Synergism of microwaves and ultrasound for advanced biorefineries

Biofuel Research Journal, 2020

Biodiesel production is generally accomplished by the transesterification of vegetable oils and animal fats with a short chain alcohol (mostly methanol) in the presence of an alkali catalyst (mostly potassium or sodium hydroxide) in continuous stirred tank reactors. This chemical reaction requires heating at around 60°C and usually takes about 60 to 120 min. When using oil/fat feedstocks containing high free fatty acids (FFA) contents, acid esterification is often required to prevent the saponification of fatty acids with the base catalyst in the subsequent transesterification. These impose high energy and time requirements. In the present study, we introduce a novel chemical multifunctional process intensifier involving a reaction zone with magnetostrictive cylindrical particles (agents) subjected to an oscillating electromagnetic field for efficient biodiesel production from high FFA content feedstocks. The results obtained revealed that the esterification and transesterification reactions could be substantially intensified under the action of an oscillating electromagnetic field that forces magnetostrictive agents to rapidly vibrate and intensify the mixing of the reagents. Complete conversion of oils was observed at an extremely short reaction time (30-180 s) and at the ambient temperature. Using the investigated technology, oil/fat mixtures with higher initial FFA contents, i.e., ~9%, could be used in alkali catalyzed transesterification processes compared with conventional reactors (capable of handling FFA contents of~2.5%).

Renewable & Sustainable Energy Reviews, 2009

2007

The material needs of society are reaching a crisis point. The demands of a growing and developing world population will soon exceed the capacity of our present fossil resource based infrastructure. In particular, the chemical industry that underpins most industries needs to respond to these challenges. The chemical manufacturing and user industries face an unprecedented range and intensity of drivers for change, the greatest of which, REACH (Registration, Evaluation and Authorisation of Chemicals) has yet to bite. In order to address the key issues of switching to renewable resources, avoiding hazardous and polluting processes, and manufacturing and using safe and environmentally compatible products, we need to develop sustainable and green chemical product supply chains. For organic chemicals and materials these need to operate under agreed and strict criteria and need to start with widely available, totally renewable and low cost carbon-the only source is biomass and the conversion of biomass into useful products will be carried out in biorefineries. Where these operate at present, their product range is largely limited to simple materials (e.g. cellulose), chemicals (e.g. ethanol) and bioenergy/biofuels. Second generation biorefineries need to build on the need for sustainable chemical products through modern and proven green chemical technologies such as bioprocessing, controlled pyrolysis, catalysis in water and microwave activation, in order to make more complex molecules and materials on which a future sustainable society will be based.

Biodiesel has emerged as a renewable and environmentally friendly alternative to traditional fossil fuels, attracting considerable interest for its ability to meet growing energy needs while mitigating environmental impacts. This review focuses on contemporary advancements in biodiesel production techniques, highlighting innovative methods aimed at improving efficiency, cost-effectiveness, and sustainability. Non-edible oils like pine oil and soapnut oil have gained prominence as viable feedstocks, offering the advantage of avoiding competition with food supplies. Cutting-edge catalytic systems, including heterogeneous catalysts, nano-catalysts, and enzyme-based approaches, have brought significant improvements to the transesterification process by ensuring higher yields and greater stability. Novel technologies, such as ultrasound-assisted and microwave-assisted transesterification, are recognized for their capacity to reduce both reaction duration and energy usage. Optimization tools like Response Surface Methodology (RSM), combined with the use of co-solvents and additives, play a key role in enhancing biodiesel production quality and efficiency. The review further explores challenges related to feedstock availability, production costs, and scalability, while proposing solutions such as genetically engineered feedstocks and the integration of biodiesel production into biorefineries. By emphasizing recent technological innovations, this study highlights the transformative potential of modern biodiesel production techniques to support a sustainable and environmentally conscious energy future.

2020

The development of an innovative and sustainable high-throughput reaction platform allows optimizing a wide range of chemical processes (materials synthesis and catalysis, among others) to tackle the Green Deal. This tool unifies, for the first time, the benefits of mechanical energy, thermal and pressure activation in continuous flow with an induction in situ heating system, facilitating the incorporation of inputs (liquids, solids and gases) with controlled pressure. As a result of the synergistic effect of this simultaneous activation, this technology will: (i) shorten reaction times; (ii) decrease temperature; (iii) improve reactions kinetics as mass transfer limitations are reduced; (iv) minimize the use of solvents; (v) decrease the reaction steps; (vi) increase the volume treated, enabling a real scale-up; and (vii) enhance the yields and/or selectivity. This new high-throughput reactor is used for the synthesis of calcium diglyceroxide (CaDG), minimizing the reaction steps and cost, to obtain a pure CaDG. This heterogeneous catalyst is used for biodiesel production and valorization of the glycerol generated as a by-product. An efficient synthesis protocol of CaDG has been developed, requiring shorter time, without heating, and no need for a solvent. This new process facilitates oil-methanol mixing in the transesterification process, thus minimizing the mass transfer limitations associated with the immiscibility of reactants. In addition, this process has been optimized by using CaDG as a solid catalyst.

Biomass conversion is a renewable alternative to produce fuels and chemicals. Development and optimization of biorefineries involves process engineering challenges at various scales, ranging from the chemistry of the conversion processes, to reactor and process design and optimization, and to enterpriselevel economic and supply chain analysis. In this article we discuss recent results in each of these levels, specifically, (a) complex thermochemical reaction network analysis using an in-house software, (b) process design and optimization for continuous production of chemicals (5-hydroxymethylfurfural) from biomass, and (c) supply chain optimization for biomass sourcing and facilities location in the midwestern US. Set in this context, we further discuss new research vistas at each level, and opportunities for advantages of integration of research tasks across multiple levels.

Renewable & Sustainable Energy Reviews, 2010

Sustainable economic and industrial growth requires safe, sustainable resources of energy. For the future re-arrangement of a sustainable economy to biological raw materials, completely new approaches in research and development, production, and economy are necessary. The ‘first-generation’ biofuels appear unsustainable because of the potential stress that their production places on food commodities. For organic chemicals and materials these needs to

2024

Background: The multicriteria assessment of advancing biorefinery to produce biodiesel (fatty acid methyl ester), glycerol, and torrefied pellets is a strategic approach towards sustainable development. Methods: A successive transesterification process was applied to separate lipids with alcohol, with a 1:7 mass-tomass ratio in the presence of a heterogeneous catalyst of chitosan/polyvinyl alcohol-sodium hydroxide (CS/PVA-NaOH), to produce biodiesel and glycerol. Moreover, the remaining biomass is extracted to produce torrefied pellets by applying torrefaction through hydrothermal liquefication at 200-300 ℃ temperature. The biorefinery system using 613 kg organic fraction of municipal solid waste (OFMSW) produced 127.3 L of biodiesel, 14.5 kg of glycerol, and 387.5 kg of torrefied pellets. The whole systematic approach revealed two distinct areas with required characterized equipment such as dryer (A = 721.28m 2), suspended in tank (V = 751.56m 3), reactor (V = 721.56m 3), cyclone (A = 743.48 m 2), grinder (Q = 1352.31 m 3 /h), compactor (Q = 1367.31 m 3 /h), correspondingly. A gate-to-gate life cycle assessment (LCA) was performed for life cycle impact assessment (LCIA) through GaBi by using the ReCiPe 2016 Mid-point (H) and Endpoint (H) approach with a functional unit of 1000 kg municipal solid waste (MSW). Significant findings: The economic assessment reveals the economic feasibility of the biorefinery project. The annual revenue determined the profitability index, which is $ 1.59 million annually, with a payback period of 1.8 years. The environmental analysis determined an eco-friendly production unit which can save 13.6% of carbon emissions by alternate use of photovoltaic energy. Conclusively, the calculated values and findings prove that biorefinery development using OFMSW is scientifically a win-win situation and notably assists in achieving circular bioeconomy and sustainable development goals (SDGs).

Progress in Energy and Combustion Science, 2019

Diesel engines are preferred over spark ignition counterparts for heavy-duty applications and power generation plants because of their higher efficiency, durability, and productivity. Currently, the research interests have been propelled towards renewable and sustainable diesel fuels such as biodiesel in order to address the environmental and energy security challenges associated with these energy systems. However, the most challenging issue concerning large-scale production of biodiesel is its relatively high cost over fossil-based diesel owing to high feedstock and manufacturing costs. Therefore, cost-effective and ecofriendly biodiesel production technologies should be necessarily developed and continuously improved in order to make this biofuel more competitive vs. its petroleum counterpart. Accordingly, this paper comprehensively reviews biodiesel manufacturing techniques from natural oils and fats using conventional and advanced technologies with an in-depth state-of-the-art focus on the utmost important unit, i.e ., transesterification reactor. The effects of the main influential parameters on the transesterification process are first discussed in detail in order to better understand the mechanisms behind each reactor technology. Different transesterification reactors; e.g. , tubular/plug-flow reactors, rotating reactors, simultaneous reaction-separation reactors, cavitational reactors, and microwave reactors are then scrutinized from the scientific and practical viewpoints. Merits and limitations of each reactor technology for biodiesel production are highlighted to guide future R&D on this topic. At the end of the paper, the sustainability aspects of biodiesel production are comprehensively discussed by emphasizing on the biorefinery concept utilizing waste-oriented oils.

2018

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