Heterogeneous Catalysis for Sustainable Energy

The need for fossil fuels and the emissions generated from these fuels are increasing daily. Researchers are concerned with global warming as well as climate change; and energy sustainability and material usages are important issues today. Waste cooking oil (WCO) can be processed into biodiesel as an alternative fuel to replace diesel. Production of biodiesel using WCO as the feedstock has been of growing interest for the last two decades. A number of research papers related to the improvements in production, raw materials and catalyst selection have been published. This paper reviews the various types of heterogeneous solid catalyst in the production of biodiesel via the transesterification of WCO. The catalysts used can be classified according to their state presence in the transesterification reaction as homogeneous or heterogeneous catalysts. Homogeneous catalysts act in the same liquid phase as the reaction mixture, whereas heterogeneous catalysts act in a solid phase with the reaction mixture. Heterogeneous catalysts are non-corrosive, a green process and environmentally friendly. They can be recycled and used several times, thus offering a more economic pathway for biodiesel production. The advantages and drawbacks of these heterogeneous catalysts are presented. Future work focuses on the application of economically and environmentally friendly solid catalysts in the production of biodiesel using WCO as the raw material.

Start your abstract here… Uses of heterogeneous catalyst in bio-energy production also refer to as green energy has been in existence and well researched. Majority of recent heterogeneous catalysts produced focus on optimizing yield of biodiesel from a single feedstock without concerted efforts been made to consider the cost of production. They are mostly developed and produced from synthetic chemicals with their attendants high cost of production. The present review summarizes the needs to produce heterogeneous solid catalyst from wastes and natural resources like clay which is available in all parts of the world.

Matthias Beller, director of the Leibniz-Institut für Katalyse (LIKAT) in Rostock, Germany, provides an overview of the research in the institute since its establishment in 1952. Find out more about the institute's research in the LIKAT virtual issue. As a result of global population growth, climate change, and limited fossil resources, humanity faces significant challenges in the coming decades that can only be solved through new technologies and more sustainable production processes. Many of our current problems can be addressed by improved chemical transformations, which offer principle solutions for the future rather than being part of the problem, as is often seen today. In this respect, catalysis – the science of the acceleration of elementary chemical processes – allows reactions to take place in a way that spares resources, increases the desired product yields, avoids by-products, and reduces the specific energy requirements. Only by applying high-performance catalysts will it be possible to meet the global demand for efficient usage of all resources. Currently, around nine out of ten chemical products make use of catalysis during their manufacture. In addition, as well as in the field of chemistry, catalysts are also increasingly applied in the fields of life science, clean energy, and environmental protection. Thus, catalysis is a science that spans across a range of disciplines, and contributes to the process of finding solutions for the grand challenges of the 21st century. To further develop this field of science, it is clearly essential to form interdisciplinary collaborations between inorganic, organic, technical, theoretical, and physical chemistry, as well as nano- and material sciences, engineering, and process technology. More than 65 years of catalytic “know-how” forms the basis of the current expertise of the Leibniz-Institute for Catalysis (LIKAT). In 1952, two professors from the University of Rostock – Günther Rienäcker (heterogeneous catalysis) and Wolfgang Langenbeck (homogeneous catalysis) – came together to establish the Research Institute for Catalysis in Rostock. This became the first institute in Europe exclusively devoted to catalysis research, which soon became part of the Academy of Sciences of the GDR. In 1959, the two fields of catalysis research separated for what would be nearly 50 years. Homogeneous, namely organometallic catalysis, remained in Rostock and led to the creation of the Institute for Organic Catalysis Research. Heterogeneous catalysis moved to Berlin and became the focus of the Institute of Inorganic Catalysis Research. Later on, under the direction of Horst Pracejus in Rostock, fundamental work on asymmetric catalysis and organometallic chemistry was performed, while in Berlin research in various areas such as material sciences, heterogeneous catalysis, and organic synthesis continued. After the German Academy of Sciences was disbanded in 1991 as a result of the country's reunification, the Center for Heterogeneous Catalysis was created in 1992 in Berlin. Two years later this center joined with three other chemistry centers and formed the Institute for Applied Chemistry Berlin-Adlershof (ACA), which was directed initially by Bernhard Lücke and then Manfred Baerns. At the same time, the Rostock Catalysis Institute, led by Günther Oehme, became a state research institute of Mecklenburg–Western Pomerania after the closure of the Academy of Sciences. From 1992 to 1997, the Max-Planck-Society, through the establishment of two research groups, “Complex Catalysis” (Uwe Rosenthal) and “Asymmetric Catalysis” (Rüdiger Selke), contributed significantly to the stabilization and modernization of this institute. After a very positive evaluation of its research efforts under the direction of Matthias Beller by the German Council of Science and Humanities, the institute became part of the Leibniz Association on 01 January 2003. Nearly three years later, with the merger of the homogeneous and heterogeneous catalysis institutes from Berlin and Rostock, respectively, the Leibniz-Institute for Catalysis (LIKAT) was legally recognized. As an affiliated research institute of the University of Rostock, LIKAT has the legal form of a registered association, and as such includes a general membership meeting, a Board of Trustees, and a Scientific Advisory Council. In the group of Matthias Beller, “Applied Homogeneous Catalysis”, important aspects of molecular-defined and nanostructured catalysts, especially of transition-metal catalysts are investigated. Fundamental strategic aims of their research are the development of new environmentally benign redox catalysts and synthetic methodologies (aminations, carbonylations), as well as their application in industry. The transfer of results from model studies and mechanistic investigations to specific chemical products or processes is a particularly important aspect here. Methodologies which have been studied in the last years were carbonylation reactions, redox transformations, aminations, and applications towards alternative energy technologies. The current research in the “Heterogeneous Catalytic Processes” department (Sebastian Wohlrab) focuses largely on: (i) oxidation catalysis (selective oxidation, ammoxidation, acetoxylation, epoxidation, oxidative dehydrogenation) and (ii) the use of biomass for chemical and energy applications (conversion of triglycerides, fatty acids and glycerol, deoxygenation of biomass, use of carbon dioxide in chemical syntheses). Complementary to these works, in the group of Hans de Vries, various aspects of “Catalysis with Renewable Resources” are under investigation. More specifically, new catalytic reactions for the conversion of renewable resources into chemicals and fuels are developed. A broad spectrum of methods and techniques are applied for this purpose: From the synthesis of porous inorganic materials that are used as heterogeneous catalysts or as selective membranes, to the development of novel homogeneous transition-metal-based catalysts. Notably, catalytic reactions are optimized by the proper use of chemical technology such as flow chemistry, micro-structured reactors, and novel separation devices. Most of the research work described here is performed in specific projects with a dedicated lifetime, often in cooperation with industry or other academic partners. Apart from that, it is the long-term goal of the institute to contribute to effective catalyst design, based on a rational approach beyond trial and error. Undoubtedly, this requires a sound knowledge of the relationship between the structural features of a given catalyst and its role in the target transformation on a molecular basis. Such direct insight can be obtained by analyzing catalysts at work, under conditions as close as possible to those applied in a true catalytic process. These objectives are pursued in the department “Catalytic in situ Studies” of Angelika Brückner. This group focuses on the development, adaptation, and use of different analytic methods to monitor catalysts in homogeneous and heterogeneous catalytic reactions; this involves on-line detection of catalytic activity/selectivity (operando spectroscopy) in gas-solid, gas-liquid, liquid-solid and gas-liquid-solid systems, as well as during different stages in catalyst synthesis (in situ spectroscopy). An important element of their research activities is the in situ investigation of electron-transfer mechanisms in photo- and electrocatalytic reactions, such as hydrogen evolution by water splitting, which also includes the adaptation and development of suitable spectroelectrochemical methods. Over the past decade, special attention has been dedicated to simultaneous couplings of several operando methods. This not only saves time and money, but also gathers accessible information, and reduces errors that may arise from applying different experimental conditions in differently designed reaction cells. To complement these methodologies, in the department of “Catalyst Discovery and Reaction Engineering” (David Linke), high-throughput technologies, engineering tools, and mechanistic studies are explored. For the latter topic, the main aim is to elaborate strategies that enable the coupling of microscopic mechanistic (micro-kinetic) and physicochemical knowledge of complex heterogeneous reactions with macroscopic observations in chemical reactors (Evgenii Kondratenko). Recently, Jennifer Strunk was appointed professor at LIKAT and the University of Rostock. Her research aim is to supplement methods and technologies in catalysis with her existing knowledge in photocatalysis. Accordingly, the new department “Heterogeneous Photocatalysis” was created in 2017. In this department, the reduction of carbon dioxide to methanol or methane is studied, with the aim of implementing ecologically and economically feasible photocatalytic processes on an industrial scale. An important objective is to provide a detailed understanding of the underlying fundamental photophysical, catalytic, and electrochemical processes. This insight should serve as a basis for the development of improved photocatalysts and devices viable for large-scale applications. For more than 40 years, the institute has had a long-standing interest of the coordination chemistry of early and late transition-metal complexes in homogeneous catalysis. Among others, this tradition is continued in the department of Torsten Beweries, where different fundamental and applied aspects of titanium and zirconium metallacycles are investigated. Moreover, the activation of small molecules and dehydrogenation and dehydrocoupling reactions for hydrogen storage are investigated with late transition-metals. Finally, detailed mechanistic studies and catalyst developments for asymmetric hydrogenations are performed (Detlef Heller). Based on modern synthetic organometallic chemistry, a fundamental understanding of structure–activity relationships is a key issue. Industrially relevant hydrogenations and hydroformylations play an important role in the department of Armin Börner. Aside from the preparation of synthetic fragrances, odor-producing substances, and agrochemicals; in particular, hydroformylations are studied for the production of bulk aldehydes. The advantage of homogeneous catalysts in these processes lies in the potential to run the reaction in a highly chemoselective, regioselective, and even stereoselective manner. In the last decade, most of the work was dedicated to the synthesis of new and patent-free phosphorus(III) compounds, and their application in rhodium-catalyzed hydroformylations. Moreover, a better description of catalysis by investigating mechanistic aspects and observing the concentration of organometallic intermediates in a time-resolved manner is also pursued, using in situ HP-NMR and in situ FTIR spectroscopy. Based on these works, over 25 patent applications have been filed together with industrial partners (such as Evonik Industries) in the past five years (Detlef Selent). On the more fundamental side in the carbonylation department, reactions are applied for the preparation of various heterocycles (Xiao-Feng Wu), such as the synthesis of flavones, furanones, benzoxazinones, among others. Most recently, Paul Kamer joined the institute and the new group “Bio-inspired Homo- and Heterogeneous Catalysis” was created. The main objective of his team is the development of new bio-inspired catalytic processes. Currently, their major activity is in the field of ligand synthesis based on phosphorus donor atoms by rational design assisted by molecular modelling. Such ligand design is also supported by thorough mechanistic (in situ) studies of catalytic reactions to acquire insight into structure–activity relationships. Recently, three junior research groups have also started their independent scientific career in Rostock, working on “Catalytic Functionalization” (Jola Pospech), “Small Molecule Activation” (Christian Hering-Junghans), and “Polymer Chemistry and Catalysis” (Oscar Esteban Mejia Vargas). For a long time, the institute's approach has simply been the combination of application-oriented basic research and its technical implementation. However, at the beginning of the millennium this strategy was expanded to link homogeneous catalytic research with heterogeneous catalysis, and to develop further synergetic combinations of catalytic processes. In the coming years, this expertise will in particular be applied to the optimal usage of resources. In this way, we hope to further contribute to the development of green and practical catalysis, which continues to be important for the sustainable development of our societies.

The excessive utilization of petroleum resources leads to global warming, crude oil price fluctuations, and the fast depletion of petroleum reserves. Biodiesel has gained importance over the last few years as a clean, sustainable, and renewable energy source. This review provides knowledge of biodiesel production via transesterification/esterification using different catalysts, their prospects, and their challenges. The intensive research on homogeneous chemical catalysts points to the challenges in using high free fatty acids containing oils, such as waste cooking oils and animal fats. The problems faced are soap formation and the difficulty in product separation. On the other hand, heterogeneous catalysts are more preferable in biodiesel synthesis due to their ease of separation and reusability. However, in-depth studies show the limited activity and selectivity issues. Using biomass waste-based catalysts can reduce the biodiesel production cost as the materials are readily available and cheap. The use of an enzymatic approach has gained precedence in recent times. Additionally, immobilization of these enzymes has also improved the statistics because of their excellent functional properties like easy separation and reusability. However, free/liquid lipases are also growing faster due to better mass transfer with reactants. Biocatalysts are exceptional in good selectivity and mild operational conditions, but attractive features are veiled with the operational costs. Nanocatalysts play a vital role in heterogeneous catalysis and lipase immobilization due to their excellent selectivity, reactivity, faster reaction rates owing to their higher surface area, and easy recovery from the products and reuse for several cycles.

The present review primarily focuses on the perspectives and state-of-the-art of heterogeneous catalysts, nanocatalysts, biocatalysts, bifunctional catalysts, metal-organic frameworks (MOF), and covalent organic frameworks (COF) for biodiesel production. The environmental concern associated with nonrenewable fossil fuels has led to finding alternative energy sources that can be used to meet global energy demands. Biofuels such as biodiesel are one of the energy sources that could replace fossil fuels. The homogeneous acid and base catalysts are generally used for commercial biodiesel production. However, homogeneous catalysts have downsides such as toxicity, corrosion, soap formation, high wastewater output, and non-reusability. Consequently, heterogeneous acid and base catalysts have been introduced that are less sensitive to moisture and free fatty acids (FFAs), easily separated and recovered, and reusable. Recently, novel catalysts such as waste biomass-derived mesoporous heterogeneous catalysts, chemically synthesized heterogeneous catalysts, metal ion-doped heterogeneous catalysts, bifunctional acid-base catalysts, and carbonaceous char-supported hetero catalysts, nanocatalysts, MOF and COF catalysts have potential to replace homogeneous base catalysts, aid in sustainable and cost-effective biodiesel production. This review provides insights into the recent advancement of various catalysts, catalyst preparation and operations, type of catalysts and suitability, catalyst efficiency, life cycle assessment, catalyst-associated challenges, and prospects for sustainable biodiesel production.

The need for non-existent or low-cost sources to be a feedstock for the biodiesel industry as a source of lipids has led to the trend of sewage sludge (containing high fat content) and thinking about it and finding ways to benefit from it. On the other hand, he use of sludge is an environmental treatment, as it rids the environment of tons of sludge produced daily and a solution to a problem for treatment plants that were looking for ways and solutions to get rid of it and save the cost of getting rid of it and converting it into clean and promising energy. It was found that the sewage sludge in all its primary and secondary types is a feedstock rich in free fatty acids (FFA), which is the raw material for the production of biodiesel, while treating it with one of the types of catalyst alcohols. According to a review of previous studies, it was found that acidic catalysts are most suitable for biodiesel production from sewage sludge, because sewage sludge has a free fatty acid content of 65-70%, which is a high percentage. It is a severely high percentage of free fatty acids found in pure vegetable oils that do not exceed 5%. The heterogeneous acid catalysts were preferred over the homogeneous ones because of the satisfactory results they provided and the high productivity of biodiesel compared to the homogeneous ones, and they are more economical as they can be reused more than once, but also many times. Reacting sewage sludge lipids with a type of catalyst alcohol and forming biodiesel called transesterification or esterification, and it may be traditional or in-site, and in-site is more important and economical than conventional. It was found from previous references that heterogeneous catalysts in general and zeolite types in particular are the most suitable for oil extracted from sewage sludge. Where The yield reached 100% using a type of zeolite.

In this work, heterogeneous calcium oxide catalysts gleaned from Polymedosa expansa and eggshell were investigated for the transesterification of crude jatropha oil with methanol, to access their prospective performance in biodiesel production as an alternative green energy resource. The best yield of biodiesel achieved was 96% in 1 h for Step 1 using 0.01:1 ratio of acid catalyst to oil and 0.6:1 ratio of alcohol to oil ratio, together with 2 h of Step 2 using 0.02:1 ratio with base catalyst CaO, derived from P. expansa, to oil ratio and 5:1 ratio of alcohol to oil. The properties of jatropha biodiesel were analyzed and found to have calorific value of 35.43 MJ/kg, density value of 895 kg/m3 and flash point of 167. The biodiesel was blended with mineral diesel from B0 to B50 for a diesel engine performance test. B20 indicated comparable characteristics with pure mineral diesel, like lowest fuel consumption rate, specific fuel consumption rate, highest brake horsepower and mechanical efficiency.

Recent advances on the nanoporous catalysts for the generation of renewable fuels

Summary To keep up with the fast-paced transitioning of the global energy sector, which is constantly thriving to enable reliable, economic, and sustainable energy production, catalysis research has been required to continuously evolve in response. The challenges in the existing systems are predominantly due to dependencies on heterogeneous solid catalysts that are susceptible to coking. In this respect, liquid-metal (LM) catalysts have been demonstrated to have a critical advantage over conventional catalysts. Recently, LMs acquired a place in catalysis, with a reputation often synonymous with interesting properties and a remarkable ability to break trade-offs between homogeneous and heterogeneous catalysis. This review bridges the fundamental principles of LM research and the recent advances in LM-based thermal and electrochemical catalysis for energy applications. Moreover, emerging approaches for the improved utilization of LMs are outlined, and the concepts requiring greater research attention that could enable the development of exciting energy solutions are highlighted.

As the cleanest energy source, hydrogen has been followed with interest by researchers around the world. However, due to the internal low density of hydrogen, it cannot be stored and used efficiently which limits the hydrogen application on a huge scale. Chemical hydrogen storage is considered as a useful method for efficient handling and storage. Due to its excellent safety, formic acid stands out. It is worth noting that the matter and energy conversion is established based on formic acid, which is not referred to in the previous documentation. In this review, the latest development of research on heterogeneous catalysis via production and application of formic acid for energy application is reported. The matter and energy conversion based on formic acid are both discussed systematically. More importantly, with formic acid as the node, biomass energy shows potential to be in a dominant position in the energy conversion process. In addition, the catalytic mechanism is also mentioned. This review can provide the current state in this field and the new inspirations for developing superior catalytic systems.

Contemporary approaches towards augmentation of distinctive heterogeneous catalyst for sustainable biodiesel production

From waste to fuel: Challenging aspects in sustainable biodiesel production from lignocellulosic biomass feedstocks and role of metal organic framework as innovative heterogeneous catalysts

Biodiesel is one of the biofuels that has been examined the most in the research and has a promising future as a replacement for fossil fuels. A catalyst is often needed to increase the manufacture of biodiesel, which is produced by transesterification or esterification. A number of difficulties with product separation, a significant amount of wastewater effuents released from the downstream filtration, and the unwanted soap created as a result of the reaction between feedstock with a high FFA composition and homogeneous base catalysts are typical problems faced by commercially available homogeneous catalysts. The use of heterogeneous magnetic catalysts in FAME production has become a focus of interest for many researchers due to its efficient catalyst separation, high catalyst recovery rate, and shorter processing time. The development of magnetic acid and base heterogeneous catalysts, as well as their efficiency in producing biodiesel, were the primary subjects of this study. Additionally, several techniques for producing magnetic particles were evaluated. Method of heterogeneous catalysts in promoting biodiesel synthesis through transesterification procedure was also investigated. To generate more self-sustaining biodiesel industries, further investigation is needed to employ waste materials as a basis for the manufacturing of heterogeneous magnetic acid and base catalysts.

The impact of heterogeneous catalyst on biodiesel production; a review

Fatty acid ethyl ester is one of the most potential alternative energy because it is renewable and environmentally friendly. Fatty acid ethyl ester is usually made by transesterification using heterogeneous alkali catalyst. Chicken bones ash (CaO) is heterogeneous alkali catalyst which is non-corrosive and environmentally friendly. It can also be separated easily from the product by filtration and less removal problem than homogeneous catalyst. This catalyst was made by grinding and calcination the chicken bones. Others variables used in this research were the dosage of the catalyst, molar ratio of ethanol to crude palm oil and reaction temperature. The best yield of the fatty acid ethyl ester was 90.052% at the condition of 17:1 ethanol to crude palm oil molar ratio, 70 °C reaction temperature, 7% of catalyst (w/w), 7 hours of reaction time and 500 rpm stirring speed.