Solid-state nuclear magnetic resonance spectroscopy is an atomic-level method to determine chemical structure, 3D structure, and dynamics of solids. It is sensitive to the structure and electronic environment at the atomic scale, and is able to distinguish between the surface facets and the interior of the nanoparticles.

“This is the first time that facet analysis of a transition metal nano-sized catalyst and the relevant electronic changes were experimentally verified, demonstrating that solid-state nuclear magnetic resonance nanocrystallography is an emerging tool in the study of metal nanocatalysts,” Prof. Polychronopoulou said.��

Jade Sterling
Science Writer
23 September 2021

The post Looking Inside Nanocrystals with Advanced Imaging Techniques to Create New Catalysts appeared first on Khalifa University.

KU Researcher worked with NYUAD to create the first woven calixarene-based covalent organic framework (COF) with plenty of tunable pores for adsorption applications

Synthetic dyes are common ingredients in the textile industry, but because of their general use, they often find their way into waterbodies from industrial wastewater, where they pollute the water and threaten water security.

Removing these polluting dyes can be achieved through adsorption, where the dyes are collected in the pores of highly porous materials that scoop the pollutants from water and trap them in the pores.

Dr. Dinesh Shetty, Assistant Professor of Chemistry, has created a tunable, two-dimensional polymeric network from an organic macrocycle called calixarenes that can selectively adsorb toxic dyes from wastewater.

Dr. Shetty is a member of the Khalifa University Center for Catalysis and Separation (CeCaS), one of KU’s 18 specialized research centers. CeCaS research aims at developing practical solutions to chemical engineering challenges faced by several industries today. In collaboration with researchers from New York University Abu Dhabi, Dr. Shetty has developed a novel structure using calixarenes to remove dyes selectively and efficiently from wastewater. Their work was recently published in the and appeared as a cover article.

Calixarenes are bowl-shaped organic molecules that consist of defined hydrophobic cavities. This unique feature allows host-guest chemistry where calixarenes play the host for small molecules and/or ions.

“Calixarene molecules have been extensively exploited as versatile supramolecular building blocks,” explained Dr. Shetty. “This is due to their ability to adopt different conformations, which refers to the spatial arrangement of atoms in a molecule, and the relative ease with which they can be functionalized, which refers to how easily a calixarene can take on new functions, features, capabilities, or properties by changing its surface chemistry.”

This is particularly true of calixarenes where the ring consists of four aromatic rings. Calixarenes work as excellent adsorbers, but in the monomer form, they can be dissolved in some solvents, which would hinder their practical use.

In a macroscopic architecture, however, calixarenes become insoluble in almost every solvent, especially in water.

To create calixarenes with a macroscopic architecture, Dr. Shetty and his team turned to covalent organic frameworks, or COFs. COFs are a class of materials that form two- or three-dimensional structures through reactions between their organic components, resulting in strong, covalent bonds that create porous, crystalline materials.����

“COFs have proven to be an important class of porous materials on account of their well-defined structures, tuneable pore functionality, and good chemical stability,” explained Dr. Shetty.

Giving calixarenes a macroscopic architecture is very challenging but if successful could allow them to be incorporated into practical platforms such as powders in cartridges or membranes.

While few researchers have attempted to build COFs with multiple ringed, or macrocyclic molecules, like calixarenes, Dr. Shetty’s team realized that a calixarene-based COF would be an ideal way to remove toxic dyes from industrial wastewater.

Dr. Shetty, along with Trabolsi research group at NYUAD, developed the first woven structures of calixarene-based COFs, making a 2D network that can be delicately tuned for each application. They joined calixarenes by creating covalent bonds between the organic molecules to link them together, then these calixarene chains were interwoven by slotting one calixarene into the bowl-shape of another, effectively stacking the chains.

The synthesized COFs showed well-defined lattice structures, indicating a highly crystalline nature for both COFs, with plenty of pores for adsorption applications. By varying the concentration of calixarene units in the solution, the stacking orientation in the COFs can be altered, meaning researchers can create both interpenetrated (meaning catenated) and non-interpenetrated frameworks. The resulting COFs featured wavy layers containing the calixarene cavities, making them attractive candidates for adsorbing small molecules.

The researchers validated the materials ability by using them for selective removal of cationic-dyes from aqueous mixtures.

Importantly, creating a structure with organized pores increases the number of molecular interactions between pollutant molecules and adsorbent. Interestingly, the COFs developed by the research team were exceptionally selective for the cationic dyes in the test mixtures without depending on the size of the molecules. The COFs also demonstrated a highly negative surface charge, allowing charge-selective removal of the dye molecules.

“With the inherently hydrophobic cavity, anionic surface, and possibility to develop these COFs in a membrane, our work has the potential to bring calixarene chemistry to an exciting materials science horizon,” said Dr. Shetty.

Jade Sterling
Science Writer
20 April 2021

The post A Tunable 2D Covalent Network for Charge-selective Removal of Toxic Dyes from Wastewater appeared first on Khalifa University.

Removing paraquat from agricultural wastewater is crucial to protecting the environment and human health but conventional materials to do so are slow-acting and not reusable. Dr. Dinesh Shetty at KU has developed a novel polymer to adsorb paraquat much more efficiently.��

Read Arabic story here:

Water quality is influenced by many natural factors but the greatest threat comes from human activity. Mining, urban development, and agriculture are among the biggest culprits, introducing pollutants into the waterways from various processes. If they enter drinking water sources, they can pose a significant threat to human health.

Paraquat is a toxic chemical that is widely used as a herbicide to control unwanted weeds and grasses that grow alongside crops. Paraquat is quick-acting and non-selective, and dangerous to humans, having been banned in several countries due to its neurodegenerative effects and toxicity. Despite this, it is still one of the most commonly used herbicides worldwide.

As world population rises, the use of pesticides and herbicides for crop protection is expected to increase. Because intensive farming methods continue to rely heavily on chemicals, the levels of persistent herbicides and pesticides prevalent in the environment will remain at dangerous levels.

Removing paraquat from agricultural wastewater is therefore crucial to protecting the environment and human health, while also supporting food security. Conventional efforts to filter out paraquat rely on materials made from clays, silica, resins and hybrid materials. However, these materials are slow-acting and not easily reusable, prompting research into new materials.

Now, Dr. Dinesh Shetty, Assistant Professor of Chemistry at Khalifa University, along with the Trabolsi research group at New York University Abu Dhabi, has developed a novel polymer that can adsorb paraquat from water more efficiently than traditional materials.

The researchers developed polycalixarenes, with multi-ring (or macrocycle) molecules that have hydrophobic cavities – areas that repel water – that can hold smaller molecules or ions. These polycalixarenes act as the adsorbants as a polycalixarene has a three-dimensional porous structure that is totally insoluble in water but selectively extracts toxic paraquat molecules. This unique quality allowed the researchers to utilize different analogs of calixarenes with increasing cavity sizes. The larger the cavity size, the more strongly the paraquat can bind to the cavity and eventually be removed. Importantly, the polymers can be easily reused by simple washing methods and still outperform commercial activated carbon currently in use.

“Because of the selective host-guest chemistry these calixarene molecules offer, they can form complexes with paraquat in water,” explained Dr. Shetty. “They outperformed not only other organic polymers, but also the activated carbon, zeolites, and various types of clay that have been used previously. They are also easy to recycle, meaning we can use our polymers repeatedly without a significant loss in adsorption efficiency.”

Dr. Shetty has also applied this technology to removing other toxic substances from water, including perfluorooctanoic acid (PFOA). PFOA is another nonbiodegradable and persistent pollutant which can accumulate in water resources and pose serious environmental issues in many parts of the world.��

Dr. Shetty is a member of the Khalifa University Center for Catalysis and Separation (CeCaS), one of KU’s 18 specialized research centers. CeCaS research aims at developing practical solutions to chemical engineering challenges faced by a number of industries today.

Jade Sterling
Science Writer
2 November 2020

The post Removing Toxic Herbicides from Water Using New Synthesized Porous Polymers appeared first on Khalifa University.

Researchers from Khalifa University have developed a simple method to produce catalysts more efficiently and precisely, which could help accelerate the development of super effective catalysts for numerous industries.

A team of researchers led by Dr. Yasser Al Wahedi, Assistant Professor of Chemical Engineering at Khalifa University and a member of the Center for Catalysis and Separations (CeCaS), and Dr. Georgia Basina, Post-Doctoral Fellow in the same department, have developed a new way of making catalysts that is more precise and effective. This simple and effective method involves embedding nanoparticles in a material dotted with ultra-small pores, known as the ‘NEMMs’ approach. The team recently published their work in.

A catalyst is a substance that can be added to a reaction to increase the reaction rate without being consumed in the process. They typically speed up a reaction by reducing the energy needed to activate the process by providing an alternate reaction pathway.

Heterogeneous catalysts, commonly used in the oil and gas industries, are catalysts that exist in a different state than the reactants—for example, the catalyst may be in a solid state, while the reactants are liquid or gas.

“Heterogeneous catalysts are crucial in many industries such as oil, gas, petrochemicals, and pharmaceuticals,” explained Dr. Al Wahedi. “A typical heterogeneous catalyst is composed of an active phase, which performs the catalytic function, and a support which enhances the active phase and its stability.”

One such example is the catalytic converter in a gasoline or diesel-fueled car. Transition metal catalysts are embedded on a solid phase support, which comes into contact with gases from the car’s exhaust stream, increasing the rate of reactions to produce fewer toxic products from pollutants in this exhaust stream. The catalytic converter is also an example of surface catalysis, where the reactant molecules are adsorbed onto a solid surface before they react with the catalyst. The rate of a surface-catalyzed reaction increases with the surface area of catalyst in contact with the reactants, and so the solid support is designed to have a very high surface area with a porous structure and honeycomb-like appearance.

“Typically, the support structure accounts for 60 to 99 percent of the weight of the total catalyst, while its role is limited to stabilizing the active component nanoparticles,” said Dr. Al Wahedi. “To enhance the catalytic performance, we need to increase the amount of active component in the structure, while keeping particle size and state optimal.”

Conventional methods to prepare catalysts often start with the support structure and then introduce the active ingredient via insertion methods such as impregnation, chemical vapor deposition or ion exchange. When manufacturers want to increase the amount of the active ingredient using these methods, it often results in poor dispersions, or a lack of control over the size of the ingredient particles.

“To overcome this issue, we can encapsulate the active nanoparticles in a mesoporous matrix comprised of the supporting material to produce a structure we term the NEMMs,” explained Dr. Basina. “This approach allows us to develop catalysts with high active component loadings while keeping the size optimal for efficient catalysis.”

The NEMMs approach involves growing a porous support material around nanoparticles of the active ingredient. They use nanoparticles that are the perfect size to serve as nucleation centers, around which a mesoporous silicon oxide (a material containing pores with diameters between 2 and 50 nanometres) matrix grows. The approach also uses surfactant molecules to create a ‘crown’ around the active component particles, which is removed after the matrix has been grown in order to leave an empty space between the active component and the mesoporous material. It is in this empty space that the catalysis reactants can be adsorbed.

The research team tested their catalyst on the selective oxidation of hydrogen sulphide, an important industrial reaction whereby toxic hydrogen sulphide is oxidized to produce sulphur.

“Our approach circumvents the limitations rooted in conventional catalyst design by allowing complete independent control over the active component nanoparticle shapes and size,” said Dr. Al Wahedi. “ We have investigated this approach on the selective oxidation of H2S reaction (commercially denoted as SuperClausTM). Compared with previous studies, our catalysts achieve near complete conversions and more than 95 percent selectivity at a fraction of the catalyst mass required.”

The ease of this synthesis method and the stability and efficiency of the resulting catalyst promise a wide spectrum of applications beyond the selective oxidation of hydrogen sulphide in myriad industries.

Jade Sterling
Science Writer
29 September 2020

The post Turning Catalyst Production Inside Out appeared first on Khalifa University.

First PhD student from KU’s Center for Catalysis and Separation (CeCaS) delivers two talks at International Conference in Spain on her pioneering catalysis research

KU PhD student Ayesha AlKhoori delivered two talks on her pioneering research in the field of catalysis and separation at the 3rd ANQUE-ICCE International Congress of Chemical Engineering, held in June in Santander, Spain. Alkhoori is the first PhD student to study under the Petroleum Institute’s Center for Catalysis and Separation (CeCaS) at Khalifa University. Working under Dr. Kyriaki Polychronopoulou, Associate Professor of Mechanical Engineering and Director of CeCaS, Alkhoori is helping to advance catalysis as a means to produce cleaner, more efficient, and economically viable fuels and chemicals.

In her first presentation, titled “Improving Metal Oxide Catalysts for Biogas Dry Reforming: Coupling of Mechanochemical Modification with Enhanced Microwave Chemistry,” AlKhoori described a research project aimed at developing catalysts that can convert carbon dioxide and methane into syngas – a process known as ‘dry reforming of methane.’ Syngas is a mixture of hydrogen gas and carbon monoxide that can be used as a starting material for producing valuable chemicals under the proper catalytic reaction conditions.

While the environmental and economic benefits of dry reforming of methane reactions are very high, Alkhoori explains that the main problem hindering the commercialization of this technology is the issue of carbon formation and sintering on the catalysts, which causes deterioration of the catalyst’s activity.

In this project, Alkhoori and Dr. Polychronopoulou are working with PhD student Aseel Hussein and MSc student Sara AlKhoori to synthesize a catalyst made from copper and the rare earth metal cerium, using a very fast synthesis method that uses microwave energy rather than typical heating.

“One of the main obstacles of the dry reforming of methane reaction is the coke deposition on the catalyst, which causes deterioration of the catalytic activity,” AlKhoori explained. She believes that one way to tackle the coke depositions, which is the formation carbonaceous deposit on the catalyst’s surface, is to control the particle size of active material on the catalyst.

To do this, the researchers prepared the copper and ceria-based catalysts, and then modified them using different treatments.

“Traditionally, noble metal catalysts (based on platinum and gold) boost the reaction in terms of activity and stability. However, their high cost excludes them from applications of dry methane reforming. That is why we are developing catalysts with copper, a transition metal, which has high catalytic activity and selectivity at a lower cost, which makes them good candidates for the reforming reaction,” AlKhoori said.

The project is ongoing, Alkhoori explained, as her team continues to work on optimizing the catalytic system to further reduce the negative coking effect.

In her second presentation, titled “Copper-Ceria Nanomaterials as Catalysts for Low Temperature H2 Purification and CO Capturing in PEMFCs,” AlKhoori discussed a project she has been working on for over three years with Dr. Polychronopoulou. The project aims to overcome the challenge of carbon monoxide poisoning in catalysts used in proton exchange membrane fuel cells (PEMFC), a type of low-temperature hydrogen fuel cell. In a typical hydrogen fuel cell, catalysts (usually made from platinum) split hydrogen gas into positively charged protons and negatively charged electrons. The electrons are used to generate electricity while the protons pass through a membrane to combine with oxygen gas at the opposite end of the fuel cell to create water.

A major challenge faced by hydrogen fuel cells today is carbon monoxide “poisoning” in catalysts. Carbon monoxide is found in commercial hydrogen gas – the fuel needed to make hydrogen fuel cells. When too much carbon monoxide collects on the catalyst, the catalyst is unable to carry out the reactions needed to split the hydrogen gas.

Alkhoori and Dr. Polychronopoulou have discovered a low-cost method to purify the hydrogen gas by developing a catalyst that oxidizes the carbon monoxide and converts it into carbon dioxide – a gas that does not interfere with the fuel cell. They developed a nanocrystalline catalyst made from copper and cerium oxide (an oxide of the rare earth metal cerium) using a microwave synthesis approach, which successfully converted carbon monoxide into carbon dioxide at low temperatures. Their catalyst is significantly cheaper to develop than traditional catalysts made of noble metals, such as platinum, ruthenium, rhodium, and gold, which means it is a commercially viable alternative to be used in real-world applications to eliminate catalyst poisoning and increase fuel cell efficiency.

The researchers have published five papers on this work, with a sixth currently under review. The papers have been published in Surface and Coatings Technology, Materials Research Bulletin, the Journal of Environmental Chemical Engineering, Molecular Catalysis, and Applied Catalysis A: General.

The ANQUE-ICCE International Congress of Chemical Engineering is organized by��, the National Association of Chemists and Chemical Engineers of Spain, in collaboration with��, the Association of Chemistry and Chemical Engineering of Cantabria. The international congress is a reference for researchers in the field of chemical engineering and chemistry applied to the industry. Alkhoori had the opportunity to exchange up-to-date information and connect with researchers and experts from different universities and countries.

Erica Solomon
Senior Editor
5 August 2019

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